Joining of SiC ceramics using CaO-Al2O3-SiO2 (CAS) glass ceramics

CaO-Al2O3-SiO2 (CAS) glass ceramics were designed and prepared using a melt-quench approach. The coefficient of the thermal expansion (CTE) of the synthesized CAS (4.12 x 10(-6) K-1) matched perfectly with that of the SiC ceramic (4.01 x 10(-6) K-1). Thermal analysis of the CAS was conducted. Then the joining of the SiC ceramics by the CAS glass ceramics under various process parameters were conducted. The bonding temperature affects the fluidity of the CAS glass and the oxidation of the SiC substrate. The holding duration decides the infiltration of the CAS glass into the SiC substrate. The optimal bonding parameter is 1400 degrees C/10 min and the corresponding highest shear strength of the SiC/CAS/SiC bonded joints in average was 56 MPa. Fracture observation was also conducted to help analyze the relationship between the interfacial microstructure and the joint strength. Finally, the formation mechanism of the SiC/CAS/SiC bonded joints was proposed.