A bearing is a mechanical component used wherever there is a need to reduce friction between two or more connected components.
Almost all existing bearings are made of rings and rolling elements in special 100Cr6 steel, known also as bearing steel.
Bearing geometries and types are now standardised and classified in accordance with ISO standards, but the materials used to make bearings are still subject to ongoing research and development.
Rolling elements were the first bearing components to be tested in materials other than 100Cr6 steel.
The first hybrid bearings, introduced a few years ago, are mainly used for aerospace applications. These owe their name to the fact that the rolling elements are made of ceramic (silicon nitride) instead of 100Cr6 steel.