Study On The Composite Plating For Stainless Steel-based Ni-HAP Biomaterial

The deposition of Ni and HAP on the stainless steel substrate was studied in this paper. The stainless steel contains Cr and the more austenite element Ni, having better corrosion resistance, higher plasticity and easier processing, as well not poisonous, and it had already been applied on the medical treatment extensively. Although the investigations on plating on the stainless steel have widely been carried on both home and abroad, the research about deposition Ni-HAP composite coating on the stainless steel was less. Some valid processing treatments were used in order to make the binding strength of the layer and the stainless steel better, and make it possible to apply them to the medical fields.Firstly, the influence of the technological parameters on the preparation of the HAP powder was investigated. The XRD examination indicated that the powder was the pure HAP. An approximately calculation for the particle diameter showed the average size of particle diameter of crystal is 35 nm or so.The influence of the temperature and the cathode electric current density on the stability of plating solution and the deposition speed have been studied.Meanwhile, some processing parameters ,such as the concentration of HAP in plating solution, cathode electric current density, temperature of solution, mixing speed, the HAP content in layer etc.,have been studied and the optimum parameters were obtained.The micro-structure, micro-hardness, wear resistance, etc., of the coatings were analysed by XRD, SEM, EDS and other instruments. Moreover, the binding strength and corrosion resistance of coatings were also studied. The results indicate that the layer is composed of the Ni and the HAP. The hardness increases with the increasing of the HAP content in the layer; Wear resistance is better than the coating of Ni; Corrosion resistance become badly with the increasing of the HAP content in layer.In addition, the mechanism of composite deposition was preliminarily discussed.The results indicate that theζelectric potential of the particle, the valid charge density and the strength of electric field between the electrode and the interface have significant influence on the composite electricity depositions; The Two- Step adsorb mechanism can satisfactorily explain the nature of composite electricity deposition.