Study on surface modification of diamond particles and thermal conductivity properties of their reinforced metal-based (Cu or Mg) composites.

An innovative molten-salt method is presented for the in-situ reactive preparation of surface-modified diamond particles. Surface-modified diamond particle reinforced metal-based (copper or magnesium) composites were prepared by spark plasma sintering. Field-emission scanning electron microscopy was used to analyze the surface morphologies of the surface-modified diamond samples and the interfacial bonding of the diamond-metal composite materials. The elemental distributions of the surface-modified diamond particles were analyzed by energy-dispersive X-ray spectroscopy, and X-ray diffraction was used to analyze the phase compositions of the samples. By means of X-ray photoelectron spectroscopy and laser Raman spectroscopy, the surface bonding and graphitization of the surface-modified diamond particles were further analyzed. The results showed that the thickness of the modification layer on the surface of diamond increased gradually with increasing holding time. The surface-modified diamond particle reinforced metal-based composite materials had high thermal conductivities. When the volume percentage of diamond was 35%, the thermal conductivities of the diamond–copper composites were as high as 602 W·m−1·K−1, and the thermal conductivity of the diamond–magnesium composites reached 286 W·m−1·K−1. Unlabelled Image • Surface-gradient-modified diamond particles were prepared using a molten-salt method. • The effects of holding time on the phase and microstructure of coating layers were investigated. • The thermal conductivities of the surface-modified diamond-reinforced metal (Cu or Mg) matrix composites were studied. [ABSTRACT FROM AUTHOR]