Regulating the surface structure of SiO2f/SiO2 composite for assisting in brazing with Nb

The high-quality joint between SiO2f/SiO2 and Nb was achieved by regulating the surface structure of SiO2f/SiO2. The fused silica as fillers in SiO2f/SiO2 surface layer was consumed by etching treatment, and quartz fibers braided in two dimensions were left. By etching treatment, the wettability of SiO2f/SiO2 was improved and the contact angle dropped from 138° to 37°. Furthermore, the surface structure of SiO2f/SiO2 was deviated from a flat to a 3D-weave, which induced the brazing alloy infiltrating into SiO2f/SiO2 and formed a “3D-pinning structure” in joint. It could reduce residual stress and enlarge joining area, which strengthened the joint.