A two-stage approach to Ni-P-SiC coatings and their friction against SiC in water

Abstract

Inspired by the low friction of self-mated SiC in water, a two-stage technique is proposed to deposit Ni-P-SiC coating with a high particle content to achieve low friction against SiC in water. The process comprises the electrophoretic deposition of SiC particles layer on a mild steel substrate followed by the electroless plating of NiP coating. The effects of SiC content on the surface appearance, phase structure and cohesive strength were studied. Much attention was paid on the friction behavior of the coatings in water. Experiment results show that compared with the traditional electroless plating method, the two-stage technique can enhance the implanted SiC particle content effectively. Notable, with the increasing of SiC content, the friction coefficient decreases correspondingly and the lowest friction coefficient of 0.015 can be achieved for the Ni-P-SiC coatings with the highest SiC particle content. The major surface degradation mode is abrasive wear during running-in then tribochemical wear dominates at the low friction stage.