Electroplating of porous PM compacts

Electroplating of PM compacts carried out as a secondary operation following compacting and sintering is essential for the quality of the product. Electroplating is usually performed on compacts in the same manner as on conventional materials, although the plating process often needs to be modified because of the porous structure of the substrate. Relevant aspects of corrosion protective electroplating have been investigated. The levelling effect and coating thickness were found to be important features, especially when iron compacts were sealed by a protective copper coating, where the presence of porosity in the coating could cause serious damage. In contrast, cathodic protection of iron compacts by zinc and zinc alloy coatings was as good as of conventional steel, even when the coatings contained pores.