Enhancement of Corrosion and Wear Resistance of Ni-P Coatings Stems from the Synergistic Effects of CrC and Heat Treatment.

This study describes the preparation of Ni-P-CrC composite coatings using pulsed electrodeposition, with varying CrC concentrations (0, 1, 2, 3, 4, and 5 g/L). Subsequently, the Ni-P-CrC composite coatings are heat-treated at different temperatures (200, 400, and 600 °C) using the characteristic of CrC oxidizing to CrO at high temperatures. The Ni-P coatings, Ni-P-CrC composite coatings, and heat-treated-state Ni-P-CrC composite coatings are compared and discussed. The results show that the hardness, wear resistance, and corrosion resistance of the composite coatings are optimized when the CrC content is 3 g/L and the heat-treatment temperature is 400 °C. This is due to the presence of oxides such as CrO on the surface of the composite coatings after heat treatment at 400 °C. By efficiently enhancing the coating's densification to the substrate, these oxides raise the composite coating's resistance to corrosion and wear. The Ni-P-CrC composite coating in its heat-treated makeup at 400 °C is found to have long-term corrosion resistance in the 3.5 wt % NaCl solution immersion test. This study provides a new idea in the field of corrosion.