Co-sintering synthesis of tubular bilayer α-alumina membrane

In order to reduce production time and costs, a co-sintering process was proposed to prepare tubular bilayer α-alumina membrane. The shrinkage mismatch between two membrane layers during co-sintering was the first problem to be solved. The selection of the co-sintering temperature was the main issue addressed in this paper. Experimental results showed that too large mismatch in the sintering shrinkage of two membrane layers could cause defects such as cracks and big pores while moderate shrinkage mismatch between two membrane layers during co-sintering was beneficial. SEM images of the membrane prepared by co-sintering at 1300 °C showed that the membrane surface was defect-free and the interfacial bonding was good. Ultrasonic treatment did not damage the microstructure and the permeability of the membrane synthesized by co-sintering at 1300 °C. The filtration of the CaCO₃ suspension showed that the membrane treated by co-sintering had a higher steady permeate flux than the membrane prepared by conventional process and can withstand a high back-flushing pressure.