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Tungsten- and nickel-containing coatings have been produced on the surface of synthetic diamond crystals by rotary chemical vapor deposition (RCVD) using tungsten hexacarbonyl, W(CO)6, and nickelocene, Ni(C5H5)2, as gaseous precursors. The thickness, composition, and morphology of the coatings have been shown to depend on the RCVD process duration and reactant concentrations in the vapor phase. The synthetic diamond microcrystals with tungsten- and nickel-containing coatings have been used to produce copper–diamond heat-conducting composites. Powder mixtures containing 50 vol % diamond with a particle size of 50, 100, or 200 μm have been consolidated by spark plasma sintering or hot pressing. It has been shown that the highest relative density (97%) and thermal conductivity (340 W/(m K)) are offered by the composites produced by spark plasma sintering using tungsten carbide-coated 50-μm diamond crystals.

Diamond/W,Cu heat-conducting composite shims were produced by the multistep route. Initially, the surface of the microdiamonds ∼200 μm in size was covered by a W/WC layer using the deposition from a vapour of tungsten carbonyl. Then, the diamond/W,Cu pills were pressed from the mixture of W/WC-covered diamonds and metal copper powder and the composite shims were sintered at 1270 K in vacuum. The thermal conductivity coefficient and coefficient of thermal expansion (CTE) measured for the diamond/W,Cu composite shims were as high as 450–650 W·m−1·K−1 and 5.5–7.5 10−6/K, respectively.

In the present study, tungsten-containing coatings on diamond particles were obtained by chemical vapor deposition using tungsten carbonyl as a precursor. It was found that tungsten reacts with diamond, which results in the formation of tungsten carbide WC crystallizing along certain crystallographic directions of the diamond crystal. Morphological studies of the coated diamonds have shown that the {111} facets of diamond are more reactive than the {100} facets.

Composite material with high thermal conductivity was obtained by the method of thermal sintering of diamonds (synthetic and impact) and copper powder and by further hot isostatic pressing. The content of diamond (the particle size is 20 - 250 μm) in the diamond copper composite was 30 - 45 weight percent. The coefficient of thermal conductivity of copper diamond composite materials based on synthetic diamonds was measured to be 700 - 750 Wm-1K-1. The coefficient of thermal conductivity of copper diamond composite materials based on impact diamonds was measured to be 850 - 900 Wm-1 K-1. The coefficient of thermal expansion (CTE) was measured to be 5.5 - 6.5 • 10-6/°C for synthetic diamonds and 6.1 - 6.5 •10-6/°C for impact diamonds. The obtained copper diamond composite materials are promising to be used as crystal holders for semiconductor crystals in THz and microwave devices.

Composite material with high thermal conductivity was obtained by the method of thermal sintering of a diamond (50 – 75%) with a size of 20 to 250 μm in a matrix of copper.Coefficient of thermal conductivity of copper diamond composite materials was measured and is 450 – 650 Wm-1K-1. The coefficient of thermal expansion CTE was measured and is 5.5 – 7.5 10-6/°C. The obtained copper diamond composite materials are promising objects for use in THz and microwave devices.

In the present study, W- and Ni-containing coatings on diamond crystals were obtained by rotary chemical vapor deposition (RCVD) using tungsten carbonyl W(CO) 6 and nickelocene Ni(C 5 H 5 ) 2 as precursors. Morphological features of the coatings deposited under different processing conditions were investigated. For obtaining bulk diamond-copper composites, mixtures of the coated and uncoated diamond crystals with a copper powder were subjected to Spark Plasma Sintering (SPS). The effects of the presence of the coatings on the diamond crystals and the size of the initial diamond particles on the microstructure, relative density and thermal conductivity of the consolidated diamond-copper composites were investigated.