Effect of SiC nanowires on the thermal shock resistance of joint between carbon/carbon composites and Li_2O-Al_2O_3-SiO_2 glass ceramics

摘要

In order to improve the bonding property of joint between SiC modified carbon/carbon (C/C) composites and Li_2O-Al_2O_3-SiO_2 (LAS) glass ceramics, SiC nanowires were attempted as the reinforcement materials in the interface region of SiC transition layer and Li_2O-MgO-Al_2O_3-SiO_2 (LMAS) gradient joining interlayer. The C/C-LAS joint with SiC nanowire-reinforced interface layer was prepared by a three-step technique of pack cementation, in situ reaction and hot-pressing. The microstructure and thermal shock resistance of the as-prepared joints were examined. The average shear strength of the joined samples with SiC nanowires increased from 24.9 MPa to 31.6 MPa after 40 thermal cycles between 1000 ℃ and room temperature, while that of the joined samples without SiC nanowires dropped from 21.4 MPa to 8.3 MPa. The increase of thermal shock resistance of the C/C-LAS joints was mainly attributed to the toughening mechanism of SiC nanowires by pullout, bridging and crack deflection.