Mechanical behavior of the joints between carbon/carbon composites and Li₂O–Al₂O₃–SiO₂ glass ceramics with YAS interlayer at high temperature

YAS (Y₂O₃–Al₂O₃–SiO₂) glass ceramics were selected to join carbon/carbon (C/C) composites and Li₂O–Al₂O₃–SiO₂ (LAS) glass ceramics through vacuum hot-pressing sintering, due to the corresponding excellent compositional and structural stability at high temperature. Microstructures, mechanical properties and fracture features of the C/C-LAS joints were investigated. The joints with YAS interlayer exhibited more favorable results than the joints with MAS (MgO–Al₂O₃–SiO₂) interlayer subsequently to shear testing at 300 and 600 °C. Strength retention of 70% for YAS joints was achieved at 600 °C, while for MAS joints the strength retention was only 28%. The joining properties amount decrease of YAS joints was due to degradation of the intrinsic properties of YAS and LAS glass ceramics. Regarding MAS joints, the poor structural stability of MAS interlayer at high temperature was the reason for the corresponding decrease. As a result, the mechanical behavior of joints at elevated temperatures was not only related to wettability and interfacial bonding, but it was also related to the intrinsic properties as well as to high-temperature stability of the interlayer and the joined substrates.