Preparation Of Mo₂C-Coated Diamond Particles And The Different Effects On The Performance Of Diamond/Al And Diamond/Cu Composites

With the rapid development of information technology,electronic components are developing toward a trend of high level of integration and miniaturization,which leads to the growing of thermal densities.Therefore,new electronic packaging materials with high thermal conductivity are required.Diamond possesses the highest thermal conductivity(1200-2000 Wm^-1K^-1)among natural materials and a very low coefficient of thermal expansion(CTE,1-2×10^-6 K^-1).Diamond reinforced metal matrix composites are considered as promising materials for electronic packaging.The interface between diamond and metal matrix plays a critical role for thermal conductivity because the interfacial thermal resistance increases as the weak bonding occurs at the interface.The surface modification of diamond particles is one of the most effective methods to improve interfacial bonding between diamond and metal matrix.Here,we used molten salts method to synthesize Mo₂C coating on diamond particles using Mo powder and compared the characteristics of the Mo₂C coatings resulted from different reaction time.Diamond/Cu composites and diamond/Al composites were fabricated using vacuum pressure infiltration.And the effects of submicro-Mo₂C layer on the interfacial bonding and thermal conductivity of the diamond/Al and diamond/Cu composites were investigated.The results showed that the thickness of Mo₂C coating decreases with the reduction of reaction time.The introduction of submicro-Mo₂C layer played different roles on the thermal conductivity of the Cu based or Al based composites.A high thermal conductivity(657 Wm^-1K^-1)was obtained when the submicro-Mo₂C layer（500 nm）introduced into diamond/Cu composites owing to the improving interfacial bonding and lower interfacial thermal resistance.Otherwise,the thermal conductivity of diamond/Al composites decreased from 553 Wm^-1K^-1 to 218 Wm^-1K^-1 after introduction of Mo₂C layer,which could be attributed to the formation of harmful granule-phase(Al₁₂Mo)at the interface of diamond and Al.And the fracture mode of diamond/Al composites changed to interfacial debonding from the ductile fracture.