Refractory is the basic material serving high temperature technology, and has a very close relationship with various industrial kilns. Various industrial kiln roads are different because of their use and use conditions. The requirements for refractories, the basic material that constitutes its theme, are also different. Different kinds of refractories also show different basic characteristics due to differences in chemical mineral composition, microstructure and production processes. Therefore, in the process of understanding and studying refractories, it is necessary to describe their basic properties and general characteristics of refractories.

Generally speaking, refractory materials: refers to inorganic non-metallic materials with a refractoriness above 1580 ° C. It includes natural ores and various products made by a certain process according to a certain purpose. It has certain high temperature mechanical properties and good volume stability, and is an essential material for various high temperature equipment.

There are many ways to classify refractory materials:

1, divided by chemical composition: refractories can be divided into acidic, alkaline and neutral;

2, according to the refractories: can be divided into general refractories (1580~1770°C) advanced refractories (1770~2000°C) extra grade refractories (2000°C above) and super refractories (more than 3000°C) four categories;

3, according to the processing and manufacturing process: can be divided into fired products, casting products, non-fired products; Divided by use: can be divided into blast furnace, open furnace, converter, continuous casting, glass kiln, cement kiln refractory materials;

4, according to the appearance: can be divided into refractory products, refractory mud, amorphous refractory materials;

5, according to the shape and size can be divided into: standard type, general type, special type, special type and super special products;

6, according to the molding process: can be divided into natural rock sawing, mud pouring, plastic molding, semi-dry molding and vibration, ramming, fusion casting molding and other products;

7, according to the chemical - mineral composition: can be divided into aluminum silicate (clay brick, high aluminum brick, semi-silicon brick) silica (silicon brick, fused quartz fired products) magnesia (magnesia brick, magnesia aluminum brick, magnesia chrome brick); Carbonaceous (carbon brick, graphite brick) dolomite, zircon, special refractory products (high purity oxide products, refractory compound products and high temperature composite materials).

Refractories must have the following basic requirements:

1, in order to meet the requirements of high temperature operation, it should have a high enough temperature without softening and melting;

2, can withstand the furnace load and the stress applied in the operation process, and does not lose the structural strength at high temperatures, does not occur softening deformation and collapse, usually expressed by the load softening temperature;

3, the volume is stable at high temperature, the kiln masonry or pouring body will not collapse due to excessive expansion of the product, or cracks due to excessive shrinkage, reducing the service life. It is usually measured by linear expansion coefficient and reburning shrinkage.

4, refractory material is greatly affected by the operating conditions of the kiln, the rapid change in temperature and uneven heating make the furnace body easy to damage. Therefore, it is required to have a certain thermal shock resistance;

The quality of refractory materials depends on its nature, which is the standard for evaluating the quality of products. The correct and reasonable selection of refractory materials is also based on their properties.