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What is Problem of Cracks in Silica Bricks
There are several situations for cracks in silicon bricks: If it is a layer crack or a vertical crack of the silicon fire brick, it is caused by the first hammer of the press without exhaust during the process of forming and pressing the silicon fire brick. If it is horizontal or net-like cracks, it is caused by the temperature rising too fast during the drying process. In another case, improper control of the firing temperature can also cause horizontal cracks on the surface of the silicon brick.
Cracks should be said to be an important part of the yield of silica bricks. If it is not properly controlled, the cost will increase substantially.
Silica refractory brick is an acidic product. Compared with the neutral product of high alumina brick, the yield is low. Another important reason is the high expansion coefficient of the silica brick. If the mold is not correctly placed, it will cause the size of the finished silica brick. Severely exceeded.
During the firing of silica bricks, the crystal changes and the volume expansion coefficient is large, which is extremely easy to produce cracks. However, if it is a microcrack, the elasticity of the structure can be improved.
The cracks of silicon bricks are divided into surface cracks and internal cracks. Among them, that is, the mechanical pressure crack and the temperature sintered crack, if the surface of the crack is criss-crossed, the length is different. It is caused by high-temperature sintering without the moisture of the product being completely dried. The kiln for firing silica bricks must be at least 150 meters above, otherwise, the temperature insulation performance is not good, and the cracking rate of the fired silica bricks It will be very high.
Spallation occurs in the product molding process. Spallation occurs when the mold is aging or the pressed brick is not exhausted. The spalled silica brick cannot be used, and the internal quality is not good, and it cannot be used at high temperatures. This kind of crack is a mechanical crack.
If it is a net-like crack, it is caused by large temperature fluctuations and unevenness in the product. Another possibility is that the aggregate and powder are mixed unevenly during the mixing and grinding process, and net-like cracks will also appear.
The horizontally cracked silica bricks appear on the outside of the kiln car brick stack during the firing process, especially the top product. It is caused by high temperature, and the fire channel for loading the kiln car is not reasonably reserved, and the flame is directly sprayed on the refractory silicon brick surface and the heat is uneven.
The cracks of silica bricks are also related to the process. If there are too many fine particles, cracks will appear. The quality of the binder added during the proportioning process will also be cracks. Drying does not discharge water or loading the kiln car is unscientific. The firing is heated. Fast, it is a bad situation that produces cracks.
If you want to control the cracks of silicon bricks, you must seriously control the production process from the raw material ratio to the molding and firing process. Every link must be paid attention to. The technical level of the production personnel has reached a certain level, and then the firing When the temperature of the refractory bricks is well controlled, the occurrence of cracks will be solved.
