Regulating the glass network structure of SiO2f/SiO2 composite joints by in-situ silica diffusion

To expand the application of SiO2f/SiO2 composites, joining is one indispensable process. However, it is hard to take care of the property of the composites and simultaneously form a robust joint. Here, a B2O3–ZnO glass filler with a loose network structure was designed to realize the self-joining of SiO2f/SiO2 composites. Results revealed that silica has a relatively rapid diffusion rate in B2O3–ZnO glass which is beneficial for the fast replacement of the glass network former. After brazing, silica diffused into the brazing seam, became a new network former and thus regulated the glass network structure. As a result, the maximum working temperature of the joint increased 200 °C compared with pristine B2O3–ZnO glass. The joints own 23.3 MPa shear strength at room temperature and remain 22.3 MPa at 600 °C. This work offers a way to achieve the joining of SiO2f/SiO2 composites and break through the original maximum working temperature of the glass filler.