Proposal for a new technique to join CFC composites to copper

The divertor design of the ITER fusion machine comprises the joint between CFC composites and the copper alloy heat sink. The main problem of the CFC–Cu joint manufacturing is the large thermal expansion mismatch of the components and the very high contact angle of molten copper on carbon substrates. The aim of this work is to develop a new technique to join CFC composite to pure copper. In order to increase the wettability of CFC by molten copper, the composite surface was modified by direct reaction with group VI transition metals which form a carbide layer and allow a large reduction of the contact angle. A morphological analysis and the mechanical and thermal shock tests were performed to characterize the CFC–Cu joined samples.