In modern steelmaking process, plug brick, as an important refractory, plays an indispensable role. It is located at the bottom of the stopper and closely cooperates with the nozzle brick to control the flow of molten steel. The performance and quality of plug bricks are directly related to the stability and safety of steelmaking process, so its importance is self-evident.

I. Structure and function of plug brick

The main function of the plug brick is to block the nozzle in the non-pouring state and prevent the leakage of molten steel. When pouring is needed, a gap is generated between the plug brick and the nozzle brick by lifting the plug rod, so that molten steel can flow out of the nozzle brick. This design not only realizes accurate control of molten steel flow, but also effectively avoids unnecessary loss of molten steel in non-pouring stage, improves steelmaking efficiency and reduces production cost.

Structurally, the plug brick is usually cylindrical or conical, and its size and shape will be customized according to the specific steelmaking equipment and process. Its bottom is connected with the stopper rod and its top is in close contact with the nozzle brick. In order to ensure good sealing performance and wear resistance, the surface of plug brick is usually finely machined to ensure its flatness and smoothness.

II. Performance characteristics of plug bricks

Plug bricks need to work in the harsh environment of high temperature, high pressure and strong corrosiveness, so their performance requirements are extremely high. The following are the main performance characteristics of plug bricks:

(1) High fire resistance

The service temperature of plug brick is usually above 1500℃, so it must have high fire resistance. The high fire resistance enables the plug brick to keep its structure stable at high temperature without melting or deformation, thus ensuring the smooth steelmaking process.

(2) Good thermal shock resistance

In the process of steelmaking, plug bricks are frequently subjected to sharp changes in temperature. For example, when the pouring and non-pouring state is switched, the temperature of the plug brick will drop from high temperature to low temperature in a short time, and then it will rise rapidly. This violent fluctuation of temperature will cause great thermal stress to the plug brick, so the plug brick needs to have good thermal shock resistance to prevent cracks and damage caused by thermal stress.

(3) Excellent wear resistance and crack resistance

The plug brick will have frequent friction and erosion with molten steel and slag during use, so its wear resistance is very important. Excellent wear resistance can effectively prolong the service life of plug bricks, reduce the replacement frequency and reduce the production cost. At the same time, the plug brick also needs to have good crack resistance to prevent cracks caused by stress concentration during use, which will lead to accidents such as molten steel leakage.

(4) Good corrosion resistance

There are many chemical components in molten steel and slag, which will corrode plug bricks. Therefore, plug bricks need to have good corrosion resistance to prevent them from being damaged by chemical erosion. Corrosion resistance not only helps to prolong the service life of plug bricks, but also ensures the quality of molten steel and prevents molten steel from being polluted by corrosion of plug bricks.

(5) No pollution to molten steel.

Plug bricks will be in direct contact with molten steel during use, so their materials must be pure and will not pollute molten steel. If the plug brick contains impurities or harmful components, it may be mixed into molten steel, affecting the chemical composition and quality of molten steel, and then affecting the performance of the final product. Therefore, it is necessary to strictly control the quality of raw materials in the production process of plug bricks to ensure that they do not contain harmful components to molten steel.

(6) Accurate size and shape

The size and shape of plug brick are very important to the realization of its function. If the size of the plug brick is inaccurate or the shape is irregular, the sealing between the plug brick and the nozzle brick may be lax, thus causing molten steel leakage. Therefore, the plug brick needs to be processed and measured accurately in the production process to ensure that its size and shape meet the design requirements.

III. Production and Quality Control of Plug Bricks

The production process of plug brick includes the selection of raw materials, batching, molding, sintering and other links. High-quality raw materials are the basis of producing high-performance plug bricks, so production enterprises need to strictly control the quality of raw materials. In the batching process, it is necessary to accurately calculate the proportion of various raw materials according to the performance requirements of plug bricks to ensure that their chemical composition and physical properties meet the standards.

Molding is the key link in the production of plug bricks, and usually pressing molding or grouting molding is used. The formed green body needs to undergo strict drying and sintering treatment to eliminate internal stress and improve its strength and fire resistance. The control of sintering temperature and time has a great influence on the quality of plug bricks. Too high or too low sintering temperature will lead to the decline of the performance of plug bricks.

Quality control is an indispensable part in the production process of plug bricks. Production enterprises need to establish a perfect quality management system and carry out strict quality inspection on each batch of products. Test items include chemical composition analysis, physical performance test and appearance inspection. Only products that pass strict inspection can leave the factory to ensure that users can obtain high quality and high performance plug bricks.

IV. Application and Market Prospect of Plug Brick

Plug bricks are widely used in steelmaking furnaces, continuous casting machines and other equipment in iron and steel industry, and are indispensable key components in steelmaking process. With the continuous development of iron and steel industry, the demand for plug bricks is increasing year by year. Especially in the production of some high-end steel products, the performance requirements of plug bricks are more stringent, which provides a broad development space for the market of high-performance plug bricks.

In addition, with the improvement of environmental protection requirements, the demand for energy saving and emission reduction in steel-making enterprises is becoming more and more urgent. High-performance plug bricks can help steel-making enterprises reduce energy consumption and pollutant emissions by improving steelmaking efficiency and reducing molten steel leakage, so their application prospects in the field of environmental protection are also very broad.

V. Conclusion

As a key refractory in steelmaking process, the importance of plug brick is self-evident. Its excellent performance characteristics and broad application prospects make it occupy an important position in the steel industry. With the continuous progress of science and technology and the continuous innovation of production technology, the performance of plug bricks will be continuously improved and their market prospects will be broader.