Introduction of electroplating process of anti-friction layer of sliding bearing

The electroplating process of the anti-friction layer of the sliding bearing: If the anti-friction coating is directly electroplated on the lining metal, the tin in the coating is easy to diffuse to the lining, so that after the bearing bush works for a period of time, the tin content in the coating drops to less than 6% (quality ). And whether it is a copper-based alloy lining or an aluminum-based alloy lining, it contains a certain amount of copper, and the tin diffused into the lining can form a brittle intermetallic compound (Cu3Sn) with copper. This not only reduces the mechanical properties of the coating, but also destroys the structure of the lining, so as to reduce the overall mechanical properties of the bearing bush. The solution to this problem is to electroplate a nickel or nickel-based alloy barrier layer (also called a gate layer or barrier layer) between the lining material and the antifriction bottom layer to inhibit the diffusion of tin into the lining [1~2].

1. In addition to the anti-corrosion effect of the tin or lead-tin alloy protective layer, the tin content in the anti-friction layer can be supplemented by diffusion during the working period of the bearing bush, so that the content of each component is relatively stable status. In addition, because this protective layer does not contain copper and is relatively soft, the bearing bush can meet the requirements of good running-in in the early stage of work. This article mainly investigates the electroplating process of bearing anti-friction layer. (Guide: Introduction to the aluminum profile spraying process)

2. Development history: The research of anti-friction coatings started earlier in foreign countries. In 1920, J. Grooff proposed the first patent for the electroplating of lead-tin alloy, which was used for electroplating of the inner surface of navy torpedo gas cylinders, and began to be used for electroplating of bearing bushes in the 1940s. In 1952, Schults (Schults) proposed a patent for the electroplating of lead-tin-copper ternary alloy on aluminum and aluminum-silicon (AlSi) alloy substrates. In 1953, Schoefe published a review of the use of lead-tin-copper alloys in bearing bushes. In 1976, JongSangKim, SuιιPyunandHyoGeunLee published a paper on the crystal plane orientation and micro-morphology of the lead-tin-copper electroplating layer [7]. In 1980, Beebe proposed a ternary alloy electroplating production process with a copper content of 2~3% (mass), tin 9-12% (mass), and the rest is copper, with a coating thickness of 15μm. In 1982, Waterman and others proposed a solution to the replacement of copper ions (Cu2+) in the ternary alloy electroplating bath.

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