Preparation and tribocorrosion behavior of electrodeposited Ni–W/ SiC composite coatings

Abstract

Ni-W composite coatings that are applied using electrodeposition exhibit excellent mechanical strength, corrosion resistance and wear resistance and are a substitute for hard chrome because they involve fewer environmental hazards than regular chromium plating processes. This study determines the effect of process parameters, such as current density (5, 10 and 15 A/dm²) and SiC concentration (0.5, 1.0 and 1.5 g/L), on the chemical composition, structure, mechanical properties and corrosion resistance of electrodeposited Ni-W/SiC composite coatings and determines the interaction between the mechanical behavior and the electrochemical reactions that occur during corrosion and friction. The experimental results show that there are no cracks on the surface of the coating and that the surface roughness increases as current density increases. As the content of W and SiC particles in the composite coating increases, the hardness and corrosion resistance of the coating increase because of solid solution strengthening and nano-ceramic particle dispersion strengthening.

In order to verify the protective performance of the coating in complex environments, a ball-on-disk abrasion tester and a potentiostat are used to determine the tribocorrosion behavior of the Ni-W/SiC composite coating against the sliding of the Al₂O₃ counter-body. In 3.5 wt%NaCl solution and at +600 mV, the corrosion and wear characteristics of composite coatings that are produce using different process parameters are determined. Analysis of the synergistic effects of corrosion and friction shows that the wear component (△W_wear) is 3–5 times greater than the corrosion component (△_Wcorr), which is the main cause of coating damage. The greater the hardness of the coating, the less mass is lost for the wear component (△W_wear). The results show that the operating parameters for producing ideal Ni-W/SiC composite coatings are a SiC particle concentration 1.0 g/L and a current density of 10A/dm². These settings give the best wear resistance in corrosive environments.