Low-temperature joining of SiC ceramics by NITE phase using CaO-Al2O3-MgO-SiO2 glass as an additive combined with surface oxidation

• Published in: Journal of the European Ceramic Society Vol. 43; no. 14; pp. 5863 - 5870
• Main Authors: He, Sheng-Jin, Su, Ling-Feng, Zhan, Chuang-Tian, Chen, Xiu-Bin, Guo, Wei-Ming, Sun, Shi-Kuan, Wu, Li-Xiang, Xue, Jia-Xiang, Lin, Hua-Tay
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2023
• Subjects: CaO-Al2O3-MgO-SiO2 glass; NITE phase; SiC joining; Surface oxidation; SiC joining; CaO-Al2O3-MgO-SiO2 glass; Surface oxidation; NITE phase
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2023.06.011

Low-temperature joining of SiC ceramics using raw CaO-Al2O3-MgO-SiO2 mixed powders (CAMS-P) and CaO-Al2O3-MgO-SiO2 glass (CAMS-G) as additives for the liquid-phase sintering of SiC nanopowders (NITE phase) in combination with surface oxidation was studied. Using CAMS-P as an additive for SiC joining required 1650 °C and produced a lower shear strength of 77.2 ± 3.5 MPa, compared to untreated SiC (108.2 ± 15.8 MPa). Using CAMS-G as an additive, the compactness of SiC joints obtained at 1550 °C was higher than that of NITE joints obtained at 1650 °C with CAMS-P as an additive. Nonetheless, the low joining temperature resulted in gaps and delaminations at the interface, and the joints strength was only 48.3 ± 5.6 MPa. Incorporating CAMS-G as an additive and surface oxidation achieved reliable NITE phase joining at 1550 °C, with no observed gaps or delaminations at the interface. The resulting joints strength was as high as 100.0 ± 0.8 MPa. The joining mechanism was discussed and compared, involving microstructural analysis.