Synthesis Of Low Thermal Expansion Alumina-magnesia-titania Materials And The Influence Of Alumina-magnesia-titania Materials On The Structure And Properties Of Alumina-graphite Material

With the development of the continuous casting technology, the demands for high performance alumina-graphite materials are more urgent. As a raw material, alumina-magnesia-titania materials is added into alumina-graphite material to improve the properties of alumina-graphite material, which has attracted people's growing attention. This paper systematically studies the preparation of low-cost alumina-magnesia-titania materials with solid-phase synthesis. Furthermore, this paper studies the influence of alumina-magnesia-titania materials on the properties of alumina-graphite material by substituting corundum powder with alumina-magnesia-titania materials.Industrial Al₂O₃ powder,TiO2 powder and analytic-purified uftra-fine MgO powder are adopted as raw materials to prepare alumina-magnesia-titania material by solid phase reaction sythesis in oxidizing atmosphere at 1500℃. Results show that: Higher reaction temperature and longer soaking time during the preperation process will faccilitate the growth of AT crystal grain, so that will affect the amount and size of cracks inside the material, and finally will affect the service performance of the material. Reduced granularity of raw materials will accelerate the surface diffuse process, so that will accelerate the sythesis reaction process, and finally will result in the increase of AT formation. Increase of MgO content may decrease the decomposition rate of AT, so that can improve thermal shock resistance of material.With the increasing of alumina-magnesia-titania material content in alumina-graphite material, the bulk density and the cold modulus of rupture of the specimens decreases. The hot modulus of rupture of alumina-graphite specimens added with alumina-magnesia-titania materials is remarkably enhanced, which is the results of the impurity absorption of alumina-magnesia-titania solide solution at high temperatures and micro-crack close. Existance of alumina-magnesia-titania solid solution not only decrease the thermal expansion coefficient of product, but also create"the micro-crack effect", so that thermal shock resistance of product gets improved.