Due to the development of science and technology, new
refractory materials have been constantly raised in the aerospace, nuclear energy, metallurgy, electronics, chemical, building materials, transportation and other industries. The requirements for use conditions are becoming more and more demanding and special. Ordinary refractories can no longer meet the new requirements. It is required that only special refractory ice with high temperature resistance, corrosion resistance, high temperature chemistry and good thermal stability can withstand such a heavy task and meet the requirements of use conditions. Special refractory materials include a wide range of content, mainly including high melting point oxides, high melting point non-oxides and composite compounds derived from them, cermets, high temperature coatings, high temperature fibers and their reinforcement materials. Among them, high melting point non-oxides are usually called refractory compounds, which include carbides, nitrides, borides, silicides and sulfides.
Special refractory materials are developed on the basis of traditional ceramics, precision ceramics, ordinary refractory materials, and functional refractory materials. They are a group of single materials or single materials such as high-purity oxides, non-oxides and carbon with a melting point above 1800°C. Various composite materials are used as raw materials and are produced by traditional production techniques or special production techniques, and their products have special properties and special purposes. They are also called special refractories.
A classification of special refractory materials
Although the cost of special refractories is relatively high, they are indispensable and irreplaceable products in many industrial sectors due to their many excellent properties. Especially in many new technologies and new fields, replacing other products in many key parts can greatly increase the service life and significantly increase economic benefits. The classification of special refractory materials is based on different properties of raw materials and products, which can be roughly divided into five aspects:
(1) High melting point oxide materials and their composite materials;
(2) Refractory compound materials (carbides, nitrides, borides, silicides, etc.) and their composite materials;
(3) Composite material of high melting point oxide and refractory metal (cermet);
(4) High-temperature amorphous materials and inorganic coatings;
(5) High-temperature fibers and their reinforcement materials.
Two characteristics of special refractory materials:
(1) High-purity raw materials
1. The use of artificially purified various raw materials
2. Using various raw materials of electrofusion, sintering and reaction synthesis;
3. Use composite materials as raw materials
4. Use fiber reinforced composite materials as raw materials.
(2) Introduce special production technology
1. Use micro powder or super micro powder technology;
2. Use spray granulation technology;
3. Using special molding technology (isostatic pressing, hot pressing, injection molding, tape casting, fusion casting, etc.);
4. Adopt high temperature fiber or fiber reinforcement technology and amorphous materials.
(3) Special firing
1. Using ultra-high temperature firing (above 1800℃);
2. It is fired under vacuum conditions or protective atmosphere conditions;
3. Use high-energy fuel to burn;
4. Using microcomputer to automatically control firing.
Three special refractory products
1. Special refractory materials for steelmaking and continuous casting
2. Special refractory materials for ultra-high temperature kilns
3. Special refractory materials for ultra-high temperature insulation
4. Special refractory materials for ceramics and transparent ceramics
5. High temperature and high pressure insulation materials
6. High temperature heating element material
7. Solid electrolyte materials
8. High temperature fiber special refractories
