Refractory castables may be cracked due to many reasons when they are used. Once the cracking phenomenon is formed, it will affect the normal use. However, it is still necessary to prevent this situation when using refractory castables, so the specific composition What are the reasons for this situation? What is the solution? Today, Henan Lite Refractories came to talk to us about the reasons and solutions for the cracks in the use of castables. Let’s take a look!
Causes of cracks in the use of castables
1. Under normal conditions, no matter how poor the performance of the castable is, it will rarely show the phenomenon of cracking, most of which may be swelling or showing cracks.
2. The mechanism of steam pressure cracking is mainly that the free water and bound water in the refractory products evaporate during the baking process, and pressurized gas is generated inside the green body. If the product has poor air permeability, or the heating rate is too fast, the generated steam cannot When the pressure caused by the combination of sweeping in time exceeds the upper limit strength of the product, it will cause mechanical damage to the refractory product, and even destructive cracking.
3. The burst of other components may be due to the internal air permeability of the castable and the thermal conductivity. When it is boring, a large steam pressure surpasses its own tensile strength, and then the phenomenon of bursting may occur. The lower the air permeability of other castables, the greater the thermal conductivity, and the greater the water vapor pressure generated during heating. The tensile strength of the castable is about 1/5 of the flexural strength. If the internal vapor pressure is not manipulated, it is easy to crack.
4. The superfine powder that can pass through the castable fills the internal pores or the colloid generated by dehydration prevents the breathable performance of the castable, and the phenomenon of cracking will also be added.
5. In addition, the baking of refractory castables before use is also an important part of the production process. Whether the baking criteria of the castables is reasonable or not determines the quality of the green body, and then directly affects its performance. , The production process and economic benefits of the manufacturer, and the baking criteria will affect the spalling and even cracking of the refractory castable body during the baking process.
6. Others will crack due to thermal stress, because the mechanism of internal thermal stress during the baking process of the castable can be understood as the two-way or three-way thermal stress around the internal particles during the baking of the product, because the castable itself is A complex heterogeneous system, the thermal stress increases with the temperature gradient, and then forms tiny but high-energy cracks in the thin part of the particle or its surroundings. When it reaches a certain value, or with the pore vapor pressure, etc. Other factors combine to form a tensile stress higher than the tensile strength of the product itself, and then lead to cracks.
