Ordinary fireclay bricks, low creep fireclay bricks, and low porosity fireclay bricks (dense fireclay bricks) are classified according to the nature of use. The standard size is 230*114*65. Low-Porosity Fireclay Bricks have strong compactness, low pores, and resistance to acid corrosion. The service life is more than 2 times longer than that of ordinary fireclay bricks.
Why Can Low Porosity Fireclay Bricks Achieve Lower Porosity?
So how does the low porosity fireclay brick achieve lower porosity? The reason is that Flint Clays are added. Because Flint Clay has high strength, strong compactness, and low water absorption. It is matched with the soft clay in the fireclay refractory brick raw materials in a reasonable proportion and then subjected to high-pressure molding. After high-temperature sintering at 1420℃, the strength of low-porosity fireclay bricks is increased, so that the porosity of the fireclay bricks is reduced.
A large number of micro-pores will be formed inside the fireclay brick during the firing process. Adding Flint Clays will prevent and inhibit the fracture of fireclay bricks by the internal micro-pores. When a large number of micro-pores are generated, the internal crack length of the fireclay brick under thermal shock becomes shorter, and the degree of interlacing and forming a network of cracks increases. Therefore, adding Flint Clay to clay bricks can effectively improve the thermal shock stability of the fireclay bricks, improve the anti-stripping property of the clay refractory bricks, and increase the service life by more than 2 times.
Like some kilns for firing non-ferrous metal products, ordinary fireclay refractory bricks often peel off bricks. The reason is that clay bricks have high porosity and large water absorption. After being subjected to a high temperature, water vapor produces stress and causes peeling.
If a certain proportion of Flint Clays are added to the fireclay bricks, the pores of the fireclay refractory bricks will be reduced, the peeling resistance and the corrosion resistance will be enhanced, which can fully meet the demanding requirements of some kiln working conditions. For example, low porosity fireclay bricks used in glass kilns also use this principle.
Requirements for the Use of Flint Clay in Low Porosity Fireclay Bricks
The Flint Clay is added into aggregates of 0-3 mm in a certain proportion, hard clay clinker, combined clay, and additives are processed into a fine powder of <0.088 mm. According to different proportions, mixing, mixing, billeting, and finally sintering and forming. Due to the high bulk density of Flint Clay, the compactness of the produced body is higher than that of fireclay refractory bricks. In the process of making blanks, adding an appropriate amount of additives can reduce the porosity of the fireclay bricks. Because the additives bring a certain proportion of alkali metal oxides, their effect can increase the amount of liquid phase in the green body matrix. So as to achieve the purpose of promoting sintering and reducing porosity.
Of course, the proportion of Flint Clay added is different for different pore requirements. In addition to some adjustments in particle gradation, matrix adjustment, etc., the aggregate must be selected. Because Flint Clay also has different grades, the performance of grade A and grade B is also different. The performance improvement of low-porosity fireclay bricks for A-grade and B-grade Flint Clay is different. That is, low-porosity fireclay bricks have different levels with pores of 17%-10%. The lower the pores, the higher the manufacturing cost, and the longer the service life.
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