Thermal shock resistance of SiC/MAS-LAS multilayer joint of carbon/carbon composites to LAS glass-ceramic

Carbon/carbon (C/C) composites were joined to lithium aluminum silicate (LAS) glass-ceramic using a joining layer consisting of a SiC transition layer and a multilayer of magnesium aluminum silicate (MAS) and LAS glass-ceramic by a two-step technique of pack cementation and hot-pressing sintering. The microstructures of the as-prepared joint were characterized by scanning electron microscopy and energy dispersive spectrometry. The design of the multilayer structure could provide more possibilities for crack propagation to release the stress in the joint. Results of the thermal shock test showed that the average shear strength of the joined samples increased from 17.9. MPa to 32.6. MPa after 50 thermal cycles between 800 °C and room temperature, which was primarily attributed to the toughening effects of microcracks. However, after 30 thermal cycles between 1000 °C and room temperature, the average shear strength of the joined samples dropped to 14.2. MPa since the crack size was beyond the tolerance of the joint.