Study On High Temperature Sliding Friction And Wear Properties Of (TiC+TiB)/Ti6Al4V Composites

Mechanical parts fail during the working condition due to wear,breakage,oxidation,etc.,and parts that fail due to material wear are as high as 80%.Therefore,studies of frictional and wear properties of materials are extremely important for extending the service life of materials.Among them,titanium and titanium alloys have become the excellent choice for mechanical parts due to its excellent comprehensive properties.In this study,we studied the wear mechanism and sliding friction and wear behavior of In-situ titanium alloy and its composites at different test temperatures(25?? 100?? 200?? 300?? 400??500?)and loads(5N?10N?15N? 20N).The surface morphology,wear debris and cross-section morphology of the titanium alloy and its composites which were in as-cast and heat-treated state were analyzed by HT-1000 high temperature friction and wear tester,SEM and EDS.In the medium temperature(300?),the wear rate of all materials studied in this paper increased with the increase of load,but the friction coefficient of TC4 was higher than that of composite materials.Under low loads,the shearing force and friction of the surface of the specimen were small,the depth of the wear scar was shallow,and the size of the abrasive chips formed was small,mainly in the form of powder and small pieces of abrasive debris.As the load increased,large-sized block-like peeling wear debris and flaky fatigue wear debris were formed.The average friction coefficient of TC4 alloy and its composites increased with the increase of test temperature.The wear rate of the material decreased first and then increased with temperature,and the minimum value was obtained at 400?.At lower temperatures,more cracks were formed on the wear surface,and the tribolayer was easily broken to form wear debris due to the presence of more cracks.As the temperature increased,the crack in the tribolayer was reduced,and the tribolayer became denser which was uneasy to form wear debris.The hardness of TC4 and TMC2 increased after 930?/2h quenching and 495?/4h aging treatment.The wear rate increased with the increase of ambient temperature,as well as that of all materials at 400? Minimum.Below 200?,there were numerous cracks on the wear surface,and the tribolayer were loose and discontinuous,presenting poor wear resistance(relative wear rate was relatively high).When the ambient temperature reached 300~500?,the tribolayer became dense,the crack was reduced,the wear debris was uneasy to form,and the wear rate was relatively low on the macroscopic.Overall the frictional and wear properties of the material could be improved to some extent after the heat treatment.