PHASE-FORMATION IN SIC METAL JOINTS AT HIGH-TEMPERATURES/

Joining of SiC to SiC was performed using Ti and Nb foils at temperatu res ranging from 1373 K to 1790 K in vacuum. The change in microstruct ures of the SiC/Ti and SiC/Nb interfaces war investigated in detail at 1673 K and 1790 K, respectively. At a bonding time of 0.3 k, TiC at t he Ti side and a mixture of Ti5Si3Cx+TiC at the SiC side were formed. Furthemore, a Ti5Si3Cx layer phase appeared between SiC and mixture of Ti5Si3Cx+TiC, upon the formation of Ti3SiC2 after the bonding time of 3.6 ks, the diffusion path was observed as follows. beta-Ti/Ti+TiC/Ti C +Ti5Si3Cx/Ti5Si3Cx/Ti3SiC2/SiC. At 1790 K, the diffusion path betwee n SiC and Nb was established as Nb/Nb2C/NbC/Nb5Si3C/NbC/SiC, and the N bSi2 phase appeared at the interface between NbC adjacent to SiC and N b5Si3C at the longer time of 72 ks.