After a period of running, the phenomenon of ending is occurred. In severe cases, it will even directly damage the boiler and affect the normal operation. In order to extend the service life of the boiler, pouring is basically used to repair places where the boiler is more severe, but the phenomenon of pouring material cracks may occur after the construction is over. Why is there such a problem? If you want to solve this problem, you must first know the cause of the crack.
1. When the castable refractory is stirred, the water and grade is not controlled well
When the amount of watering is mixed, the amount of water is too much, which is easy to make the internal pore rate of the pouring materials high, the intensity is reduced, the natural solidification time is too long, and the maintenance time will increase. If the amount of water is too small, the liquidity of the watering is not good, the vibration is not dense, and the pores and bubbles are easy to leave, and the strength will also be greatly reduced.
2. Inaccurate control of stirring and construction time
When mixing the watering, the mixing time must be strictly controlled. The time is too short, which will cause the mixing of the pouring materials to be mixed, not dense, and the strength is reduced. On the surface, the aggregate sinks at the bottom, resulting in the reduction of the intensity of the watering. The watering should be used up within 30 minutes after the stirring is completed.
3. Dental time control is not good
Here is the release of the refractory castable materials. When it is not completely hardened, when is the most suitable release? When the intensity of the watering can be guaranteed and its edges and corners are not damaged due to the damage of the demarcation, it can be removed. To facilitate the release of the mold, the pouring surface of all molds before pouring should be coated with a layer of oil.
4. The time of refractory castable materials is not well controlled
After the construction is completed, there must be sufficient natural drying period, so that most of the water in the refractory layer can be precipitated, so as to prevent a large amount of water from discharging a large amount of water during the oven, causing the refractory layer to burst and fall off. The principle of drying the oven pays attention to "should be long or short, it should not be fast." It should be carried out in accordance with the predetermined oven curve, the heating speed should be uniform and stable, control the constant temperature time and temperature, and keep the temperature fluctuations not greater than ± 20 ° C. To prevent too fast temperature, water cannot be discharged in time, breaking through the wear resistance and refractory layer; secondly, prevent the temperature in the refractory and wear resistance layer too large, generate huge thermal stress, and cause the abrasion resistance to cracking, raising, and falling off.
