Effect of Processing Parameters on Thermal Cycling Behavior of Al₂O₃-Al₂O₃ Brazed Joints

In the present study, alumina ceramics were active metal brazed at different temperatures ranging from 1163 K to 1183 K (890 °C to 910 °C) using TICUSIL (68.8Ag-26.7Cu-4.5Ti in wt pct) foil as filler alloy of different thicknesses. The brazed joints were subjected to thermal cycling for 100 cycles between 323 K and 873 K (50 °C and 600 °C). The microstructural and elemental composition analysis of the brazed joints were performed by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) before and after thermal cycling. Helium (He) leak test and brazing strength measurement were also conducted after thermal cycling for 100 cycles. The joint could withstand up to 1 × 10⁻⁹ Torr pressure and brazing strength was higher than 20 MPa. The experimental results demonstrated that joints brazed at the higher temperature with thinner filler alloy produced strong Al₂O₃-Al₂O₃ joints.