Study On Friction And Wear Behavior Of TD3 Alloys And Surface Modification

TD3 alloy is a kind of Ti₃ Al based alloy with medium Nb content.As an structure material with low density and high temperature resistance,TD3 has been attracted the attention of aerospace industry.At present,the research for TD3 alloy is mostly concentrated on its microstructure and mechanical properties,and the study on its tribological properties has not been reported.In this paper,the friction coefficient,wear mark morphology and wear volume of TD3 alloy under different loading and sliding speed were studied.The mechanism of friction and wear of TD3 alloy was preliminarily investigated.In order to improve the friction and wear properties of TD3 alloy,two modified layers were prepared on TD3 alloy by thermal oxidation and ion nitriding.The morphology,composition,phase structure and hardness of the modified layer were analyzed by optical microscope?OA?,scanning electron microscope?SEM?,energy spectrum analyzer?EDS?,X ray diffraction?XRD?and microhardness tester.The results show that a dense and uniform oxide layer was formed on TD3 alloy,which containing TiO₂ and Al2O3.The thickness is 7?m,and its surface hardness is up to 638HV;The nitrided layer on the surface of TD3 alloyis formed with TiN and Ti2 N.The nitrided layer is composed of compound layer and transition layer,the thickness is up to 80 ?m,and the hardness of the layer is1190 HV,which is more than 3 times of the hardness of the substrate.The friction coefficient of TD3-O and TD3-N alloys under different loading and sliding speed was studied by reciprocating friction and wear tester.The appearance,size and composition of the grinding mark were measured and analyzed by SEM,EDS and white light interference 3D profilometer.The experimental results show that the average friction coefficient of TD3-O decreases by 50%,and the wear volume decreases by 0.197,and the oxide layer has better friction and wear properties comparing with TD3 alloy.Compared with TD3 alloy,the friction coefficient and wear volume of TD3-N under different loads are reduced,and the wear volume under 100 g load is reduced by more than 50%.The friction and wear properties of TD3 alloy have been improved after nitriding.