Novel two-step method for joining alumina ceramic by using Al2O3 powder followed by glass infiltration

Abstract

In this work, a novel two-step joining method was developed to join alumina ceramics for high-temperature applications. First, alumina ceramics were bonded using Al₂O₃ powder at 1550°C. Subsequently, the Dy₂O₃–Al₂O₃–SiO₂ glass was infiltrated into the interlayer at 1450°C to obtain the alumina/alumina joints with dense composite interlayer composed by Al₂O₃, Dy₂Si₂O₇, and few glass phase. The content of Al₂O₃ in the composite interlayer reached 52.7%. As a result, the coefficient of thermal expansion mismatch between the interlayer and the alumina ceramic was reduced to only 2%. The flexural strength of the joints at room temperature was equivalent to that of the alumina ceramic. Furthermore, the flexural strength of the joints at 1000°C reached about 90% of that of alumina ceramics under the same conditions. After the thermal cycles from room temperature to 1000°C for 50 times, there was no significant change in the flexural strength of the joints.