Friction and Wear Performances of Ni-P Coatings by Chemical Plating after Crystallization Treatment

Amorphous Ni-P coating was prepared on the surface of ZL113 aluminum alloy by electroless plating. The surface morphologies, chemical element contents and phase compositions of the coating at different crystallization temperatures were characterized by SEM, EDS and XRD, respectively. The effect of crystallization temperature on coating micro-hardness was analyzed, and the wear mechanism was investigated with HSR-2M type reciprocation friction abrasion tester. The results show that the grain size of Ni-P coating increases with the increases of crystallization temperature, Ni based compounds are formed in the coating, and the hardness is the highest at the temperature of 350 °C. After 350 °C, if the crystallization temperature increases continuously, and the grain size increases a little fast a reverse effect of Hall-Petch with the intensity of Ni diffraction peak increasing is shown. The friction coefficient increases first and then decreases with the increases of crystallization temperature. The friction coefficient is minimum, and the wear resistance is the best at 350 °C. The wear mechanism is abrasive wear, abrasive+adhesive wear and abrasive wear at the crystallization temperatures less than 350 °C, 350 °C, more than 350 °C, respectively.