Study On The Wear And Corrosion Resistance Of Ni-P Micro/Nano-diamond Composite Coatings

With the rapid development of advanced equipment manufacturing technology,the mechanical parts need better performance of wear and corrosion resistance.The traditional Ni-P electroless coaing can't meet the higher requirement.As reinforcement particles,Al₂O₃,MoS₂,Ti O₂,CNT and Diamond grit can improve the performance of Ni-P electroless coating.At present,the mechanism of anti-wear and corrosion resistance of Ni-P diamond composite coatings were not been fully understood,and few studies on the effect of Nano/Micro-diamond particle sizes on the wear and corrosion resistance have been carried out.In order to improve the wear and corrosion resistance,the Ni-P-Micro/Nano diamond composite coatings have been prepared in this study.The effect of diamond particle sizes on the properties of Ni-P-diamond composite coatings has been investigated.In this paper,the Ni-P-diamond composite coatings with various Micro/Nano sizes diamond particls were prepared after 2h of plating.Finally,the coatings were heat-treated?400?�2h?to enhance its mechanical properties.The microstructure,phase composition,hardness,bond strength and surface roughness were obverted and investigated.The effect of diamond particle sizes on the dry friction behavior,abrasive wear performance and corrosive resistance properties were investigated.The following main conclusions were obtained.With the diamond suspension solution which contained with the dispersant of polyethylene glycol 400,surfactant of OP-10 and Sodium hexametaphosphate,and with the mixed ultrasonic and mechanical stirring methods,the diamond particles can be dispersed uniformly in the composite coatings.The thickness of the coatings reach up to 30?m by 2 hour of plating.The diamond particles were homogeneously distributed in the Ni-P matrix without agglomeration.The content of diamond particles on the Ni-P-Nano-diamond coatings is6.7%¹1.3%and 21%³0%on the Ni-P coatings.It was demonstrated that the Ni-P amorphous phase is transformed into Ni₃P and Ni.The hardness of Ni-P-diamond composite coatings were higher than Ni-P coating.The hardness of Ni-P-Micro-diamond coatings were higher than that of Ni-P-Nano-diamond coatings.The hardness of both Ni-P-Micro-diamond and Ni-P-Nano-diamond coating increased as the diamond particle size increased.Ni-P-D?9?m?coating with the highest hardness of 1350HV.Ni-P and Ni-P-diamond composite coatings well bonded with steel substrate.The addition of Nano-diamond particles can reduce the surface roughness value while the Micro-diamond particles increase the surface roughness.The surface roughness is increased with the diamond particle sizes.The incorporation of Nano-diamond particles can reduce the friction coefficient of Ni-P coating,and its friction coefficient was increased with the increasing of the diamond particle sizes.The friction coefficient of Ni-P-Micro-diamond particle coating was decreased with the increasing of the diamond particle sizes.Due to the present of diamond particles,the friction wear resistance can be enhanced.The friction wear resistance of Ni-P-Micro-diamond coatings is better than that of Ni-P-Nano-diamond coating,and the wear resistance of the Ni-P-D coatings are increased with the increase of diamond particle sizes.The Ni-P-D composite coatings displayed the higher abrasive wear resistance in comparison with the Ni-P coating.The abrasive wear resistance of Ni-P-Micro-diamond coating is better than Ni-P-Nano-diamond coatings,and the abrasive resistance of the Ni-P-D coatings is increased as the increase of diamond particle sizes.After heat-treatment,the polarization potential is more negative and the resistance value is smaller.It means that the heat-treatment lower the corrosion resistance.With the incorporation of Nano/micro-diamond particles,the corrosion potential of Ni-P-diamond composites shifts to more positive value,and the corrosion current density is lower and the capacitive arc radius increase.It means that the incorporation of nano/micro diamond particles can increase the corrosion resistance.The corrosion potential shifts to more positive value and the capacitive arc radius is larger as the nano-diamond particle sizes increased.It indicate that the corrosion resistance of Ni-P-Nano-diamond composites were decreased as the Nano-diamond particle sizes increased.It was observed from the static immersion corrosion test that incorporation of Nano/micro diamond particles can increase the hydrochloric acid corrosion resistance of Ni-P-D composites.The corrosion rate of Ni-P-Nano-diamond composites is increased as the increase of Nano-diamond particle sizes.Ni-P-D?4?m?owns the lowest corrosion rate.