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Electroless nickel-silicon carbide composite plating

Electroless nickel-silicon carbide composite plating plays an active part as a replacement for hard chromium plating, by making use of the features of electroless plating (plating of non-conductive materials, such as resins and ceramics, and also uniform plating of complex-shaped materials) and the features of composite plating (composite plating of hard nickel-phosphorus plated metals and wear-resistant fine particles, like silicon carbide).
Type of plating Features (characteristic value)
Electroless nickel-silicon carbide composite plating - On electroless nickel-phosphorus plating films, which is a matrix metal of composite plating, the bonding force between the matrix metal and silicon carbide particles is strengthened by heat treatment, and the matrix itself hardens. Furthermore, the composite effect with the silicon carbide particles enables a low friction coefficient, and improves the life of sliding parts dramatically.

  As-plated Heat-treated
Ni-P-SiC Hv 650~750 Hv1050 (heated at 250°C)
Ni-B-SiC Same as above Same as above (heated at 400°C)
(From “Zukai Saisentan Hyomenshori Gijutsu no Subete”; Kanto Gakuin University Surface Engineering Research Institute, Kogyo Chosakai Publishing)
Adoption examples
Electroless nickel-silicon carbide composite plating
Cross-section SEM photo of composite plating film
Figuratively speaking, a composite plating film is like “mamemochi (rice cake with beans).” Inorganic particles, such as ceramics and organic particles such as Teflon, which are several micrometers to several tens of nanometers in size (role of beans here), are uniformly dispersed in the plating film (role of a white rice cake here). For the rice-cake-like matrix, single plating or alloy plating is used. In other words, composite plating is a particle-dispersed composite material deriving the advantages of two different materials: matrix metal and dispersed particles in combination. By plating while various types of fine particles are suspended in an electro/electroless plating solution, a composite plating film with these fine particulates contained in the plating film can be obtained.