Effect of roughness of the substrate on High-temperature wear behavior of electroless nickel-phosphorus coatings

In this study، electroless coating of nickel-phosphorus on two types of substrates، i. e. sand-blasted and electropolished samples، were applied. Both samples were annealed at 400˚C for one hour in a heat treatment oven. The pin-on-disk wear tests were carried out at 250˚C under normal load of 5N and sliding speed of 0. 5 m/s with a sliding distance of 300 m. Morphology and wear behavior of the samples were studied by a scanning electron microscope equipped with energy dispersive X-ray spectroscopy analysis device (EDX). Results indicate that electroless Ni-P coating on the sand blasted substrate is more wear resistance than that on the electropolished substrate، wear type for the former is adhesive and the worn sample of the latter coating contained a lot of micro-cracks.