Rolling contact bearings, material for bearing surfaces, and process therefor
US4935388A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 29, 1985 |
| Grant date | Jun 19, 1990 |
| Priority date | — |
| Expiry date | Apr 29, 2005 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S384/913
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The reliability of silicon nitride bodies for use in bearings can be greatly improved by control of microstructural flaws which produce bright specular reflections when metallographically prepared surfaces of the composites are examined microscopically in low angle incident light, dark field reflected light, or reflected polarized light viewed through a crossed polarizing analyzer. The population of such flaws can be controlled by modestly increasing the normal amount of intergranular phase and longer than normal milling times before sintering. Size classification of the powder before compression also improves the performance of the body. The fatigue cycles to failure of ten percent of the silicon nitride surfaces tested at 6.9 GPa contact stress in accelerated bearing failure ASTM Test STP 771 (L.sub.10 parameter) for sintered bodies prepared according to this invention is increased by about an order of magnitude over the values obtained with the best previously known type of silicon nitride body for bearing applications.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.