Joining of SiC/SiCf ceramic matrix composites for fusion reactor blanket applications

Using a preceramic polymer, joints between SiC/SiCf ceramic matrix composites were obtained. The polymer, upon pyrolysis at high temperature, transforms into a ceramic material and develops an adhesive bonding with the composite. The surface morphology of 2D and 3D SiC/SiCf composites did not allow satisfactory results to be obtained by a simple application of the method initially developed for monolithic SiC bodies, which employed the use of a pure silicone resin. Thus, active or inert fillers were mixed with the preceramic polymer, in order to reduce its volumetric shrinkage which occurs during pyrolysis. In particular, the joints realized using the silicone resin with Al-Si powder as reactive additive displayed remarkable shear strength (31.6 MPa maximum). Large standard deviation for the shear strength has nevertheless been measured. The proposed joining method is promising for the realization of fusion reactor blanket structures, even if presently the measured strength values are not fully satisfactory