High thermal conductivity of Cu-B/diamond composites prepared by gas pressure infiltration

A gas pressure infiltration method was used to prepare diamond particles reinforced Cu-B alloy matrix composites (Cu-xB/diamond, x = 0.3 and 1.0 wt%). The Raman spectroscopy and X-ray diffraction (XRD) analysis confirm the formation of boron carbide (B4C) at the Cu/diamond interface. The amount of interfacial boron carbide increases with increasing boron content in the Cu matrix. A high thermal conductivity of 868 W/mK and corresponding coefficient of thermal expansion of 5.3 × 10−6/K are obtained in the Cu-0.3 wt%B/diamond composite. When the boron content increases to 1.0 wt% B, the thermal conductivity decreases to 647 W/mK. It is found that boron carbide plays a critical role in improving the interfacial bonding and enhancing the thermal conductivity of the Cu-B/diamond composites; however, too much interfacial boron carbide will deteriorate the thermal conductivity of the composites.