Microstructure evolution of diamond with molybdenum coating and thermal conductivity of diamond/copper composites fabricated by spark plasma sintering

Molybdenum (Mo) coating was deposited on the diamond surface by vacuum micro-vapor deposition. Effects of deposition parameters on the formation of Mo coating on the diamond different crystal face was investigated. The mechanism of diamond metallization evolution, fracture mode and thermal conductivity of diamond/copper composites were discussed. It is shown that the coating of diamond particles is starting with point-like particles grew up to be continuous, dense spherical coating, and the compactness of the coating on diamond <100> facet always takes precedence over diamond <111> facet. The Mo coating on the diamond surface deposited at 1050 °C for 50 min shows the best quality. The fracture modes of Mo-coated diamond/copper composites are composed of diamond debonding from copper matrix, diamond transgranular fracture and copper ductile fracture, but some pores existed at the interfere, it concludes that the Mo₂C prepare a Cu/Mo/diamondinterlayer between the diamond and copper matrix could improve the bonding between diamond and copper matrix, but the effect of Mo₂C coating on strengthen the interfacial bonding is limited. The highest thermal conductivity of the composites achieved the value of 329 W/(m K).