Surface Modification and Wear Resistance of Electroless Ni-P Based Duplex Alloy Coating

Abstract

Ni-P-W multi-layered alloy coating was electrolessly deposited on 10 x 15 x 1.5 mm mild steel capons. The coated samples were heat treated between 200 – 800 °C and the resultant effect of the annealing on the small scale structure and mechanical properties of coating was studied by using X-ray diffraction, Scanning electron microscopy, nano-indenter, pin-on disc wear tester and interferometry Spectroscopy. The result shows that the as-deposited amorphous duplex coatings crystallise in steps as the annealing temperature increases and this gives raise to new phase formation in the mechanical properties of the coating. The study reveals the impact of high temperature annealing on the microstructure, morphology and microhardness of this duplex coating within certain temperature range; which was attributed to the formation of new Ni3P and Ni-W phases, its grain refinement and consequently, better linear microhardness and wear resistance relationship within given temperatures.