Process and properties of SiC brazing through multicomponent oxide assisted by electrothermal shock

An electrothermal shock-assisted high-temperature brazing technology was proposed in this work, which successfully achieved the joining of 18.77Gd₂O₃-4.83Y₂O₃-28.22TiO₂-8.75ZrO₂-39.43Al₂O₃ multicomponent oxide filler and SiC ceramics. The SiC brazed joint with an optimal shear strength of 136.27 MPa was achieved under 20 A DC current and 800 W cut-off power by using carbon fiber as the heating element. The Al₂O₃ and TiO₂ components in the multi-component oxide filler metal were very important to achieve a good SiC ceramic brazing joint. TiO₂ reacted with SiC at high temperature to generate a Ti-rich interfacial reaction layer with a thickness of ~10 μm at the interface, and Al₂O₃ penetrated into the base metal to form a pinning effect, which was beneficial to improve the brazed joint strength. However, when the heat input was too large, the SiC base metal would decompose seriously, and a large amount of C element would diffuse to the brazing seam, resulting in obvious crack defects. The shear strength would be reduced to ~60 MPa, and the fracture completely occurred in the brazing seam.