Precious metal plating, applications

Fig. 8.15 A facility for manual electroplating. The modular equipment is suitable for both rack- and barrel-plating. Construction materials include corrosion-resistant PVC-clad steel and stainless steel. Applications include precious-metal plating in the electronics industry. Power supply and control circuitry are located above the tanks. (Courtesy PMD Chemicals Ltd.)...

Once the initial conductive metallic film has been prepared as described virtually any coating suitable for electrodeposition can be applied to it. In practice the most usual system is nickel-chromium ( chrome plating ), which— provided application is as it should be—gives excellent resistance to abrasion, to corrosion, and generally is very durable. For certain types of work, coatings of precious metal (especially gold) are popular. 

Rather than using plate electrodes, a much higher surface area is obtained by using reticulated (foam) cathodes (Chapter 2, section 2.4.2). This principle is exploited in the patented RETEC cell which employs one of three types of cathode (1) Copper foam is standard for many applications (2) Nickel foam used for special applications and (3) Carbon foam, particularly for precious metals (this aids subsequent refining operations, and minimizes contamination by base metals). 

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