Microstructure and thermal properties of copper–diamond composites with tungsten carbide coating on diamond particles

• WC coating was successfully synthesized on diamond particles in molten salts.
• WC coating obviously promoted the wettability of diamond and copper matrix.
• WC coating greatly enhanced the thermal conductivity of Cu–diamond composite.
• The composites are suitable candidates for heat sink applications.

An effective method for preparing tungsten carbide coating on diamond surfaces was proposed to improve the interface bonding between diamond and copper. The WC coating was formed on the diamond surfaces with a reaction medium of WO3 in mixed molten NaCl–KCl salts and the copper–diamond composites were obtained by vacuum pressure infiltration of WC-coated diamond particles with pure copper. The microstructure of interface bonding between diamond and copper was discussed. Thermal conductivity and thermal expansion behavior of the obtained copper–diamond composites were investigated. Results indicated that the thermal conductivity of as-fabricated composite reached 658 W m− 1 K− 1. Significant reduction in coefficient of thermal expansion of the composite compared with that of pure copper was obtained.