Aluminum titanate based composite porous ceramics with both high porosity and mechanical strength prepared by a special two-step sintering method

In this work, we develop a two-step sintering technology special for porous ceramics to resolve the contradiction between porosity and mechanical strength. It contains a first long-time sintering at the relatively low temperature (T-1) and a second fast sintering at higher temperature (T-2). Porous ceramics of aluminum titanate-strontium feldspar-mullite (ASM) ternary composite were prepared by this method, and exhibit both high porosity and high mechanical strength. The effects of T-1 and T-2 on the phase composition, microstructure, porosity, pore size distribution, mechanical strength and thermal expansion coefficient (TEC) of ASM porous ceramics are systematically studied. The sample sintered at T-1 = 1400 degrees C & T-2 = 1500 degrees C shows optimum performance: the porosity, bulk density, and mean pore diameter (D-50) are 63.48%, 1.20 g/cm3 and 15.94 mm, respectively; while the flexural strength reaches 9.22 MPa and the TEC is 2.9 x 10(-6)/K. The two-step sintering technology provides a powerful tool to develop porous ceramics with excellent comprehensive properties. (c) 2020 Elsevier B.V. All rights reserved.