| Title of Invention | SLIDING ELEMENT AND PROCESS FOR ITS PRODUCTION |
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| Abstract | A sliding element with a formative support layer and an electrodeposited sliding layer thereon which is formed from an alloy with the alloy constituents tin, antimony and copper, the fractions of which in % by weight are antimony 5 to 20%, copper 0.5 to 20%, remainder tin, where the content of lead is < 0.7% and the total content of other fractions is < 0.5%, is improved with regard to the properties of its sliding bearing layer in that in the sliding bearing layer, the tin crystals are predominantly globular-shaped. This is possible through an electrolytic deposition with an electrolyte which has, as wetting agent, preferably a C13C15-oxo alcohol, a C16C18-fatty alcohol or a C13-oxo alcohol with a degree of ethoxylation between 10 and 30, where the deposition composition and rate is adjusted through the addition of large-molecular auxiliaries. |
| Full Text | Sliding element: and process for its production The invention relates to a sliding element with a formative support layer and an electrodeposited sliding layer thereon which is formed from an alloy with the alloy constituents tin, antimony and copper, the fractions of which in % by weight are antimony 5 to 20%, copper 0.5 to 20%, remainder tin, where the content of lead is content of other fractions is The invention also relates to a process for producing a sliding element by electrolytically applying a sliding layer of an alloy with the alloy constituents tin, antimony and copper to a formative support layer. A sliding bearing layer of the type mentioned at the start is known, for example, through DE 82 06 353 U1. Here, the sliding bearing layer is electrodeposited onto a support layer which is located on a steel support pan. The sliding bearing layer has a thickness of about 20 µm. It is also desired that the copper content of the sliding bearing layer is below 0.5% by weight because a higher copper content, according to the objection, has a harmful effect on the fatigue strength of the sliding bearing layer. In practice, the known sliding bearing layer is produced electrolytically using a wetting agent which is sold under the name Igepal CO 880 by Rhodia Novecare and is a nonylphenol ethoxylate with 30 ethoxy (EO) units. The electrolytic layer construction takes place with a columnar crystallization and permits no useful layers which are essentially larger than 20 µm. Consequently, the service life of the sliding bearing layers is naturally very restricted on account of the unavoidable abrasion. The object of the present invention is to provide a sliding bearing layer with improved use properties. According to the invention, this object is achieved with a sliding bearing of the type mentioned at the start in that in the sliding bearing layer the tin crystals are predominantly globular-shaped. The object is also achieved according to the invention by a process of the type mentioned at the start charac- terized by the use of an electrolyte based on fluoroboric acid and metal fluoroborates in aqueous solution, which has the following ingredients: and also possible auxiliaries which do not pass into the sliding bearing layer to be produced, where, using at least one auxiliary on the basis of its molecular size, the migration rate of the ions of the elements forming the sliding layer is controlled such that predominantly globular-shaped tin crystals are formed. It has been found that by producing the sliding layer in a manner such that the majority of the tin crystals (> 50%) have a globular structure - and not a needle- shaped or columnar structure as hitherto - an extra- ordinarily uniform structure of the sliding layer is achieved. The globular structure of the tin crystals can be achieved by controlling the deposition rate by adding large-molecular auxiliaries, such as, in parti- cular, gelatine and/or resorcinol, as a result of which the composition of the sliding layer and the structure which forms is adjusted in the desired manner. In this connection, the use of wetting agents which are formed by a C13C15-OXO alcohol, a C16C18-fatty alcohol or a C18- oxo alcohol with a degree of ethoxylation between 10 and 30 is expedient. A preferred wetting agent is an oxo alcohol with a degree of ethoxylation of 20. The structure formed according to the invention has an extraordinarily uniform structure in which uniform and likewise essentially globular antimony-rich deposits arise in uniform distribution. Consequently, a signi- ficantly more stable sliding layer is achieved which can also be used in large thicknesses of clearly 20 µm, in particular above 50 µm, in a manner which is stable, homogeneous and free from delaminations. Thus, sliding layers with a thickness of, for example, 500 µm can be constructed directly. In connection with structures and crystallization, "globular" particles are to be understood as meaning those whose particle size has a ratio of the largest dimension to the smallest dimension of Suitable wetting agents are sold in particular under the brand Lutensol by BASF. Of particular suitability are the wetting agents (EO = degree of ethoxylation): Lutensol AO 11 C13C15-oxo alcohol with 11 EO Lutensol AO 30 C13C15-OXO alcohol with 30 EO Lutensol AT 13 C16C18-fatty alcohol with 13 EO Lutensol AT 25 C16C18-fatty alcohol with 25 EO Lutensol TO 12 C13-oxo alcohol with 12 EO Lutensol TO 20 C13-oxo alcohol with 20 EO Lutensol ON 110 C13-oxo alcohol with 20 EO. The wetting agents Lutensol ON 110 and TO 20 have proven to be particularly suitable for producing the sliding bearing layer according to the invention and avoiding dendrite formation. Lutensol ON 110, i.e. a C13-OXO alcohol with 20 EO is particularly preferred. In a preferred embodiment of the sliding element according to the invention, the copper fraction in the sliding layer is between 3 and 6%. Contrary to the teaching of the utility model 82 06 353 U1, the increased copper fraction leads to an increase in the load-bearing capacity and in the fatigue strength of the sliding layer. According to the invention, there- fore, a copper fraction can be provided which is not only above the advantageously desired copper content of generally considered in the cited specification of at most 2%. The preferred antimony fraction in the sliding layer is between 8 and 17% by weight. The preferred copper fraction is between 2 and 7%. The fraction of the globular-shaped tin crystals in the sliding layer is preferably more than 70%, further preferably more than 80%. The sliding element according to the invention can be a customary cylindrical sliding bearing sleeve, a section of such a sliding bearing sleeve or else an essentially flat element. The formative support element consists of metal and can conventionally consist of steel with a plated bearing metal which has emergency lubricating properties. The sliding layer according to the invention is applied to this support element. Since the sliding layer according to the invention with a large layer thickness can be applied with a high stability, it is also possible to omit the bearing metal layer and to directly apply the sliding layer to a formative support element made of metal. According to the invention, the experimental results below for working examples are illustrated: A base electrolyte (without wetting agent) with the following composition was prepared: The resorcinol and the gelatine are auxiliaries which influence the composition and the deposition rate of the layer which is formed. Resorcinol essentially influences the composition while the large molecules of gelatine influence the crystal structure, the roughness and the layer composition. For this purpose, the gelatine concentration can expediently be adjusted to between 0.1 and 0.5 g/1. The electrolytic deposition was carried out using a constant current of 2 A/dm2 using tin electrodes at a bath temperature of from 22 to 24°C. The steel substrate has been precoated (electrolyti- cally) with a nickel layer. The SnSbCu depositions were performed either on rotating rod electrodes or on sheet metal strips. The deposition on rotating rod electrodes avoids uncontrolled dendrite growth which would have adversely affected the experimental results. Compared with a reference standard wetting agent as has hitherto customarily been used, all of the investigated wetting agents lead to a different structure during deposition. In particular, the dendrite growth is considerably reduced. In this regard, the use of the wetting agents Lutensol ON 110 and Lutensol TO 20 is particularly advantageous. Using the mentioned wetting agents, in particular using the preferably used wetting agents, a sliding layer is thus realized which differs from the sliding layers to date as regards its crystalline structure and offers considerable handling advantages. In particular, the layer can be constructed with virtually any desired thicknesses, thereby achieving freedom, which is hitherto not being present, with regard to the layer thicknesses and the construction of the sliding elements. Patent claims 1. Sliding element with a formative support layer and an electrodeposited sliding layer thereon which is formed from an alloy with the alloy constituents tin, antimony and copper, the fractions of which in % by weight are antimony 5 to 20%, copper 0.5 to 20%, remainder tin, where the content of lead is and the total content of other fractions is bearing layer, the tin crystals are predominantly globular-shaped. 2. Sliding element according to Claim 1, charac- terized in that the sliding bearing layer is coated with a thickness > 20 µm. 3. Sliding element according to Claim 1 or 2, charac- terized in that the copper fraction in the sliding bearing layer is between 3% and 6%. 4. Sliding element according to one of Claims 1 to 3, characterized in that the antimony fraction in the sliding bearing layer is between 8 and 17%. 5. Sliding element according to one of Claims 1 to 4, characterized in that the copper fraction is between 0.5 and 7%. 6. Process for producing a sliding element by electrolytically applying a sliding layer of an alloy with the alloy constituents tin, antimony and copper to a formative support layer, charac- terized by the use of an electrolyte based on fluoroboric acid and metal fluoroborates in aqueous solution, which has the following ingre- dients: Sn2+ 15 to 80 g/1 Sb3+ 0.5 to 20 g/1 Cu2+ 0.05 to 10 g/1 HBF4 20 to 200 g/1 wetting agent 0.05 to 5 g/1 and also possible auxiliaries which do not pass into the sliding bearing layer to be produced, where, using an auxiliary on the basis of its molecular size, the migration rate of the ions of the elements forming the sliding layer is controlled such that predominantly globular-shaped tin crystals are formed. 7. Process according to Claim 6, characterized in that the wetting agent is a C13C15-oxo alcohol, a C16C18-fatty alcohol or a C18-oxo alcohol with a degree of ethoxylation between 10 and 30. 8. Process according to Claim 7, characterized in that the wetting agent used is an oxo alcohol with a degree of ethoxylation of 20. 9. Process according to Claim 6 or 8, characterized in that the wetting agent is used in a concentra- tion of from 0.1 to 3.0 g/1. 10. Process according to one of Claims 6 to 9, charac- terized in that the electrolytic deposition rate is adjusted to from 0.3 to 1.5 µm/min. A sliding element with a formative support layer and an electrodeposited sliding layer thereon which is formed from an alloy with the alloy constituents tin, antimony and copper, the fractions of which in % by weight are antimony 5 to 20%, copper 0.5 to 20%, remainder tin, where the content of lead is the total content of other fractions is improved with regard to the properties of its sliding bearing layer in that in the sliding bearing layer, the tin crystals are predominantly globular-shaped. This is possible through an electrolytic deposition with an electrolyte which has, as wetting agent, preferably a C13C15-oxo alcohol, a C16C18-fatty alcohol or a C13-oxo alcohol with a degree of ethoxylation between 10 and 30, where the deposition composition and rate is adjusted through the addition of large-molecular auxiliaries. |
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| Patent Number | 271018 | |||||||||
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| Indian Patent Application Number | 1545/KOL/2008 | |||||||||
| PG Journal Number | 06/2016 | |||||||||
| Publication Date | 05-Feb-2016 | |||||||||
| Grant Date | 29-Jan-2016 | |||||||||
| Date of Filing | 08-Sep-2008 | |||||||||
| Name of Patentee | ZOLLERN BHW GLEITLAGER GMBH & CO. KG. | |||||||||
| Applicant Address | ALTE LEIPZIGER STRASSE 117-118 38124 BRAUNSCHWEIG | |||||||||
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| PCT International Classification Number | F16C33/12; F16C33/14; F16C33/04 | |||||||||
| PCT International Application Number | N/A | |||||||||
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