What is the reason for frequent cracks in refractory castables?
In the application of refractory materials, refractory castable is an important material. However, during use, It often suffer from cracking problems. So, what are the causes of frequent cracks in refractory material castables?
1: Material shrinkage and thermal expansion
Refractory castables will shrink to a certain extent during the curing process. If the shrinkage is too large, it will cause stress inside the castable and lead to cracks. In addition, refractories castables will be affected by thermal expansion when used at high temperatures. If the thermal expansion coefficients do not match, cracks will also occur.
2: Quality issues of the material itself
The quality problems of refractory castables are also one of the reasons for frequent cracks. If the raw materials such as aggregates and powders in the castable are of poor quality or the ratio is unreasonable, it will affect the performance of the castable and lead to cracks.
3: Influence of environmental factors
Environmental factors are also one of the causes of frequent cracks in refractory castables. For example, a high temperature and dry environment will cause the water in the castable to evaporate too quickly, causing cracks. In addition, temperature changes in the environment will also affect the curing process of the castable, leading to the occurrence of cracks.
4: Construction problems caused cracks in the refractory castables
Construction problems lead to cracks in refractories castables. There are many problems, from mixing and adding water to raw materials to pouring to curing and baking, which may eventually lead to cracks. For example, the first step of adding water: adding too much or too little water will affect the quality of the castables; the second step is stirring and pouring: short stirring time will lead to uneven mixing of the materials, reduced strength, and uncontrolled demoulding time after pouring. Good; then the maintenance is not in place: the maintenance is not in accordance with the prescribed method and time, and baking is started before reaching the standard; it is the problem of baking: different refractory castables have different baking curves. If baking If the baking curve is not followed, if the temperature rises too fast, cracks will occur.
Regarding construction issues, it is still necessary to grasp the standardization of the construction process, and it should be carried out by a professional construction team, and each process should be strictly controlled to reduce the probability of cracks.
5: The lining design is unreasonable
The unreasonable lining design is reflected in the insufficient number and width of the circumferential and longitudinal expansion joints. As a result, when the temperature in the furnace rises, the refractory materials expand in volume and squeeze each other to cause cracks. When encountering this situation, it is necessary to appropriately widen the circumferential and longitudinal expansion joints so that they will not be squeezed when heated and expanded.
In order to reduce the occurrence of cracks, we need to control and adjust many aspects such as material selection, construction and maintenance, material quality, and environmental factors. At the same time, regular inspection and maintenance are also required during use to ensure the normal use and extended service life of refractory castables.
