Electroless deposition and characterization of Ni-P-WC composite alloys

A composite coating Ni-P-WC was produced using an electroless deposition technique from citrate bath containing WC powder. The influence of plating parameters such as WC content, pH, temperature and stirring rate on the content of WC codeposited with Ni-P alloys were investigated. The maximum value of WC (50-55 V-p) codeposited can be achieved at a particle content of 20 gL(-1) in the electrolyte, at pH 5.5-6, temperature 85-90 degrees C and stirring rate of 150 rpm. Surface morphology and microstructure of Ni-P-WC coatings were determined by means of SEM and X-ray diffraction. It was found that the phase structure of the solid solution cannot be varied by codeposition of WC particles in Ni-P alloys, and it only influences the growth of the crystal planes. The properties of the composite such as hardness and abrasion resistance were also examined and compared with WC free nickel deposited layer. The presence of WC particles in the deposit significantly was found to improve the hardness and abrasion resistance of composite coatings. (c) 2006 Elsevier B.V. All rights reserved.