Study On The Microstructure And Properties Of Refractory Metal Coatings Prepared By Plasma Spraying

With the continuous development of global science and technology today,increasingly complex production conditions impose more stringent technical requirements on mechanical equipment.In order to meet the requirements for the use of mechanical parts and components in extreme working conditions,it is clear that replacing parts and materials in a traditional way has relatively great technical difficulties and high costs.It has attracted great attention that plasma spraying technology can make it have more excellent performance and wider application range without changing the original material.In this paper,pure Ta coating was prepared by plasma spraying to study the friction and wear properties of the rough surface of the coating under different loads.Subsequently,a pure Mo coating was prepared by plasma spraying technology,and the microstructure and properties of the coating were studied by changing the process parameters.Finally,under specific process parameters,the Mo coating with special morphology was prepared by plasma spraying,and the friction and wear properties of the coating on the rough surface and smooth surface were studied using the comparative experiment method.(1)The pure Ta coating was prepared on the surface of 45# steel by plasma spraying technology.The influences of the process parameters on the microstructure,surface morphology and friction performance of the coating were studied.The friction and wear of the coating and the counterpart under different loads were studied.The properties were discussed and the results show that the change of process parameters has a great influence on the surface morphology and microstructure of the coating.The relative increase of current will cause the increase in the degree of coating oxidation,and the rough surface of the coating in the condition of adding lubrication occurs the phenomenon that.Only the protruding metal peaks were locally flattened,while the coating itself is less worn.(2)The experiment of preparing Ta coating by plasma spraying proves that the process parameters have a great influence on the surface morphology of the coating.Therefore,a pure Mo coating was prepared on the surface of 45# steel using plasma spraying technology.The influence of process parameters on the microstructure,surface morphology,roughness and hardness of the Mo coating was further systematically studied.The results show that the effect of voltage parameters during plasma spraying on the surface morphology and roughness of the coating is more significant than that of the current parameters.When the plasma spraying voltage is 165 V and the current is 360 A,the pure Mo coating has a higher deposition rate and better organization and performance.(3)On the basis of the previous experiments,by setting special plasma spraying process parameters,a frosted coating with uniformly distributed Mo metal particles was prepared.At the same time,the Mo coating was prepared by the same process parameters,and then the smooth surface was obtained after polishing.The friction and wear characteristics of frosted coating and smooth coating were compared by fretting friction test.The results show that the matte coating with metal particles on the surface has excellent wear resistance and a low coefficient of friction at 100 N load,while the smooth coating has severe wear at the same 100 N load.At lower loads of 10 N,20 N,and 60 N,the wear resistance and friction coefficient of the smooth coating are better than those of the matte coating.