Silicon nitrides are characterized by an excellent combination of material properties. Si3N4 is nearly as light as silicon carbide (SiC), but their microstructure gives them excellent thermal shock resistance and their high fracture toughness makes them resistant to impacts and shocks.
The microstructure consists of elongated crystals that interlock into micro-rods. One application where this combination of properties has proven particularly useful is the machining of gray cast iron or cast iron with ceramic inserts.
Unlike hard metals or other cutting materials, machining processes can be performed with ceramic inserts at maximum speed without the use of cooling lubricants.
The combination of good tribological properties and excellent fracture toughness makes silicon nitride ceramics predestined for applications, such as balls and rolling elements for light and extremely heavy-duty ceramic forming tools, precise bearings,and automotive components subject to high stress. And it is exploited in welding processes with the good thermal shock resistance and high temperature resistance.
Thanks to silicon nitrides’ outstanding chemical and physical characteristics ceramic components have replaced conventional materials, they are widely used in many seal ring, bearing and sealing technology applications.
Silicon nitride has a decisive impact on the functionality, reliability and service life of these components. Combined bearings made of ceramic materials and carbon or reinforced plastic are surprisingly light yet very stiff, are not easily impacted by centrifugal forces and feature very good emergency and dry running properties. For example, a radial bearing combined with a ceramic bearing sleeve and a bearing bush made of carbon.
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