Preparation, corrosion, and wear resistance of Ni‐Mo/Al composite coating reinforced with Al particles

In this research, Ni‐Mo/Al composite coatingswere deposited froma citrate bath containing Al metallic particles. The impact of Al particle content in the bath on the microstructure, texture, thickness, current efficiency, wear and corrosion behaviors of Ni–Mo/Al coatings was surveyed. The [200] preferred orientation developed slowly to the [111] orientation with increasing Al loadings in the bath. The results showed that electroplating at 40 °C and citrate ion concentration of 0.15 M had the highest current efficiency and produced a dense coating free of cracks. Because of the presence of Mo, the morphology of the matrix changed froma regular pyramidal structure for Ni‐Al composite coatings to cauliflower for Ni‐Mo/Al composite coatings. The wear resistance of coatings decreased due to the increase of Al content in the coating. The polarization tests indicated that the corrosion resistance of the Ni‐Mo/Al composite coating was enhanced by adding Al metal particles. This was due to the increase of Al content and decrease of the grain size of the coatings.