High temperature resistance of ceramics

Ceramics are non-metallic inorganic materials that exhibit excellent mechanical, physical and chemical properties at high temperatures. Under normal circumstances, the heat resistance temperature range of ceramics is between 1000℃-1800℃, but different kinds of ceramics have different heat resistance properties. For example, the melting point of alumina ceramics can reach 2072 ° C, while the use temperature of silicon carbide ceramics in an oxidizing atmosphere can reach more than 1500 ° C.

The main material of high temperature resistant ceramic parts

(1) Alumina

Alumina is a common high temperature resistant ceramic material, so alumina ceramic parts have high hardness, high strength, excellent heat resistance and corrosion resistance, so it is widely used in the field of high temperature manufacturing, electronics industry, biomedical and other fields.

(2) Zirconia

Zirconia has excellent mechanical properties, chemical stability, thermal conductivity and high temperature stability, is a common ceramic material, zirconia ceramic parts can be used in a variety of high temperature applications. It has been used in the field of high temperature and corrosion resistance technology.

Other high temperature resistant ceramics (such as Al2O3, ZrO, MgO, CaO, ThO2, Cr2O3, SiO2, BeO, 3 Al2O3·2SiO2, etc.), carbide ceramics, boride ceramics, nitride ceramics and silicide ceramics

Different kinds of ceramics, their high temperature resistance is also different. Here are some common ceramics and their high temperature resistance:

1. Ordinary porcelain: high temperature resistance at about 800 degrees;

2. High aluminum porcelain: high temperature resistance at about 1600 degrees;

3. Zirconia ceramics: high temperature resistance at about 2000 degrees;

4. Silicon carbide ceramics: high temperature resistance at about 2500 degrees;

5. Silicon nitride ceramics: high temperature resistance at about 2800 degrees.

Performance characteristics of high temperature resistant ceramic parts

High temperature resistant ceramic parts as a special ceramic material parts, it shows a variety of characteristics in high temperature environment.

(1) High temperature stability

High temperature resistant ceramic parts have good high temperature stability, and their thermal stability and thermal expansion rate are relatively low at high temperatures, so that high temperature resistant ceramic parts can be used stably for a long time in a high temperature environment.

(2) Excellent mechanical properties

High temperature resistant ceramic parts have good strength and hardness, and can maintain their performance at high temperatures for a long time.

(3) Excellent corrosion resistance

High temperature resistant ceramic parts show excellent corrosion resistance in acid, alkali, salt, oxide and other environments.

With the continuous development of science and technology, high temperature resistant ceramic parts have been widely used in various fields. Alumina, zirconia and other oxides are the main materials of high temperature resistant ceramic parts, it has good thermal conductivity and mechanical properties, can withstand high temperature and corrosion and other harsh conditions, showing excellent high temperature stability and corrosion resistance.

Classification of high temperature ceramic parts

Ceramic bearings, bushings, engine covers, heat shields, valves, pistons, seals, pins and tubes, fasteners, screws and nuts, crucible, protective sleeves, injection parts, flanges, nozzles, rapid cutting, gears, road rollers, fire protection equipment, pumps... And other industries, insulation cooling parts, equipment spare parts.

High temperature stability of ceramics

Due to the high stability of ceramics at high temperatures, the chemical and physical properties of ceramics will undergo some changes under high temperature conditions. One of the most obvious is the thermal conductivity and thermal expansion coefficient of the ceramic. At high temperatures, the thermal conductivity of the ceramic increases, while the coefficient of thermal expansion decreases, making it more stable.

Fourth, how to avoid ceramic cracking in high temperature environment

Although ceramics have high temperature stability, there are also some problems, such as easy to crack during rapid heating and cooling. Therefore, in order to avoid this situation, you need to pay attention to the following points:

1. Avoid rapid temperature rise: the coefficient of thermal expansion of ceramics is small, so rapid temperature rise is easy to lead to thermal stress, thereby damaging the ceramic structure. Therefore, it should be heated slowly.

2. Avoid sudden cooling: the coefficient of thermal expansion of ceramics is small, and the cooling speed is too fast, which will also lead to thermal stress, so the ceramics should be cooled slowly during the high temperature process.

3. Add the appropriate flux: Adding a certain amount of flux in the process of manufacturing ceramics can change the sintering temperature and sintering time of ceramics, thereby improving the high temperature resistance of ceramics.