Investigation on brazing of zirconia ceramic with Bi₂O₃-B₂O₃-Al₂O₃ glass

50Bi₂O₃-45B₂O₃-5Al₂O₃ (BBA) glass was used to braze ZrO₂ ceramic. The results showed the glass braze could wet ZrO₂ well, and the wetting contact angle reached 20.1° when the temperature was 750 °C. Good bonding could be obtained in the temperature range of 635–750 °C for 30 min using the glass. When the temperature was 635 °C, the products in the joint were Al₄B₂O₉ whiskers, while that were Al₄B₂O₉ whiskers and Al₅BO₉ crystals when the temperature was 650–700 °C. Al₅BO₉ crystals were the main products in the joint when the temperature was >700 °C. The shear strength of the joints first increased and then decreased with the increase in brazing temperature; maximum shear strength of 75 MPa was obtained when the ZrO₂ was brazed at 675 °C. Al₄B₂O₉ whiskers and Al₅BO₉ crystals could hinder crack propagation and thus enhanced the joint, but excessive products could damage the mechanical properties of the brazed joint.