Title of Invention	A PROCESS FOR CATHODICALLY ELECTRODEPOSITING A SELECTED METALLIC MATERIAL ON A PERMANENT OR TEMPORARY SUBSTRATE IN NANOCRYSTALLINE FORM
Abstract	The invention discloses a process for forming coatings or free-standing deposits of nano-crystalline metals, metal alloys or metal matrix composites. The process employs drum plating or selective plating processes involving pulse electrode-position and a non-stationary anode or cathode. Novel nano-crystalline metal matrix composites and micro components are disclosed as well. Also described is a process for forming micro-components with grain sizes below 1000 nm.

Title of Invention

A PROCESS FOR CATHODICALLY ELECTRODEPOSITING A SELECTED METALLIC MATERIAL ON A PERMANENT OR TEMPORARY SUBSTRATE IN NANOCRYSTALLINE FORM

Abstract

The invention discloses a process for forming coatings or free-standing deposits of nano-crystalline metals, metal alloys or metal matrix composites. The process employs drum plating or selective plating processes involving pulse electrode-position and a non-stationary anode or cathode. Novel nano-crystalline metal matrix composites and micro components are disclosed as well. Also described is a process for forming micro-components with grain sizes below 1000 nm.

Full Text	A PROCESS FOR CATHODICALLY ELECTRODEPOSITING A SELECTED METALLIC MATERIAL PERMANENT OR TEMPORARY SUBSTRATE IN NANOCRYSTALLINE FORM Field of the Invention The invention relates to a process for cathodically electrodepositing a selected metallic material permanent or temporary substrate in nanocrystalline form, and particularly to a process for forming coatings of pure metals, metal alloys or metal matrix composites on a work piece which is electrically conductive or contains an electrically conductive surface layer or forming free-standing deposits of nano-crystalline metals, metal alloys or metal matrix composites by employing pulse electrodeposition. The process employs a drum plating process for the continuous production of nanocrystalline foils of pure metals, metal alloys or metal matrix composites or a selective plating (brush plating) process, the processes involving pulse electrodeposition and a non- stationary anode or cathode. Novel nano-crystalline metal matrix composites are disclosed as well. The invention also relates to a pulse plating process for the fabrication or coating of micro -components. The invention also relates to micro- components with grain sizes below 1,000nm. The novel process can be applied to establish wear resistant coatings and foils of pure metals or alloys of metals selected from the group of Ag, Au, Cu, Co, Cr, Ni, Fe, Pb, Pd, Pt, Rh, Ru, Sn, V, W and Zn and alloying elements selected from C, P, S and Si and metal matrix composites of pure metals or alloys with particulate additives such as metal powders, metal alloy powders and metal oxide powders of Al, Co, Cu, In, Mg, Ni, Si, Sn, V, and Zn; nitrides of Al, B and Si; C (graphite or diamond); carbides of B, Cr, Bi, Si, W; and organic materials such as PTFE and polymer spheres. The selective plating process is particularly suited for in-situ or field applications such as the repair or the refurbishment of dies and moulds, tur- bine plates, steam generator tubes, core reactor head penetrations of nuclear power plants and the like. The continuous plating process is particularly suited for pro- ducing nanocrystalline foils e.g. for magnetic applications. The process can be applied to high strength, equiaxed micro-components for use in electronic, bio- medical, telecommunication, automotive, space and consumer applications. Description of Prior Art/Background of the Invention Nanocrystalline materials, also referred to as ultra-fine grained materials, nano- phase materials or nanometer-sized materials exhibiting average grains sizes smaller or equal to l00nm, are known to be synthesized by a number of methods including sputtering, laser ablation, inert gas condensation, high energy ball mill- ing, sol-gel deposition and electrodeposition. Electrodeposition offers the capa- bility to prepare a large number of fully dense metal and metal alloy compositions at high production rates and low capital investment requirements in a single syn- thesis step. The prior art primarily describes the use of pulse electrodeposition for producing nanocrystalline materials. Erb in US 5,352,266 (1994) and in US 5,433,797 (1995) describes a process for producing nanocrystalline materials, particularly nanocrystalline nickel. The na- nocrystalline material is electrodeposited onto the cathode in an aqueous acidic electrolytic cell by application of a pulsed DC current. The cell also optionally contains stress relievers. Products of the invention include wear resistant coat- ings, magnetic materials and catalysts for hydrogen evolution. Mori in US 5,496,463 (1996) describes a process and apparatus for composite electroplating a metallic material containing SiC, BN, Si3N4, WC, TiC, TiO2, Al2O, ZnB3, diamond, CrC, MoS2, coloring materials, polytetrafluoroethylene (PTFE) and microcapsules. The solid particles are introduced in fine form into the electrolyte. Adler in US 4,240,894 (1980) describes a drum plater for electrodeposited Cu foil production. Cu is plated onto a rotating metal drum that is partially submersed and rotated in a Cu plating solution. The Cu foil is stripped from the drum surface emerging from the electrolyte, which is clad with electroformed Cu. The rotation speed of the drum and the current density are used to adjust the desired thickness of the Cu foil. The Cu foil stripped from the drum surface is subsequently washed and dried and wound into a suitable coil. Icxi in US 2,961,395 (1960) discloses a process for electroplating an article with- out the necessity to immerse the surface being treated into a plating tank. The hand-manipulated applicator serves as anode and applies chemical solutions to the metal surface of the work piece to be plated. The work piece to be plated serves as cathode. The hand applicator anode with the wick containing the electrolyte and the work piece cathode are connected to a DC power source to generate a metal coating on the work piece by passing a DC current. Micromechanical systems (MEMS) are machines constructed of small moving and stationary parts having overall dimensions ranging from 1 to 1,000um e.g. for use in electronic, biomedical, telecommunication, automotive, space and con- sumer technologies. Such components are made e.g. by photo-electroforming, which is an additive process in which powders are deposited in layers to build the desired structure e.g. by laser enhanced electroless plating. Lithography, electroforming and molding (LIGA) and other photolithography related processes are used to overcome aspect ratio (parts height to width) related problems. Other techniques employed include silicon micromachining, through mask plating and microcontact printing. 3. Summary: It is an object of the invention to provide a reliable and flexible pulse plating pro- cess for forming coatings or free-standing deposits of nano-crvstalline metals, metal alloys or metal matrix composites. It is a further object of the invention to provide micro components with signifi- cantly improved property-dependent reliability and improved and tailor-made desired properties for overall performance enhanced microsystems. Prefered embodiments of the invention are defined in the corresponding depend- ent claims. The present invention provides a pulse plating process, consisting of a single ca- thodic on time or multiple cathodic on times of different current densities and sin- gle or multiple off times per cycle. Periodic pulse reversal, a bipolar waveform alternating between cathodic pulses and anodic pulses, can optionally be used as well. The anodic pulses can be inserted into the waveform before, after or in be- tween the on pulse and/or before, after or in the off time. The anodic pulse cur- rent density is generally equal to or greater than the cathodic current density. The anodic charge (Qanodic) of the "reverse pulse" per cycle is always smaller than the cathodic charge (Qcathodic). Cathodic pulse on times range from 0.1 to 50 msec (1-50), off times from 0 to 500msec (1-100) and anodic pulse times range from 0 to 50 msec, preferably from 1 to 10msec. The duty cycle, expressed as the cathodic on times divided by the sum of the cathodic on times, the off times and the anodic times, ranges from 5 to 100 %, preferably from 10 to 95 %, and more preferably from 20 to 80 %. The frequency of the cathodic pulses ranges from 1Hz to 1kHz and more preferably from l0Hz to 350Hz. Nano-crystalline coatings or free-standing deposits of metallic materials were ob- tained by varying process parameters such as current density, duty cycle, work piece temperature, plating solution temperature, solution circulation rates over a wide range of conditions. The following listing describes suitable operating pa- rameter ranges for practising the invention: Average current density (if determinable, anodically or cathodically): 0.01 to 20A/cm2, preferably 0,1 to 20A/cm2, more preferably 1 to 10A/cm2 Duty Cycle 5 to 100% Frequency: 0 to l000Hz Electrolyte solution temperature: - 20 to 85 °C Electrolyte solution circulation/agitation rates: cathode area (0.0001 to 101/min.cm2) Work piece temperature: -20 to 45 °C Anode oscillation rate: 0 to 350 oscillations/min Anode versus cathode linear speed: 0 to 200 meter/min (brush) 0.003 to 0.16m/min (drum) -6- The present invention preferably provides a process for plating nanocrystalline metals, metal matrix composites and microcomponents at deposition rates of at least 0.05 mm/h, preferably at least 0.075 mm/h, and more preferably at least 0.1 mm/h. In the process of the present invention the electrolyte preferably may be agitated by means of pumps, stirrers or ultrasonic agitation at rates of 0 to 750 ml/min/A (ml solution per minute per applied Ampere average current), preferably at rates of 1 to 500 ml/min/A. In the process of the present invention optionally a grain refining agent or a stress relieving agent selected from the group of saccharin, coumarin, sodium lauryl sulfate and thiourea can be added to the electrolyte. This invention provides a process for plating nanocrystalline metal matrix com- posites on a permanent or temporary substrate optionally containing at least 5% by volume particulates, preferably 10% by volume particulates, more preferably 20% by volume particulates, even more preferably 30% by volume particulates and most preferably 40% by volume particulates for applications such as hard facings, projectile blunting armor, valve refurbishment, valve and machine tool coatings, energy absorbing armor panels, sound damping systems, connectors on pipe joints e.g. used in oil drilling applications, refurbishment of roller bearing axles in the railroad industry, computer chips, repair of electric motors and gen- erator parts, repair of scores in print rolls using tank, barrel, rack, selective (e.g. brush plating) and continuous (e.g. drum plating) plating processes using pulse electrodeposition. The particulates can be selected from the group of metal pow- ders, metal alloy powders and metal oxide powders of Al, Co, Cu, In, Mg, Ni, Si, Sn, V, and Zn; nitrides of Al, B and Si; C (graphite or diamond); carbides of B, Bi, Cr, Si, W; M0S2; and organic materials such as PTFE and polymer spheres. The particulate average particle size is typically below 10 mm, preferably below 1000 nm (1 mm), preferably 500 nm, and more preferably below 100 nm. The particulate additives average particle size may be in the range of 100 nm to 10 pm, in the range of 500 nm to 10 mm, in the range of 1000 nm to 10 mm or below 100 nm. The process of this invention optionally provides a process for continuous (drum or belt) plating nanocrystalline foils optionally containing solid particles in sus- pension selected from metal powders, metal alloy powders and metal oxide pow- ders of Al, Co, Cu, In, Mg, Ni, Si, Sn, V, and Zn; nitrides of Al, B and Si; C (graphite or diamond); carbides of B, Bi, Si, W; M0S2, and organic materials such as PTFE and polymer spheres to impart desired properties including hardness, wear resistance, lubrication, magnetic properties and the like. The drum or belt provides a temporary substrate from which the plated foil can be easily and con- tinuously removed. According to a preferred embodiment of the present invention it is also possible to produce nanocrystalline coatings by electroplating without the need to submerse the article to be coated into a plating bath. Brush or tampon plating is a suitable alternative to tank plating, particularly when only a portion of the work piece is to be plated, without the need to mask areas not to be plated. The brush plating ap- paratus typically employs a soluble or dimensionally stable anode wrapped in an absorbent separator felt to form the anode brush. The brush is rubbed against the surface to be plated in a manual or mechanized mode and electrolyte solution containing ions of the metal or metal alloys to be plated is injected into the sepa- rator felt. Optionally, this solution also contains solid particles in suspension se- lected from metal powders, metal alloy powders and metal oxide powders of Al, Co, Cu, In, Mg, Ni, Si, Sn, V, and Zn; nitrides of Al, B and Si; C (graphite or diamond); carbides of Bi, Si, W; M0S2; and organic materials such as PTFE and polymer spheres to impart desired properties including hardness, wear resistance, lubrication and the like. In the case of drum, belt or brush plating the relative motion between anode and cathode ranges from 0 to 600meters per minute, preferably from 0.003 to l0meters per minute. In the process of this invention micro components for micro systems including micro-mechanical systems (MEMS) and micro-optical-systems with grain sizes equal to or smaller than 1,000nm can be produced. The maximum dimension of the microcomponent part is equal to or below lmm and the ratio between the maximum outside dimension of the microcomponent part and the average grain size is equal to or greater than 10, preferably greater than 100. The micro components of the present invention preferably may have an equiaxed microstructure throughout the plated component, which is relatively independent of component thickness and structure. It is another aspect of the present invention to provide micro components where the average grain size remains at least an order of magnitude smaller than the ex- ternal dimensions of the part, thus maintaining a high level of strength. The micro components according to this invention have significantly improved property-dependent reliability and improved and tailor-made desired properties of MEMS structures for overall performance enhanced microsystems by preferably equiaxed electrodeposits, eliminating the fine grain to columnar grain transition in the microcomponent, and simultaneously reducing the grain size of the deposits below l,000nm. Other features and advantages of this invention will become more apparent in the following detailed description and examples of preferred embodiments of the invention, together with the accompanying schematic drawings, in which: Figure 1 shows a cross-sectional view of a preferred embodiment of a drum plat- ing apparatus. Figure 2 shows a cross sectional view of a preferred embodiment of a brush plat- ing apparatus; and Figure 3 shows a plan view of a mechanized motion apparatus for generating a mechanized stroke of the anode brush. Figure 1 schematically shows of a plating tank or vessel (1) filled with an elec- trolyte (2) containing the ions of the metallic material to be plated. Partially sub- mersed into the electrolyte is the cathode in the form of a rotating drum (3) elec- trically connected to a power source (4). The drum is rotated by an electric motor (not shown) with a belt drive and the rotation speed is variable. The anode (5) can be a plate or conforming anode, as shown, which is electrically connected to the power source (4). Three different anode dispositions can be used: Conformal an- odes, as shown in Figure 1, that follow the contour of the submerged section of the drum (3), vertical anodes positioned at the walls of the tank (1) and horizontal anode positioned on the bottom of the tank (1). In case of a foil (16) of metallic material being electrodeposited on the drum (3), the foil (16) is pulled from the drum surface emerging from the electrolyte (2), which is clad with the electro- formed metallic material. Figure 2 schematically shows a workpiece (6) to be plated, which is connected to the negative outlet of the power source (4). The anode (5) consists of a handle (7) with a conductive anode brush (8). The anode contains channels (9) for supplying the electrolyte solution (2) from a temperature controlled tank (not shown) to the anode wick (absorbent separator) (10) . The electrolyte dripping from the absorb- ent separator (10) is optionally collected in a tray (11) and recirculated to the tank. The absorbent separator (10) containing the electrolyte (2) also electrically insu- lates the anode brush (8) from the workpiece (6) and adjusts the spacing between anode (5) and cathode (6). The anode brush handle (4) can be moved over the workpiece (6) manually during the plating operation, alternatively, the motion can be motorized as shown in figure 3. Figure 3 schematically shows a wheel (12) driven by an adjustable speed motor (not shown). A traversing arm (13) can be rotatably attached (rotation axis A) to the rotating wheel (12) at various positions x at a slot (14) with a bushing and a set screw (not shown) to generate a desired stroke. The stroke lenght can be ad- justed by the position x (radius) at which the rotation axis A of traversing arm is mounted at the slot (14). In Figure 3 the traversing arm (13) is shown to be in an no-stroke, neutral position with rotation axis A in the center of the wheel (12). The traversing arm (13) has a second pivot axis B defined by a bearing (not shown), that is slidably mounted in a track (15). As the wheel (12) rotates, the rotation of the traversing arm (13) around axis A at position x causes the travers- ing arm (13) to reciprocate in the track (15) and to pivot around axis B. An anode (5) having the same features as shown in Fig. 2 is attached to the traversing arm (13) and moves over the workpiece (6) in a motion depending on the position x. Usually the motion has the shape of figure eight. The anode (5) and the work- piece (6) are connected to positive and negative outlets of a power source (not shown), respectively. The cinematic relation is very similar to that of a steam engine. This invention relies on producing nanocrystalline coatings, foils and microsystem components by pulse electrodeposition. Optionally solid particles are suspended in the electrolyte and are included in the deposit. Nanocrystalline coatings for wear resistant applications to date have focused on increasing wear resistance by increasing hardness and decreasing the friction coef- ficient though grain size reduction below l00nm. It has now been found that in- corporating a sufficient volume fraction of hard particles can further enhance the wear resistance of nanocrystalline materials. The material properties can also be altered by e.g. the incorporation of lubricants (such as M0S2 and PTFE). Generally, the particulates can be selected from the group of metal powders, metal alloy powders and metal oxide powders of Al, Co, Cu, In, Mg, Ni, Si, Sn, V, and Zn; nitrides of Al, B and Si; C (graphite or dia- mond); carbides of B, Bi, Si, W; M0S2; and organic materials such as PTFE and polymer spheres. Example 1 Nanocrystalline NiP-B4C nanocomposites were deposited onto Ti and mild steel cathodes immersed in a modified Wstt§J>ath for nickel using a soluble anode made of a nickel plate and a Dynatronix (Dynanet PDPR 20-30-100) pulse power supply. The following conditions were used: Anode/anode area: soluble anode: Ni plate, 80cm2 Cathode/cathode area: Ti or mild steel sheet/appr. 5cm2 Cathode: fixed Anode: fixed Anode versus cathode linear speed: N/A Average cathodic current density: 0.06A/cm2 ton/toff: 2msec/ 6msec Frequency: 125Hz Duty Cycle: 25% Deposition time: 1 hour Deposition Rate: 0.09mm/hr Electrolyte temperature: 60°C Electrolyte circulation rate: vigorous agitation (two direction mechanical impeller) Basic Electrolyte Formulation: 300g/lNiSO4.7H2O 45g/l NiCl2.6H2O 45g/l H3BO3 18g/lH3PO4 0.5-3ml/l surfactant to a surface tension of 0-2g/l sodium saccharinate 360 g/1 boron carbide, 5 mm mean particle diameter pH 1.5-2.5 The hardness values of metal matrix composites possessing a nanocrystalline ma- trix structure are typically twice as high as conventional coarse-grained metal ma- trix composites. In addition, the hardness and wear properties of a nanocrystalline N1P-B4C composite containing 5.9weight% P and 45volume% B4C are compared with those of pure coarse-grained Ni, pure nanocrystalline Ni and electrodeposited Ni-P of an equivalent chemical composition in the adjacent table. Material hard- ening is controlled by Hall-Petch grain size strengthening, while abrasive wear resistance is concurrently optimized by the incorporation of B4C participate. Table: N1P-B4C nanocomposite properties Example 2 Nanocrystalline Co based nanocomposites were deposited onto Ti and mild steel cathodes immersed in a modified Watts bath for cobalt using a soluble anode made of a cobalt plate and a Dynatronix (Dynanet PDPR 20-30-100) pulse power supply. The following conditions were used: Anode/anode area: soluble anode (Co plate)/ 80cm2 Cathode/cathode area: Ti (or mild steel) sheet/appr. 6.5cm2 Cathode: fixed Anode: fixed Anode versus cathode linear speed: N/A Peak cathodic current density: 0.100A/cm2 Peak anodic current density: 0.300A/cm2 Cathodic ton/ toff Anodic ton (tanodic): 16msec / 0msec / 2msec Frequency: 55.5Hz Cathodic duty cycle: 89 % Anodic duty cycle: 11% Deposition time: 1 hour Deposition Rate: 0.08mm/hr Electrolyte temperature: 60°C Electrolyte circulation rate: 0.151iter/min/cm2 cathode area (no pump flow; agita- tion) Electrolyte Formulation: 300 g/1 CoSO4-7H2O 45 g/1 CoCl2-6H2O 45 g/1 H3BO3 2 g/1 C7H4NO3SNa Sodium Saccharinate 0.1 g/1 C12H25O4SNa Sodium Lauryl Sulfonate (SLS) 100 g/1 SiC, pH2.5 In the adjacent table, the hardness and wear properties of a nanocrystalline Co- SiC composite containing 22volume% SiC are compared with those of pure coarse-grained Co and pure nanocrystalline Co. Hall-Petch grain size strength- ening controls material hardening, while abrasive wear resistance is concurrently optimized by the incorporation of SiC particulate. Table: Co nanocomposite properties Continuous plating to produce foils e.g. using drum plating nanocrystalline foils optionally containing solid particles in suspension selected from pure metals or alloys with paniculate additives such as metal powders, metal alloy powders and metal oxide powders of Al, Co, Cu, In, Mg, Ni, Si, Sn, V, and Zn; nitrides of Al, B and Si; C (graphite or diamond); carbides of B, Bi, Si, W; and organic materials such as PTFE and polymer spheres to impart desired properties including hard- ness, wear resistance, lubrication, magnetic properties and the like has been ac- complished. Nanocrystalline metal foils were deposited on a rotating Ti drum partially immersed in a plating electrolyte. The nanocrystalline foil was electro- formed onto the drum cathodically, using a soluble anode made of a titanium container filled with anode metal and using a pulse power supply. For alloy foil production, a stream of the additional cation at a predetermined concentration was continuously added to the electrolyte solution to establish a steady state concen- tration of alloying cations in solution. For metal and alloy foil production con- taining matrix composites, a stream of the composite addition was added to the plating bath at a predetermined rate to establish a steady state content of the addi- tive. Three different anode dispositions can be used: Conformal anodes that fol- low the contour of the submerged section of the drum, vertical anodes positioned at the walls of the vessel and horizontal anode positioned on the bottom of the vessel. Foils were produced at average cathodic current densities ranging from 0.01 to 5 A/cm2 and preferably from 0.05 to 0.5A/cm2. The rotation speed was used to adjust the foil thickness and this speed ranged from 0.003 to 0.15rpm (or 20 to l000cm/hour) and preferably from 0.003 to 0.05rpm (or 20 to 330cm/hour) Example 3: metal matrix composite drum plating Nanocrystalline Co based nanocomposites were deposited onto a rotating Ti drum as described in example 3 immersed in a modified Watts bath for cobalt. The nanocrystalline foil, 15cm wide was electroformed onto the drum cathodically, using a soluble cobalt anode contained in a Ti wire basket and a Dynatronix (Dy- nanet PDPR 20-30-100) pulse power supply. The following conditions were used: Anode/anode area: conforming soluble anode (Co Pieces in Ti basket)/undetermined Cathode/cathode area: Ti 600cm2 Cathode: rotating Anode: fixed Anode versus cathode linear speed: 0.018rpm Average Current Density: 0.075A/cm2 Peak cathodic current density: 0.150A/cm2 Peak anodic current density: N/A Cathodic ton/ toff/ Anodic ton (tanodic): 1msec / 1msec / 0msec Frequency: 500Hz Cathodic duty cycle: 50 % Anodic duty cycle: 0% Deposition time: 1 hour Deposition Rate: 0.05 mm/hr Electrolyte temperature: 65°C Electrolyte circulation rate: 0.151iter/min/cm2 cathode area (no pump flow; agitation) Electrolyte Formulation: 300 g/1 CoSO4x7H2O 45 g/1 CoCl2x6H2O 45 g/1 H3BO3 2 g/1 C7H4NO3SNa Sodium Saccharinate 0.1 g/1 C12H25O4SNa Sodium Lauryl Sulfonate (SLS) 5 g/1 Phosphorous Acid 35 g/1 SiC, .5 g/1 Dispersant pH1.5 The Co/P-SiC foil had a grain size of 12 run, a hardness of 690 VHN, contained 1.5% P and 22volume% SiC. Example 4 Nanocrystalline nickel-iron alloy foils were deposited on a rotating Ti drum par- tially immersed in a modified Watts bath for nickel. The nanocrystalline foil, 15cm wide was electroformed onto the drum cathodically, using a soluble anode made of a titanium wire basket filled with Ni rounds and a Dynatronix (Dynanet PDPR 50-250-750) pulse power supply. The following conditions were used: Anode/anode area: conforming soluble anode (Ni rounds in a metal cage)/undetermined Cathode/cathode area: submersed Ti drum/appr. 600cm2 Cathode: rotating at 0.018rpm (or 120cm/hour) Anode: fixed Anode versus cathode linear speed: 120cm/hour Average cathodic current density: 0.07A/cm2 ton/toj: 2msec/2msec Frequency: 250Hz Duty Cycle: 50 % Production run time: 1 day Deposition Rate: 0.075mm/hr Electrolyte temperature: 60°C Electrolyte circulation rate: 0.151iter/min/cm2 cathode area Electrolyte Formulation: 260 g/1 NiSO4-7H2O 45 g/1 NiCl2-6H2O 12g/lFeCl2-4H2O 45 g/1 H3BO3 46 g/1 Sodium Citrate 2 g/1 Sodium Saccharinate 2.2 ml/1 NPA-91 pH2.5 Iron Feed Formulation: 81g/lFeSO4-7H2O Hg/lFeCl2-4H2O 9 g/1 Sodium Citrate 4 g/L H2SO4 0.5 g/1 Sodium Saccharinate pH2.2 rate of addition: 0.3 1/hr Composition: 23-27 wt.%Fe Average grain size: 15 run Hardness: 750Vickers Selective or brush plating is a portable method of selectively plating localized areas of a work piece without submersing the article into a plating tank. There are significant differences between selective plating and tank and barrel plating appli- cations. In the case of selective plating it is difficult to accurately determine the cathode area and therefore the cathodic current density and/or peak current density is variable and usually unknown. The anodic current density and/or peak current density can be determined, provided that the same anode area is utilized during the plating operation, e.g. in the case of flat anodes. In the case of shaped anodes the anode area can not be accurately determined e.g. in the case of a shaped anode and a shaped cathode the "effective" anode area also changes during the plating operation. Selective plating is performed by moving the anode, which is covered with the absorbent separator wick and containing the electrolyte, back and forth over the work piece, which is typically performed by an operator until the desired overall area is coated to the required thickness. Selective plating techniques are particularly suited for repairing or refurbishing articles because brush plating set-ups are portable, easy to operate and do not re- quire the disassembly of the system containing the work piece to be plated. Brush plating also allows plating of parts too large for immersion into plating tanks. Brush plating is used to provide coatings for improved corrosion resistance, im- proved wear, improved appearance (decorative plating) and can be used to salvage worn or mismachined parts. Brush plating systems and plating solutions are com- mercially available e.g. from Sifco Selective Plating, Cleveland. Ohio, which also provides mechanized and/or automated tooling for use in high volume production work. The plating tools used comprise the anode (DSA or soluble), covered with an absorbent, electrically non-conductive material and an insulated handle. In the case of DSA anodes, anodes are typically made of graphite or Pt-clad titanium and may contain means for regulating the temperature by means of a heat exchanger system. For instance, the electrolyte used can be heated or cooled and passed through the anode to maintain the desired temperature range. The absorbent sepa- rator material contains and distributes the electrolyte solution between the anode and the work piece (cathode), prevents shorts between anode and cathode and brushes against the surface of the area being plated. This mechanical rubbing or brushing motion imparted to the work piece during the plating process influences the quality and the surface finish of the coating and enables fast plating rates. Selective plating electrolytes are formulated to produce acceptable coatings in a wide temperature range ranging from as low as -20°C to 85°C. As the work piece is frequently large in comparison to the area being coated selective plating is often applied to the work piece at ambient temperatures, ranging from as low as -20°C to as high as 45°C. Unlike "typical" electroplating operations, in the case of se- lective plating the temperature of the anode, cathode and electrolyte can vary sub- stantially. Salting out of electrolyte constituents can occur at low temperatures and the electrolyte may have to be periodically or continuously reheated to dis- solve all precipitated chemicals. A Sifco brush plating unit (model 3030 - 30A max) was set up. The graphite an- ode tip was inserted into a cotton pouch separator and either attached to a mecha- nized traversing arm in order to generate the "brushing motion" or moved by an operator by hand back and forth over the work piece, or as otherwise indicated. The anode assembly was soaked in the plating solution and the coating was de- posited by brushing the plating tool against the cathodically charged work area that was composed of different substrates. A peristaltic pump was used to feed the electrolyte at predetermined rates into the brush plating tool. The electrolyte was allowed to drip off the work piece into a tray that also served as a "plating solution reservoir" from which it was recirculated into the electrolyte tank. The anode had flow-through holes/channels in the bottom surface to ensure good electrolyte distribution and electrolyte/work piece contact. The anode was fixed to a traversing arm and the cyclic motion was adjusted to allow uniform strokes of the anode against the substrate surface. The rotation speed was adjusted to in- crease or decrease the relative anode/cathode movement speed as well as the an- ode/substrate contact time at any one particular location. Brush plating was nor- mally carried out at a rate of approximately 35-175 oscillations per minute, with a rate of 50-85 oscillations per minute being optimal. Electrical contacts were made on the brush handle (anode) and directly on the work piece (cathode). Coatings were deposited onto a number of substrates, including copper, 1018 low carbon steel, 4130 high carbon steel, 304 stainless steel, a 2.5in OD steel pipe and a weldclad 1625 pipe. The cathode size was 8cm2, except for the 2.5in OD steel pipe where a strip 3cm wide around the outside diameter was exposed and the weldclad 1625 pipe on which a defect repair procedure was performed. A Dynatronix programmable pulse plating power supply (Dynanet PDPR 20-30- 100) was employed. Standard substrate cleaning and activation procedures provided by Sifco were used. Example 5: Nanocrystalline pure nickel was deposited onto an 8cm2 area cathode with a 35cm2 anode using the set-up described. Usually, the work piece has a substan- tially larger area than the anode. In this example a work piece (cathode) was se- lected to be substantially smaller than the anode to ensure that the oversized an- ode, although being constantly kept in motion, always covered the entire work piece to enable the determination of the cathodic current density. As a non- consumable anode was used, N1CO3 was periodically added to the plating bath to maintain the desired Ni2+ concentration. The following conditions were used: Anode/anode area: graphite/3 5cm2 Cathode/cathode area: mild steel/8cm2 Cathode: stationary Anode: oscillating mechanically automated at 50 oscillations per minute Anode versus cathode linear speed: 125cm/min Average cathodic current density: 0.2A/cm2 f ton/toff 8msec/2msec Frequency: 100 Hz Duty Cycle: 80%, Deposition time: lhour Deposition rate: 0.125mm/hr Electrolyte temperature: 60°C Electrolyte circulation rate: 10ml solution per min per cm2 anode area or 220ml solution per min per Ampere average current applied Electrolyte Formulation: 300 g/1 NiSO4-7H2O 45 g/1 NiClr6H2O 45 g/1 H3BO3 2 g/1 Sodium Saccharinate 3ml/lNPA-91 pH: 2.5 Average grain size: 19nm Hardness: 600Vickers Example 6: Nanocrystalline Co was deposited using the same set up described under the fol- lowing conditions: Anode/anode area: graphite/3 5cm2 Cathode/cathode area: mild steel/8cm2 Cathode: stationary Anode: oscillating mechanically automated at 50 oscillations per minute Anode versus cathode linear speed: 125cm/min Average cathodic current density: 0.10A/cm2 Wtoff: 2msec/6msec Frequency: 125Hz Duty Cycle: 25% Deposition time: lhour Deposition rate: 0.05mm/hr Electrolyte temperature: 65°C Electrolyte circulation rate: 10 mL solution per min per cm2 anode area or 440 ml solution per min per Ampere average current applied Electrolyte Formulation: 300 g/L CoSO4-7H2O 45 g/L CoCl2-6H2O 45 g/L H3BO3 2 g/L C7H4NO3SNa Sodium Saccharinate 0.1 g/L Ci2H25O4SNa Sodium Lauryl Sulfonate (SLS) pH2.5 Average grain size: 13nm Hardness: 600Vickers Example 7: Nanocrystalline Ni/20%Fe was deposited using the set up described before. A 1.5in wide band was plated on the OD of a 2.5in pipe by rotating the pipe along its longitudinal axis while maintaining a fixed anode under the following condi- tions: Anode/anode area/effective anode area: graphite/3 5cm /undetermined Cathode/cathode area: 2.5inch OD steel pipe made of 210A1 carbon steel/undetermined Cathode: rotating at 12 rpm Anode: stationary Cathode versus Anode linear speed: 20cm/min Average cathodic current density: undetermined; Total current applied: 3.5A WW- 2msec/6msec Frequency: 125Hz Duty Cycle: 25% Deposition time: lhour Deposition rate: 0.05mm/hr Electrolyte temperature: 55°C Electrolyte circulation rate: 0.44 liter solution per min per Ampere applied Electrolyte Formulation: 260 g/1 NiSO4-7H2O 45 g/1 NiCl2-6H2O 7.8 g/1 FeCl2-4H2O 45 g/1 H3BO3 30 g/1 Na3C6H5O7-2H2O, Sodium Citrate 2 g/1 Sodium Saccharinate Iml/1NPA-91 pH3.0 Average grain size: 15 nm Hardness: 750Vickers Example 8: A defect (groove) in a weldclad pipe section was filled in with nanocrystalline Ni using the same set up as in Example 1. The groove was about 4.5cm long, 0.5cm wide and had an average depth of approximately 0.175mm, although the rough finish of the defect made it impossible to determine its exact surface area. The area surrounding the defect was masked off and nano Ni was plated onto the de- fective area until its original thickness was reestablished. Anode/anode area: graphite/3 5 cm2 Cathode/cathode area: 1625/undetermined Cathode: stationary Anode: oscillating mechanically automated at 50 oscillations per minute Anode versus cathode linear speed: 125cm/min Average cathodic current density: undetermined WW" 2msec/6msec Frequency: 125Hz Duty Cycle: 25% Deposition time: 2hour Deposition rate:0.087mm/hr Electrolyte temperature: 55°C Electrolyte circulation rate: 0.44 liter solution per min per Ampere average current applied Electrolyte Formulation: 300 g/1 NiSO4-7H2O 45 g/1 NiCl2-6H2O 45 g/1 H3BO3 2 g/1 Sodium Saccharinate 3ml/lNPA-91 pH3.0 Average grain size: 20nm Hardness: 600Vickers Microcomponents, having overall dimensions below l,000^im (lmm), are gaining increasing importance for use in electronic, biomedical, telecommunication, automotive, space and consumer applications. Metallic macro-system components with an overall maximum dimension of lcm to over lm containing conventional grain sized materials (l-l,000nm) exhibit a ratio between maximum dimension and grain size ranges from 10 to 106. This number reflects the number of grains across the maximum part dimension. When the maximum component size is re- duced to below lmm using conventional grain-sized material, the component can be potentially made of only a few grains or a single grain and the ratio between the maximum micro-component dimension and the grain size ranges approaches 1. In other words, a single or only a few grains stretch across the entire part, which is undesirable. To increase the part reliability of micro-components the ratio between maximum part dimension and grain size ranges must be increased to over 10 through the utilization of a small grained material, as this material class typically exhibits grain size values 10 to 10,000 times smaller than conventional materials. For conventional LIGA and other plated micro-components, electrodeposition initially starts with a fine grain size at the substrate material. With increasing de- posit thickness in the growth direction; however, the transition to columnar grains is normally observed. The thickness of the columnar grains typically ranges from a few to a few tens of micrometers while their lengths can reach hundreds of mi- crometers. The consequence of such structures is the development of anisotropic properties with increasing deposit thickness and the reaching of a critical thick- ness in which only a few grains cover the entire cross section of the components with widths below 5 or 10 \im. A further decrease in component thickness results in a bamboo structure resulting in a significant loss in strength. Therefore the microstructure of electrodeposited micro-components currently in use is entirely incommensurate with property requirements across both the width and thickness of the component on the basis of grain shape and average grain size. Heretofore, parts made of conventionally grain-sized materials that have been known to suffer from severe reliability problems with respect to mechanical prop- erties such as the Young modulus, yield strength, ultimate tensile strength, fatigue strength and creep behavior have been shown to be extremely sensitive to proc- essing parameters associated with the synthesis of these components. Many of the problems encountered are caused by incommensurate scaling of key microstruc- tural features (i.e. grain size, grain shape, grain orientation) with the external size of the component resulting in unusual property variations normally not observed in macroscopic components of the same material. Example 9: Metal micro-spring fingers are used to contact IC chips with high pad count and density and to carry power and signals to and from the chips. The springs provide high pitch compliant electrical contacts for a variety of interconnection structures, including chip scale semiconductor packages, high-density interposer connectors, and probe contactors. The massively parallel interface structures and assemblies enable high speed testing of separated integrated circuit devices affixed to a com- pliant carrier, and allow test electronics to be located in close proximity to the integrated circuit devices under test. The micro-spring fingers require high yield strength and ductility. A 25 mm thick layer of nanocrystalline Ni was plated on 500 mm long gold-coated CrMo fingers using the following conditions: Anode/anode area: Ni/4.5xl0-3cm2 Cathode/cathode area: Gold Plated CrMo/approximately 1 cm2 Cathode: stationary Anode: stationary Anode versus cathode linear speed: 0 cm/min Average cathodic current density: 50mA/cm2 ton/toff: 10msec/20msec Frequency: 33Hz Duty Cycle: 33% Deposition time: 120 minutes Deposition Rate: 0.05mm/hr Electrolyte temperature: 60°C Electrolyte circulation rate: None Electrolyte Formulation: 300 g/1 NiSO4-7H2O 45 g/1 NiCl2-6H2O 45 g/1 H3BO3 2 g/1 Sodium Saccharinate 3ml/lNPA-91 pH3.0 Average grain size: 15-20nm Hardness: 600Vickers The nano-fingers exhibited a significantly higher contact force when compared to "conventional grain-sized" fingers. WE CLAIM : 1. A process for cathodically electrodepositing a selected metallic material such as described herein on a permanent or temporary substrate in nanocrystalline form at a deposition rate of at least 0.05 mm/h, comprising: providing an aqueous electrolyte such as described herein containing ions of said metallic material, agitating the electrolyte at an agitation rate in the range of 0.0001 to 10 liter per min and per cm2 anode or cathode area or at an agitation rate in the range of 1 to 750 milliliter per min and per Ampere, and passing single or multiple cathodic-current pulses between said anode and said cathode. 2. The process as claimed in claim 1, wherein a duty cycle is in the range of 5 to 100%. 3. The process as claimed in any preceding claim, wherein a frequency of the cathodic-current pulses is in the range of 0 to 1000 Hz. 4. The process as claimed in any preceding claim, wherein the single or multiple cathodic-current pulses between said anode and said cathode have a peak current density in the range of about 0.01 to 20 A/cm2, 5. The process as claimed in claim 4, wherein the peak current density of the cathodic-current pulses is in the range of about 0.1 to 20 A/cm2. 6. The process as claimed in claim 5, wherein the peak current density of the cathodic-current pulses is in the range of about 1 to 10 A/cm2. 7. The process as claimed in any preceding claim, wherein said selected metallic material is (a) a pure metal selected from the group consisting of Ag, Au, Cu, Co, Cr, Ni, Fe, Pb, Pd, Rt, Rh, Ru, Sn, V, W, Zn, or (b) an alloy containing at least one of the elements of group (a) and alloying elements selected from the group consisting of C, P, S and Si. 8. The process as claimed in any preceding claim, wherein a tcathodic-on- time period is in the range of 0.1 to 50 msec, a tcathodic-off time period is in the range of 0 to 500 msec and a tcathodic-on- time period is in the range of 0 to 50 msec. 9. The process as claimed in claimed in claims 2 to 8, wherein the duty cycle is in the range of 10 to 95%. 10. The process as claimed in claim 9, wherein the duty cycle is in the range of 20 to 80%. 11. The process as claimed in any preceding claim, wherein the deposition rate is at least 0.075 mm/h. 12. The process as claimed in claim 11, wherein the deposition rate is at least 0.1 mm/h. 13. The process as claimed in any preceding claim, which comprises agitating the electrolyte at an agitation rate in the range of I to 500 milliliter per min and per Ampere. 14. The process as claimed in any preceding claim, which comprises agitating the electrolyte by means of pumps, stirrers or ultrasonic agitation. 15. The process as claimed in any preceding claim, which comprises a relative motion between anode and cathode. 16. The process as claimed in claim 15, wherein the speed of the relative motion between anode and cathode ranges from 0 to 600 m/min. 17. The process as claimed in claim 16, wherein the speed of the relative motion between anode and cathode ranges from 0.003 to 10 m/min. 18. The process as claimed in claims 15 to 17. wherein the relative motion is achieved by rotation of anode and cathode relative to each other. 19. The process as claimed in claim 18, wherein a rotational speed of rotation of anode and cathode relative to each other ranges from 0.003 to 0.15 rpm. 20. The process as claimed in claim 19, wherein a rotational speed of rotation of anode and cathode relative to each other ranges from 0.003 to 0.05 rpm. 21. The process as claimed in claims 15 to 17, wherein the relative motion is achieved by a mechanized motion generating a stroke of the anode and the cathode relative to each other. 22. The process as claimed in claims 15 or 21, wherein the anode is wrapped in an absorbent separator, 23. The process as claimed in any preceding claim, wherein said electrolyte contains a stress relieving agent or a grain refining agent selected from the group of saccharin, coumarin, sodium lauryl sulfate and thiourea. 24. The process as claimed in any preceding claim, wherein said electrolyte contains particulate additive such as described herein selected from pure metal powders, metal alloy powders or metal oxide powders of Al, Co, Cu. In. Mg, Ni, Si, Sn, V and Zn, nitrides of Al, B and Si, carbon C (graphite or diamond), carbides of B, Bi, Si, W, or organic materials such as PTFE and polymers spheres, whereby the electrodeposited metallic material contains at least 5% of said particulate additives. 25. The process as claimed in claim 24. wherein the electrodeposited metallic material contains at least 10% of said particulate additives. 26. The process as claimed in claim 24, wherein the electrodeposited metallic material contains at least 20% of said particulate additives. 27. The process as claimed in claim 24 wherein the electrodeposited metallic material contains at least 30% of said particulate additives. 28. The process as claimed in claim 24, wherein the electrodeposited metallic material contains at least 40% of said particulate additives. 29. The process as claimed in claim 24, wherein the particulate additives average particle size is in the range of 100 nm to 10 mm. 30. The process as claimed in claim 29, wherein the particulate additives average particle size is in the range of 500 nm to 10 mm. 31. The process as claimed in claim 30, wherein the particulate additives average particle size is in the range of 1000 nm to 10 um. 32. The process as claimed in claim 31, wherein the particulate additives average particle size is below 100 nm. 33. Microcomponent produced by a pulse electrodeposition process as claimed in claims 1 to 28. having a maximum dimension of 1 mm. an average grain size equal to or smaller than 1000 nrn the ratio between the maximum outside dimension of the microcomponent part and the average grain size being greater than 10. 34. Microcomponent as claimed in claim 33, wherein the ratio between the maximum outside dimension of the microcomponent part and the average grain size being in excess of 100. 35. Microcomponent. as claimed in claims 33 and 34, which has an equiaxed micro-structure. The invention discloses a process for forming coatings or free-standing deposits of nano-crystalline metals, metal alloys or metal matrix composites. The process employs drum plating or selective plating processes involving pulse electrode-position and a non-stationary anode or cathode. Novel nano-crystalline metal matrix composites and micro components are disclosed as well. Also described is a process for forming micro-components with grain sizes below 1000 nm.

Full Text

A PROCESS FOR CATHODICALLY ELECTRODEPOSITING
A SELECTED METALLIC MATERIAL PERMANENT OR
TEMPORARY SUBSTRATE IN NANOCRYSTALLINE FORM
Field of the Invention
The invention relates to a process for cathodically electrodepositing a
selected metallic material permanent or temporary substrate in nanocrystalline
form, and particularly to a process for forming coatings of pure metals, metal
alloys or metal matrix composites on a work piece which is electrically conductive
or contains an electrically conductive surface layer or
forming free-standing deposits of nano-crystalline metals, metal alloys or metal
matrix composites by employing pulse electrodeposition. The process employs a
drum plating process for the continuous production of nanocrystalline foils of pure
metals, metal alloys or metal matrix composites or a selective plating (brush
plating) process, the processes involving pulse electrodeposition and a non-
stationary anode or cathode. Novel nano-crystalline metal matrix composites are
disclosed as well. The invention also relates to a pulse plating process for the
fabrication or coating of micro -components. The invention also relates to micro-
components with grain sizes below 1,000nm.
The novel process can be applied to establish wear resistant coatings and foils of
pure metals or alloys of metals selected from the group of Ag, Au, Cu, Co, Cr, Ni,
Fe, Pb, Pd, Pt, Rh, Ru, Sn, V, W and Zn and alloying elements selected from C, P,
S and Si and metal matrix composites of pure metals or alloys with particulate
additives such as metal powders, metal alloy powders and metal oxide powders of
Al, Co, Cu, In, Mg, Ni, Si, Sn, V, and Zn; nitrides of Al, B and Si; C (graphite or
diamond); carbides of B, Cr, Bi, Si, W; and organic materials such as PTFE and
polymer spheres. The selective plating process is particularly suited for in-situ or
field applications such as the repair or the refurbishment of dies and moulds, tur-
bine plates, steam generator tubes, core reactor head penetrations of nuclear power
plants and the like. The continuous plating process is particularly suited for pro-
ducing nanocrystalline foils e.g. for magnetic applications. The process can be
applied to high strength, equiaxed micro-components for use in electronic, bio-
medical, telecommunication, automotive, space and consumer applications.
Description of Prior Art/Background of the Invention
Nanocrystalline materials, also referred to as ultra-fine grained materials, nano-
phase materials or nanometer-sized materials exhibiting average grains sizes
smaller or equal to l00nm, are known to be synthesized by a number of methods
including sputtering, laser ablation, inert gas condensation, high energy ball mill-
ing, sol-gel deposition and electrodeposition. Electrodeposition offers the capa-
bility to prepare a large number of fully dense metal and metal alloy compositions
at high production rates and low capital investment requirements in a single syn-
thesis step.
The prior art primarily describes the use of pulse electrodeposition for producing
nanocrystalline materials.
Erb in US 5,352,266 (1994) and in US 5,433,797 (1995) describes a process for
producing nanocrystalline materials, particularly nanocrystalline nickel. The na-
nocrystalline material is electrodeposited onto the cathode in an aqueous acidic
electrolytic cell by application of a pulsed DC current. The cell also optionally
contains stress relievers. Products of the invention include wear resistant coat-
ings, magnetic materials and catalysts for hydrogen evolution.
Mori in US 5,496,463 (1996) describes a process and apparatus for composite
electroplating a metallic material containing SiC, BN, Si3N4, WC, TiC, TiO2,
Al2O, ZnB3, diamond, CrC, MoS2, coloring materials, polytetrafluoroethylene
(PTFE) and microcapsules. The solid particles are introduced in fine form into
the electrolyte.
Adler in US 4,240,894 (1980) describes a drum plater for electrodeposited Cu foil
production. Cu is plated onto a rotating metal drum that is partially submersed and
rotated in a Cu plating solution. The Cu foil is stripped from the drum surface
emerging from the electrolyte, which is clad with electroformed Cu. The rotation
speed of the drum and the current density are used to adjust the desired thickness
of the Cu foil. The Cu foil stripped from the drum surface is subsequently washed
and dried and wound into a suitable coil.
Icxi in US 2,961,395 (1960) discloses a process for electroplating an article with-
out the necessity to immerse the surface being treated into a plating tank. The
hand-manipulated applicator serves as anode and applies chemical solutions to the
metal surface of the work piece to be plated. The work piece to be plated serves
as cathode. The hand applicator anode with the wick containing the electrolyte
and the work piece cathode are connected to a DC power source to generate a
metal coating on the work piece by passing a DC current.
Micromechanical systems (MEMS) are machines constructed of small moving
and stationary parts having overall dimensions ranging from 1 to 1,000um e.g. for
use in electronic, biomedical, telecommunication, automotive, space and con-
sumer technologies.
Such components are made e.g. by photo-electroforming, which is an additive
process in which powders are deposited in layers to build the desired structure e.g.
by laser enhanced electroless plating. Lithography, electroforming and molding
(LIGA) and other photolithography related processes are used to overcome aspect
ratio (parts height to width) related problems. Other techniques employed include
silicon micromachining, through mask plating and microcontact printing.
3. Summary:
It is an object of the invention to provide a reliable and flexible pulse plating pro-
cess for forming coatings or free-standing deposits of nano-crvstalline metals,
metal alloys or metal matrix composites.
It is a further object of the invention to provide micro components with signifi-
cantly improved property-dependent reliability and improved and tailor-made
desired properties for overall performance enhanced microsystems.
Prefered embodiments of the invention are defined in the corresponding depend-
ent claims.
The present invention provides a pulse plating process, consisting of a single ca-
thodic on time or multiple cathodic on times of different current densities and sin-
gle or multiple off times per cycle. Periodic pulse reversal, a bipolar waveform
alternating between cathodic pulses and anodic pulses, can optionally be used as
well. The anodic pulses can be inserted into the waveform before, after or in be-
tween the on pulse and/or before, after or in the off time. The anodic pulse cur-
rent density is generally equal to or greater than the cathodic current density. The
anodic charge (Qanodic) of the "reverse pulse" per cycle is always smaller than the
cathodic charge (Qcathodic).
Cathodic pulse on times range from 0.1 to 50 msec (1-50), off times from 0 to
500msec (1-100) and anodic pulse times range from 0 to 50 msec, preferably from
1 to 10msec. The duty cycle, expressed as the cathodic on times divided by the
sum of the cathodic on times, the off times and the anodic times, ranges from 5 to
100 %, preferably from 10 to 95 %, and more preferably from 20 to 80 %. The
frequency of the cathodic pulses ranges from 1Hz to 1kHz and more preferably
from l0Hz to 350Hz.
Nano-crystalline coatings or free-standing deposits of metallic materials were ob-
tained by varying process parameters such as current density, duty cycle, work
piece temperature, plating solution temperature, solution circulation rates over a
wide range of conditions. The following listing describes suitable operating pa-
rameter ranges for practising the invention:
Average current density (if determinable, anodically or cathodically): 0.01 to
20A/cm2, preferably 0,1 to 20A/cm2, more preferably 1 to 10A/cm2
Duty Cycle 5 to 100%
Frequency: 0 to l000Hz
Electrolyte solution temperature: - 20 to 85 °C
Electrolyte solution circulation/agitation rates: cathode area (0.0001 to 101/min.cm2)
Work piece temperature: -20 to 45 °C
Anode oscillation rate: 0 to 350 oscillations/min
Anode versus cathode linear speed: 0 to 200 meter/min (brush) 0.003 to
0.16m/min (drum)
-6-
The present invention preferably provides a process for plating nanocrystalline
metals, metal matrix composites and microcomponents at deposition rates of at
least 0.05 mm/h, preferably at least 0.075 mm/h, and more preferably at least
0.1 mm/h.
In the process of the present invention the electrolyte preferably may be agitated
by means of pumps, stirrers or ultrasonic agitation at rates of 0 to 750 ml/min/A
(ml solution per minute per applied Ampere average current), preferably at rates
of 1 to 500 ml/min/A.
In the process of the present invention optionally a grain refining agent or a stress
relieving agent selected from the group of saccharin, coumarin, sodium lauryl
sulfate and thiourea can be added to the electrolyte.
This invention provides a process for plating nanocrystalline metal matrix com-
posites on a permanent or temporary substrate optionally containing at least 5%
by volume particulates, preferably 10% by volume particulates, more preferably
20% by volume particulates, even more preferably 30% by volume particulates
and most preferably 40% by volume particulates for applications such as hard
facings, projectile blunting armor, valve refurbishment, valve and machine tool
coatings, energy absorbing armor panels, sound damping systems, connectors on
pipe joints e.g. used in oil drilling applications, refurbishment of roller bearing
axles in the railroad industry, computer chips, repair of electric motors and gen-
erator parts, repair of scores in print rolls using tank, barrel, rack, selective (e.g.
brush plating) and continuous (e.g. drum plating) plating processes using pulse
electrodeposition. The particulates can be selected from the group of metal pow-
ders, metal alloy powders and metal oxide powders of Al, Co, Cu, In, Mg, Ni, Si,
Sn, V, and Zn; nitrides of Al, B and Si; C (graphite or diamond); carbides of B,
Bi, Cr, Si, W; M0S2; and organic materials such as PTFE and polymer spheres.
The particulate average particle size is typically below 10 mm, preferably below
1000 nm (1 mm), preferably 500 nm, and more preferably below 100 nm. The
particulate additives average particle size may be in the range of 100 nm to 10
pm, in the range of 500 nm to 10 mm, in the range of 1000 nm to 10 mm or below
100 nm.
The process of this invention optionally provides a process for continuous (drum
or belt) plating nanocrystalline foils optionally containing solid particles in sus-
pension selected from metal powders, metal alloy powders and metal oxide pow-
ders of Al, Co, Cu, In, Mg, Ni, Si, Sn, V, and Zn; nitrides of Al, B and Si; C
(graphite or diamond); carbides of B, Bi, Si, W; M0S2, and organic materials such
as PTFE and polymer spheres to impart desired properties including hardness,
wear resistance, lubrication, magnetic properties and the like. The drum or belt
provides a temporary substrate from which the plated foil can be easily and con-
tinuously removed.
According to a preferred embodiment of the present invention it is also possible to
produce nanocrystalline coatings by electroplating without the need to submerse
the article to be coated into a plating bath. Brush or tampon plating is a suitable
alternative to tank plating, particularly when only a portion of the work piece is to
be plated, without the need to mask areas not to be plated. The brush plating ap-
paratus typically employs a soluble or dimensionally stable anode wrapped in an
absorbent separator felt to form the anode brush. The brush is rubbed against the
surface to be plated in a manual or mechanized mode and electrolyte solution
containing ions of the metal or metal alloys to be plated is injected into the sepa-
rator felt. Optionally, this solution also contains solid particles in suspension se-
lected from metal powders, metal alloy powders and metal oxide powders of Al,
Co, Cu, In, Mg, Ni, Si, Sn, V, and Zn; nitrides of Al, B and Si; C (graphite or
diamond); carbides of Bi, Si, W; M0S2; and organic materials such as PTFE and
polymer spheres to impart desired properties including hardness, wear resistance,
lubrication and the like.
In the case of drum, belt or brush plating the relative motion between anode and
cathode ranges from 0 to 600meters per minute, preferably from 0.003 to
l0meters per minute.
In the process of this invention micro components for micro systems including
micro-mechanical systems (MEMS) and micro-optical-systems with grain sizes
equal to or smaller than 1,000nm can be produced. The maximum dimension of
the microcomponent part is equal to or below lmm and the ratio between the
maximum outside dimension of the microcomponent part and the average grain
size is equal to or greater than 10, preferably greater than 100.
The micro components of the present invention preferably may have an equiaxed
microstructure throughout the plated component, which is relatively independent
of component thickness and structure.
It is another aspect of the present invention to provide micro components where
the average grain size remains at least an order of magnitude smaller than the ex-
ternal dimensions of the part, thus maintaining a high level of strength.
The micro components according to this invention have significantly improved
property-dependent reliability and improved and tailor-made desired properties of
MEMS structures for overall performance enhanced microsystems by preferably
equiaxed electrodeposits, eliminating the fine grain to columnar grain transition in
the microcomponent, and simultaneously reducing the grain size of the deposits
below l,000nm.
Other features and advantages of this invention will become more apparent in
the following detailed description and examples of preferred embodiments of the
invention, together with the accompanying schematic drawings, in which:
Figure 1 shows a cross-sectional view of a preferred embodiment of a drum plat-
ing apparatus.
Figure 2 shows a cross sectional view of a preferred embodiment of a brush plat-
ing apparatus; and
Figure 3 shows a plan view of a mechanized motion apparatus for generating a
mechanized stroke of the anode brush.
Figure 1 schematically shows of a plating tank or vessel (1) filled with an elec-
trolyte (2) containing the ions of the metallic material to be plated. Partially sub-
mersed into the electrolyte is the cathode in the form of a rotating drum (3) elec-
trically connected to a power source (4). The drum is rotated by an electric motor
(not shown) with a belt drive and the rotation speed is variable. The anode (5) can
be a plate or conforming anode, as shown, which is electrically connected to the
power source (4). Three different anode dispositions can be used: Conformal an-
odes, as shown in Figure 1, that follow the contour of the submerged section of
the drum (3), vertical anodes positioned at the walls of the tank (1) and horizontal
anode positioned on the bottom of the tank (1). In case of a foil (16) of metallic
material being electrodeposited on the drum (3), the foil (16) is pulled from the
drum surface emerging from the electrolyte (2), which is clad with the electro-
formed metallic material.
Figure 2 schematically shows a workpiece (6) to be plated, which is connected to
the negative outlet of the power source (4). The anode (5) consists of a handle (7)
with a conductive anode brush (8). The anode contains channels (9) for supplying
the electrolyte solution (2) from a temperature controlled tank (not shown) to the
anode wick (absorbent separator) (10) . The electrolyte dripping from the absorb-
ent separator (10) is optionally collected in a tray (11) and recirculated to the tank.
The absorbent separator (10) containing the electrolyte (2) also electrically insu-
lates the anode brush (8) from the workpiece (6) and adjusts the spacing between
anode (5) and cathode (6). The anode brush handle (4) can be moved over the
workpiece (6) manually during the plating operation, alternatively, the motion can
be motorized as shown in figure 3.
Figure 3 schematically shows a wheel (12) driven by an adjustable speed motor
(not shown). A traversing arm (13) can be rotatably attached (rotation axis A) to
the rotating wheel (12) at various positions x at a slot (14) with a bushing and a
set screw (not shown) to generate a desired stroke. The stroke lenght can be ad-
justed by the position x (radius) at which the rotation axis A of traversing arm is
mounted at the slot (14). In Figure 3 the traversing arm (13) is shown to be in an
no-stroke, neutral position with rotation axis A in the center of the wheel (12).
The traversing arm (13) has a second pivot axis B defined by a bearing (not
shown), that is slidably mounted in a track (15). As the wheel (12) rotates, the
rotation of the traversing arm (13) around axis A at position x causes the travers-
ing arm (13) to reciprocate in the track (15) and to pivot around axis B. An anode
(5) having the same features as shown in Fig. 2 is attached to the traversing arm
(13) and moves over the workpiece (6) in a motion depending on the position x.
Usually the motion has the shape of figure eight. The anode (5) and the work-
piece (6) are connected to positive and negative outlets of a power source (not
shown), respectively. The cinematic relation is very similar to that of a steam
engine.
This invention relies on producing nanocrystalline coatings, foils and microsystem
components by pulse electrodeposition. Optionally solid particles are suspended
in the electrolyte and are included in the deposit.
Nanocrystalline coatings for wear resistant applications to date have focused on
increasing wear resistance by increasing hardness and decreasing the friction coef-
ficient though grain size reduction below l00nm. It has now been found that in-
corporating a sufficient volume fraction of hard particles can further enhance the
wear resistance of nanocrystalline materials.
The material properties can also be altered by e.g. the incorporation of lubricants
(such as M0S2 and PTFE). Generally, the particulates can be selected from the
group of metal powders, metal alloy powders and metal oxide powders of Al, Co,
Cu, In, Mg, Ni, Si, Sn, V, and Zn; nitrides of Al, B and Si; C (graphite or dia-
mond); carbides of B, Bi, Si, W; M0S2; and organic materials such as PTFE and
polymer spheres.
Example 1
Nanocrystalline NiP-B4C nanocomposites were deposited onto Ti and mild steel
cathodes immersed in a modified Wstt§J>ath for nickel using a soluble anode
made of a nickel plate and a Dynatronix (Dynanet PDPR 20-30-100) pulse power
supply. The following conditions were used:
Anode/anode area: soluble anode: Ni plate, 80cm2
Cathode/cathode area: Ti or mild steel sheet/appr. 5cm2
Cathode: fixed
Anode: fixed
Anode versus cathode linear speed: N/A
Average cathodic current density: 0.06A/cm2
ton/toff: 2msec/ 6msec
Frequency: 125Hz
Duty Cycle: 25%
Deposition time: 1 hour
Deposition Rate: 0.09mm/hr
Electrolyte temperature: 60°C
Electrolyte circulation rate: vigorous agitation (two direction mechanical impeller)
Basic Electrolyte Formulation:
300g/lNiSO4.7H2O
45g/l NiCl2.6H2O
45g/l H3BO3
18g/lH3PO4
0.5-3ml/l surfactant to a surface tension of 0-2g/l sodium saccharinate
360 g/1 boron carbide, 5 mm mean particle diameter
pH 1.5-2.5
The hardness values of metal matrix composites possessing a nanocrystalline ma-
trix structure are typically twice as high as conventional coarse-grained metal ma-
trix composites. In addition, the hardness and wear properties of a nanocrystalline
N1P-B4C composite containing 5.9weight% P and 45volume% B4C are compared
with those of pure coarse-grained Ni, pure nanocrystalline Ni and electrodeposited
Ni-P of an equivalent chemical composition in the adjacent table. Material hard-
ening is controlled by Hall-Petch grain size strengthening, while abrasive wear
resistance is concurrently optimized by the incorporation of B4C participate.
Table: N1P-B4C nanocomposite properties
Example 2
Nanocrystalline Co based nanocomposites were deposited onto Ti and mild steel
cathodes immersed in a modified Watts bath for cobalt using a soluble anode
made of a cobalt plate and a Dynatronix (Dynanet PDPR 20-30-100) pulse power
supply. The following conditions were used:
Anode/anode area: soluble anode (Co plate)/ 80cm2
Cathode/cathode area: Ti (or mild steel) sheet/appr. 6.5cm2
Cathode: fixed
Anode: fixed
Anode versus cathode linear speed: N/A
Peak cathodic current density: 0.100A/cm2
Peak anodic current density: 0.300A/cm2
Cathodic ton/ toff Anodic ton (tanodic): 16msec / 0msec / 2msec
Frequency: 55.5Hz
Cathodic duty cycle: 89 %
Anodic duty cycle: 11%
Deposition time: 1 hour
Deposition Rate: 0.08mm/hr
Electrolyte temperature: 60°C
Electrolyte circulation rate: 0.151iter/min/cm2 cathode area (no pump flow; agita-
tion)
Electrolyte Formulation:
300 g/1 CoSO4-7H2O
45 g/1 CoCl2-6H2O
45 g/1 H3BO3
2 g/1 C7H4NO3SNa Sodium Saccharinate
0.1 g/1 C12H25O4SNa Sodium Lauryl Sulfonate (SLS)
100 g/1 SiC, pH2.5
In the adjacent table, the hardness and wear properties of a nanocrystalline Co-
SiC composite containing 22volume% SiC are compared with those of pure
coarse-grained Co and pure nanocrystalline Co. Hall-Petch grain size strength-
ening controls material hardening, while abrasive wear resistance is concurrently
optimized by the incorporation of SiC particulate.
Table: Co nanocomposite properties
Continuous plating to produce foils e.g. using drum plating nanocrystalline foils
optionally containing solid particles in suspension selected from pure metals or
alloys with paniculate additives such as metal powders, metal alloy powders and
metal oxide powders of Al, Co, Cu, In, Mg, Ni, Si, Sn, V, and Zn; nitrides of Al,
B and Si; C (graphite or diamond); carbides of B, Bi, Si, W; and organic materials
such as PTFE and polymer spheres to impart desired properties including hard-
ness, wear resistance, lubrication, magnetic properties and the like has been ac-
complished. Nanocrystalline metal foils were deposited on a rotating Ti drum
partially immersed in a plating electrolyte. The nanocrystalline foil was electro-
formed onto the drum cathodically, using a soluble anode made of a titanium
container filled with anode metal and using a pulse power supply. For alloy foil
production, a stream of the additional cation at a predetermined concentration was
continuously added to the electrolyte solution to establish a steady state concen-
tration of alloying cations in solution. For metal and alloy foil production con-
taining matrix composites, a stream of the composite addition was added to the
plating bath at a predetermined rate to establish a steady state content of the addi-
tive. Three different anode dispositions can be used: Conformal anodes that fol-
low the contour of the submerged section of the drum, vertical anodes positioned
at the walls of the vessel and horizontal anode positioned on the bottom of the
vessel. Foils were produced at average cathodic current densities ranging from
0.01 to 5 A/cm2 and preferably from 0.05 to 0.5A/cm2. The rotation speed was
used to adjust the foil thickness and this speed ranged from 0.003 to 0.15rpm (or
20 to l000cm/hour) and preferably from 0.003 to 0.05rpm (or 20 to 330cm/hour)
Example 3: metal matrix composite drum plating
Nanocrystalline Co based nanocomposites were deposited onto a rotating Ti drum
as described in example 3 immersed in a modified Watts bath for cobalt. The
nanocrystalline foil, 15cm wide was electroformed onto the drum cathodically,
using a soluble cobalt anode contained in a Ti wire basket and a Dynatronix (Dy-
nanet PDPR 20-30-100) pulse power supply. The following conditions were
used:
Anode/anode area: conforming soluble anode (Co Pieces in Ti
basket)/undetermined
Cathode/cathode area: Ti 600cm2
Cathode: rotating
Anode: fixed
Anode versus cathode linear speed: 0.018rpm
Average Current Density: 0.075A/cm2
Peak cathodic current density: 0.150A/cm2
Peak anodic current density: N/A
Cathodic ton/ toff/ Anodic ton (tanodic): 1msec / 1msec / 0msec
Frequency: 500Hz
Cathodic duty cycle: 50 %
Anodic duty cycle: 0%
Deposition time: 1 hour
Deposition Rate: 0.05 mm/hr
Electrolyte temperature: 65°C
Electrolyte circulation rate: 0.151iter/min/cm2 cathode area (no pump flow;
agitation)
Electrolyte Formulation:
300 g/1 CoSO4x7H2O
45 g/1 CoCl2x6H2O
45 g/1 H3BO3
2 g/1 C7H4NO3SNa Sodium Saccharinate
0.1 g/1 C12H25O4SNa Sodium Lauryl Sulfonate (SLS)
5 g/1 Phosphorous Acid
35 g/1 SiC, .5 g/1 Dispersant
pH1.5
The Co/P-SiC foil had a grain size of 12 run, a hardness of 690 VHN, contained
1.5% P and 22volume% SiC.
Example 4
Nanocrystalline nickel-iron alloy foils were deposited on a rotating Ti drum par-
tially immersed in a modified Watts bath for nickel. The nanocrystalline foil,
15cm wide was electroformed onto the drum cathodically, using a soluble anode
made of a titanium wire basket filled with Ni rounds and a Dynatronix (Dynanet
PDPR 50-250-750) pulse power supply. The following conditions were used:
Anode/anode area: conforming soluble anode (Ni rounds in a metal
cage)/undetermined
Cathode/cathode area: submersed Ti drum/appr. 600cm2
Cathode: rotating at 0.018rpm (or 120cm/hour) Anode: fixed
Anode versus cathode linear speed: 120cm/hour
Average cathodic current density: 0.07A/cm2
ton/toj: 2msec/2msec
Frequency: 250Hz
Duty Cycle: 50 %
Production run time: 1 day
Deposition Rate: 0.075mm/hr
Electrolyte temperature: 60°C
Electrolyte circulation rate: 0.151iter/min/cm2 cathode area
Electrolyte Formulation:
260 g/1 NiSO4-7H2O
45 g/1 NiCl2-6H2O
12g/lFeCl2-4H2O
45 g/1 H3BO3
46 g/1 Sodium Citrate
2 g/1 Sodium Saccharinate
2.2 ml/1 NPA-91
pH2.5
Iron Feed Formulation:
81g/lFeSO4-7H2O
Hg/lFeCl2-4H2O
9 g/1 Sodium Citrate
4 g/L H2SO4
0.5 g/1 Sodium Saccharinate
pH2.2
rate of addition: 0.3 1/hr
Composition: 23-27 wt.%Fe
Average grain size: 15 run
Hardness: 750Vickers
Selective or brush plating is a portable method of selectively plating localized
areas of a work piece without submersing the article into a plating tank. There are
significant differences between selective plating and tank and barrel plating appli-
cations. In the case of selective plating it is difficult to accurately determine the
cathode area and therefore the cathodic current density and/or peak current density
is variable and usually unknown. The anodic current density and/or peak current
density can be determined, provided that the same anode area is utilized during
the plating operation, e.g. in the case of flat anodes. In the case of shaped anodes
the anode area can not be accurately determined e.g. in the case of a shaped anode
and a shaped cathode the "effective" anode area also changes during the plating
operation. Selective plating is performed by moving the anode, which is covered
with the absorbent separator wick and containing the electrolyte, back and forth
over the work piece, which is typically performed by an operator until the desired
overall area is coated to the required thickness.
Selective plating techniques are particularly suited for repairing or refurbishing
articles because brush plating set-ups are portable, easy to operate and do not re-
quire the disassembly of the system containing the work piece to be plated. Brush
plating also allows plating of parts too large for immersion into plating tanks.
Brush plating is used to provide coatings for improved corrosion resistance, im-
proved wear, improved appearance (decorative plating) and can be used to salvage
worn or mismachined parts. Brush plating systems and plating solutions are com-
mercially available e.g. from Sifco Selective Plating, Cleveland. Ohio, which also
provides mechanized and/or automated tooling for use in high volume production
work. The plating tools used comprise the anode (DSA or soluble), covered with
an absorbent, electrically non-conductive material and an insulated handle. In the
case of DSA anodes, anodes are typically made of graphite or Pt-clad titanium and
may contain means for regulating the temperature by means of a heat exchanger
system. For instance, the electrolyte used can be heated or cooled and passed
through the anode to maintain the desired temperature range. The absorbent sepa-
rator material contains and distributes the electrolyte solution between the anode
and the work piece (cathode), prevents shorts between anode and cathode and
brushes against the surface of the area being plated. This mechanical rubbing or
brushing motion imparted to the work piece during the plating process influences
the quality and the surface finish of the coating and enables fast plating rates.
Selective plating electrolytes are formulated to produce acceptable coatings in a
wide temperature range ranging from as low as -20°C to 85°C. As the work piece
is frequently large in comparison to the area being coated selective plating is often
applied to the work piece at ambient temperatures, ranging from as low as -20°C
to as high as 45°C. Unlike "typical" electroplating operations, in the case of se-
lective plating the temperature of the anode, cathode and electrolyte can vary sub-
stantially. Salting out of electrolyte constituents can occur at low temperatures
and the electrolyte may have to be periodically or continuously reheated to dis-
solve all precipitated chemicals.
A Sifco brush plating unit (model 3030 - 30A max) was set up. The graphite an-
ode tip was inserted into a cotton pouch separator and either attached to a mecha-
nized traversing arm in order to generate the "brushing motion" or moved by an
operator by hand back and forth over the work piece, or as otherwise indicated.
The anode assembly was soaked in the plating solution and the coating was de-
posited by brushing the plating tool against the cathodically charged work area
that was composed of different substrates. A peristaltic pump was used to feed
the electrolyte at predetermined rates into the brush plating tool. The electrolyte
was allowed to drip off the work piece into a tray that also served as a "plating
solution reservoir" from which it was recirculated into the electrolyte tank. The
anode had flow-through holes/channels in the bottom surface to ensure good
electrolyte distribution and electrolyte/work piece contact. The anode was fixed
to a traversing arm and the cyclic motion was adjusted to allow uniform strokes of
the anode against the substrate surface. The rotation speed was adjusted to in-
crease or decrease the relative anode/cathode movement speed as well as the an-
ode/substrate contact time at any one particular location. Brush plating was nor-
mally carried out at a rate of approximately 35-175 oscillations per minute, with a
rate of 50-85 oscillations per minute being optimal. Electrical contacts were made
on the brush handle (anode) and directly on the work piece (cathode). Coatings
were deposited onto a number of substrates, including copper, 1018 low carbon
steel, 4130 high carbon steel, 304 stainless steel, a 2.5in OD steel pipe and a
weldclad 1625 pipe. The cathode size was 8cm2, except for the 2.5in OD steel
pipe where a strip 3cm wide around the outside diameter was exposed and the
weldclad 1625 pipe on which a defect repair procedure was performed.
A Dynatronix programmable pulse plating power supply (Dynanet PDPR 20-30-
100) was employed.
Standard substrate cleaning and activation procedures provided by Sifco were
used.
Example 5:
Nanocrystalline pure nickel was deposited onto an 8cm2 area cathode with a
35cm2 anode using the set-up described. Usually, the work piece has a substan-
tially larger area than the anode. In this example a work piece (cathode) was se-
lected to be substantially smaller than the anode to ensure that the oversized an-
ode, although being constantly kept in motion, always covered the entire work
piece to enable the determination of the cathodic current density. As a non-
consumable anode was used, N1CO3 was periodically added to the plating bath to
maintain the desired Ni2+ concentration. The following conditions were used:
Anode/anode area: graphite/3 5cm2
Cathode/cathode area: mild steel/8cm2
Cathode: stationary
Anode: oscillating mechanically automated at 50 oscillations per minute
Anode versus cathode linear speed: 125cm/min
Average cathodic current density: 0.2A/cm2 f
ton/toff 8msec/2msec
Frequency: 100 Hz
Duty Cycle: 80%,
Deposition time: lhour
Deposition rate: 0.125mm/hr
Electrolyte temperature: 60°C
Electrolyte circulation rate: 10ml solution per min per cm2 anode area or 220ml
solution per min per Ampere average current applied
Electrolyte Formulation:
300 g/1 NiSO4-7H2O
45 g/1 NiClr6H2O
45 g/1 H3BO3
2 g/1 Sodium Saccharinate
3ml/lNPA-91
pH: 2.5
Average grain size: 19nm
Hardness: 600Vickers
Example 6:
Nanocrystalline Co was deposited using the same set up described under the fol-
lowing conditions:
Anode/anode area: graphite/3 5cm2
Cathode/cathode area: mild steel/8cm2
Cathode: stationary
Anode: oscillating mechanically automated at 50 oscillations per minute
Anode versus cathode linear speed: 125cm/min
Average cathodic current density: 0.10A/cm2
Wtoff: 2msec/6msec
Frequency: 125Hz
Duty Cycle: 25%
Deposition time: lhour
Deposition rate: 0.05mm/hr
Electrolyte temperature: 65°C
Electrolyte circulation rate: 10 mL solution per min per cm2 anode area or 440 ml
solution per min per Ampere average current applied
Electrolyte Formulation:
300 g/L CoSO4-7H2O
45 g/L CoCl2-6H2O
45 g/L H3BO3
2 g/L C7H4NO3SNa Sodium Saccharinate
0.1 g/L Ci2H25O4SNa Sodium Lauryl Sulfonate (SLS)
pH2.5
Average grain size: 13nm
Hardness: 600Vickers
Example 7:
Nanocrystalline Ni/20%Fe was deposited using the set up described before. A
1.5in wide band was plated on the OD of a 2.5in pipe by rotating the pipe along
its longitudinal axis while maintaining a fixed anode under the following condi-
tions:
Anode/anode area/effective anode area: graphite/3 5cm /undetermined
Cathode/cathode area: 2.5inch OD steel pipe made of 210A1 carbon
steel/undetermined
Cathode: rotating at 12 rpm
Anode: stationary
Cathode versus Anode linear speed: 20cm/min
Average cathodic current density: undetermined;
Total current applied: 3.5A
WW- 2msec/6msec
Frequency: 125Hz
Duty Cycle: 25%
Deposition time: lhour
Deposition rate: 0.05mm/hr
Electrolyte temperature: 55°C
Electrolyte circulation rate: 0.44 liter solution per min per Ampere applied
Electrolyte Formulation:
260 g/1 NiSO4-7H2O
45 g/1 NiCl2-6H2O
7.8 g/1 FeCl2-4H2O
45 g/1 H3BO3
30 g/1 Na3C6H5O7-2H2O, Sodium Citrate
2 g/1 Sodium Saccharinate
Iml/1NPA-91
pH3.0
Average grain size: 15 nm
Hardness: 750Vickers
Example 8:
A defect (groove) in a weldclad pipe section was filled in with nanocrystalline Ni
using the same set up as in Example 1. The groove was about 4.5cm long, 0.5cm
wide and had an average depth of approximately 0.175mm, although the rough
finish of the defect made it impossible to determine its exact surface area. The
area surrounding the defect was masked off and nano Ni was plated onto the de-
fective area until its original thickness was reestablished.
Anode/anode area: graphite/3 5 cm2
Cathode/cathode area: 1625/undetermined
Cathode: stationary
Anode: oscillating mechanically automated at 50 oscillations per minute
Anode versus cathode linear speed: 125cm/min
Average cathodic current density: undetermined
WW" 2msec/6msec
Frequency: 125Hz
Duty Cycle: 25%
Deposition time: 2hour
Deposition rate:0.087mm/hr
Electrolyte temperature: 55°C
Electrolyte circulation rate: 0.44 liter solution per min per Ampere average current
applied
Electrolyte Formulation:
300 g/1 NiSO4-7H2O
45 g/1 NiCl2-6H2O
45 g/1 H3BO3
2 g/1 Sodium Saccharinate
3ml/lNPA-91
pH3.0
Average grain size: 20nm
Hardness: 600Vickers
Microcomponents, having overall dimensions below l,000^im (lmm), are gaining
increasing importance for use in electronic, biomedical, telecommunication,
automotive, space and consumer applications. Metallic macro-system components
with an overall maximum dimension of lcm to over lm containing conventional
grain sized materials (l-l,000nm) exhibit a ratio between maximum dimension
and grain size ranges from 10 to 106. This number reflects the number of grains
across the maximum part dimension. When the maximum component size is re-
duced to below lmm using conventional grain-sized material, the component can
be potentially made of only a few grains or a single grain and the ratio between
the maximum micro-component dimension and the grain size ranges approaches
1. In other words, a single or only a few grains stretch across the entire part,
which is undesirable. To increase the part reliability of micro-components the
ratio between maximum part dimension and grain size ranges must be increased to
over 10 through the utilization of a small grained material, as this material class
typically exhibits grain size values 10 to 10,000 times smaller than conventional
materials.
For conventional LIGA and other plated micro-components, electrodeposition
initially starts with a fine grain size at the substrate material. With increasing de-
posit thickness in the growth direction; however, the transition to columnar grains
is normally observed. The thickness of the columnar grains typically ranges from
a few to a few tens of micrometers while their lengths can reach hundreds of mi-
crometers. The consequence of such structures is the development of anisotropic
properties with increasing deposit thickness and the reaching of a critical thick-
ness in which only a few grains cover the entire cross section of the components
with widths below 5 or 10 \im. A further decrease in component thickness results
in a bamboo structure resulting in a significant loss in strength. Therefore the
microstructure of electrodeposited micro-components currently in use is entirely
incommensurate with property requirements across both the width and thickness
of the component on the basis of grain shape and average grain size.
Heretofore, parts made of conventionally grain-sized materials that have been
known to suffer from severe reliability problems with respect to mechanical prop-
erties such as the Young modulus, yield strength, ultimate tensile strength, fatigue
strength and creep behavior have been shown to be extremely sensitive to proc-
essing parameters associated with the synthesis of these components. Many of the
problems encountered are caused by incommensurate scaling of key microstruc-
tural features (i.e. grain size, grain shape, grain orientation) with the external size
of the component resulting in unusual property variations normally not observed
in macroscopic components of the same material.
Example 9:
Metal micro-spring fingers are used to contact IC chips with high pad count and
density and to carry power and signals to and from the chips. The springs provide
high pitch compliant electrical contacts for a variety of interconnection structures,
including chip scale semiconductor packages, high-density interposer connectors,
and probe contactors. The massively parallel interface structures and assemblies
enable high speed testing of separated integrated circuit devices affixed to a com-
pliant carrier, and allow test electronics to be located in close proximity to the
integrated circuit devices under test.
The micro-spring fingers require high yield strength and ductility. A 25 mm thick
layer of nanocrystalline Ni was plated on 500 mm long gold-coated CrMo fingers
using the following conditions:
Anode/anode area: Ni/4.5xl0-3cm2
Cathode/cathode area: Gold Plated CrMo/approximately 1 cm2
Cathode: stationary
Anode: stationary
Anode versus cathode linear speed: 0 cm/min
Average cathodic current density: 50mA/cm2
ton/toff: 10msec/20msec
Frequency: 33Hz
Duty Cycle: 33%
Deposition time: 120 minutes
Deposition Rate: 0.05mm/hr
Electrolyte temperature: 60°C
Electrolyte circulation rate: None
Electrolyte Formulation:
300 g/1 NiSO4-7H2O
45 g/1 NiCl2-6H2O
45 g/1 H3BO3
2 g/1 Sodium Saccharinate
3ml/lNPA-91
pH3.0
Average grain size: 15-20nm
Hardness: 600Vickers
The nano-fingers exhibited a significantly higher contact force when compared to
"conventional grain-sized" fingers.
WE CLAIM :
1. A process for cathodically electrodepositing a selected metallic material
such as described herein on a permanent or temporary substrate in
nanocrystalline form at a deposition rate of at least 0.05 mm/h, comprising:
providing an aqueous electrolyte such as described herein containing ions
of said metallic material, agitating the electrolyte at an agitation rate in the range
of 0.0001 to 10 liter per min and per cm2 anode or cathode area or at an agitation
rate in the range of 1 to 750 milliliter per min and per Ampere, and
passing single or multiple cathodic-current pulses between said anode
and said cathode.
2. The process as claimed in claim 1, wherein a duty cycle is in the range of
5 to 100%.
3. The process as claimed in any preceding claim, wherein a frequency of
the cathodic-current pulses is in the range of 0 to 1000 Hz.
4. The process as claimed in any preceding claim, wherein the single or
multiple cathodic-current pulses between said anode and said cathode have a
peak current density in the range of about 0.01 to 20 A/cm2,
5. The process as claimed in claim 4, wherein the peak current density of the
cathodic-current pulses is in the range of about 0.1 to 20 A/cm2.
6. The process as claimed in claim 5, wherein the peak current density of the
cathodic-current pulses is in the range of about 1 to 10 A/cm2.
7. The process as claimed in any preceding claim, wherein said selected
metallic material is (a) a pure metal selected from the group consisting of Ag, Au,
Cu, Co, Cr, Ni, Fe, Pb, Pd, Rt, Rh, Ru, Sn, V, W, Zn, or (b) an alloy containing at
least one of the elements of group (a) and alloying elements selected from the
group consisting of C, P, S and Si.

8. The process as claimed in any preceding claim, wherein a tcathodic-on- time
period is in the range of 0.1 to 50 msec, a tcathodic-off time period is in the range of
0 to 500 msec and a tcathodic-on- time period is in the range of 0 to 50 msec.
9. The process as claimed in claimed in claims 2 to 8, wherein the duty cycle
is in the range of 10 to 95%.
10. The process as claimed in claim 9, wherein the duty cycle is in the range
of 20 to 80%.
11. The process as claimed in any preceding claim, wherein the deposition
rate is at least 0.075 mm/h.
12. The process as claimed in claim 11, wherein the deposition rate is at least
0.1 mm/h.
13. The process as claimed in any preceding claim, which comprises agitating
the electrolyte at an agitation rate in the range of I to 500 milliliter per min and
per Ampere.
14. The process as claimed in any preceding claim, which comprises agitating
the electrolyte by means of pumps, stirrers or ultrasonic agitation.
15. The process as claimed in any preceding claim, which comprises a
relative motion between anode and cathode.
16. The process as claimed in claim 15, wherein the speed of the relative
motion between anode and cathode ranges from 0 to 600 m/min.
17. The process as claimed in claim 16, wherein the speed of the relative
motion between anode and cathode ranges from 0.003 to 10 m/min.
18. The process as claimed in claims 15 to 17. wherein the relative motion is
achieved by rotation of anode and cathode relative to each other.
19. The process as claimed in claim 18, wherein a rotational speed of rotation
of anode and cathode relative to each other ranges from 0.003 to 0.15 rpm.
20. The process as claimed in claim 19, wherein a rotational speed of rotation
of anode and cathode relative to each other ranges from 0.003 to 0.05 rpm.
21. The process as claimed in claims 15 to 17, wherein the relative motion is
achieved by a mechanized motion generating a stroke of the anode and the
cathode relative to each other.
22. The process as claimed in claims 15 or 21, wherein the anode is wrapped
in an absorbent separator,
23. The process as claimed in any preceding claim, wherein said electrolyte
contains a stress relieving agent or a grain refining agent selected from the
group of saccharin, coumarin, sodium lauryl sulfate and thiourea.
24. The process as claimed in any preceding claim, wherein said electrolyte
contains particulate additive such as described herein selected from pure metal
powders, metal alloy powders or metal oxide powders of Al, Co, Cu. In. Mg, Ni,
Si, Sn, V and Zn, nitrides of Al, B and Si, carbon C (graphite or diamond),
carbides of B, Bi, Si, W, or organic materials such as PTFE and polymers
spheres, whereby the electrodeposited metallic material contains at least 5% of
said particulate additives.
25. The process as claimed in claim 24. wherein the electrodeposited metallic
material contains at least 10% of said particulate additives.
26. The process as claimed in claim 24, wherein the electrodeposited metallic
material contains at least 20% of said particulate additives.
27. The process as claimed in claim 24 wherein the electrodeposited metallic
material contains at least 30% of said particulate additives.
28. The process as claimed in claim 24, wherein the electrodeposited metallic
material contains at least 40% of said particulate additives.
29. The process as claimed in claim 24, wherein the particulate additives
average particle size is in the range of 100 nm to 10 mm.
30. The process as claimed in claim 29, wherein the particulate additives
average particle size is in the range of 500 nm to 10 mm.
31. The process as claimed in claim 30, wherein the particulate additives
average particle size is in the range of 1000 nm to 10 um.
32. The process as claimed in claim 31, wherein the particulate additives
average particle size is below 100 nm.
33. Microcomponent produced by a pulse electrodeposition process as
claimed in claims 1 to 28. having a maximum dimension of 1 mm. an average
grain size equal to or smaller than 1000 nrn the ratio between the maximum
outside dimension of the microcomponent part and the average grain size being
greater than 10.
34. Microcomponent as claimed in claim 33, wherein the ratio between the
maximum outside dimension of the microcomponent part and the average grain
size being in excess of 100.
35. Microcomponent. as claimed in claims 33 and 34, which has an equiaxed
micro-structure.
The invention discloses a process for forming coatings or free-standing
deposits of nano-crystalline metals, metal alloys or metal matrix composites. The
process employs drum plating or selective plating processes involving pulse
electrode-position and a non-stationary anode or cathode. Novel nano-crystalline
metal matrix composites and micro components are disclosed as well. Also
described is a process for forming micro-components with grain sizes below
1000 nm.

Documents:

1651-KOLNP-2004-(19-01-2012)-FORM 27.pdf

1651-KOLNP-2004-FORM 27.pdf

1651-kolnp-2004-granted-abstract.pdf

1651-kolnp-2004-granted-assignment.pdf

1651-kolnp-2004-granted-claims.pdf

1651-kolnp-2004-granted-correspondence.pdf

1651-kolnp-2004-granted-description (complete).pdf

1651-kolnp-2004-granted-drawings.pdf

1651-kolnp-2004-granted-examination report.pdf

1651-kolnp-2004-granted-form 1.pdf

1651-kolnp-2004-granted-form 13.pdf

1651-kolnp-2004-granted-form 18.pdf

1651-kolnp-2004-granted-form 3.pdf

1651-kolnp-2004-granted-form 5.pdf

1651-kolnp-2004-granted-gpa.pdf

1651-kolnp-2004-granted-reply to examination report.pdf

1651-kolnp-2004-granted-specification.pdf

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Patent Number

225421

Indian Patent Application Number

1651/KOLNP/2004

PG Journal Number

46/2008

Publication Date

14-Nov-2008

Grant Date

12-Nov-2008

Date of Filing

03-Nov-2004

Name of Patentee

INTEGRAN TECHNOLOGIES, INC.

Applicant Address

1 MERIDIAN ROAD, TORONTO, ONTARIO M9W 4Z6

Inventors:

#	Inventor's Name	Inventor's Address
1	PALUMBO GINO	9 TYLER PLACE, TORONTO, ONTARIO M9R 1L8
2	MCCREA JONATHAN	709 MARKHAM ST., APT.1, TORONTO, ONTARIO M6G 2M2
3	HIBBARD GLENN D	674 SHAW ST., TORONTO, ONTARIO M6G 3L7
4	GONZALEZ FRANCISCO	18 LARKIN AVENUE, TORONTO, ONTARIO M6S 1L8
5	TOMANTSCHGER KLAUS	6197 MONTEVIDEO RD., MISSISSAUGA, ONTARIO L5N 2E8
6	ERB UWE	33 WOOD STREET, SUITE 1608, TORONTO, ONTARIO M4Y 2P8
7	BROOKS IAIN	33 GLEBE RD. E., APT. 3, TORONTO, ONTARIO M4S 1N7

PCT International Classification Number

C25D 1/04

PCT International Application Number

PCT/EP2002/007023

PCT International Filing date

2002-06-25

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1		1900-01-01	Antigua And Barbuda