Research On Evolution,function And Wear Mechanism Of Artificial Tribo-layer For Titanium Matrix Composite

Because of its excellent comprehensive properties,titanium matrix composite was the first choice of mechanical parts,but its tribological properties still need to be improved.Adding additives is a method to improve the friction and wear properties of titanium matrix composites.In this paper,titanium matrix composite was selected as sliding material,W6Mo5Cr4V2Co5 high speed steel was selected as grinding material,multilayer graphene(MLG)and Fe₂O₃were added as nano-additives.The dry sliding friction and wear behavior and characteristics of titanium matrix composite under different types of nano-additives,different loads were studied.SEM,LSM,LSCM,XRD and other analysis methods were used to shape the characteristics of the artificial friction layer.The morphology,structure and composition of the artificial friction layer were characterized,and the evolution,function and wear mechanism of the artificial friction layer of titanium matrix composite were systematically studied and discussed.The results showed that when MLG or Fe₂O₃nan-particles were added,due to the lack of bearing capacity or lubrication capacity,the friction layer lost its protective effect,resulting in high friction,wear coefficient and plastic deformation area.The friction layer formed by MLG/Fe₂O₃nano-omposite and MLG+Fe₂O₃mechanical mixture effectively reduce wear and friction due to the existence of protective friction film.There was a critical load in the mixture of MLG/Fe₂O₃nano-composites and MLG+Fe₂O₃.At or below the critical load,excellent friction performance was obtained due to the existence of protective tribo-layer.When the load was higher than the critical load,the tribological performance was worse again.The addition of multilayer graphene/nano-Fe₂O₃composite could improve the tribological properties of TMCs and reduce the friction coefficient by 50%.There wa s a critical addition of MLG/Fe₂O₃,which made TMCs undergo a transition from severe wear to slight wear.Multilayer graphene/nano-Fe₂O₃composite got a good protective effect,which was due to the formation of a protective tribo-layer,preventting the direct contact between the pin and disk surface,thus improving the tribological performance.The thickness of tribo-layer was(15-20)?m,which was composed of MLG/Fe₂O₃(1:2)nanocomposites.Its structure was similar to a"roller"structure.Adding MoS₂could improve the tribological properties of TMCs and reduce the friction coefficient.At the same time,there was a critical value for the effect of MoS₂on the tribological properties of titanium matrix composites,which made TMCs undergo a transition from severe wear to slight wear.With the increase of MoS₂content,titanium matrix composite gradually changed from severe adhesive wear to slight adhesive wear,which was one of the reasons for the decrease of material wear.A layer of wear-resistant protective layer was formed between titanium matrix composite and wear-resistant material,so as to protect the matrix material and improve the friction performance of titanium matrix composite.