Silica brick-physical properties

1. Acid-base resistance

Silica brick is an acidic refractory material, which has strong resistance to acidic slag erosion, but when it is strongly corroded by alkaline slag, it is easily damaged by oxides such as AI2O3, and has good resistance to oxides such as CaO, FeO, and Fe2O3.

2. Expansibility

The thermal conductivity of silica bricks increases with the increase of working temperature, without residual shrinkage. During the oven process, the volume of silica bricks increases with the increase of temperature. In the oven process, the maximum expansion of silica brick occurs between 100 and 300 ℃, and the expansion before 300 ℃ is about 70% to 75% of the total expansion. The reason is that SiO2 has four crystal form transformation points of 117℃, 163℃, 180~270℃ and 573℃ in the oven process. Among them, the volume expansion caused by cristobalite is the largest between 180~270℃.

3. Deformation temperature under load

The higher deformation temperature under load is the advantage of silica bricks, which is close to the melting point of tridymite and cristobalite, which is between 1640 and 1680°C.

4. Thermal stability

The biggest shortcomings of silica bricks are low thermal shock stability and low refractoriness, generally between 1690 and 1730 ℃, which limits their application range. The key to determining the thermal stability of silica bricks is the density, and the density is one of the important signs to determine its quartz conversion. The lower the density of the silica brick, the more complete the lime conversion and the smaller the residual expansion during the oven process.

5. Silica brick-precautions for use

When the working temperature is lower than 600~700℃, the volume of the silica brick changes greatly, the performance of resistance to rapid cooling and heating is poor, and the thermal stability is not good. If the coke oven is operated at this temperature for a long time, the masonry will be easily broken.

Classification of silica bricks

There are many varieties of silica bricks, which can be divided into: silica bricks for coke ovens, silica bricks for hot blast stoves, silica bricks for electric furnaces, silica bricks for glass kilns, etc.

Silicon refractory bricks used in coke ovens are different according to the content of SiO2 used in the coke oven, and the orientation of the use in the coke oven is different. The production process of the refractory brick manufacturers is also different. The raw materials and specifications of refractory bricks and the use of silicon refractory bricks in coke oven masonry. Refractory bricks for masonry coke ovens should have: the softening temperature under load is higher than the maximum temperature of the application part; the ability to resist sudden temperature changes within the temperature change scale of the application part; can resist the corrosion of various media that may be encountered in the application part The wall of the carbonization chamber has excellent heat conduction function one by one, and the lattice refractory brick has excellent heat storage function and so on.