AN ELECTRICAL-RESISTANCE HEATING TECHNIQUE FOR JOINING ELECTROCONDUCTIVE CERAMICS

An electrical resistance heating system for joining ceramics was developed, which was based on input current control by thyristor switching. The joining of electroconductive ceramics was carried out in Ar gas by pinching adherends between two electrodes. If the current applied to the adherends was not controlled, cracks occurred in the ceramic by thermal shock, but it was clear that a high joint strength could be obtained by thyristor controlled current switching. Joined material contained no cracks and joining could be completed in a few minutes with use of low electric energy. The joint strength of ZrB2/ZrB2 bonded at 1173 K was 200 MPa in 4 point bending mode, and that of electroconductive-SIALON bonded at 1223 K was 400 MPa.