At present, there are two main measures to improve the burst resistance of refractory castables, reasonable drying and heating system and the application of explosion-proof additives. Due to the different production conditions of various kilns, it is difficult to formulate a unified and reasonable drying and heating up system. Therefore, anti burst substances are often added to improve the burst resistance of refractory castables. The new high strength erosion resistant castable has excellent erosion resistance and good thermal shock resistance, which makes it widely used in the lining of key parts of large kilns. In the production process, the structure, particle gradation, material and additives are adjusted to improve its burst resistance, but at the same time, it also brings some problems, such as too fast setting speed, delayed hardening and instantaneous loss of fluidity, resulting in frequent burst of refractory castable.
In view of the frequent burst of high-strength corrosion-resistant refractory castable in the process of use, with a burst thickness of 50 ~ 100mm, it is proposed to select a polypropylene explosion-proof fiber commonly used in refractory castable to improve or solve such problems again. Polypropylene explosion-proof fiber is made of polyethylene, with fine fiber and large length diameter ratio. Therefore, it has a large specific surface area, which is conducive to softening and melting. Of course, it is also related to the low melting point of the material itself.
The spalling and bursting mechanism of refractory castable means that the refractory castable is the result of the combined action of high steam pressure and uneven thermal stress produced in the baking process. During the baking process of refractory castable, a large amount of internal steam is generated, especially the volatilization of crystal water in the casting body, which is easy to volatilize to the surface of refractory castable through pores between 150 ~ 250 ℃. If the temperature is not controlled properly at this time, excessive steam pressure in the castable will cause the pouring body to burst. Therefore, polyethylene explosion-proof fiber is used to form the melting gap of polyethylene explosion-proof fiber in the temperature range (150 ℃ ~ 220 ℃) in which a large amount of internal steam is generated during the baking of refractory castable, forming a spacing and causing the drawing effect, To minimize the influence on the expansion of pouring body during the evaporation of internal steam of crystal water.
After adding explosion-proof fiber to the refractory castable, the effect of fiber melting on the porosity, strength, corrosion resistance and wear resistance of the castable should also be considered in the process of use. The softening and melting temperature of explosion-proof fiber of different characteristic materials has not the only effect on the burst resistance of the refractory castable. The appearance, length, diameter The material composition also jointly affects the anti burst performance of the refractory castable, and the influence of multiple factors such as body density, strength, porosity and air permeability of the refractory castable itself is not completely impossible to cause the burst of the refractory castable. Therefore, there are many factors causing the burst of the refractory castable, which need to be further studied.