Preparation of copper–diamond composites with chromium carbide coatings on diamond particles for heat sink applications

Cr7C3 coatings were formed on diamond particles for improving the wettability between diamond particles and copper. The coatings were formed with a reaction medium of chromium in mixed molten salt. Copper–diamond composites with Cr7C3 coatings on diamond particles have been fabricated by vacuum pressure infiltration method. The microstructure of interfacial bonding between diamond and copper was discussed. Thermal conductivity and thermal expansion behavior of the obtained copper–diamond composites with various fractions of diamond particles were investigated. The as-fabricated composite exhibit a thermal conductivity of 562 W m−1 K−1 associated with coefficient of thermal expansion of 7.8 × 10−6 K−1 with a Cr7C3-coated diamond volume fraction of 65%. These results indicate that the obtained composites are suitable for being heat sink applications. •Cr7C3 coatings were successfully formed on diamond particles in molten salt.•Cr7C3 coatings obviously promoted the wettability of diamond and copper matrix.•Cr7C3 coatings greatly enhanced thermal conductivity of Cu–diamond composites.•The composites are suitable candidates for being heat sink applications.