Silica brick properties

The material of silica brick is quartzite as raw material, with the participation of a few mineralizers. Fired at high temperature, its mineral composition is composed of tridymite, cristobalite and glassy composition at high temperature, and its AiO2 content is above 93%. In the well-fired silica bricks, the content of tridymite accounts for 50%-80%; cristobalite is second, accounting for only 10%-30%; while the content of quartz and glass phases fluctuates at 5%-15%.

Silica bricks properties-Expansion

The thermal conductivity of the silica brick increases with the increase of the working temperature, and there is no remaining shortening. During the oven process, the volume of the silica brick increases with the increase of the temperature. In the oven process, the expansion of silica brick is between ℃, and the expansion before 300℃ is about 70%~75% of the total expansion. The reason is that SiO2 exhibits four crystal transformation points at 117°C, 163°C, 180~270°C and 573°C during the oven process, and the volume expansion caused by cristobalite is between 180~270°C.

Silica bricks properties-Softening temperature under load

The high deformation temperature under load is the advantage of silica brick, which is close to the melting point of tridymite and cristobalite, about 1640~1680℃.

Silica bricks properties-Thermal stability

The defects of silica bricks are low thermal shock stability and low refractoriness, generally between 1690 and 1730 °C, which limits their application scale. The key to determining the thermal stability of silica brick is density, and the density is one of the important signs to confirm its quartz transformation. The smaller the density of the silica brick, the more complete the conversion of its lime, and the smaller the residual swelling that occurs during the oven process.