Rolling contact bearings, material for bearing surfaces, and pro

Details Rolling contact bearings, material for bearing surfaces, and pro Rolling contact bearings, material for bearing surfaces, and pro

1985-04-29

1990-06-19

Lechert, Jr., Stephen J.

Compositions: ceramic

Ceramic compositions

Refractory

252 12, 264 60, 264 63, 384907, 384910, 384913, 501122, 501123, C04B 3558

Patent

active

049353888

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.

REFERENCES:
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patent: 4073845 (1978-02-01), Buljan et al.
patent: 4264547 (1981-04-01), de Pous
patent: 4350771 (1982-09-01), Smith
patent: 4388085 (1983-06-01), Sarin et al.
McLaughlin, J. J., "Alternate Ceramic Roller Bearing Program Final Report" Final Report on NASC Contract N00019-81-C-0284, Nov. 1983.
Glover, D., "A Ball-Rod Rolling Contact Fatigue Tester", ASTM STP 771, American Society for Testing and Materials, 1982.
Baumgartner, H. R. et al, "Ceramic Materials in Rolling Contact Bearings", Final Report on NASC Contract N00019-75-C-0197, Oct. 1976.
Baumgartner, H. R. et al, "Silicon Nitride in Rolling Contact Bearings", Final Report on NASC Contract N00019-76-C-0157, Aug. 1975.
Baumgartner, H. R. et al, "Finishing Techniques for Silicon Nitride Bearings", Final Report on ARMY Contract DAAG46-74-C-0055, Mar. 1976.
Lucek, J. W. et al, "Investigation of the Use of Ceramic Material in Aircraft Engine Bearings", Final Report on Contract NASC N00019-767-C-0251, Jun. 1979.
Lucek, J. W. et al, "Severe Environment Testing of Silicon Nitride Rolling Elements", Final Report on NASC Contract N00019-77-C-0551, Nov. 1979.

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