Enhanced thermal conductivity and long-term stability of diamond/aluminum composites using SiC-coated diamond particles

In this study, diamond/aluminum composites were fabricated by the use of gas pressure infiltration. The effects of SiC-coated diamond particles on composite performance were investigated in terms of: (1) controlling the thermal conductivity (TC) during composite fabrication and (2) providing long-term stability. Al₄C₃ spontaneously forms at the interface of the diamond particles and the Al matrix. An excess amount of Al₄C₃ interphase adversely affects the composite, due to its low TC and hygroscopic behavior. Because the SiC coating of diamond particles suppressed the formation of Al₄C₃ during the fabrication, the composite contained a low amount of Al₄C₃ and showed higher a TC (528 W/m·K) than uncoated diamond/Al composite (376 W/m·K), along with significantly higher moisture resistance. The thermal expansion coefficient (CTE) of the SiC-coated diamond/Al composite was determined to be 7.2 ppm/K at room temperature. The composite exhibited long-term stability up to 500 °C as the Al-C reaction was prevented by the SiC coating. Moreover, it displayed excellent thermal shock resistance between 300 °C and room temperature. Graphical Abstract: [Figure not available: see fulltext.]