Microstructure, mechanical property and bonding mechanism of SiC ceramic joint using a novel Y2Si2O7/Mullite glass-ceramic interlayer

Joining of SiC ceramics with a pre-oxidized or unoxidized surface and the subsequent mechanical properties have been studied using Y2O3-Al2O3-SiO2 glass bonding method, and the mechanism of interface bonding was revealed. The joining parameter of interest was temperature from 1400 degrees C to 1500 degrees C for a dwell time 10 min. The microstructure, compositions, and interfacial properties were characterized via electron microscopy and X-ray diffractometry. A multiphase glass-ceramic interlayer mainly consisting of Y2Si2O7 and mullite was formed in the joint, which possessed good thermal matching with the SiC substrate. Moreover, the softening temperature of glass-ceramic could exceed to 1200 degrees C. The joint obtained from the pre-oxidized SiC substrate exhibited a more reliable interface bonding than the unoxidized surface. A preferable shear strength of 48 MPa was achieved within 10 min at 1420 degrees C. The elemental diffusion at the interface and the chemical bonding between glass -ceramic and SiC contributed to a reliable SiC-SiC joint.