Effect of molybdenum carbide intermediate layers on thermal properties of copper–diamond composites

Molybdenum carbide (Mo 2 C) coated diamond particles were prepared by molten salts method and the copper–diamond composites were obtained by vacuum pressure infiltration of Mo 2 C-coated diamond particles with pure copper. The formation mechanism of the Mo 2 C layers was investigated, and the microstructure, thermal conductivity and thermal expansion behavior of the obtained copper–diamond composites were studied. The coated layers were formed by using a reaction medium of MoO 3 in mixed molten salts, and the formation mechanism of the Mo 2 C layers on diamond particles was investigated. The result indicates that the formation of Mo 2 C layers occurred in two steps, that is, the reduction of MoO 3 to MoO 2 and the reduction of MoO 2 to Mo 2 C. The wettability between diamond particles and copper was effectively improved, and the relative density of the copper–diamond composites achieved 99.5%. The thermal conductivity reached 596 W m −1 K −1 , and the coefficient of thermal expansion was 7.15 × 10 −6 K −1 of the composites with 60 vol.% Mo 2 C-coated diamond. This composite is expected to be suitable for electronic packaging applications.