The influence of morphology and composition of metal–carbide coatings deposited on the diamond surface on the properties of copper–diamond composites

Abstract In this work, tungsten- and molybdenum-containing coatings on diamond were obtained by rotary chemical vapor deposition (RCVD) or by treating the diamond microcrystals in a hot press (HP)/spark plasma sintering (SPS) facility. In the HP facility, heating was realized by external heating elements; no electric current was passing through or induced in the die. In RCVD, tungsten carbonyl W(CO)6 was used as a precursor. In the case of HP and SPS, powders of tungsten, molybdenum and tungsten trioxide WO3 were used as sources of the metal. It was found that the morphology and phase composition of the coatings depend on the deposition conditions and the metal source. HP and SPS were further used for fabricating bulk copper–50 vol% diamond composites. The thermal conductivity of the copper–diamond composites decreased as the holding time during their consolidation by HP or SPS increased owing to delamination of the WC coating from the diamond surface. A Mo-containing coating deposited by the SPS treatment allowed obtaining a copper–diamond composite with a thermal conductivity of 420 W m−1 K−1.