Effect of surface coatings on the properties of diamond/glass composites

It is emergent to study and develop new ceramic (glass) matrix composites with high thermal conductivity. Improving the bonding condition of the interface between the matrix and reinforcement is an important way to increase the thermal conductivity of these composites. Based on copper plating and controlled oxidation of diamond particles and Cr-coated diamond particles, diamond reinforced glass matrix composites were successfully synthesized by spark plasma sintering (SPS). Their micro-morphology, interface bonding condition and thermal conductivity were investigated. It is shown that diamond particles are distributed in the glass matrix uniformly, while the Cu/diamond interface and Cr/Cu interface are the weakest bonding interface in the two types of composites, respectively. The thermal conductivity of these composites increases with increasing diamond content. The thermal conductivity of the diamond/glass composites decreases with increasing Cu coating thickness; because of chemical bonding between Cr and diamond particles and Cr diffusion in Cu coatings, the thermal conductivity of the Cr-coated diamond/glass composites increases with increasing Cu coating thickness. When the diamond particle size is 100 μm, the diamond volume fraction is 70% and the Cu coating thickness is 1.59 μm, the Cr-coated diamond/glass composite has the highest thermal conductivity about 91.0 W·m^-1·K^-1.