Proposal for a modified non-active brazing alloy for joining CFC composites to copper

A novel method based on the modification of a commercial brazing alloy was evaluated and used for joining CFC (carbon fiber reinforced carbon composite) to pure copper. This paper deals with the development of a flat and curved joint concept providing a versatile and cheap joining technology, i.e. a single step brazing process by using an innovative brazing alloy deriving from a commercial one. The brazing of CFC to Cu was performed by using a commercial non-active braze. RF-magnetron sputtering and galvanic processes have been used to modify the commercial non-active braze by coating it with Cr, an active element. The aim is to increase its wettability on CFC, instead of using an active braze, having potential embrittlement issues. Optical microscopy and scanning electron microscopy coupled with energy-dispersive spectroscopy were used to evaluate the microstructure and composition of the CFC/Cu joints. In order to evaluate the mechanical strength of the joint, a lap test in compression has been performed.