DWhen archeologists discovered cylindrical beech wood pieces in excavated vehicle wheels they concluded that even 2,700 years ago, the benefits of roller bearings were known.
Towards the end of the 19th Century the first ball grinding machine was invented. This allowed production of the thrust bearing (a development of the original roller bearing) to be perfected. Other bearing types, such as self-aligning ball bearings followed at the beginning of the 20th Century.
In the 1960s, increasing demands for ever more reliable bearings led to the introduction of oxide, nitride and carbide ceramics and this development continues to this day. Ceramic has a history stretching back almost 24,000 years.
Today the benefits of technical ceramics are required for many highly-demanding applications. Compounds such as silicon nitride, silicon carbide and zirconia ceramic are increasingly being specified and used worldwide. The incredibly high fracture toughness KIc of silicon nitride (to 7,5 MPa · √m ) is one of the highest-strength materials known.