Silicon nitride – Si₃N₄

Silicon Nitride (Si₃N₄) has a unique grain structure which delivers both exceedingly high strength and toughness, and exceptionally high thermal shock resistance. This makes it very suitable for the most demanding conditions.

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Because of their exceptional thermal shock resistance, silicon nitrides are often used in situations where non-ferrous molten metals are handled. The cost of these parts is generally higher than white ceramics, so they are only used in situations where other ceramics cannot withstand the conditions.

What is sialon?

Sialon is a combination of silicon nitride and aluminium oxide. It is mostly known for its thermal shock capabilities and non-wetting characteristics for molten metals.

Can you bring silicon nitride parts in direct contact with molten metals?

Yes, it can withstand direct contact with most non-ferrous molten metals. It is often used as thermocouple tubes or risers in foundries.

Which type of Silicon nitride is most common?

SSN is most frequently used. It is densified by pressureless sintering in a nitrogen atmosphere at around 1750°C. In order to aid densification, various combinations of sintering additives such as yttrium oxide, magnesium oxide and aluminium oxide are used.

Why are precision balls made of silicon nitride?

Silicon nitride has a very low friction coefficient and an excellent wear rate, which makes it very suitable for bearings. Ceramic bearings are used in the most demanding conditions because of their unique characteristics.

Electrical properties

Mechanical properties

Thermal properties

Temperature application

Properties Density g/cm3 Porosity % Mechanical properties Hardness (Vickers) kg/mm2 Compressive strength N/mm2 Bending strength N/mm2 E-modulus kN/mm2 Weibull modulus m Fracture toughness K1c Mpam Coefficient of friction Thermal properties
(Max. use temperature) *in air ℃ *in inert atm. ℃ Thermal shock resistance Expansion coefficient *20C - 200C *20C - 600C *20C - 1000C Thermal conductivity at 20C W/mK Electrical properties (Resistivity) * at 20C ohm cm * at 400C ohm cm * at 1000C ohm cm

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Silicon nitride – Si3N4

Silicon nitride

Silicon nitride – Si₃N₄