Stress analysis in the preparation of bi-layer membranes by co-sintering process

Based on the theory of 'constrained sintering', stress of the membrane exerted by a rigid substrate was calculated. Results show that the tensile stress from supports can decrease driving force and consequently increase the sintering temperature of supported membranes. The optimal sintering temperatures, 1350°C and 1180°C for α-Al₂O₃ and ZrO₂ supported membranes respectively, are determined by combining membrane strength and sintering driving force. Meanwhile, a method is proposed to calculate the stress developed in the co-sintering process of the supported multilayer membrane. For ZrO₂/α-Al₂O₃ bi-layer membrane, the calculated results show that due to the contribution of the compressive stress, the sintering driving force increases and the α-Al₂O₃ membranes can be sintered effectively after co-sintering at 1200°C. Moreover, the top-layer ZrO₂ membrane should be thicker than 10 μm so as to exert sufficient compressive stress on the sub-layer α-Al₂O₃ membrane with thickness of 15 μm.