Effect of the microstructure on the properties of synthetic aluminosilicate articles

Abstract

In silicate systems, which are very important in refractory technology, an equilibrium state is virtually unobtainable even with prolonged heat treatment. Therefore, in order to get close to the equilibrium state, it is necessary to carry out special preparation of the raw material by homogenizing it simultaneously with the fine milling of the components and by chemical codeposition followed by high-temperature firing or melting during which the synthesis of mullite is achieved.

A study of the process of mullite formation in the corundum-clay and corundum-quartzite systems under load

“…There have been numerous studies on the mullite formation process in high-alumina systems of various compositions [3][4][5][6][7][8][9][10][11].…”

Deformation properties of synthetic mullite refractories at high temperatures

“…The basic versions of the production technology are being perfected as a result of research being done at the D. I. Mendeleev Moscow Institute of Chemical Technology [i], the Ukrainian Scientific-Research Institute of Refractories [2, 3], the Podol'sk refractories factory* [4,5], and in other organizations. However, this technology for high-alumina refractories, being traditional, is complicated by the need to make two firings (briquet and finished goods), and double milling (alumina and chamotte).The Eastern Institute of Refractories has developed a simplified method for making synthetic, high-alumina refractories by direct synthesis from finely milled alumina and granular quartz [6,7].The working proprties of aluminous refractories, including their load resistance at high temperatures, largely depend on the ratio of the crystalline phases making up the brick. Suitable distribution of crystalline phases and a small amount of glassy phase are the distinctive features of high-alumina materials obtained by the direct synthesis of mullite from alumina and silica of different grain sizes, using a method developed by the Eastern Refractories Institute.…”

“…A positive effect on reinforcing the structural rigidity of high-alumina materials prepared by synthesizing coarse-grained quartzite and dispersed alumina is exerted by the presence of a relatively small amount of liquid phase, whose distribution in the structure of the refractory has a local character [6,12]. Its siliceous composition and accordingly high viscosity also hinders mutual displacement of the aggregates of corundum grains, mullite, and residual cristobalite, i.e.,!tends to increase the deformation resistance.…”