Tribocorrosion behaviour of Ni–SiC composite coatings under lubricated conditions

Tribocorrosion behaviour of Ni–SiC (30 μm size of SiC particles) micro-composite coatings, with a thickness about 50 μm, sliding against corundum balls in a 0.5 M Na2SO4 solution at room temperature was investigated. In-situ electrochemical measurements were performed on samples of different amount and dispersion state of SiC particles. These composite coatings are used in the automotive industry. The influence of SiC particles dispersion in the nickel matrix on potential, current, coefficient of friction, and wear missing volume was established. The dispersion of SiC particles in the nickel matrix was found to greatly affect the current and potential during fretting-corrosion. The results show that an incorporation of SiC particles in non-uniform agglomerations causes the most active surface and highest material loss. The non-uniformity distribution of SiC particles is due to the non-observance of agitation parameters during homogenizing process. The coatings with uniform distribution posses a good wear-corrosion resistance and almost no wear loss volume at low number of fretting cycles.