论文部分内容阅读
In order to improve the of wear and heat resistance of Al alloys,the electro-deposition of Ni-Co-P/Si3N4 coating on a hyper-eutectic Al-Si casting alloy was studied in this paper.The weight,thickness,hardness,surface morphology,composition and wearing resistance of Ni-Co-P/Si3N4 coating have been measured by analytical balance,optical microscope,micro-hardness tester,SEM,EDS and abrasion tester.It shows that Ni-Co-P/Si3N4 coating is in a shape of cystiform and Si3N4 particles are uniformly distributed in the composite coating.And Ni3P alloy which come into being after heat treatment,can strengthen the coating and improve the hardness and wearing resistance of the coating.By an orthogonal experiment,the effect of process parameters,such as electric current density,temperature,PH,plating time and component of electroplating bath on the performance of Ni-Co-P/Si3N4 electroplated coating,such as thickness,hardness,contents of Si3N4 in the coating and deposition speed,have been obtained.It is found that the wearing resistance of the coating is improved with the increase of hardness and contents of Si3N4 in the coating,but with increasing contents of P and Co in the coating,the coating becomes harder,more fragile and the adhesion performance gets poor.Then the optimal technological parameters of composite plating were suggested.