Enhanced thermal conductivity in diamond/copper composites with tungsten coatings on diamond particles prepared by magnetron sputtering method

Tungsten coatings of 45–300 nm thickness were sputtered deposited on diamond particle surfaces, and diamond/Cu composites were obtained through pressureless infiltration of liquid copper into a bed of coated diamond particles. The composition of the as-deposited coatings was investigated. The effects of coating characteristics on the microstructure, gas tightness and thermal conductivities (TC) of the diamond/Cu composite were also discussed. Results showed that the originally smooth diamond surface are uniformly covered by nanosized tungsten cone arrays. Tungsten coatings with a thickness above 93 nm was found to be the most effective in improving the densification of overall composites and minimizing the interface thermal resistance between reinforcement and matrix. The thermal conductivity of composites reached 731 ± 10 W m−1 K−1 with a 300 nm tungsten coating and achieved a maximum of 796 ± 11 W m−1 K−1 with 218 nm coating. In addition, the interface thermal resistance between matrix and coated diamond particles was discussed in accordance with the calculations using a theoretical model.