Zero Expansion Silica Brick

Zero expansion silica brick is a new type of high-quality refractory brick, a replacement product of silica brick, with excellent thermal shock resistance! It has been water-cooled at 1100 degrees for more than 50 times without any cracks. Operating temperature: below 1200 degrees, under working conditions requiring thermal shock resistance! This product is suitable for use in acidic atmospheres.

1. Zero expansion silica brick SiO2 content is greater than 99%, with excellent corrosion resistance and acid resistance;
2. Low Fe2O3 content is less than 0.1%, no pollution to products (such as glass liquid, etc.);
3. Low flux index (Al2O3+2R2O) is less than 0.3%;
4. The thermal expansion rate is close to zero, so there is no need to reserve expansion joints during repairs, which increases the tightness of the masonry;
5. Excellent thermal stability, the product will not explode during hot repair, and can be repaired directly at high temperatures without stopping the furnace;
6. After repair (hot repair), peeling and other phenomena will not occur, and it is safe and reliable for long-term use;
7. Good corrosion resistance. Due to the lack of calcium, corrosion cannot form

Zero expansion silica bricks are used in:Oxygen combustion furnace, colorless/colored bottle glass kiln, superstructure, float kiln, high temperature, high load and high alkali glass tank kiln;

Why do zero expansion silica bricks expand?

1. Physical and chemical changes of zero-expansion silica bricks during the firing process.

During the firing process, there are the following changes in temperature order: residual water is discharged from the bricks below 150°C, Ca(OH)2 begins to decompose at 450°C; when Ca(OH)2 dehydration is completed at 40 ~ 500°C, the silica particles The bond with lime is destroyed and the strength of the green body is greatly reduced. In the temperature range of 550650, -synthetic changes to -synthetic. Due to the 0.82% volume expansion during the phase change process, microcracks with different densities will appear in the crystal. At 600700, CaO and SiO2 undergo a solid phase reaction, and the strength of the brick increases. Starting from 1100, the transformation speed of Yingshi increased greatly, and the proportion of green bricks dropped significantly. At this time, the volume of the green bricks is greatly increased due to the timely transformation into a low-proportion variant. At this time, although the liquid phase is continuously increasing, cracks still appear in the range of 1100~1200.

2. The volume of zero expansion silica brick changes during the heating process, and the volume is different at different temperature stages.

According to the changing characteristics of various siliceous bodies, they can be divided into stages below 600, 600~1100, 1100~1250 and above 1250. There are significant extensions to the 500600 model's timely transformation. At 700800, CaO and SiO2 undergo a solid phase reaction, resulting in micro-shrinkage. At 1000~1100, the shrinkage is obvious due to the formation of liquid phase. Starting from about 1200, due to the acceleration of time-dependent transformation, the green body begins to expand violently, and the starting temperature and rising trend vary greatly depending on the type of raw materials.
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