Silica mullite brick production process principle

The process principle of the silica brick used in cement kiln in the production process is as follows:
It is well known that silicon carbide has high refractoriness and is stable at 2600 ° C in a reducing atmosphere; hardness is high (Mohs hardness 9 to 9.5), second only to diamond; thermal conductivity is high [64.4 W (at 500 ° C) m·K) -1, 875 ° C is 41.4 W · (m · K) -1; the coefficient of thermal expansion is relatively small (5.0 × 10 -6 ° C -1). SiC is a covalent bond, there is no so-called sinter, and a new phase is formed by chemical reaction to achieve sintering, that is, reaction sintering. Therefore, silicon carbide products are classified into clay bonding, mullite bonding, and dioxide oxidation according to the bonding phase. Products such as silicon bonding, Si2N2O bonding, Si3N4 bonding, and Sialon bonding. Among them, the strength of mullite and mullite gold fused plastic is high. See Table Si2N2O bonding, Si3N4 bonding, Sialon bonding SiC products and recrystallized silicon carbide products. Although the strength and other indicators are very high, the production technology is complex and the equipment requirements are high. Not only the high cost of the product, but also the high thermal conductivity of the product is not the ideal refractory material for the cement kiln.
In the late 1980s, the study began to study the complex phase refractories of oxides and non-oxides in binary and even ternary systems. As a well-known non-oxide, SiC attracts attention, so corundum bricks, silicon motiles, etc. have been successfully developed. These composite refractories are characterized by higher temperature and high temperature strength than single oxide materials, and oxidation resistance is better than single SiC. The oxidation of these composite materials is protective oxidation, and the SiC of the surface of the material is oxidized to SiO2 on the surface of the material. The formation of a protective layer gradually prevents further penetration of oxygen into the interior of the article. These composite products have a lower firing temperature than a single oxide product and a high product strength.