Ceramics Joining Using Explosive Metal Foil

A capacitor discharge joining technique used to fabricate alumina (A1₂O₃) tile - titanium foil - A1₂O₃ tile joint was investigated with focusing to increase the bonding strength. Several kAs pulse current was supplied from 8.28 muF storage capacitor to the 50 mum thickness titanium foil which was sandwiched between the A1₂O₃ tiles with various pressures. The temperature of the foil was rapidly increased owing to ohmic heating with the large current, and then the foil was liquefied and vaporized. The A1₂O₃ tiles were successfully bonded when the input energy to the titanium foil was higher than the energy required for the foil vaporization. However, the foil explosion cracked the tiles when the input energy exceeds a critical value. Increasing the circuit inductance from 1.13 muH to 64.8 muH, the critical energy of tile cracking increases from 160 J to 507 J. The maximum bonding strength of 3200 N was obtained when the circuit inductance was 21.8 muH. An investigation of the interfacial structure of the joints using electron probe microanalysis revealed that distinct reaction areas existed in the interlayer.