The influence of thermochemical treatments on interface quality and properties of copper/carbon-fibre composites

Abstract High-strength carbon fibers were submitted to various thermochemical treatments in order to obtain a uniform and tough coating of copper particles on their surfaces. After heat treatment in the range 700–1000°C under argon atmosphere they were chemically treated in NaOH, HNO 3 , C 3 H 6 O and HF baths with different concentrations. The last of these solutions was used for the first time in this investigation. The results show that both the thermal and chemical treatments greatly influence the binding quality of copper particles to the fibers which is crucial for a reliable composite material. The results also indicated that heat treatment at 100°C for 2 h and chemical treatment with HF led to a ‘porous’ and groovy surface resulting in a uniform and thin layer of copper after electroplating. Microstructural evolution at different steps was followed by means of optical and scanning electron microscopy and a mechanism for copper growth at the surface of the fibers is proposed. Finally the coated fibers were chopped and sintered with copper powder. The influence of sintering conditions on electrical and thermal conductivities of the composite material was studied and the strength and composition of the interface was examined by the SEM technique.