Study On Mechanics And Friction And Wear Properties Of Graphene Reinforced TiH₂ Matrix Composites

Titanium matrix composites have been widely used in petrochemical,biomedical,aerospace and other fields because of their good corrosion resistance,oxidation resistance,biocompatibility,low density and non-magnetism.However,high preparation cost,low strength and poor wear resistance of titanium matrix composites limit their further application in these fields.Therefore,reducing the cost of titanium alloy and improving the wear resistance and strength of materials have become the research focus in recent years.Since Ti H2 is one of the intermediate products of hydrogenation dehydrogenation(HDH)method,the production cycle and cost of titanium matrix composites prepared from Ti H2 powder are greatly shortened.In this experiment,Ti H2 matrix composites with different contents of graphene were successfully prepared by ball milling method and discharge plasma sintering technology with Ti H2 powder and graphene nanosheets as raw materials,and the composites were hot-rolled.OM,XRD,SEM and other equipment were used to observe the morphology and microstructure of the composite powder.The tensile and wear resistance of the composite were tested at room temperature,and the strengthening mechanism and wear mechanism of the composite were analyzed and discussed.The feasibility of dehydrogenation behavior of Ti H2 powder was analyzed by thermal analysis test.According to the test results of DSC and TG,Ti H2 begins to decompose at 445?in argon atmosphere,and the decomposition rate of Ti H2 is greatly accelerated when the temperature exceeds 450?.When the temperature exceeds 670?,the quality of Ti H2 powder does not decrease,indicating that the dehydrogenation process of Ti H2 is complete.The phase transformation of Ti H2 in argon atmosphere is mainly divided into three stages:Ti H2?Ti H?(Ti)(solid solution)?Ti.The samples sintered by spark plasma have good density,and the density of the composites is further increased after the hot rolling deformation of the sintered samples,and the density is all over 98.6%.The introduction of graphene effectively strengthens the mechanical properties of graphene /Ti H2 matrix composites,and with the increase of graphene content,the mechanical properties of the composites at room temperature also gradually improve.Compared with pure titanium(Vickers hardness is 149 HV and tensile strength is 551MPa),when the mass of graphene increases to 0.8wt%,the Vickers hardness and tensile strength of the composite are268 HV and 821 MPa,respectively,increasing by 79% and 49%.The strength and Vickers hardness of pure titanium and composite materials are further improved after hot rolling.The Vickers hardness and tensile strength of pure titanium after hot rolling are 214 HV and702MPa.After hot rolling,the Vickers hardness and tensile strength of the composite with0.8wt% graphene content are 348 HV and 1059 MPa,respectively,which are increased by 62%and 50%.For composite materials,the strengthening mechanism should be: fine grain strengthening,load transfer strengthening,solid solution strengthening.The reciprocating sliding friction experiment results show that the friction coefficient of graphene/Ti H2 matrix composites is lower than that of pure titanium.When the applied load is constant,the friction coefficient decreases with the increase of graphene content,and the wear rate decreases with the increase of graphene content.When the graphene content is constant,the friction coefficient of the composites decreases with the increase of the applied load,and the wear rate increases with the increase of the load.