Clay refractory brick is a kind of refractory material widely used in high-temperature industry. With its excellent high temperature resistance, corrosion resistance, wear resistance and thermal shock resistance, it has become an indispensable lining material for many high-temperature equipment. This paper will introduce the characteristics of clay refractory bricks and their applications in different industrial fields in detail.

I. Definition and classification of clay refractory bricks

Clay refractory brick is a refractory material made of refractory clay as the main raw material and sintered at high temperature. According to their chemical composition and uses, clay refractory bricks can be divided into ordinary clay bricks, high-alumina clay bricks and special-purpose clay bricks. The Al₂O₃ content of ordinary clay brick is generally between 30% and 45%, which is mainly used for general high temperature furnace lining; The Al₂O₃ content of high alumina clay brick is more than 45%, which has higher fire resistance and corrosion resistance, and is suitable for lining parts with higher requirements on fire resistance. According to different industrial needs, special purpose clay bricks are added with special additives or adopt special production technology to meet specific use requirements, such as anti-peeling high-alumina bricks and anti-erosion clay bricks.

II. Characteristics of clay refractory bricks

(1) High temperature resistance

The fire resistance of clay refractory brick is usually between 1580 C and 1850 C, and it can withstand high temperature environment for a long time without melting or significant deformation. The fire resistance of high alumina clay brick is higher, which can reach above 1850°C, and it is suitable for furnace lining materials under extreme high temperature conditions. This high-temperature resistance enables clay refractory bricks to provide reliable protection for the furnace body and prolong the service life of the furnace body in high-temperature industrial production such as steel, cement and glass.

(2) Corrosion resistance

Clay refractory bricks have good corrosion resistance and can resist the erosion of many chemicals. Its main components are Al₂O₃ and SiO₂, which form stable chemical bonds at high temperature, making the brick not easy to be corroded by acidic or alkaline substances. For example, in the iron and steel smelting process, clay refractory bricks can resist the chemical erosion of slag and molten iron; In cement production, it can withstand the chemical action of cement clinker. This corrosion resistance not only reduces the damage of furnace lining, but also reduces the maintenance cost and downtime.

(3) Wear resistance

In high-temperature industrial production, the flow of materials and the erosion of airflow in the furnace will cause wear on the lining materials. Clay refractory bricks have high hardness and wear resistance, which can effectively resist these mechanical effects. Its cold-pressing strength is generally between 250 and 550 kg/cm, and the strength of high-alumina clay brick is higher, which can bear greater mechanical load. This anti-wear performance enables clay refractory bricks to maintain the integrity of the lining in the long-term use process, and reduces the risk of lining damage and leakage caused by wear.

(4) Thermal shock resistance

Clay refractory bricks have good thermal shock resistance and can remain stable in the environment of rapid temperature change. Its linear expansion rate is between 0.4% and 0.7%, which can keep the size relatively stable when the temperature changes. This thermal shock resistance enables clay refractory bricks to avoid cracking and peeling caused by thermal stress in industrial production with frequent startup and shutdown or large temperature fluctuation, thus prolonging the service life of furnace lining.

(5) Low iron content and impurities

The iron content of clay refractory bricks is usually low, Fe₂O₃ content is generally less than 2.5%, and the iron content of high alumina clay bricks is even lower. Bricks with low iron content and impurities can reduce the oxidation and reduction reaction of iron at high temperature, and avoid lining damage and slag viscosity increase caused by iron oxide formation. This is of great significance to improve the service life of furnace lining and reduce the fluidity of slag.

(6) high dimensional accuracy

Clay refractory bricks can ensure high dimensional accuracy through accurate mold forming and high temperature sintering in the production process. Its dimensional tolerance is usually within ±1 mm, which can meet the strict requirements of industrial furnace masonry. High-precision dimensions not only improve the masonry quality of furnace lining, but also reduce the gaps in the masonry process, and enhance the integrity and sealing of furnace lining.

III. Application fields of clay refractory bricks

Clay refractory bricks have been widely used in many industrial fields because of their excellent properties.

(1) Iron and steel industry

In iron and steel production, clay refractory bricks are mainly used as lining materials for blast furnaces, hot stoves, ladles, hot metal ladles and other equipment. Because of its high refractoriness and corrosion resistance, high alumina clay brick is often used in key parts of blast furnace, such as furnace bottom and hearth. Ordinary clay bricks are used in checker bricks, vaults and other parts of hot blast stoves. Clay refractory bricks can withstand the erosion of high-temperature molten iron and slag, and at the same time resist the erosion of high-temperature airflow, providing reliable protection for steel production equipment.

(2) Building materials industry

In cement production, clay refractory bricks are widely used in the lining of cement rotary kiln, preheater, calciner and other equipment. Its corrosion resistance and wear resistance can effectively resist the chemical erosion of cement clinker and the wear of materials, and prolong the service life of kiln lining. In addition, clay refractory bricks are also used in the breast wall, crown and other parts of glass melting furnace, which can withstand the high temperature erosion of glass liquid and the erosion of air flow.

(3) Energy industry

In the field of energy, clay refractory bricks are used for lining of coke ovens, boilers, garbage incinerators and other equipment. Its high temperature resistance and corrosion resistance can withstand the heat and chemical erosion caused by high temperature fuel combustion, and at the same time resist the wear of acid gas and ash in flue gas. The application of clay refractory bricks not only improves the operation efficiency of energy equipment, but also reduces the maintenance cost and downtime of equipment.

(4) Civil field

In addition to industrial applications, clay refractory bricks are also widely used in civil fields, such as home fireplaces, pizza oven and outdoor ovens. Its good high temperature resistance and thermal shock resistance can ensure the safety and stability of the furnace body in the long-term use process, and its beautiful appearance and good thermal insulation performance also add a comfort and warmth to family life.

IV. Production and quality control of clay refractory bricks

The production process of clay refractory brick includes raw material preparation, molding, drying and sintering. High-quality raw materials are the basis of producing high-quality clay refractory bricks, and high-purity refractory clay and bauxite are usually selected as the main raw materials. In the forming process, high-pressure forming technology is adopted to ensure the density and strength of the brick body. The drying and sintering processes need to strictly control the temperature and time to ensure the performance of the brick.

In order to ensure the quality of clay refractory bricks, production enterprises usually establish a strict quality control system. Quality inspectors will sample each batch of products, including chemical composition analysis, physical performance test and appearance inspection. Only products that meet the quality standards can be sold out of the factory. In addition, manufacturers will provide customized products and services according to customers' needs to meet the special requirements of different industrial fields.

V. Future development trend

With the continuous development of industrial technology, the performance requirements of refractories are getting higher and higher. As a traditional refractory, clay refractory bricks are constantly undergoing technological innovation and product upgrading. In the future, the development trend of clay refractory bricks will mainly focus on the following aspects:

(1) improve fire resistance and corrosion resistance.

By improving the production process and adding high-performance additives, the fire resistance and corrosion resistance of clay refractory bricks are further improved to meet the requirements of higher temperature and worse environment.

(2) enhancing thermal shock resistance

Develop a new type of clay refractory brick material to improve its thermal shock resistance, so that it can maintain better stability in industrial production with frequent temperature changes and reduce damage caused by thermal stress.

(3) Green production

In the production process, more environmentally-friendly production technology and equipment are adopted to reduce energy consumption and pollutant discharge and realize the sustainable development of clay refractory brick production.

(4) Intelligent production and application

Combined with industrial internet and big data technology, intelligent monitoring and management of clay refractory brick production are realized, and production efficiency and product quality are improved. At the same time, an intelligent refractory application system is developed to monitor the use state of furnace lining in real time, which provides scientific basis for the maintenance and management of industrial furnaces.

In a word, clay refractory brick, as an important refractory material, plays an irreplaceable role in high-temperature industrial production with its excellent performance and wide application fields. With the continuous progress and innovation of technology, clay refractory bricks will surely show a broader application prospect in the future industrial development.