Thermal shock resistance and thermal conductivity of diamond-Cu composite coatings on Cu substrate via mechanical milling method

In this work, diamond-Cu composite coatings were successfully fabricated on T2 pure Cu substrate by mechanical milling (MM) method. Effects of raw diamond particle size, diamond content and milling time on the microstructure and properties of the coatings were investigated. The results showed that the diamond particle size in the coating was mainly distributed between hundreds of nanometers and several micrometers. The microhardness of the coating was much higher than that of the Cu substrate. Larger raw diamonds would contribute to the thermal shock resistance of the coating, due to the interfacial strengthening of diamond inlay structure and the buffering effect of inner layer. The coating with optimum microstructure and thermal shock resistance could be synthesized at the raw diamond dimension of 105 μm, the diamond content of 30 wt% and the milling duration of 7 h. The formation mechanism of the coating was discussed. The thermal diffusion was closely related to the crystal structure of copper and interfacial bonding between diamond and copper. The thermal conductivity of the coated sample improved to 336.938 W m−1 K−1 after subsequent annealing treatment, even higher than that of T2 pure copper substrate.