The properties of clay products fluctuate within a relatively large range,Insulation Brick which is due to the large fluctuation range of the chemical composition of the products (the content of Al2O3 fluctuates between 30 and 46%) and the difference in production processes. The refractoriness of clay products fluctuates from 1580 to 1770°C,Insulation Brick which mainly depends on the chemical composition of the product,Insulation Brick and the ratio of Al2O3/SiO2 increases. The increase of flux impurities, especially alkali metal oxides,Insulation Brick will significantly reduce the refractoriness of products. The load softening temperature mainly depends on its chemical mineral composition and density, but the latter does not affect the end temperature of load softening, but increases the starting deformation temperature. The low bulk density of the bricks will also make the load softening start temperature low.
Therefore, to increase the load softening start temperature of clay products,Insulation Brick generally should proceed from the following aspects: increase the Al2O3 content in the product,Insulation Brick especially increase the Al2O3 content of the matrix: increase the firing temperature and use multiple clinker ingredients;Insulation Brick increase the molded clay bricks The volume density. The thermal shock resistance of clay bricks is relatively good,Insulation Brick and the fluctuation range is large, generally more than 10 times (1100℃ water cooling),Insulation Brick which is not too large with the linear expansion coefficient of clay products (the average linear expansion coefficient between 20~1300℃ is 4.5*10-6~5.8*10-6/℃) and there is no polycrystalline brick deformation phenomenon and obvious grain structure.
Clay products are weakly acidic refractory products,Insulation Brick and their acidity increases with the increase of SiO2 content. It has certain corrosion resistance to acid, but poor resistance to alkaline corrosion. Therefore,Insulation Brick clay products are suitable as refractory materials for acid kilns. Large-scale clay refractory bricks for glass kilns are clay refractory bricks with a unit weight of not less than 50kg for masonry glass kilns.
This standard also makes the following provisions for the section cracking of bricks. For bricks whose cross-section spall length is less than 400mm: when the spall width is 0.26~0.50mm,Insulation Brick the length is not more than 40mm; when the spall width is 0.51~1mm, the length is not more than 25mm. Bricks with a length greater than 400mm: When the spall width is 0.26~0.50mm,Insulation Brick the length is not more than 80mm; when the spall width is 0.51~1mm, the length is not more than 50mm. For cracks with a spall width of less than 0.25mm,Insulation Brick the length is not limited. There shall be no gaps or cracks larger than 1mm on the section.
Precautions for the use of clay bricks: The properties of clay brick products produced by different molding methods are different. There are many molding methods for clay bricks. It can be formed by hand molding,Insulation Brick ramming molding, extruder molding, mud casting molding,Insulation Brick and high-pressure molding by press. Even if the chemical composition and raw material types of clay bricks are exactly the same,Insulation Brick they will have different properties due to different molding methods.
