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US3836374A
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Hot pressed silicon nitride
Assignee: Saint Gobain Abrasives Inc
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Filing: 1972-12-26
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Granted: 1974-09-17
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Expires: 1992-12-26
Abstract
Abstract A hot pressed silicon nitride product is described, the product having high strength at room temperature as well as high strength at elevated temperature. The product has a flexural strength in excess of 100,000 psi at 20*C., in excess of 90,000 psi at 1,200*C., in excess of 35,000 psi at 1,375*C, and preferably above 45,000 psi at 1,375*C. A preferred form of the product includes between .25 and 2.0 mg in the form of complex silicate, which silicate also contains a limited amount of iron, aluminum and calcium. The complex silicate has a liquidus above 1,400*C. The product has a density between 3.1 and 3.3 g/cc, the total oxygen content of the product being less than 5%.
Inventors
- 👤 D Richerson
- 👤 M Washburn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 17:42
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/593
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
13 words
The product of claim 1 wherein the MgO/CaO ratio is greater than 4.
Claim 2
Dependent Claim
14 words
The product of claim 1 wherein the calcium content is less than 0.1 percent.
Claim 3
Dependent Claim
43 words
The product of claim 1 wherein the composition of the complex silicate falls above the line ABCDE in the high SiO2 portion of the RO.SiO2.Al2O3 ternary composition diagram shown in the drawing wherein A, B, C, D, and E have the following compositions:
Claim 4
Dependent Claim
82 words
A monolithic, high density silicon nitride product, whose silicon nitride is predominantly beta phase, the product having a density between 3.1 and 3.3 g/cc, the product being characterized by a rupture modulus in excess of 90,000 psi at 1,200* C. and in excess of 45,000 psi at 1,375* C., the silicon nitride containing a complex metal silicate whose composition is such that its liquidus is above 1,400* C., the product having a total oxygen content of between 2 percent and 5 percent.
Claim 5
Dependent Claim
119 words
A bulk, high density silicon nitride product, whose silicon nitride is predominantly beta phase, the product having a density between 3.1 and 3.3 g/cc, the product being characterized by a rupture modulus in excess of 90,000 psi at 1,200* C. and in excess of 45,000 psi at 1,375* C., the silicon nitride containing between .25 percent and 2 percent of magnesium, in the form of magnesium silicate, with a minor amount of metallic impurities, including iron, calcium and aluminum, the amount of such metallic impurities being below the amount necessary to form any complex with the magnesium silicate having a liquidus less than 1,400* C., the product having a total oxygen content of between 2 percent and 5 percent.
Claim 6
Dependent Claim
120 words
A dense, bulk silicon nitride product, whose silicon nitriDe is predominantly beta phase, the product being characterized by a rupture modulus in excess of 90,000 psi at 1,200* C. and in excess of 45,000 psi at 1,375* C., the silicon nitride containing between .3 percent and .9 percent of magnesium with a minor amount of other metals, including iron, calcium and aluminum, the metallic content being in the form of a complex silicate, the iron content being less than .30 percent, the calcium being less than .1 percent and the aluminum being less than .5 percent, the product having a density between 3.1 and 3.2 g/cc, the product having a total oxygen content of between 2 percent and 5 percent.
Claim 7
Dependent Claim
33 words
The product of claim 1 having a room temperature modulus of rupture of the product after exposure to air at 1,400*C for 70 hours is on the order of 70,000 psi and above.
Claim 8
Dependent Claim
23 words
The product of claim 1 which can resist rupture under a 45, 000 psi load at 1,200* C for at least 1 hour.
References Cited (Backward Citations)
GB970639A
Cited
GB1092637A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-16 | 1978-03-18 | 1978-09-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-16 | 1982-03-18 | 1982-09-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-16 | 1986-03-18 | 1986-09-17 | $7700.00 | Window Closed / Lapsed |