Characterisation of joined surface modified SiCf/SiC composites

This work has focused on surface engineering coupled with brazing to join SiCf/SiC composites and to improve the joint strength. The surface engineering was carried out through the Selective Thermal Removal (STR) of SiC fibres from a SiCf/SiC composite to obtain “brush-like” surfaces; the modified composites were then joined by means of an AgCuTi braze alloy. In order to investigate whether a “brush-like” interface could enhance the mechanical strength of the joint by increasing mechanical interlocking with the brazing alloy at the micron scale, the joints were tested with and without surface engineering by means of single lap offset under compression. The treatment to form a roughened surface suitable for mechanical keying of the braze metal led to an improved ductility of the joint; the fracture surfaces demonstrated that the proposed method is promising, even though the treatment damages locally the composite.