Effect of particle size of nano-diamond on wear and corrosion resistance of electroless Ni-P composite coatings

To improve the wear resistance and corrosion resistance of coatings, the Ni-P-D composite coatings which contained various size of nano-diamond particles were prepared by electroless plating.The effects of nano-diamond size on microstructure, mechanical properties, friction characteristics, abrasive wear performance and corrosion resistance of Ni-P coatings were investigated by SEM, XRD, tribological and abrasive wear testing as well as electrochemical experiment.It is discovered that the Ni-P-D composite coatings containing nano-diamond particles with thickness of about 30 μm and well bonding to the steel substrate could be obtained.Ni-P-D composite coating containing 50 nm diamond particles has the highest hardness, the best friction wear resistance and abrasive wear resistance.With the decrease of nano-diamond particle's size, the coefficient of friction decreases, and the corrosion resistance of Ni-P-D composite coating increases.Ni-P-D composite coating containing 5 nm diamond particles has the lowest coefficient of friction and strongest corrosion resistance.