Study on the Microstructure of SiC Ceramic Joint Bonding by CaO-Al2O3 Glass-ceramic Solder

Abstract

Abstract In this paper, 49.77wt.% CaO-50.23wt.% Al2O3 (CA) glass has been designed, fabricated and studied for the joining of SiC ceramics. The thermophysical properties, crystallization kinetics, crystallization behavior of glass solder, and the microstructure of the joint were analyzed and discussed in detail. It is found that the melting point of CA glass solder is 1437 °C, the crystallization activation energy is 274.07 kJ/mol, and the precipitated crystal is 12CaO·7Al2O3. The minimum wetting angle of CA solder on pre-oxidized SiC ceramics is 23°. The joint interface is well combined, and two crystal phases of 2CaO·Al2O3·SiO2 and 12CaO·7Al2O3 are formed in the weld. The typical microstructure of a SiC ceramic joint with CA glass solder is SiC/2CaO·Al2O3·SiO2+12CaO·7Al2O3/SiC at 1550 °C for 10 min.