Properties of alumina/Al/alumina joints produced in air atmosphere

Abstract

Two types of alumina of different purity were bonded to molten aluminium in air. For bonding of high purity alumina, the bonding behaviour was independent of the bonding pressure, and the shear strength was 75 MN m⁻², which was in good agreement with the value for bonds produced in vacuum or an inert gas atmosphere. For bonding of low purity alumina, the bonding behaviour was dependent on the bonding pressure. When the specimen was bonded with no loading on the bond interface, the shear strength was 50 MN m⁻². In the bonding operation, aluminium penetrated into the alumina, and deoxidised the silica to form free silicon. The free silicon crystallised at the bond interface. When the specimen was bonded under a pressure of 2 MN m⁻², aluminium remained at the bond interface, and the shear strength was 75 MN m⁻². MST/1671