Tribological properties of copper-matrix composites against laser-cladded Co06 coating on 30CrMoSiVA steel at elevated temperatures

Laser cladding coating is identified as an ideal choice for improving the surface properties and prolonging the lifetime of brake discs. In this study, Co06 coating was fabricated on 30CrMoSiVA steel extracted from brake discs for high-speed trains through laser cladding technology, and the frictional behavior and wear mechanisms of a novel copper-matrix composite mated with 30CrMoSiVA steel and Co06 coating, respectively, were investigated at temperatures from 25 to 800 °C. Results showed that the microhardness of Co06 coating was almost twice that of 30CrMoSiVA steel. Generally, Co06 coating displayed better wear resistance than 30CrMoSiVA steel. Copper-matrix composite against Co06 coating featured the comparatively more stable friction curves in comparison with that against 30CrMoSiVA steel. Similar general trends were observed in the friction coefficient and wear rate of copper-matrix composite sliding against two different counterparts as temperature increased. Compared with that against 30CrMoSiVA steel, copper-matrix composite against Co06 coating at 25 °C exhibited similar wear rate and lower friction coefficient, slightly lower wear rate and similar friction coefficient at 600 °C, and higher wear rate and friction coefficient at 800 °C. The primary wear mechanisms of copper-matrix composite against two different counterparts at 25 °C were slight adhesive wear combined with oxidation and abrasive wear, severe adhesive wear combined with oxidation and abrasive wear at 600 °C, and delamination wear combined with oxidation and slight abrasive wear at 800 °C.