What is the Reason for the Network Cracks in High Alumina Refractory Bricks?

The surface of high-alumina refractory bricks often have network cracks, which is a defect in the production of high-alumina bricks. The causes of such network cracks are often complicated. In addition, in order to avoid these quality problems, what else should refractory manufacturers avoid during the production process?

Causes of Network Cracks in High-Alumina Refractory Bricks

1. The impurity content of clinker (especially R2O content), the amount of fine powder added, the critical particle size, the mixing quality of mud, the humidity and temperature of the green body drying medium, the shrinkage of the green body during firing, and the secondary mullite reaction and corundum recrystallization, etc., will cause network patterns on the surface of the product.

Rongsheng High-Alumina Refractory Bricks Manufacturer

2. The sintering of high-alumina bricks is liquid phase sintering. The formation temperature and amount of the liquid phase, and the atmosphere conditions during firing are also important factors causing surface network cracks.

3. The sintering degree and firing atmosphere of high-alumina refractory bricks and the volatiles present in the gas phase have a great influence on the network cracks on the surface of high-alumina products. Poorly sintered clinker continues to shrink during the firing process of the product, causing the product to crack and crack. At the same time, the secondary mullite in the poorly sintered clinker is not sufficient. During the firing process of the product, the secondary mullite of the clinker itself continues, which is an inherent factor causing inconsistent shrinkage of the product. This leads to an increase in the number of network cracks in the products and an increase in the degree of cracking.

4. The degree of network cracking on the surface of high-aluminum refractory brick products is also closely related to the water absorption rate of the clinker used. The greater the water absorption rate of the clinker, the greater the degree of network cracking. When making bricks with clinker with high water absorption, the clinker itself must continue to complete the sintering process during the firing process. The product shrinks greatly and unevenly, so it is easy to crack and network.

5. In addition, the firing atmosphere in the kiln is also one of the reasons for the network cracks in high-aluminum products. When firing high-aluminum products, the atmosphere in the kiln requires a weak oxidizing flame and excess air coefficient control. The network cracks on the surface of the product tend to decrease with the increase of the excess air coefficient, but the fluctuation of the excess air coefficient should not be too large.

In addition, the surface network cracks of high-alumina refractory brick products are mostly generated on the brick surface in the gaps of the bricks. Therefore, it can be inferred that when the excess air coefficient in the kiln is small, or a reducing atmosphere is generated, CO is easily retained in these places due to the small brick joints, thereby reducing Fe2O3 in the product to FeO. The airflow on the brick surface facing the channel is relatively smooth, so it will not be affected by the atmosphere changes, and no network cracks will be generated.

Warm reminder: Frequent changes in the properties of the combustion atmosphere should be avoided as much as possible during the firing process, so this alternating change will damage the surface.

Refractory materials are basic materials for the production and operation and technological development of national economic industries such as steel, cement, glass, and chemicals, and play an indispensable and important role in the development of high-temperature industrial production. In the hometown of refractory materials, a refractory team that insists on value return, adhering to the uncomplaining and persistent pursuit, and the spirit of loyalty to customers and continuous creation of value for customers, will make Zhengzhou Rongsheng RefractoryCompany a leading brand in the refractory industry. Innovate in inheritance and develop in innovation! The high-spirited Rongsheng people are stepping into the next glory with the spirit of Kuafu chasing the sun and the attitude of an industry leader!