Hardness and wear resistance of Ni/Al_2O_3 composite coatings by electrodeposition

摘要

Ni/Al_2O_3 composite coatings were prepared by direct current (DC), single pulse current (PC) and pulse reversal current (PRC), respectively. The hardness and wear resistance of the coatings were investigated and the morphology and elements distribution in cross-section were analyzed by the application of SEM/EDS, XRF and XRD equipped with stress measuring device. The results show that the hardness of the three kinds of coatings increase with increasing Al_2O_3 content. The coating prepared by PRC plating exhibits higher hardness and better wear resistance, while that of DC plating has lower hardness and poorer wear resistance. The higher hardness and better wear resistance of coating of PRC plating can be ascribed to fine microstructure and weaker stress between substrate and coatings.