INTERFACIAL REACTION AND STRENGTH OF SIC TA/SIC JOINT/

SiC was bonded to SiC using Ta foils at temperatures from 1673 to 1773 K for 3.6 similar to 144 ks in vacuum. The reaction phase and microst ructure formed at the an interfaces between SiC and Ta were investigat ed. At the initial stage, an hexagonal Ta2C phase is formed at the Ta side of the reaction zone, and the hexagonal Ta5Si3Cx phase at the int erface SiC/Ta2C. At a longer bonding time, Ta and Ta2C were consumed a nd the cubic TaC, hexagonal TaSi2 and Ta5Si3Cx phase were detected in the reaction zone. The reaction layer grew with the joining time follo wing the parabolic law, and the activation energy for the growth was 2 66 kJ/mol. At a constant bonding temperature of 1773 K, the strength o f the SiC joint showed a maximum at the bonding time of 28.8 ks. The b rittle single phase of TaSi2 decreases the strength of the SiC joint.