Processes And Wear Behaviours Of Ni-Si₃N₄ Electroplated Coatings

Composite plating is an effective way to gain wear resistance material. Si₃N₄particles are used in composite plating with the characteristics of high hardness,good wear resistance and performance stability. Si₃N₄ particles were mixed in Wattselectroplating solution to get Ni-Si₃N₄ composite coatings. The friction and wearbehavior of Ni-Si₃N₄ coatings were investigated.The suitable surfactants of Ni-Si₃N₄ composite plating were defined by simplycolorimetric estimation. An optimum technology of Ni-Si₃N₄ composite plating isproposed by single factor experiment, which gives suitable sedimentation velocityof particles, high hardness and Si₃N₄ content of coatings. The friction and wearmechanism of composite coatings were studied by friction and wear experiments,and the morphology of friction pair was analyzed.The results show that Ni-Si₃N₄ composite coatings have good adhesion andcorrosion resistance. More Si₃N₄ particles content results in higher coating hardnessand better wear resistance. Serious adhesion wear appears when Ni-Si₃N₄ compositecoatings are against carbon steel in the condition of dry friction. In wet friction,light ploughing, adhesion wear and spalling occur when Ni-Si₃N₄ against 45 steel,Ni-Si₃N₄ coatings have little wear and better resistance. Serious ploughing andfatigue fracture appear when Ni-Si₃N₄ against heat treatment 45 steel, the wearvalue of heat treatment 45 steel increases quickly. When Ni-P-Si₃N₄ against heattreatment 45 steel, 'transfer choice' of wear debris appears. Because coatinghardness is improving, the wear value of heat treatment 45 steel decreases largely.CrN coating has higher hardness and shows wonderful anti-wear and frictionreducing properties. When it against heat treatment 45 steel, friction pair are inwhole-film lubrication.