Preparation of porous Al_2TiO_5 ceramics reinforced by in situ formation of mullite whiskers

摘要

Due to the low thermal expansion coefficient and high temperature resistance, porous Al_2TiO_5 ceramic is a promising candidate for use in high-temperature gas purifier, diesel tail gas processor and catalyst support. In this paper, Al_2TiO_5-based porous ceramics reinforced by in situ formation of mullite whiskers were fabricated by reaction sintering method using γ-AlOOH, TiO_2, SiO_2 and AlF_3 as raw materials, Fe_2O_3 as modifying agent, respectively. Results show that apparent porosity of the composite porous ceramics is increased from 33.3% to 45-52% when the raw materials for mullite were added, and the com-pressive strength of the porous ceramic is above 11 MPa. The in situ synthesized mullite whiskers, with the size of 0.5-0.6 μm in diameter and 6-8 μm in length, formed interlocking structure in the pores of Al_2TiO_5-based porous ceramics, which is beneficial to improve the strength and increase the specific surface area of the porous ceramics.