Surface Petreatment Of La91 And Preparation And Properties Of Si-DLC Films

As a popular material in the field of light metals,magnesium-lithium alloy has attracted much attention in the industrial field in recent years because of its high specific strength and stiffness,good thermal conductivity,electromagnetic shielding and damping.However,due to the defects of poor mechanical properties and easy corrosion of magnesium-lithium alloy,it hinders the wide use of magnesium-lithium alloy.In order to improve the service performance of magnesium-lithium alloy,researchers mainly explore the way of surface treatment,and enhance its surface mechanical properties and corrosion resistance by means of surface modification and deposition of film,so as to promote the application of magnesium-lithium alloy.In this paper,silicon doped diamond-like carbon（Si-DLC）films were prepared on the surface of LA91 magnesium-lithium alloy by cage hollow cathode discharge technology.The micro morphology and microstructure of the films were characterized by SEM,AFM and Raman spectroscopy.The adhesion,friction and wear properties and corrosion resistance of the films were evaluated by scratch test,friction and wear test and electrochemical performance evaluation methods.The following conclusions are drawn:Under the condition of bias voltage,argon ion and hydrogen ion are used to etch the matrix of LA91 magnesium-lithium alloy,and the micro rough structure is constructed on the surface.With the increase of etching time,the roughness of the matrix surface increases gradually.The Si-DLC monolayer film was prepared on the surface of LA91 substrate after etching.The adhesion test results showed that the surface cleanliness and roughness increased,the"latch"effect between the substrate and Si-DLC monolayer film increased,and the adhesion between the substrate and Si-DLC monolayer film increased.At the same time,the friction,wear and corrosion resistance of Si-DLC monolayer film increased,but the etching for a long time had an adverse effect on the friction,wear and corrosion resistance of the monolayer film.The Si-DLC multilayer thick film with alternating soft and hard was prepared on the surface of LA91 substrate after etching.The microstructure test shows that the film has a typical DLC amorphous film structure.The mechanical property test results show that the design of the multilayer film alleviates the interlayer stress and improves the microhardness of the film,reaching 158.1 HV_0.1.The binding performance of membrane base has been greatly improved;The test results of friction,wear and corrosion resistance show that the multilayer film design improves the crack diffusion resistance and reduces the number of pores（especially through holes）in the film,so as to improve the wear resistance and corrosion resistance of Si-DLC film.