Effect of holding time on the interfacial microstructure and mechanical properties of K9 glass/B₂O₃-Bi₂O₃-TiO₂/pure Ti brazing joints

The mixed brazing-filler-material of B₂O₃, Bi₂O₃ and TiO₂ was used to realize the joining of K9 glass and pure Ti at low temperature through brazing. The effects of holding time on the microstructure and properties of the joints were studied by optical microscopy and SEM. The results showed that the shear strength of joints was 11.5 MPa, 15.1 MPa and 12.1 MPa when the composition of B₂O₃:Bi₂O₃:TiO₂ was 5:4:1 and the brazing temperature was 650 °C, as the holding time was 60, 80 and 100 min, respectively. K9 glass/brazing-filler-material was densely bonded with a reaction layer, while the pure Ti/brazing-filler-material side interface was straight with no obvious transition layer and dissolution phenomenon. One kind of joint fracture was brittle fracture completely in the metal and brazing layer, the shear strength was 11.5 MPa. The other was a mixed brittle fracture which happened partially in the metal and brazing layer and partially in the glass-side. The maximum shear strength of the joint with mixed brittle fracture was 16.7 MPa.