Air-brazed Al2O3 joint with a novel bismuth glass

Abstract Polycrystalline alumina ceramics were air-brazed using bismuth glass with a chemical composition of 50Bi 2 O 3 –40B 2 O 3 –10ZnO (mol.%) at a relatively low temperature. ZnAl 2 O 4 particles were formed insitu in the joints and the particles grew rapidly with an increase in joining temperature and holding time increasing. In addition, penetration of the alumina substrate by the glass became increasingly serious at higher temperatures and holding durations. The mechanical properties of the joints were investigated and the maximum shear strength was determined to be 50 MPa when brazed at 650 °C for 0 min.