Electroplating Process for the Anti-Friction Layer of Sliding Bearings

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The electroplating process of the anti-friction layer in sliding bearings is a critical step that ensures long-term performance and durability. When applying the anti-friction coating directly onto the fabric metal, tin tends to diffuse into the base material over time. As the bearing operates, the tin content in the coating may drop below 6% (by weight), while the copper-based alloy remains as an aluminum-based alloy. This can lead to the formation of brittle intermetallic compounds like Cu₃Sn between the tin and copper, which degrades mechanical properties and weakens the structural integrity of the bearing. To prevent this issue, it is common practice to deposit a thin layer of nickel or a nickel-based alloy between the fabric material and the anti-friction layer. This barrier layer helps control tin diffusion and maintains the stability of the coating composition during operation. It also enhances the running-in characteristics of the bearing at the start of its service life. The use of tin or lead-tin alloy protective layers not only provides corrosion resistance but also ensures a more uniform distribution of tin within the anti-friction layer. Since these layers do not contain copper, they are relatively soft, allowing for better initial wear-in performance. This makes them ideal for applications where smooth operation and low friction are essential. The development of anti-friction coatings for bearings has a long history. In 1920, Groov (J. Grooff) filed the first patent for electroplating lead-tin alloys, initially used for torpedo gas cylinders. By the 1940s, the technique was applied to bearing pads. In 1952, Schults proposed a patent for electroplating lead-tin-copper ternary alloys on aluminum and aluminum-silicon substrates. Later, Schoefe introduced the use of lead-tin-copper alloys for bushings. In 1976, Jong Sang Kim, Su Il Pyun, and Hyo Geun Lee published a paper titled "Pore-Orientation and Microscopic Tracing of Lead-Tin-Copper Electroplating Layers." In 1980, Beebe introduced a process for electroplating copper-containing ternary alloys with 2–3% copper and 9–12% tin, with a coating thickness of 15μm. In 1982, Waterman et al. developed a method to replace copper ions (Cu²⁺) in ternary alloy plating baths, further improving the quality and consistency of the coating. This article explores the key steps and challenges involved in the electroplating of anti-friction layers for sliding bearings, emphasizing the importance of proper coating design and application techniques. Bearing Related Knowledge - Repair methods for imported bearings - Features of deep groove ball bearings - Key considerations when purchasing imported bearings - Temperature issues in SKF bearings and causes of overheating - Proper techniques for assembling and disassembling bearings For more information, visit [China Bearing Network](http://www.chinabearing.net). Previous: Analysis of electric fan bearings and preloading techniques – The role of bearing brackets and layout features.

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