Effect of Joining Temperature on Microstructure and Properties of SiC Ceramic Joints with CaO-Al₂O₃-MgO-SiO₂-TiO₂ Glass Solder

Pressureless sintered SiC ceramics were joined with a noval glass solder of CaO-Al₂O₃-MgO-SiO₂-TiO₂ (CAMST). The effect of joining temperature (1 300-1 450℃) on the microstructure and mechanical properties of SiC ceramic joints was investigated. The results show that CAMST glass solder could effectively connect SiC ceramics at 1 350-1 450℃. The thickness of the weld was about 36 μm when the joining temperature was 1 350℃, and large pores were observed in the interlayer between base metal and weld; the shear strength of the joint was (21.4±2.7) MPa. When the joining temperature was 1 400℃, the thickness of the weld was about 3 μm, and the base metal was well bonded with weld; the shear strength of the joint was (47.6±6.2) MPa. When the joining temperature was 1 450℃, the thickness of the weld was about 50 μm; the base metal was well bonded with weld, but there were crack defects in the weld; the shear strength of the joint was (20.9±3.9) MPa. The joining temperature had no significant effect on the hardness of the weld.