Silicon nitride insulation ring

The operating temperature of a polysilicon reduction furnace is usually 1000-1200°C. With their high resistivity (>10¹⁴ Ω·cm) and high temperature resistance, silicon nitride insulation rings can effectively isolate the electrode from the furnace body to prevent current leakage and short circuit.

As the connecting part between the electrode and the furnace body, silicon nitride insulation rings need to withstand mechanical loads and thermal stress. Its high bending strength (700 MPa) and low thermal expansion coefficient (3.1-3.3×10⁻⁶/°C) can ensure sealing at high temperature and prevent leakage of the reducing gases (H₂, HCl).

In environments containing chlorine, silicon powder and acid gases, silicon nitride insulation rings are far more resistant to corrosion than those made of traditional materials (such as quartz or alumina), which can avoid reduction in the life of equipment due to material wastage.

ADVANTAGES OF SILICON NITRIDE:

For silicon nitride, the long-term working temperature can reach 1400°C and the short-term working temperature is 1700°C, which is suitable for the high-temperature environments for polysilicon deposition.

Silicon nitride is not easy to crack when the temperature is quickly rising or decreasing (such as when opening/shutdown of the furnace), which can reduce the frequency of equipment maintenance.

Silicon nitride almost doesn’t react to the gases in the furnace, such as hydrogen, hydrogen chloride, trichlorosilane as well as silicon melts, which can avoid contaminating the silicon materials.

Silicon nitride has high hardness (HRA 92-94) and excellent wear resistance, which can adapt to frequent start-stop and scour of the gases.

COMPARISONS OF DIFFERENT MATERIALS: