Effects of dual-layer coatings on microstructure and thermal conductivity of diamond/Cu composites prepared by vacuum hot pressing

• Cu/Diamond composite was fabricated by introducing Cu/W dual layer coating and vacuum hot pressing
• W inner layer was applied by annealing with loose W powder leading to a multilayer coating consisting of W/W2C/WC/Diamond
• The outer Cu layer deposited by electroless plating show a submicron grain structure and a full coverage over the W layer
• Adhesion was significantly enhanced via the strong bonding of the WC/Diamond interface and the wetting of W surface by Cu
• The diamond/Cu composites show excellent thermal property.

Diamond/Cu composites with high density and good thermal properties are fabricated by vacuum hot pressing via designing dual layers on the diamond particles. Different types of inner tungsten layers are coated on diamond after annealing with the loose tungsten powder, and the outer copper layer is then deposited using electroless plating. The effects of dual layers on the microstructure and thermal conductivities of diamond/Cu composite are investigated. The results indicate that the tungsten coating exhibits integrated and uniform structure when the diamond is treated with tungsten powder at 900 °C for 2 h. This tungsten coating improves the interfacial bonding and minimizes the thermal boundary resistance between the diamond and the copper matrix. Moreover, the outside copper coating promotes the sintering process, and hence favors the low-temperature densification of diamond/Cu composites. The thermal conductivity of diamond/Cu composites reaches 721 W m− 1 K− 1, which is close to the theoretical value.