Optimization of braze sealing process for ZrO2/Ti6Al4V glass connections: Interface impact studies

This study systematically investigates the interface-strengthening mechanisms of bismuth-based sealing glass for brazing Ti6Al4V titanium alloy and ZrO₂ ceramic in an air environment. As key materials in aerospace, biomedical, and electronic packaging applications, the reliable joining of titanium alloys and ceramics is significant for expanding their composite applications. Given the thermal sensitivity of sealing glass, which requires precise control of the bonding temperature to achieve reliable connections, this study explores the influence of brazing temperature and holding time on the interface structure and mechanical properties. When the brazing process parameters were optimized to 650 °C/30 min, the joint achieved the highest shear strength, with an average value of 35 MPa. Under these optimized conditions, a composite structure consisting of nanoscale Bi₄Ti₃O₁₂ precipitates and Bi single-phase formed at the interface, effectively enhancing the bonding strength of the heterogeneous materials through chemical bonding. When the temperature exceeded the critical value or the holding time was extended, abnormal coarsening of the precipitates occurred, leading to intensified stress concentration effects and a significant decline in interfacial bonding strength. By establishing the correlation mechanism among process parameters, interface structure, and mechanical properties, this study confirms that controlling the size of interfacial precipitates is a key factor in improving the bonding strength of metal/ceramic joints.