Direct joining of CFC to copper

The ITER divertor design foresees the joint between CFC (carbon fibre reinforced carbon composites) as armor material and a Cu alloy in the heat sink. The purpose of this work is to realize a new joining method between CFC and a pure copper interlayer, required to accommodate the thermal expansion mismatch between CFC and the copper alloy. The joining technique is based on the direct copper casting on CFC surface, which was previously modified by direct reaction with a transition metal of the VI B group. The formation of a carbide layer on CFC surface improves the wettability of molten copper on CFC. The process was also successfully applied to join silicon doped CFC to copper. The paper includes the results of the morphological analysis, the mechanical tests on the joined samples and preliminary thermal fatigue tests.