Title of Invention

DEVICE FOR GAS DYNAMIC DEPOSITION OF POWDER MATERIALS

Abstract

ABSTRACT The present invention relates to a gas dynamic spray device for depositing a large variety of coatings by spraying materials in powder form. The objective of this invention is to provide a device having enhanced functional and technological capabilities compared to previously disclosed gas dynamic spray devices. The device disclosed herein yields higher deposition efficiency of sprayed powder materials, thereby making the device and the process of deposition using the device economical. The device also permits coating of a wider range of powders (metal & metal alloys, cermets, metal polymer blends etc.) and can also be effectively used as a manual coating tool. The invention also relates to a method of depositing powder materials employing the above device. The device presented has utility in a wide spectrum of engineering industries viz. Powder generation, automotive, metallurgical, electrical etc. for producing coatings for different functional applications.

Full Text

This invention relates to a device for the deposition of powder materials. This invention particularly relates to a gas dynamic spray device for depositing powder materials. The device of the present invention is useful in engineering industry, the power industry, metallurgy and other industrial spheres to produce one- and multi-layer coatings for different functional purposes. The invention also relates to a method of depositing powder materials employing the device. Devices useful for gas dynamic spray including a powder feeder and supersonic nozzle unit located in one body, and a control console of powder particle velocity including blank-control elements for a component concentration defining (helium, hydrogen) in the working mixture with air are well known. Reference, in this context, may be made to Russian Patent No. 1618777, MKIC 23 4/20, 1984. The disadvantages of the device disclosed in the above said patent are its technological and functional limitations, particularly low output, constraints on powder materials types that can be deposited due to the low temperature maintained during the coating process and inability to change elastic characteristics of the powder material as there is no a facility in the system to effect the change, for example, a gas heater. Besides, the presence of a feeder with driver and nozzle unit in the form of manual tool in a single whole body makes the device heavy and increases its size. Consequently, the process of coating employing the device is of limited utility and inconvenient to operate. Mother type of gas dynamic spray device has been disclosed in another Russian Patent No. Patent RF No. 1674585, MKI C 23 26/00,1989, which comprises a source of compressed gas, a supersonic nozzle imit and a working gas heater. The disadvantage connected with this device is that the heater is in the form of a long electric conduction pipe the inside part of which is a 3neumatic channel of the working gas, which causes increase of the heater size and weight. \ccordingly, the device cannot be used as a manual handy tool. Besides, the powder used for coating is introduced only in the sub-critical region of the supersonic nozzle, which is not always appropriate, and the device does not permit a nozzle operation mode change that is desirable vhile using some types of powder materials for coating. fAnother patent bearing number RU 2 075 535 CI titled "Equipment for Spraying Coatings on Internal Surfaces of Pipes" filed by the same applicants refers to an invention pertaining to a spray gun mounting and moving apparatus for providing coatings on internal surfaces of pipes only. The patent mainly describes a gun mounting & moving mechanism to enable deposition of coatings on internal surfaces of pipes using a cold gas-dynamic spraying system, which consists of supersonic nozzle, pre-chamber, gas heater. The gun mounting &. moving mechanism is connected by means of an air duct with powder feeder and control panel installed on carriage of moving device. The gripping and turning mechanism connects the pipe to be coated with an isolating chamber and suction system, and forms a dust-isolating channel allowing collection and repeated use of excessive powder. The major disadvantages of the mechanism referred to in the patent are: • Meant for depositing on internal surface of the pipe • Heavy weight and not possible to operate by hand • Limited choice of depositing materials • Difficulties in cleaning and changing of the powder Considering the importance of the gas dynamic spray technique in depositing a variety of protective coatings on various substrates which are required in many engineering industries viz. power, automotive, metallurgy, electrical and other industrial spheres to produce one- and multi¬layer coatings for different functional purposes to enhance component durability and performance, there is a need to develop a device which is handy, efficient and cost effective. Therefore, the main objective of the present invention is to provide a device for depositing powder materials, the resulting product being useful for various engineering applications. Another objective of the present invention is to provide a device for depositing powder materials having enhanced functional and technological capabilities such as coating on open places, coating regions which are difficult to access, coating regions having semi-closed volumes and coating the inside of a reservoir etc. Still another objective of the present invention is to provide a device for depositing powder materials, which results in saving of powder materials used for coating through enhanced deposition efficiency, thereby making the device, and the process of coating using the device, economical. Yet another objective of the present invention is to provide a device for depositing powder materials which can be used for coating a much wider range o/powder materials than the previously disclosed gas dynamic spray devices. Further objective of the present invention is to provide a device for depositing powder materials, which is very handy and lighter its effective use as a manual coating tool. The above objectives of the present invention are achieved by providing the device in the form of two blocks connected by flexible pneumatic-electrical cables. One of these is a spray block, which is in the form of a manual handy tool with remote control including a supersonic nozzle that is connected with a gas heater, the metallic body of which is provided with an electro¬thermal-insulator with through parallel pneumatic channels and built-in heater elements. The total pneumatic channels flow section is designed for the condition Re > 2300, where Re- the Reynolds number, and the nozzle is placed with possibility to change the position relative to its Eixis and connected with the powder feeder with a flexible pneumatic cable, and a checker located along the axis with possibility to introduce a gas-powder mixture into the sub-critical as well as the super-critical nozzle section. The other block is a block of spray control and monitoring. It includes the electronic request systems, automatic temperature control of the heater working gas by control of electric power supplied to the heater elements by an electric cable and also the distant control element^br the electric driver of the powder feeder. The above characteristics are not found in other gas dynamic techniques disclosed and available in the technical literature. Hence, the present device is being presented as an invention. The device of the present invention is shown in the drawings accompanying this specification. In the drawings, Figure 1 - shows the plan view of the device of the present invention Figure 2 - shows the constructional features of the heater incorporated in the device Figure 3 - shows the construction of the nozzle According to the present invention, there is provided a gas dynamic spray device for depositing powder materials comprising two blocks (1 & 14) connected by flexible pneumatic-electric cables (12&17), one of the blocks being a spray block (1) provided with a distant control and comprises of a gas heater unit (2) having a metallic body (3) housing an electro-thermal insulator (4), pneumatic channels (5) and heater elements (6), the gas heater unit being also provided with a branch pipe (7) at the top for the supply of the working gas, the gas heater unit being further provided with a thermal probe (8), a switch on button {9) for a distant powder feeder driver (10) and a nozzle (11), the nozzle being fixed to the gas heater imit (2), the nozzle being placed in such a>way that it is capable of changing its position relative to its axis, and being also connected to the powder feeder (10) by a flexible pneumatic cable (12) and a checker (13) which is directed along the nozzle axis to enable introduction of the gas-powder mixture into the sub-critical as well as the super-critical nozzle section. The second block (14) consisting of a spray control and monitoring unit, comprising of an electronic system (15) being coimected to the heater elements (6) of the first block (1) by an electric cable (16), also including the blast control elements powered by the compressed gas source, which are connected by pneumatic cables (17) with the gas heater (2) through the branch pipe (7) and also being connected to the powder feeder (10) through pneumatic cable (18) with manometers, this second block additionally including a gas temperature indicator (19) connected with a thermal probe (8). The constructive peculiarities of the gas heater (2), namely, a number of pneumatic channels (5), their diameter and length, provide intensive heating including the most efficient heat transfer from the heater elements (6) at the cost of organizing transitional or turbulent regime of their overflow with their surface temperature saving in the range of available values (at operation) for materials of heat elements (6). This, in particular, increases its useful life. The possibility to change the position of the nozzle (especially when using a planar nozzle) relative to its axis allows manual tool operation to provide an optimal incident angle of the gas-powder jet on the coating surface to control coating quality and to ensure high productivity of the coating process. The peculiarities of powder introduction (see Fig.3) provide for uniform spraying of both metal powders (for which introduction into sub-critical region is preferable) as well various other powder mixtures including cermet materials, metal-polymer blends etc. (for which introduction into supercritical region of the nozzle is preferred). This can significantly widen the technological capabilities of the device. The reduction in size and weight of the spray block (1) are due to the efficient construction of the gas heater (2), i.e. availability of several pneumatic channels in a thermal insulator (5) (50 times shorter than a prototype), which also leads to lower the working gas losses. Appropriate selection of number of channels and their diameter, taking into consideration filling up the flow section by heater elements (6), allows parameters for gas flow over the heater elements to be set in a manner such that the Reynolds number (Re) assimies a value greater than 2300. This significantly enhances heat pick-up due to the transitional or turbulent flow. Effective heat removal from the heater elements (6) to the working gas also allows the temperature of heater elements to be kept low (in comparison with the prototype) and, therefore, enables supply of higher power (if necessary) to provide conditions of high heat flow. This permits increase of productivity on the whole. The heater elements are made in the form of spiral from an alloy of high electrical resistance and provided from a net work of 220/3 80V. The device covered by the present invention works as follows. A compressed gas and electric power are supplied to the control and monitoring block (14). The required value of the working gas temperature is controlled by electronic system (15) that is connected to electro-heater elements (6) through an electric cable (16). The compressed gas is supplied by blast-control units to the gas heater (2) through a pneumatic cable (17) and branch pipe (7), and to the powder feeder (10) through pneumatic cable (18) to establish the necessary gas pressure. When the necessary pressure, controlled by manometers, is attained in the powder feeder (10) and gas heater (2), electric power is supplied from the electronic system (15) by an electric cable (16). Travelling through the heater pneumatic channels (5), the working gas enters the supersonic nozzle (11) where it is accelerated up to a supersonic velocity and exits into the atmosphere. When the device comes to the stationary operating mode in respect of temperature and pressure of the working gas, the powder-feeder electric driver (10) is switched on by pushing the distant control button (9). As a result, the gas-powder mixture is introduced into the nozzle (11) through the pneumatic cable (12) using the checker (13) axially directed to the sub-critical region (Fig.3a) or super-critical region (Fig.Sb). The sprayed powder in the nozzle (U) is accelerated and heated by a gas jet from the heater (2) and the high-velocity powder stream impacts on the substrate in question to form a coated product. In the device, a deviation of the working gas temperature by 1-2% (depending on the circuit sensitivity) from the set value is automatically corrected. The electronic system (15) either discoimects the gas heater (2) (when there is an increase of temperature) or cuts it in (when there is a decrease of temperature) by a signal from the thermal probe (8) to automatically provide the set value. The device of the present invention on the whole, performed in the form of two blocks coimected functionally by the flexible elements, provides a facility to work at a considerable distance one block from the other and from a source of compressed gas and electric power. The device enables spraying of a wide variety of coatings on inaccessible elements of constructions, semi-closed volumes and reservoirs, including repair and re-construction works. Advantages of the invention The device facilitates depositing powders by using two blocks separated by a considerable distance. One block is in the form of a manual handy tool while the other block is for spray control and monitoring. The device facilitates deposition of powders on inaccessible parts of constructions, semi-closed volumes and reservoirs, including of repair and re-construction works. I The device has enhanced functional and technological capabilities. // is capable of depositing a wide range of powder materials (metal & metal alloys, cermet, metal-polymer blends etc.) on a variety of substrate materials (metal & metal alloys, a range of non-metals etc.). 4. The device helps in saving powder materials used for deposition because of the enhanced deposition efficiency that it permits, thereby making the device and the process of deposition using the device economical. 5. The device can be used as a handy manual tool and is convenient to operate. We Claim: 1. A Gas dynamic spray device for depositing powder materials, comprising two blocks (1 & 14) connected by flexible pneuinatic-electric cables (12«&17), one of these blocks being a spraying block (1), provided with a distant control and comprises a gas heater unit (2) having a metallic body (3) housing an elected thermal insulator (4), pneumatic channels (5) and heater elements (6), the gas heater unit being also provided with a branch pipe (7) at the top for the supply of gas, the gas heater unit being also provided with an electro-thermal insulator (8) a switch-on button (9) for a distant powder feeder driver (10), and a nozzle (11), the nozzle bay fixed to the gas heater unit (2) in such a way that it is capable of changing its position relative to its axis, the nozzle being also connected to the powder feeder (10) by a flexible pneumatic cable (12) and a checker (13) which is directed along the nozzle axis to enable introduction of the gas-povvder mixture into the sub-critical as well as the super¬critical nozzle sections, the second block (14), which is a spray control and monitoring unit, comprises of a electronic system (15), the second block (14) consisting of the spray control and monitoring unit, comprising of an electronic system (15) being cormected to the heater elements (6) of the first block (1) by an electric cable (16), also including the blast control elements powered by the compressed gas source, which are cormected by pneumatic cables (17) with the gas heater (2) through the branch pipe (7) and also being cormected to the powder feeder (10) through pneimiatic cable (18) with manometers, the second block additionally including a gas temperature indicator (19) cormected with a thermal probe (8) 2. A device as claimed in claim 1 wherein the heater elements are made in the form of spiral from an alloy of high electrical resistance and powered from a network of 220/380 V. 3. A device for depositing powder materials substantially as described in Figs.l to 3 of the drawing accompanying this specification

Documents:

0944-mas-2001 abstract-duplicate.pdf

0944-mas-2001 abstract.pdf

0944-mas-2001 claims-duplicate.pdf

0944-mas-2001 claims.pdf

0944-mas-2001 correspondence-others.pdf

0944-mas-2001 correspondence-po.pdf

0944-mas-2001 description (complete)-duplicate.pdf

0944-mas-2001 description (complete).pdf

0944-mas-2001 drawings-duplicate.pdf

0944-mas-2001 drawings.pdf

0944-mas-2001 form-1.pdf

0944-mas-2001 form-19.pdf

0944-mas-2001 form-3.pdf