Highly dense diamond particle-reinforced Ni-P coatings fabricated by pulse-stirring co-electrodeposition

Abstract

Highly durable nickel-phosphorus/diamond (Ni-P/diamond) compositecoatings were developed and successfully fabricated viaco-electrodeposition. Large diamond particles,20−30 μm,were co-electrodeposited into a Ni-P matrix. This work investigates the influence of bath stirring and current density on the diamond particle content in their deposits and tribological properties. The resulting coatings had uniformly distributed diamond particles in their deposits. Unlike the samples prepared using continuous stirring, those prepared by pulse-stirring appeared to have a much higher diamond particle concentration in the coatings. Energy dispersive X-ray spectroscopy (EDS) shows that diamond contents of up to 25.98 wt% can be achieved by pulse-stirring at a current density of 0.1 A/cm2. The friction coefficient was found to be relatively low and fluctuated in the range of 0.12 to 0.2. After subjecting specimens to a sliding wear test against a ZrO2counter surface, no worn area was observed in the samples prepared using pulse-stirring at current densities of 0.05 A/cm2and higher. This pulse-stirring fabrication technique allows the production of highly dense diamond particles incorporated into coatings with significantly enhanced wear resistance.

Keywords

• composite coating
• co-electrodeposition
• friction coefficient
• wear resistance