Silicon Nitride Sintering Furnace With Great Performance In Corrosion Wear Resistance

The Introduction of Silicon Nitride

Silicon nitride ceramics have been widely used in aerospace and military industry, mechanical engineering, communications, electronics, automobiles, energy, chemical biology and other fields because of their high temperature resistance, corrosion resistance, wear resistance and unique electrical properties.

Especially in the field of high temperature structural ceramics, silicon nitride ceramics are new materials with the best comprehensive properties, most possibly to replace nickel-based alloys.

Features

• Heat resistance, under normal pressure, Si3N4 has no melting point which decomposes directly at about 1870 °C. It can resist oxidation to 1400 °C with the actual use reaches 1200 °C (mechanical strength will decrease when it exceeds 1200 °C).

• Small thermal expansion coefficient (2.8-3.2) × 10^-6/℃, high thermal conductivity, thermal shock resistance, no cracking from room temperature to 1000℃ thermal shock.

• Small friction coefficient (0.1), self-lubricating, (friction coefficient of oiled metal surface 0.1-0.2)

• Stable chemical properties, corrosion resistance, does not react with other inorganic acids except hydrofluoric acid, does not react with oxygen in a dry atmosphere of 800 °C, and starts to form a silicon oxide film on the surface when the temperature exceeds 800 °C. The high silicon oxide film becomes stable gradually, and a dense silicon oxide film can be formed with oxygen at about 1000 ℃. It can be kept basically stable to 1400℃.

• High hardness, wear resistance, Mohs hardness is second only to diamond, cubic boron amide, boron carbide, silicon carbide, and mechanical shock resistance.

Application in Aerospace & Military Industry

Taking the turbojet engine of an aircraft as an example, the temperature of the compressor parts is below 650 ℃, and currently titanium alloys, aluminum alloys and heat-resistant steels are mainly used. The temperature in the combustion zone of the combustion chamber is as high as 1800-2000 °C. After the introduction of air cooling, the wall temperature of the combustion chamber is still above 900 °C. , The protective layer is often sprayed, and the dispersion-strengthened alloy can be used to prepare a 1200 ℃ natural burning chamber without coating.

Mechanism ceramic silicon nitride is heat-resistant and can still have high strength and stiffness at 1400 °C (but the mechanical strength will decrease when it exceeds 1200 °C), but it is relatively brittle. The use of continuous fiber reinforced reinforced ceramics can be used in turbine components, especially It is the ceramic blades of the small engine, the outer turbine ring and the air bearing. In addition, the specific density of silicon nitride ceramics is only 41% of that of steel bearings, which can effectively reduce the weight of aircraft engines and reduce fuel consumption.