ELECTRODEPOSITION AND CHARACTERIZATION OF Ni - Co - P - BN DISPERSION COATINGS

Functional plating such as alloys or dispersion coatings have been widely used in metal finishing industry. In general, dispersion coatings are deposited from plating baths containing suspended particles such as metal oxides, carbides, metals or organic materials,(l-3) Codeposited particles in the dispersion coatings have the remarkable influence on the properties of the deposits depending on their type, size, contents and also mode of the distribution of the particles. Metal matrix also play an important role in the dispersion coatings. Therefore, it is very important to study the metal deposition parameters in the preparation of dispersion coatings and also to control the codeposition process of the particles in the metal matrix.(4-9) Ni-P alloy deposits containing PTFE particles are the typical dispersion coatings which have the nobel lubricating properties. ( 1 0-1 1 ) Hardness of Ni-P-PTFE dispersion coating was found to increase upon the heat treatment of the coating at 400 C to give 900-1100 Hv. The Ni-P alloy deposits containing 7-10 wt% P have been found to have the amorphous structure and the hardness of the deposits were increased by the heat treatment. The hardness of Ni-Co-P alloy deposits was retained to considerablly greater level compared with Ni-P alloy coating. Ni-Co-P-Si3N4 dispersion coatings have been found to have the excellent wear properties.(l2) Hexagonal boron nitride(BN) is an inert and heat-resistant material and has the lubricating property when used at higher temperatures. In the present study, electroplating of Ni-Co-P-BN dispersion coatings has been carried out to provide the lubricating, wearand corrosion-resistant coatings having high hardness.