Tribological behaviours of Ti 3 SiC 2 under current carrying conditions

Abstract

High purity Ti₃SiC₂ samples were prepared by infiltration sintering method. The tribological behaviours of high pure bulk Ti₃SiC₂ dry sliding against a GCr15 bearing steel disc were experimentally investigated on a pin on disc type tester under different sliding speeds from 5 to 50 m s⁻¹, different electric currents from 0 to 60 A and different normal pressures from 0·1 to 0·6 MPa. It was found that the Ti₃SiC₂ sample exhibits an increasing friction coefficient (0·15–0·71) and an increasing wear rate (0·91–4·69×10⁻⁶ mm³ N⁻¹ m⁻¹) with the electric current increasing from 0 to 60 A; the normal pressure (0·1–0·6 MPa) and the sliding speed (5–50 m s⁻¹) also have a complex but relatively weak influence on them. The changes can be attributed to the presence of a frictional oxide film consisting of an amorphous mixture of Si, Ti and Fe oxides on the friction surface. The oxide film was formed, and the percentage of coverage was relatively higher when the electric current was 0 A. The oxide film could be formed, but the percentage of coverage was decreased with the increase in electric current. Few of the oxides were generated, and almost no oxide film was formed in the friction surface when the electric current was 60 A. The frictional coefficient and the wear rate of Ti₃SiC₂ increased with increasing electric current. The coefficient of friction and the wear rate (×10⁻⁶ mm³ N⁻¹ m⁻¹) of Ti₃SiC₂ were of 0·15 and 1·73, 0·25 and 2·52, 0·42 and 3·35 and 0·62 and 4·69 under the normal pressure of 0·3 MPa, the sliding speed of 50 m s⁻¹ and the electric currents of 0, 20, 40 and 60 A respectively.