Surface modification of carbon/carbon composites to improve their wettability by copper

This work proposes a simple and low cost method to modify the surface of undoped and silicon-doped carbon/carbon composites (C/C) in order to widen their application field in particular when joined to metals. The C/C surface was modified using W, Mo and Cr in an attempt to improve its wettability by copper.W, Mo and Cr powders are applied to C/C surface by the slurry technique and successively heat treated in Ar atmosphere to perform a solid state reaction with C/C. As a consequence, Cu wetting on C/C is improved and direct joining of C/C to Cu is feasible without any filler metal. The reactions between the C/C surface and the deposited metal powders were investigated by X-ray diffraction analysis, optical and electron microscopy. The best results in terms of wettability of molten copper on C/C have been achieved by modifying C/C with Cr. Cr forms a homogeneous carbide layer on the C/C surface with strong adhesion which provides a suitable substrate for molten copper. Because of the importance of surface wetting behaviour in certain applications (e.g. joining C/C to metals), C/C surface modification may enhance their use.