The balance of thermal conductivity and stability of diamond/Cu composites through interfacial design of Cr–CuCr dual coatings

Interface design and optimization is critical to enhance the interfacial bonding and thermal properties of the diamond/Cu composites. Herein, Cr and CuCr30 dual coatings with the different thickness on diamond particles were deposited by magnetron sputtering. The Cr element on diamond particles transformed to Cr 3 C 2 during sintering, with coexisting interfacial phases of Cr 3 C 2 and Cu to strengthen the interface bonding. Relatively thicker interlayers (∼200 nm and ∼270 nm) act as an effective bridge between diamond and Cu, improving wettability and reducing thermal stress, where no obvious debonding was found and the compact diamond/Cu composites were achieved. The results suggest that the interface structure evolution plays a critical role in determining the thermal conductivity, CTE and thermal cycling behavior of diamond/Cu composites. By measuring the thermal conductivity before and after thermal cycling, we found that the composites with an intermediate thickness of the interlayer possessed the maximum thermal conductivity (686 W/mK), while that with a thicker interlayer presented a better comprehensive performance with a relatively high initial thermal conductivity (646 W/mK), compatible CTE (7.49×10 -6 /K from room temperature to 200 °C) and stable thermal cycling performance (4% attenuation of thermal conductivity for 300 cycles from -50 °C to 150 °C). This work demonstrates that a trade-off exists between maximizing initial thermal conductivity and ensuring long-term thermal stability for diamond/Cu composites.