Combining Cr pre-coating and Cr alloying to improve the thermal conductivity of diamond particles reinforced Cu matrix composites

Weak interface bonding inhibits high thermal conductive potential of diamonds in metal matrix composites reinforced with diamond particles (Cu/diamond composites). With an attempt to modify the Cu/diamond interface, we combine Cr pre-coating and Cr alloying to produce Cu-Cr/Cr-diamond composites by gas pressure infiltration. High resolution transmission electron microscopy (HRTEM) results reveal that Cr pre-coating on the diamond surface before infiltration promotes the formation of highly active graphite-like structures. These structures enhance the interfacial reaction and intensify the formation of a uniform and dense carbide layer on the diamond surface. By altering the Cr concentration in the Cu-Cr alloy matrix, the thickness of interfacial carbide layer is tailored. As a result, a maximum thermal conductivity of 810Wm(-1) K-1 is achieved in the Cu-0.5 wt% Cr/Cr-diamond composite, which is the highest value among Cr-modified Cu/diamond composites reported so far. The high thermal conductivity is attributed to optimal interface conditions: moderate thickness of interfacial carbide layer, uniform and dense carbide layer on the diamond surface, and crystallographically aligned interfacial graphite layers. This study offers a new route to modifying interface bonding and to enhancing thermal conductivity of Cu/diamond composites. (C) 2018 Elsevier B.V. All rights reserved.