Configuration of multi-phase interlayers for thermal conductivity enhancement of diamond/Al composites

Interface design is critical for enhancement of interfacial bonding and thermal properties of diamond/Al composites as promising thermal management materials. Herein, we propose a new strategy combining in-situ formation of WC (W 2 C)-W coatings and gas pressure infiltration (GPI) process to construct diamond-WC (W 2 C)-W-Al 5 W interlayers to improve the interfacial bonding and thermal properties of diamond/Al composite. The microstructure of the modified coatings and their effect on interfacial bonding and thermal properties of diamond/Al composites were examined. By altering deposition time in only several minutes, the thickness of the coatings ranged from ∼100 nm to ∼400 nm was tailored. Results showed the interfacial bonding of the composites was greatly improved, while the thermal conductivity was initially increased with the thickness and decreased with a maximum thermal conductivity of 677 W/mK achieved. Besides the moderate thickness of W interlayers, the high thermal conductivity was also attributed to the interface configuration with the following characteristics: small amount of W carbides on diamond side, uniform and dense W metal interlayer in middle, as well as W-Al intermetallic sublayer on Al side. The successful configuration of diamond-WC (W 2 C)-W-Al 5 W-Al interface greatly promoted the balance of the interfacial thermal resistance and interfacial bonding to maximize the thermal conductivity of the composites, which was among the first-class team reported for diamond/metal composites modified by W-related coatings. This study offers a feasible method to prepare effective W coatings for modifying interfacial bonding and enhancing the thermal properties of diamond/Al composites.