Thermal conduction and strength of diamond-copper composite sandwich obtained by SPS diffusion bonding with Ti interlayer

Abstract

Complex diamond/Cu composites prepared using diffusion bonding by spark plasma sintering (SPS) can realize the full potential of such composites. However, a high thermal conductivity (TC) cannot be achieved due to the diffusion-bonded interface's low bond strength and acoustic mismatch. An intermetallic compound Cu2Ti and a carbide TiC were generated on the diffusion-bonded interface after adding a titanium (Ti) interlayer. The intermetallic compound Cu2Ti and carbide TiC change the mechanical bonding into chemical bonding between diamond and Cu, significantly improving the interfacial bond strength as the diffusion-bonded interface's shear strength increased from 44.94 to 61.23 MPa. And the shear fracture changes from brittle to ductile approximately to that of the Cu matrix. In the meantime, the phonon-regulating effect of the carbide TiC enables interfacial TC in the diamond/TiC/Cu structure to be stronger than that in the diamond/Cu structure. The Ti interlayer can improve the bond strength of the SPS diffusion-bonded interface and acoustic matching of diamond/Cu composites as the TC increased from 347.73 W/(m·K) to 483.37 W/(m·K), which is 86.47% of the base metal.