US4935388A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Rolling contact bearings, material for bearing surfaces, and process therefor
Assignee: Saint Gobain Abrasives Inc
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Filing: 1985-04-29
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Granted: 1990-06-19
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Expires: 2005-04-29
Abstract
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 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.
Inventors
- 👤 John W. Lucek
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 12:42
CPC Classifications
F; F16; F16C; F16C33/00; F16C33/30; C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/593; C04B35/597; Y; Y10; Y10S; Y10S384/00; Y10S384/90; Y10S384/907; Y10S384/91; Y10S384/913
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
47 words
A ceramic material comprising a predominant volume of grains of silicon nitride or silicon oxynitride bonded together by an intergranular phase, said ceramic material having an L 10 value of at least four million stress cycles in ASTM test STP 771 under 6.9 gigapascals applied contact stress.
Claim 2
Dependent Claim
47 words
A ceramic material comprising a predominant volume of grains of silicon nitride or silicon oxynitride bonded together by an intergranular phase, said ceramic material having an L 10 value of at least four million stress cycles in ASTM test STP 771 under 6.9 gigapascals applied contact stress.
Claim 3
Dependent Claim
22 words
A material according to claim 1, wherein said intergranular phase occupies less than one tenth of the total volume of the material.
Claim 4
Dependent Claim
36 words
A ceramic material comprising a predominant volume of granules of silicon nitride or silicon oxynitride bonded together by an intergranular phase, said ceramic material having an average largest flaw as described, of less than 40 μm.
Claim 5
Dependent Claim
36 words
A ceramic material comprising a predominant volume of granules of silicon nitride or silicon oxynitride bonded together by an intergranular phase, said ceramic material having an average largest flaw as described, of less than 40 μm.
Claim 6
Dependent Claim
39 words
A ceramic material comprising a predominant volume of granules of silicon nitride or silicon oxynitride bonded together by an intergranular phase, said ceramic material having optical heterogeneities the largest of which is not more than 70 microns in diameter.
Claim 7
Dependent Claim
39 words
A ceramic material comprising a predominant volume of granules of silicon nitride or silicon oxynitride bonded together by an intergranular phase, said ceramic material having optical heterogeneities the largest of which is not more than 70 microns in diameter.
Claim 8
Dependent Claim
16 words
A material according to claim 4, wherein said maximum value is not more than 50 microns.
Claim 9
Dependent Claim
17 words
A material according to claim 2, comprising not less than 1.5 percent by weight of magnesium oxide.
Claim 10
Dependent Claim
17 words
A rolling contact bearing incorporating a bearing surface consisting predominantly of a material according to claim 6.
Claim 11
Dependent Claim
17 words
A rolling contact bearing incorporating a bearing surface consisting predominantly of a material according to claim 5.
Claim 12
Dependent Claim
17 words
A rolling contact bearing incorporating a bearing surface consisting predominantly of a material according to claim 4.
Claim 13
Dependent Claim
17 words
A rolling contact bearing incorporating a bearing surface consisting predominantly of a material according to claim 3.
Claim 14
Dependent Claim
17 words
A rolling contact bearing incorporating a bearing surface consisting predominantly of a material according to claim 2.
Claim 15
Dependent Claim
17 words
A rolling contact bearing incorporating a bearing surface consisting predominantly of a material according to claim 1.
Claim 16
Dependent Claim
117 words
In a process for the manufacture of ceramic material comprising the steps of mixing a predominant amount of fine silicon nitride or silicon oxynitride powder with a minor amount of a finely ground binder material, said binder material comprising a predominant amount of oxides or carbonates of alkaline earth metals or mixtures thereof, milling the mixture of ceramic and binder material for at least six hours in a liquid dispersant, drying the milled mixed powder under sufficient pressure and heat to densify it into a coherent body, the improvement wherein the dried milled mixed powder is size classified before compression so as to eliminate from the compressed powder any aggregate having a diameter greater than five microns.
Claim 17
Dependent Claim
117 words
In a process for the manufacture of ceramic material comprising the steps of mixing a predominant amount of fine silicon nitride or silicon oxynitride powder with a minor amount of a finely ground binder material, said binder material comprising a predominant amount of oxides or carbonates of alkaline earth metals or mixtures thereof, milling the mixture of ceramic and binder material for at least six hours in a liquid dispersant, drying the milled mixed powder under sufficient pressure and heat to densify it into a coherent body, the improvement wherein the dried milled mixed powder is size classified before compression so as to eliminate from the compressed powder any aggregate having a diameter greater than five microns.
Claim 18
Dependent Claim
114 words
In a process for the manufacture of ceramic material comprising the steps of mixing a predominant amount of fine silicon nitride or silicon oxynitride powder with a minor amount of a finely ground binder material, said binder material comprising a predominant amount of oxides or carbonates of alkaline earth metals or mixtures thereof, milling the mixture of ceramic and binder material for at least six hours in a liquid dispersant, drying the milled mixed powder, and compressing the dried milled mixed powder under sufficient pressure and heat to density it into a coherent body, the improvement wherein said milling of the mixture of ceramic and binder material is continued for at least twenty-four hours.
Claim 19
Dependent Claim
114 words
In a process for the manufacture of ceramic material comprising the steps of mixing a predominant amount of fine silicon nitride or silicon oxynitride powder with a minor amount of a finely ground binder material, said binder material comprising a predominant amount of oxides or carbonates of alkaline earth metals or mixtures thereof, milling the mixture of ceramic and binder material for at least six hours in a liquid dispersant, drying the milled mixed powder, and compressing the dried milled mixed powder under sufficient pressure and heat to density it into a coherent body, the improvement wherein said milling of the mixture of ceramic and binder material is continued for at least twenty-four hours.
Claim 20
Dependent Claim
18 words
A material according to claim 1 wherein the volume of optical anomalies is <20% of the total material.
References Cited (Backward Citations)
US3836374A
Cited
US4073845A
Cited
US4350771A
Cited
US4264547A
Cited
US4388085A
Cited
JPS59184771A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-06-18 | 1993-12-18 | 1994-06-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-06-18 | 1997-12-18 | 1998-06-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-06-18 | 2001-12-18 | 2002-06-19 | $7700.00 | Window Closed / Lapsed |