Structure,Thermal Expansion and Thermal Stability of Aluminium Titanate Materials
XU Gang HAN Gaorong (Department of Materials Science and Engineering,Silicon State Key Lab,Zhejiang University, Hangzhou 310027)
In this paper,research on the structure,thermal expansion and thermal stability of aluminium ti- tanate materials is reviewed. Aluminium titanate is a member of the pseudobrookite family, which belongs to or-thorhombic system. Aluminium titanate ceramics exhibit a very low thermal expansion coefficient,low thermal conductivity and excelleng thermal shock resistance. These propertis arise from the microstructure of Al2TiO3 which is characterized by microcracking along the grain boundaries because of the pronounced anisotropy in thermal expansion of its crystallites. However,aluminium titanate is only stable from the kinetic point of view at low temperature and has a strong tendency to decompose into the parent oxide below 1280C? The formation of Al2TiO5-MgTi2O5 or Al2TiO5-Fe2TiO5 solid solution, which can decrease the thermodynamic decomposition temperature and increase the structure entropy of aluminium tianate,can effectively improve the thermal stability in comparison to pure Al2TiO5. The mechanism of the decomposition of aluminium titanate in reductive atmosphere is unclear and needs further investigation.