High-strength SiC joints with a novel in-situ formed SiC/Al4SiC4 joining filler

The in-situ formed SiC/Al4SiC4 joining layer was used to join monolithic SiC using an electric field-assisted sintering technique. A multiphase powder of Al4C3/SiC/Al4SiC4 was used as the initial joining material to obtain the in-situ reaction layer of SiC/Al4SiC4 via the appropriate interface reactions. The bending strength as high as 240.5 +/- 6.6 MPa was obtained for the sample joined at 1800 degrees C, which was higher than the strength of the unjoined SiC matrix. Sound joints were obtained when Al4C3 was completely transformed to Al4SiC4, and a fully dense SiC/Al4SiC4 joining layer was consolidated. The integration of the joining layer with the SiC matrix was improved by a high amount of liquid phase formed at the interface. The proposed SiC/Al4SiC4 joining layer, with good thermal matching with SiC matrix, shows a great potential to be applied as a joining material for SiC-based ceramic matrix composites.