Influence of pressure on bonding of alumina with molten aluminium as insert

Abstract

Alumina cylinders of 91% purity were bonded at 1073 K with aluminium foil of different thicknesses (5 and 50 μm) under different pressures (0–2 MPa) to examine the effect of pressure on the reaction of molten aluminium with silica contained in alumina as a binding agent. The reaction process at the bonding interface was also examined. The thicknesses of the interlayer and the reaction zone decreased with decreasing foil thickness. The interlayer was composed of silicon crystals and hypereutectic Al–Si alloy melt. Cavities were also observed. The constitution of the interlayer changed with time following the migration of silicon from the alumina: the amount of Al–Si alloy decreased with time, and the amounts of crystallised silicon and the total cavity volume increased with time. The bonding pressure reduced the thicknesses of the interlayer and the reaction zone. The amount of silicon contained in the interlayer was also reduced by pressure.

MST/3035