Effect of molybdenum particles on thermal and mechanical properties of graphite flake/copper composites

Abstract

Graphite flakes (GFs) in the GF/Cu composites generally fail to exert the advantage of the negative coefficient of thermal expansion (CTE) on account of the weak interfacial bonding between GFs and Cu. In this work, a rivet-joint strategy is adopted to surmount the dilemma. By introducing submicron Mo particles into the Cu matrix through the chemical synthesis process, various GF/Cu composites with the improved alignment of GFs via the method of tape-casting and hot-pressing sintering have been prepared. Due to the combined effects of Mo particle strengthened Cu and the rivet-joint interfacial architecture deriving from the in-situ synthesized MoxC, optimized thermal/mechanical properties of GF/Cu–Mo composites have been achieved. The 50 vol% GF/Cu composite with 1 wt% Mo shows the in-plane thermal conductivity of 598 W⋅m−1⋅K−1 and the through-plane CTE of −2.92×10−6K−1 (25–100 ∘C). Simultaneously, the bending strength is 40% higher than the 50 vol% GF/Cu composite. This strategy could promote the development of composites with improved combined structural and functional properties.