Current carrying friction and wear characteristics of Ti₃AlC₂ by novel method of infiltration sintering

Abstract

High purity Ti₃AlC₂ samples were prepared by an infiltration sintering method. The current carrying friction and wear characteristics of high pure bulk Ti₃AlC₂ dry sliding against a GCr₁₅ bearing steel disc were experimentally investigated on a pin-on-disk type tester at several sliding speeds from 20 to 60 m s⁻¹, different electric currents from 0 to 100 A and normal pressures from 0·1 to 0·6 MPa. It was found that the highly pure Ti₃AlC₂ exhibits an increasing friction coefficient (0·11–0·65) and an increasing wear rate (2·13–7·75×10⁻⁶ mm³ N⁻¹ m⁻¹) with the electric current increasing from 0 to 100 A; the normal pressure (0·1–0·6 MPa) and the sliding speed (20–60 m s⁻¹) also have a complex but relatively weak influence on them. The minimum value of friction coefficient was 0·11 when the sliding electric current, speed and normal pressure were set to 0 A, 60 m s⁻¹ and 0·6 MPa; the wear rate reached the maximum value 7·75×10⁻⁶ mm³ N⁻¹ m ⁻¹ when the sliding electric current, speed and normal pressure respectively were set to 100 A, 60 m s⁻¹ and 0·6 MPa. The low friction coefficient can be attributed to the presence of a continuous frictional oxide film consisting of an amorphous mixture of Al, Ti and Fe oxides on the friction surface, which have a significant antifriction effect on the friction surfaces. The percentage of oxide film cover was relatively higher when the electric current was 0 A, while the percentage of oxide film cover decreased with increasing electric current. The increase in the wear rate was ascribed to the ablation of the electric arc when the electric current was high.

Keywords:

• Ti₃AlC₂
• Infiltration sintering
• Electric current
• Oxide film
• Coefficient of friction
• Wear rate

This work was supported by Project 2007E104 funded by National Nature Science Foundation of China (grant no. U1034003) and Shaanxi Province Natural Science Foundation of China.