Effect of milling time on microstructure evolution and tribological properties of TiB2−graphite hybrid reinforced Cu matrix composites

The effect of milling time on the microstructure and tribological properties of TiB 2 −graphite hybrid reinforced Cu matrix composites was investigated. Hot-press sintering method was used to prepare the composites with different milling time (4, 6, 8, 10 and 12 h), and the tribological behaviors were studied. The results revealed that the relative density and electric conductivity of the composites initially increased and then decreased with an increase in milling time. The composites fabricated by milling for 6 h had the highest relative density and electric conductivity, which are 99.1% and 42.8%(IACS), respectively. The friction coefficient and wear rate of the composites initially decreased and then increased with an increase in milling time. The lowest friction coefficient and wear rate were measured to be 0.234 and 1.974×10 −5 mm 3 /(N·m), respectively, for the composites synthesized after 6 h of milling. The primary wear mechanism of the composites milled for 6 h was abrasive wear.