Two body abrasion wear behaviour of Cu–ZrB2 composites against SiC emery paper

Abstract

The effect of ZrB2 (1, 3, 5, 10 wt%) reinforcement on two-body abrasion wear properties of Cu was studied using pin-on-disc wear tester. The relative density of Cu–ZrB2 composites varied in the range between 96.0 and 99.7%, and in particular, relative density of copper was lowered with the addition of ZrB2. Among all the composites, Cu–10ZrB2 showed maximum hardness (1.25 GPa) and yield strength (261 MPa). However, the improvement of mechanical properties of Cu with ZrB2 was marginal. On the other hand, the ZrB2 addition significantly affected the wear properties of Cu. The steady-state coefficient of friction (COF) of Cu was reduced from 0.56 to 0.16 with the addition of ZrB2. Pure Cu exhibited a high wear coefficient (17.33 × 10−2) due to its softness and high ductile nature. The abrasive wear resistance of Cu was considerably improved with the addition of ZrB2 (up to 3 wt%) by resisting the cutting forces of SiC abrasives (counterbody). A low wear coefficient of 2.4 × 10−2 was evident for Cu–3ZrB2 composites and the wear was reduced by 7.33 times compared to pure Cu. Further addition of ZrB2 reinforcement lowered wear resistance of Cu composites. Nevertheless, the wear resistance of Cu composites was substantially better than pure Cu. The wear mechanisms were proposed based on microstructural analysis of worn surfaces of Cu–ZrB2 composites, SiC emery paper (counterbody) and wear debris. The present study demonstrates the advantage of selecting ZrB2 as reinforcement in improving the abrasion wear resistance of Cu.