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US4172109A
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Pressureless sintering beryllium containing silicon carbide powder composition
Assignee: Stemcor Corp
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Filing: 1978-08-28
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Granted: 1979-10-23
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Expires: 1998-08-28
Abstract
Abstract A sinterable silicon carbide mixture is described which is prepared by mixing finely-divided silicon carbide containing between about 0.5 and about 5.0 percent by weight of excess carbon with a finely-divided beryllium-containing additive wherein the amount of beryllium in the mixture is equal to between about 0.03 and about 1.5 percent by weight of the powder. A dense silicon carbide ceramic product is prepared from the powder mixture by pressureless sintering wherein the article is initially shaped and subsequently sintered in a beryllium-containing atmosphere at a temperature from about 1950 DEG to about 2300 DEG C.
Inventors
- 👤 Richard H. Smoak
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 13:25
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/56; C04B35/565
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
85 words
A method of pressureless sintering silicon carbide powders containing beryllium or a beryllium-containing compound as a densification aid to produce a silicon carbide ceramic material having a density of at least 85 percent of theoretical which comprises the steps of: (a) shaping said powders into a green product, and (b) sintering said green product in an atmosphere containing beryllium, wherein the partial pressure of beryllium in the atmosphere during sintering is equal to or greater than the equilibrium vapor pressure of beryllium in said product.
Claim 2
Independent Claim
85 words
A method of pressureless sintering silicon carbide powders containing beryllium or a beryllium-containing compound as a densification aid to produce a silicon carbide ceramic material having a density of at least 85 percent of theoretical which comprises the steps of: (a) shaping said powders into a green product, and (b) sintering said green product in an atmosphere containing beryllium, wherein the partial pressure of beryllium in the atmosphere during sintering is equal to or greater than the equilibrium vapor pressure of beryllium in said product.
Claim 3
Dependent Claim
17 words
The method of claim 1 wherein the partial pressure of beryllium is at least 10 -4 atmosphere.
Claim 4
Dependent Claim
25 words
The method of claim 1 wherein the silicon carbide containing powders include beryllium in an amount between about 0.03 and about 1.5 percent by weight.
Claim 5
Dependent Claim
13 words
The method of claim 1 wherein the sintering atmosphere includes an inert gas.
Claim 6
Dependent Claim
16 words
The method of claim 1 wherein the beryllium in the atmosphere is introduced as beryllium carbide.
Claim 7
Dependent Claim
34 words
The method of claim 1 wherein the silicon carbide powder also contains boron or a boron-containing compound as a densification aid in an amount of up to about 1.5 percent by weight of boron.
Claim 8
Dependent Claim
21 words
The method of claim 6 wherein boron is included in an amount between about 0.1 and about 0.3 percent by weight.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-10-22 | 1983-04-23 | 1983-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-10-22 | 1987-04-23 | 1987-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-10-22 | 1991-04-23 | 1991-10-23 | $7700.00 | Window Closed / Lapsed |