Optimization of process parameters, microstructure, and thermal conductivity properties of Ti-coated diamond/copper composites prepared by spark plasma sintering

Titanium coating was deposited on the diamond surface by the vacuum micro-vapor deposition method to improve the wettability and enhance the interfacial bonding between diamond and copper. The Ti-coated diamonds were used as the reinforcement particles to fabricate Ti-coated diamond/copper composites by the spark plasma sintering, and the effects of process parameters on the microstructure and thermal conductivity of Ti-coated diamond/copper composites were systematically considered. SEM, EDS, and XRD methods were adopted to analyze the microstructure characteristics and interlayer of the composites. It was showed that TiC formed homogenously, continuous and compactly, aside from some tiny porous appearing on the diamond surface and the thickness of Ti coating was about 300 nm. The TiC interlayer strengthened the interfacial bonding, bridged the diamond particles with copper matrix perfectly, and the formation of compacted Ti-coated diamond/copper composites was verified by microscopic analysis. The relative density of Ti-coated diamond/copper composites was 98.72%, but the thermal conductivity of the composites was only 230.82 W/m*K at the optimal process parameters of 900 °C, 80 MPa, and 40 min, mainly due to some cavities existed at the Ti-coated diamond surface which caused phonons to scatter and decreased the TC of the composites.