Why do cracks appear in the production process of high-quality silicon bricks?

In the production process of high-quality silicon bricks, from raw material selection to fired products, irrationality in every link may cause cracks. The firing and molding process are the main factors affecting the generation of cracks in high-quality silicon bricks, but the role of other factors cannot be ignored. Let's follow the high-quality silicon brick manufacturers to learn about it!

① In the selection of high-quality silicon brick raw materials, if there are many rapidly changing silica and improper firing control, cracks can easily occur. The grain size of crystalline silica also affects the formation of cracks. If the quartz grain is larger, the firing expansion will be large, the rotation will be slow, and it will be easy to loose, and the product will be prone to cracks. Reasonable selection of mineralizers and appropriate addition of waste silica bricks can reduce the sintering expansion and crack formation of adobe.

② There are too many coarse particles during batching, and cracks will appear around the particles during firing. The structure of the brick is difficult to densify, and local cracks are prone to occur, making it difficult to obtain products with smooth edges and corners on the surface. Adding fine powder is beneficial to reduce firing expansion, reduce cracks and volume changes in the brick body, and improve the yield of high-quality silicon bricks.

③ The raw materials of high-quality silicon bricks are mixed unevenly, and the expansion of each part of the green body is uneven during firing, which will lead to cracks; excessive moisture in the blank will also cause spallation.

④ It is easy to generate cracks if the molding control of high-quality silicon bricks is not good. In theory, the use of vibration molding will not cause spallation. As long as you pay more attention when unloading the mold, there will be few other cracks. However, the production of large-scale products in China mostly adopts machine molding and double-sided pressurization to reduce the occurrence of layer density. The pressurization system that is light first and then heavy is conducive to gas removal and can reduce the occurrence of spallation. Multiple pressurization has a higher density and a lower layer density than one pressing, which can reduce vertical cracks. Unreasonable cloth will produce serious density unevenness, resulting in a significant increase in various cracks. When it comes to fabrics, it is difficult to reach the corners and grooves naturally, the pressing force is small, and it tends to be multi-fabric, and in some places it is even necessary to beat it densely in advance.

High-quality silicon brick work in progress The unreasonable drying system itself will also lead to cracks; if these cracks cannot be detected after drying, they will continue to expand during firing.

The unreasonable loading system of high-quality silicon bricks will also lead to increased cracks; for example, special bricks need to be installed inside the car when loading, and standard ordinary bricks need to be installed outside; the protruding parts of the bricks or the parts prone to cracks are inward; The top of the kiln car should be covered with some thin bricks to avoid the direct impact of the flame, etc., otherwise cracks will increase. The physical and chemical changes of high-quality silicon bricks of refractory materials during the firing process are an important basis for determining the firing system. Unreasonable firing system can lead to a large number of cracks. However, even if the firing system is reasonably formulated, the actual firing system will be different from the theoretical firing system due to the influence of the kiln body structure, loading method, actual air volume, changes in brick types, and specific operations. Adjusting the firing system in real time according to changes in raw materials, brick types, and output is the key to ensuring a reasonable firing. This is the case with inverted flame kilns, and it is also the case with tunnel kilns, although the adjustment of the firing system of tunnel kilns is relatively troublesome. In addition, improper operation will also lead to cracks. For example, if a burner is opened too large, a certain part of the kiln body leaks air, and a certain exhaust port is not well exhausted, the firing system will be strongly changed, causing a large number of cracks in some parts of the kiln car. Therefore, full attention must be paid to the rationality of the firing system in the generation.