A gradient LMAS interlayer joint of SiC coated C/C composites to LAS glass ceramics

A gradient Li2O–MgO–Al2O3–SiO2 (LMAS) glass ceramics interlayer was designed and prepared by vacuum hot-pressing to join SiC coated carbon/carbon (C/C) composites and Li2O–Al2O3–SiO2 (LAS) glass ceramics. The SiC transition layer could effectively infiltrate into the C/C substrates and firmly adhere to the LMAS interlayer. Both the Mg content and microhardness decreased gradually from the SiC side to the LAS glass ceramics side in the gradient LMAS interlayer. The thermal expansion coefficient (CTE) of LMAS glass ceramics increased with the increase of Mg content. The obtained shear strength of the welded sample with a gradient interlayer design was about 30.7% higher than that of the sample without the gradient design. The gradient LMAS interlayer could effectively improve the distribution of process-induced thermal stress in the joint, relieve the mismatch of CTE between SiC transition layer and LAS glass ceramics and increase the bonding strength of the joint.