Refractory bricks for glass kilns mainly include silica bricks, alkaline bricks, fused zirconium corundum bricks, mullite bricks, etc. according to their different materials.
1. Silica brick
Silica bricks have good high-temperature properties such as high softening temperature under load and low temperature reduction. They also have good high-temperature corrosion resistance. Due to their mature production technology and low price, silica bricks are widely used in glass kilns. As we all know, the mineral composition of silica bricks includes cristobalite, tridymite, residual quartz and a small amount of silicate liquid phase. When the silica bricks are used, the transformation of various crystal phases is still in progress, and there are relatively large changes in the crystal phase transformation process. Large volume changes lead to poor thermal shock stability of silica bricks. When the temperature reaches 1470°C, the tridymite in the silica brick will transform into cristobalite. Cristobalite is the most stable crystal phase in the silica brick, which will enhance the physical and chemical properties of the silica brick. When some parts of the kiln are lower than At 1470°C, the presence of tridymite will reduce the performance of the silica bricks. In particular, alkali dust or alkali vapor will corrode the wollastonite (CaO·Si02) in the silica bricks, and glass will begin to form in the silica bricks. phase, and the glass phase will gradually melt the large particles of silicon oxide in the silica bricks, causing the silica bricks to dissolve and peel off, thus affecting the use effect of the silica bricks.
2. Alkaline bricks
Alkaline bricks have strong corrosion resistance to alkali dust, but in the high temperature area of the grid body, magnesia bricks are easily corroded by Si02, V205 and CaO, causing the volume of the grid bricks to expand and cause peeling. In the middle and lower part of the lattice body, which is the condensation area of the lattice body, magnesia bricks are prone to sulfate corrosion reactions. Directly bonded magnesia-chromium bricks are currently the best choice for the middle and lower latticework. However, the Cr203 in directly bonded magnesia-chrome bricks will pollute water resources. Some European and American countries have banned the use of magnesia-chromium bricks. I believe that my country will also restrict it soon. Use of chromium-containing products.
Alkaline bricks have high thermal conductivity, large expansion turbulence and high variability. They will deform when the kiln is baked, which is not conducive to the sealing of the kiln body. Compared with mullite bricks, the heat dissipation of the wall increases, which increases the cost of kiln insulation.
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