The effect of pumice reinforcing particles on the corrosion-and wear-resistance of Ni/Co-pumice bilayer coatings by electroplating

Abstract

The purpose of this study was to develop a corrosion- and wear-resistant coating using electroplating, which is economically viable. Nickel (Ni)/cobalt (Co)-pumice coating applied on the steel surface by electroplating may well meet expectations according to the results of this study. Ni was first applied on the steel surface to create a corrosion-resistant layer and an intermediate layer to increase adhesion, and the subsequent Co layer with the pumice-reinforcing phase was applied on the Ni layer to increase wear and corrosion resistance. With addition of the reinforcing phase (3, 5, and 10 g l−1) to the matrix, the structure was changed from the needle shape to the pyramid shape that this change improved the corrosion resistance. The highest resistance (6.11 kΩ) was observed by using 5 g l−1 of reinforcing material. Adding pumice particles to the coating increased the stiffness number so that by adding 10 g l−1 of reinforcing material, the stiffness number reached to 649 HV and the wear resistance of the coating was improved by adding 3 g l−1 of pumice particles to the coating by changing the wear mechanism and reducing friction coefficient.