High-quality clay bricks for glass kilns are mainly made of refractory clay, and the main components include Al2O3 and SiO2. They have high refractoriness and a certain ability to resist acidic erosion, but poor resistance to alkaline erosion. They are mainly used in parts of glass kilns where the working temperature is around 1300℃, such as the lower part of the regenerator, checker bricks and wall bricks, flue bricks and pool bottom, etc.
Sillimanite bricks are made of sillimanite minerals through high temperature sintering or slurry casting, and have high thermal shock stability, high corrosion resistance and good wear resistance. Its refractoriness is as high as 1770-1830℃, and it is mainly used for the molding of glass tank kiln flow holes, blast furnace linings, and ceramic industrial kiln tools.
Clay bricks are acidic bricks. As the Al2O3 content in the brick increases, the acidity gradually weakens.
The specific gravity of quartz in the brick is 2.65 g/cm3, the specific gravity of quartz is 2.32 g/cm3, and the specific gravity of mullite is 3.15 g/cm3. The higher the Al2O3 content in the clay brick, the more mullite crystals there are, and the greater the true specific gravity of the brick. The same is true for refractoriness. When the impurity composition remains unchanged, the more Al2O3 content, the higher the refractoriness. Various other properties have no direct relationship with the Al2O3 content. The thermal conductivity of clay bricks is the lowest among all refractory materials.
Low load softening temperature
Low load softening temperature is the biggest disadvantage of clay bricks. However, due to its easy molding, it can be made into any shape, and the use of different raw materials and methods can make the properties of the products very different. Therefore, it can be used in almost any part of the pool furnace when the requirements are not high, the service life is not long, and the temperature is not high, so it can be called a universal refractory material.
The melting points of the two main crystal phases (mullite and SiO2 crystals) that make up clay bricks are both above 1700℃. Why is the load softening point of clay bricks only 1200→1400℃? Although the decomposition and melting part of mullite is not accurate, it can still be used to study clay bricks.
In fact, in addition to SiO2 and Al2O3, clay bricks also contain a certain percentage of Fe2O3, R2O and other oxides. This will cause the Y point and point temperatures to drop by 200-300℃. Even at 1050℃, a large amount of liquid phase will appear. Therefore, the load softening temperature of clay bricks is low, while the refractoriness is high. The difference between these two temperatures is about 300-400℃.
From this, it can be seen that although the refractoriness of clay bricks is as high as about 1700℃, the load softening temperature is only about 1300℃. Therefore, it cannot bear weight or pressure when used at high temperatures. When clay bricks are eroded by a large amount of R2O, their softening temperature will further drop to about 1050℃.
Sillimanite bricks are refractory bricks made of sillimanite minerals. Sillimanite is converted into mullite and free silica after high-temperature calcination. Sillimanite bricks are generally produced by high-temperature sintering and slurry casting. Sillimanite bricks have better physical and chemical properties than high-alumina bricks, with a refractoriness of 1770-1830℃ and a load softening starting point of 1500-1650℃. Sillimanite bricks are mainly used for the molding of glass tank kiln flow holes, blast furnace linings, furnace throats, and ceramic industrial kiln furniture.
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Brand/ltem |
Special clay bricks |
Low porosity clay brick |
Pool furnace bricks |
Tin bath bottom brick |
Sillimanite Brick |
|
|
HX-SN35 |
HX-DN-15 |
HX-B |
HX-TBB-B |
HX60 |
HX65 |
|
|
Al2O3 % |
≥45 |
≥42 |
≥40 |
≥40 |
≥60 |
≥65 |
|
Fe2O3 % |
≤1.3 |
≤1.5 |
≤2.0 |
≤1.2 |
≤1.0 |
≤1.0 |
|
R2O % |
≤1.0 |
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|
Apparent Porosity % |
≤14 |
≤15 |
≤22 |
≤22 |
≤18(25) |
≤18(25) |
|
Bulk Density g/cm3 |
≥2.35 |
≥2.30 |
≥2.15 |
≥2.15 |
≥2.5(2.25) |
≥2.55(2.30) |
|
Cold crushing strength MPa |
≥70 |
≥50 |
≥35 |
≥35 |
≥85 |
≥85 |
|
Permanent Linear Change1500℃×2hr |
±0.2 |
1400℃×2hr 0～-0.5 |
1400℃×2hr 0～-0.5 |
±0.1 |
±0.1 |
|
|
Refractoriness under Load 0.2MPa,T2 ℃ |
≥1500 |
≥1470 |
≥1400 |
≥1450 |
≥1630 |
≥1650 |
|
Thermal Shock Resistance(DIN51068) |
≥20 |
1000℃水冷 ≥20 |
1000℃水冷 ≥20 |
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|
Refractoriness ℃ |
≥1770 |
≥1750 |
≥1690 |
≥1710 |
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|
Application |
Regenerator wall, flue superstructure, rear lining |
Melting pool bottom and pool wall |
Tin bath bottom brick |
This product has good resistance to glass liquid erosion and thermal shock, and is suitable for the material channels, cover plates and forming parts of daily glass and electronic glass melting furnaces: furnace head crucibles, punches, barrels, troughs, basins, bowls, etc. |
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Note: The data in parentheses are applicable to special-shaped, large-scale products and handmade bricks.
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