Low activation brazing materials and techniques for SiCf/SiC composites

A low activation brazing technique for silicon carbide fiber reinforced silicon carbide matrix composites (SiCf/SiC) is presented; this technique is based on the use of the 78Si-22Ti (wt%) eutectic alloy. The joints obtained take advantage of a melting point able to avoid composite fibre-interface degradation. All the joints showed absence of discontinuities and defects at the interface and a fine eutectic structure. Moreover, the joint layer appeared well adherent both to the matrix and the fibre interphase and the brazing alloy infiltration looked sufficiently controlled. The joints of SiCf/SiC composites showed 71±10 MPa almost pure shear strength at RT and up to 70 MPa at 600 deg. C