Friction and wear behavior of Cu-La2O3 composite sliding against 52100 bearing steel in vacuum

Abstract

Cu-La2O3 nanocomposite used as sliding electrical contact materials for satellites and spacecraft was fabricated via internal oxidation method followed by powder metallurgy. The Cu-La2O3 composites were subjected to the microstructure analysis, microhardness and tensile test. The tribological properties were performed using a pin-on-disk УТИ TB100 type vacuum tribometer in vacuum, rubbing against 52100 type bearing steel disk at different applied loads varied from 10 to 40 N. Results indicated that the La2O3 particles were uniformly dispersed in the copper matrix, and the size of La2O3 particles was below 50 nm. Besides, the La2O3 reinforcement was effective in improving tensile strength and microhardness. When the La2O3 content was 1.3 wt %, the tensile strength and microhardness of the Cu-La2O3 reached a maximum of 329 MPa and 118 Hv, respectively. The coefficient of friction slightly increased with the increasing La2O3 content. The wear rate of Cu-1.3 wt% La2O3 nanocomposite was 3.3 × 10−3 mg m −1 for 500 m in vacuum, which was reduced by 39% compared with that of pure Cu. When the normal load increased from 10 to 40 N, the wear mechanisms changed from abrasive wear to severe plastic deformation, delamination wear and fatigue wear.