载流条件下Ti_3SiC_2陶瓷材料的摩擦学特性

Tribology Properties of Ti_3SiC_2 under the Current-Carrying Conditions

研究了三元层状化合物钛硅碳(Ti_3SiC_2)材料在载流滑动条件下的摩擦学特性。试验在盘一块式大功率载流高速摩擦试验机上进行,用A3钢盘作为对磨体;滑动速度为20～60 m/s,法向压强为0.4～0.8 MPa,电流强度为0,50和100 A。结果表明,在适当的速度和载荷条件下,Ti_3SiC_2陶瓷表现出良好的载流摩擦学特性。但载流条件下的摩擦系数和磨损率都比非载流条件下的大,且随电流强度的增大而增大。载流条件下,摩擦系数随法向压强和速度的增大而减小;磨损率随法向压强的增大呈下降趋势,随速度的增高而增大。SEM & XRD观察和分析结果表明,载流情况下Ti_3SiC_2摩擦面表层生成的TiC等硬质结晶相是导致摩擦系数增大的主要原因;而其磨损率增大主要由微电弧烧蚀与机械摩擦的交互作用及热-力耦合作用两部分共同影响所致。微电弧烧蚀作用引起Ti_3SiC_2表层氧化、熔融和分解,因而耐磨性发生改变。

The current-carrying tribology behaviors of a highly pure titanium-silicon-carbide Ti3SiC2 bulk were studied. Tests were carried out on a block-on-disk type friction tester with electric current loading function, using a low carbon steel disk as the friction counterpart, the sliding speed was 20～60 m/s, the normal pressure was 0.4～0.8 MPa, and the electric currents was 0, 50 and 100 A. The result showed that Ti3SiC2 has a good friction and wear performance even under the current carrying condition. However both the friction coefficient and Ti3SiC2 wear rate are larger than that of without electric current. The larger the electric current density is, the larger friction coefficient and wear rate are Under the current-carrying conditions, the friction coefficient decreased with the increase in the normal pressure and sliding speed. The wear rate of Ti3SiC2 decreased with the increase in the normal pressure and increased with the sliding speed. The friction surfaces were observed and analyzed by SEM ＆ XRD. The hard TiC and other crystalline phases generated on the friction surface of Ti3SiC2, under the current-carrying conditions, could be a main reason for the increase of the friction coefficient. The increase of Ti3SiC2 wear rate may be imputed to two parts： the interaction of micro-arc ablation and mechanical friction, and the coupled action of thermal and mechanical effect. The micro-arc ablation makes the oxidation, melting and decomposition of the friction surface and the crack creating of the subsurface, inducing the changing of the wear property of Ti3SiC2 material.