Structure analysis of friction layer of copper matrix composites reinforced by composite ceramic (TiC-B4C) powder

Abstract

To alleviate the issues of matrix softening and excessive wear faced by copper-based composites matched with C/C–SiC disc during high-speed braking, the research was conducted to investigate the impact of composite ceramic (TiC–B4C, TB) powder on copper matrix composites prepared through conventional powder metallurgy method. TiC–B4C powder was produced using the high-energy ball milling method, and a suitable milling time (48 h) was established to obtain the maximum disorder degree. The results revealed that TB2 (6% TB) had the highest densification and the best mechanical and thermal performance, as compared to other composites. However, there were differences in tribological properties, with TB4 (10% TB) achieving the maximum friction coefficient, while TB2 (6% TB) exhibited more stable friction performance. As the TB powder content increased, larger tribo-films were formed on the worn surface. However, the influence of TB powder content (less than 10% TB) on friction performance was mainly due to mechanical strength and structural tightness, rather than the formation of tribo-films. The friction layer consisted of three parts: the top nanostructure layer composed of nanoparticles (C, Cu, Fe, B, O, and Ti), the middle tribo-film composed of graphite and B2O3, and the lower elastic deformation zone.