Study On Aluminium Titanate Stabilized And Composite Ceramics Of Aluminium Titanate And Mullite

Aluminium titanate (AT) has characteristics of high melting point, low thermal expansion coefficient, low heat conductivity, low elastic ratio, excellent thermal shock resistance and shock resistance. But AT has two fatal defects of poor thermal stability and low mechanical strength, and its application was restricted. Aluminium titanate and mullite (MAT) composite ceramic is a kind of new high-heat material, which combines low thermal expansion coefficient and good thermal shock resistance merits of AT with good mechanical strength and high-heat performances of mullite,and has extensive applied prospect. Gelcasting process is a new molding method that can prepare high homogeneous, high density, complicated shape ceramic products.On the basis of the effects of MgO, SiO₂ and Fe₂O₃ additives on thermal stability of AT were systematically studied, and use stable aluminium titanate and industrial mullite as major raw materials, MAT composite ceramics were prepared by two molding process of drying and gelcasting. The relationships of performances dependence of composition, process and structure were investigated through measuring the physical, mechanical, thermal, and high-heat properties and analyzing XRD and SEM of MAT composite ceramics.The results of AT prepared by gelcasting showed that mill time, dispersant content and solid volume fraction have great influence on rheological behaviors of Al₂O₃-TiO₂ slurry. When the mill time was 4h, the additive of dispersant was 3%, and the solid volume content was 45%, this technological condition was optimal to prepare AT by gelcasting.Research on the stability of AT indicated that MgO and Fe₂O₃ used as additives could promote the synthesis of AT and restrain the decomposition of AT, moreover, the effects of MgO were better than Fe₂O₃. Multiple additives of MgO-SiO₂, MgO-Fe₂O₃, Fe₂O₃-SiO₂ all could restrain the high-heat thermal decomposition of AT, and multiple additives were superior to single additives on the effects of restraining thermal decomposition of AT. The test examples of AT, which were prepared by both adding 10mol% MgO and 15mol % SiO₂, didn't decompose after 50h thermal retardation at 1100℃, and even after 150h thermal retardation the decomposition ratio was only 9.5%.