Enhancement of Corrosion and Wear Resistance of Ni-P Coatings Stems from the Synergistic Effects of Cr3C2 and Heat Treatment.

This study describes the preparation of Ni-P-Cr3C2 composite coatings using pulsed electrodeposition, with varying Cr3C2 concentrations (0, 1, 2, 3, 4, and 5 g/L). Subsequently, the Ni-P-Cr3C2 composite coatings are heat-treated at different temperatures (200, 400, and 600 °C) using the characteristic of Cr3C2 oxidizing to Cr2O3 at high temperatures. The Ni-P coatings, Ni-P-Cr3C2 composite coatings, and heat-treated-state Ni-P-Cr3C2 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 Cr3C2 content is 3 g/L and the heat-treatment temperature is 400 °C. This is due to the presence of oxides such as Cr2O3 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-Cr3C2 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.

Enhancement of the Wear Resistance and Corrosion Resistance of Electroplated Ni-W-B Coatings Using PDA-Functionalized VC.

In this study, vanadium carbide (VC) was used as the raw material to synthesize PDA-functionalized VC (P-VC). VC and P-VC were added as nanoreinforced materials to the Ni-W-B coating. The effects of the two nanomaterials on the morphology, wear resistance, and corrosion resistance of the Ni-W-B coatings were investigated and compared. The experimental results show that the surface of the Ni-W-B/P-VC coating is denser and more uniform than that of the Ni-W-B and Ni-W-B/VC coatings, and there are no obvious defects on the surface. According to the hardness test, the Ni-W-B/P-VC coating reaches the highest microhardness of 887.1 HV. According to the friction and wear tests, the Ni-W-B/P-VC coating has the shallowest scratches, the lowest average friction coefficient (COF = 0.274), and the lowest wear rate (9.578 × 10-8 mm2/N). The corrosion resistance is the best, the corrosion rate is 0.0456 mm/y, and the impedance value Rt reaches 14,501 Ω·cm2.