Silicon nitride is a technical ceramic. It has a unique combination of mechanical, chemical and thermal properties. It is a relatively light material, resistant to high temperatures with particularly good resistance to wear and mechanical abrasion. It is used in the production of mechanical parts in particularly demanding environments (in terms of temperature or corrosive atmosphere) for applications requiring high friction. This ceramic is used in ball bearing components, as seals or as welding and brazing supports/guides.
The properties of silicon nitride
Silicon nitride is a technical ceramic that can be found naturally in the form of a mineral (nierite, found in certain meteorites). It can also be produced by heating a silicon powder in a nitrogen atmosphere from 1300 °C to 1400 °C. It is known in the form of 3 polymorphs: a gamma phase which is cubic, an alpha phase which is trigonal and a beta phase which is hexagonal.
It is a particularly hard and resistant ceramic: it has abrasion resistance, good corrosion resistance and high wear resistance. It has high mechanical strength. Silicon nitride is relatively light (its density is about 3.2 g/cm3). It has good temperature resistance: it can be used for the manufacture of parts used up to 1200 °C in air. This material offers high dimensional stability, even at high temperatures. It is also a good electrical insulator. In addition, silicon nitride has a low wettability to molten metals.
Silicon nitride has a fairly good chemical inertness: it is resistant to chemicals but reacts in the presence of hot sulphuric acid or dilute hydrofluoric acid. It also has good toughness and excellent resistance to mechanical impact and shock.
|Material||StarCeram® Silicon Nitride N 7000|
|Composition (by weight)||> 99% Si3N4|
|Open porosity (%)||0|
|Compresive strength (MPa)||3000|
|Flexural resistence (MPa)||900|
|Module of elasticity (GPa)||310|
|Maxximum operating temperature (°C)||1200|
|Specific heat (J/Kg.K)||800|
|Thermal Conductivity at100 °C (W/m.K)||25|
|Coefficient of expansion (10-6/K)||3,4|
|Resistance at 20 °C (ohm.cm)||1011-1012|
|Resistance at 1000 °C (ohm.cm)||107|
What silicon nitride products do we offer?
There are no standard silicon nitride products, we produce on demand according to customer drawings and specifications.
Kyocera's silicon nitride parts are produced by cold isostatic pressing, green machining and nitrogen pressure sintering. If the dimensional requirements are high, or good roughness is required, we can machine the silicon nitride after sintering with diamond tools.
In what areas is silicon nitride used?
Due to its high thermal and mechanical properties, silicon nitride can be used in applications with particularly demanding environments. It can be used at extreme temperatures, for mechanically highly stressed parts or in corrosive and abrasive environments.
The material is used, for example, in the manufacture of burner tips, heat exchangers and firing supports. Thanks to its low electrical conductivity, it can be used to protect electrical circuits in aeronautics or as a seal (all the more effective thanks to its dimensional stability). This ceramic is also used in machining in the form of ceramic inserts for turning and milling, the manufacture of wire guides and other highly stressed mechanical parts.
Its wear resistance makes it a good choice of material for use in high-performance, high-speed ball bearings.