Study of tribological characteristics and wear mechanism of nano-particle strengthened nickel-based composite coatings under abrasive contaminant lubrication

In desert areas, abrasive particles entering the machines cause serious wear of the sliding components. To improve the wear resistance of the machine parts, the Al2O3, TiO2, Si3N4, diamond nano-particle strengthened nickel-based brush plating composite coatings were prepared by co-deposition of nano-particles with Ni metal–matrix. The effects of different types of nano-particle and nano-particle contents, in the solution, on the tribological properties of the composite coatings under abrasive lubrication conditions were tested on a commercial ball-on-disk friction and wear test machine. The scanning electron microscopy (SEM) was used to reveal the wear mechanisms. The results show that all of the composite coatings have finer microstructures and higher micro-hardness compared with the pure nickel coating, but only n-diamond/Ni and n-Al2O3/Ni composite coatings show improved tribological properties. Among them, the n-Al2O3/Ni composite coating has the highest cost performance. And the optimum Al2O3 nano-particle content in the solution is 20 g/L. The main wear mechanisms of the composite coating are plastic deformation, micro-cutting, and scuffing.