Aluminum titanate (Al2TiO5)-mullite composites with excellent thermal shock resistance were studied. Aluminum titanate with a moderately high mechanical strength and a low thermal expansion coefficient was obtained by inhibiting grain growth by the addition of mullite. The composites were fabricated from mono-dispersed powders, produced by the stepwise alkoxide hydrolysis of tetraethylorthosilicate, Si(OC2H5)4 and titanium tetraethoxide, Ti(OC2H5)4, in an Al2O3 ethanolic colloidal suspension. Several thermal durability tests were performed: annealing tests at the critical decomposition temperature, 1100ºC, for 100 h; cyclic thermal shock between 750º and 1400ºC for 100 h; and water quenching from 950º to room temperature (RT). Changes in the microstructure, thermal expansion coefficient, and strength were determined. The composites with 70-80 vol% Al2TiO5 showed the best thermal durability, exemplified by little change in their microstructure during the thermal durability tests. The role of microcracks in thermal shock resistance, strength, Young's modulus, sound velocity, and thermal expansion coefficient is discussed here.

Keywords: Al2TiO5, Mullite, Thermal durability, Thermal expansion coefficient, Thermal shock