Achieving well-balanced mechanical and tribological properties of copper matrix self-lubricating composites by adding pre-metallized B4C particles with core-shell microstructure

Copper matrix self-lubricating composites have the advantage of low friction coefficient, but usually suffer from the low mechanical strength, ductility and wear resistance. Ceramic particles reinforcing has been demonstrated an effective way in strengthening metal matrix composites. However, the poor wettability was always a critical issue. In this study, B4C particles were introduced into a copper matrix self-lubricating composite. Before spark plasma sintering, the B4C particles were pre-metallized with Ni to form a core-shell microstructure (Ni@B4C), which improves wettability and bonding strength with the copper alloy, builds up a coherent/semi-coherent interface, and notably enhances mechanical properties. After the incorporation of pre-metallized Ni@B4C particles, the compressive strength, hardness and engineering strain are increased by 62, 113 and 76%, respectively. What is more, the composite exhibits improved tribological performances. Owing to the successful transfer of lubricant WS2 to the wear surface during sliding as well as the greatly enhanced hardness, its friction coefficient is decreased to 0.16, while the wear rate is reduced to 7.53 × 10−6 mm3/N·m, which is 81% lower than that of CW. The composite achieves well-balanced mechanical and tribological properties after pre-metallized B4C particles incorporation.