US5037626A
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US
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Process for producing silicon carbide whiskers using seeding agent
Assignee: Advanced Industrial Materials
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Filing: 1988-11-22
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Granted: 1991-08-06
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Expires: 2008-11-22
Abstract
Abstract A processing for producing silicon carbide whiskers in which a source of silica is mixed with a residual oil or crude petroleum and the resultant mixture is heated in a substantially nonoxidizing atmosphere at temperature sufficiently high to carbonize the residual oil or crude petroleum, thereby forming an intimate mixture of carbon and silica. The intimate mixture is then heated in a nonoxidizing atmosphere in the presence of a seeding component comprising an element selected from the group consisting of boron, the rare earths, Group IA, Group IB, Group VB, Group VIB, Group VIIB and Group VIII of the Periodic Table of Elements at temperatures sufficiently high to induce the reaction between carbon and silica to form silicon carbide. The resultant silicon carbide product will contain a relatively high concentration of silicon carbide whiskers.
Inventors
- 👤 Phillman N. Ho
- 👤 Roy T. Coyle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 21:20
CPC Classifications
C; C30; C30B; C30B25/00; C30B25/005; C30B29/00; C30B29/10; C30B29/36
Claims Analysis
Total Claims: 40
Claim 1
Independent Claim
144 words
A process for producing silicon carbide whiskers which comprises: (a) mixing a source of carbon selected from the group consisting of residual oils and crude petroleum with a source of silica; (b) heating said mixture of said silica source and said carbon source in a substantially nonoxidizing atmosphere at temperatures sufficient to carbonize the carbon source and thereby form an intimate mixture of carbon and silica; (c) heating said intimate mixture of carbon and silica in a nonoxidizing atmosphere in the presence of a seeding component comprising an element selected from the group consisting of boron, the rare earths, Group IA, Group IB, Group VB, Group VIB, Group VIIB and Group VIII of the Periodic Table of Elements at temperatures sufficient to induce a reaction between said carbon and said silica to form silicon carbide; and (d) recovering a product containing silicon carbide whiskers.
Claim 2
Dependent Claim
144 words
A process for producing silicon carbide whiskers which comprises: (a) mixing a source of carbon selected from the group consisting of residual oils and crude petroleum with a source of silica; (b) heating said mixture of said silica source and said carbon source in a substantially nonoxidizing atmosphere at temperatures sufficient to carbonize the carbon source and thereby form an intimate mixture of carbon and silica; (c) heating said intimate mixture of carbon and silica in a nonoxidizing atmosphere in the presence of a seeding component comprising an element selected from the group consisting of boron, the rare earths, Group IA, Group IB, Group VB, Group VIB, Group VIIB and Group VIII of the Periodic Table of Elements at temperatures sufficient to induce a reaction between said carbon and said silica to form silicon carbide; and (d) recovering a product containing silicon carbide whiskers.
Claim 3
Dependent Claim
15 words
A process as defined by claim 1 wherein said carbon source comprises a residual oil.
Claim 4
Dependent Claim
15 words
A process as defined by claim 1 wherein said carbon source comprises a crude petroleum.
Claim 5
Dependent Claim
17 words
A process as defined by claim 2 wherein said residual oil is an atmospheric petroleum residual oil.
Claim 6
Dependent Claim
17 words
A process as defined by claim 2 wherein said residual oil is a vacuum petroleum residual oil.
Claim 7
Dependent Claim
30 words
A process as defined by claim 2 wherein said residual oil contains components boiling above about 350° C. and has a viscosity greater than about 1.0 centipoise at 25° C.
Claim 8
Dependent Claim
32 words
A process as defined by claim 6 wherein said residual oil is selected from the group consisting of petroleum residual oils, oil shale liquids, coal liquids and liquids derived from tar sands.
Claim 9
Dependent Claim
28 words
A process as defined by claim 2 wherein said residual oil comprises a petroleum residual oil having an initial boiling point at atmospheric pressure above about 200° C.
Claim 10
Dependent Claim
28 words
A process as defined by claim 2 wherein said residual oil comprises a petroleum residual oil having an initial boiling point at atmospheric pressure above about 350° C.
Claim 11
Dependent Claim
28 words
A process as defined by claim 2 wherein said residual oil is produced by removing components boiling below about 560° C. at atmospheric pressure from a crude petroleum.
Claim 12
Dependent Claim
33 words
A process as defined by claim 1 wherein said silica source is selected from the group consisting of silica, fumed silica, hydrated silica, dried silica gel, dried silica sol and organic silicon compounds.
Claim 13
Dependent Claim
22 words
A process as defined by claim 1 wherein said silica source yields silica particles having a size less than about 10 microns.
Claim 14
Dependent Claim
31 words
A process as defined by claim 1 wherein the heating in step (b) is carried out at a temperature below that at which silica and carbon react to form silicon carbide.
Claim 15
Dependent Claim
40 words
A process as defined by claim 1 wherein said seeding component comprises an element selected from the group consisting of lithium, potassium, sodium, rubidium, neodymium, niobium, vanadium, tantalum, chromium, molybdenum, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, copper, and boron.
Claim 16
Dependent Claim
26 words
A process as defined by claim 14 wherein said seeding component comprises an element selected from the group consisting of cobalt, vanadium, iron, boron and nickel.
Claim 17
Dependent Claim
12 words
A process as defined by claim 15 wherein said element is cobalt.
Claim 18
Dependent Claim
12 words
A process as defined by claim 15 wherein said element is vanadium.
Claim 19
Dependent Claim
39 words
A process as defined by claim 1 wherein a sufficient amount of said seeding component is present in step (c) such that the mole ratio of said element to the silicon present ranges between about 0.01 and about 2.0.
Claim 20
Dependent Claim
20 words
A process as defined by claim 1 wherein said seeding component is incorporated into the carbon source in step (a).
Claim 21
Dependent Claim
25 words
A process as defined by claim 1 wherein said seeding component is mixed with the intimate mixture of carbon and silica formed in step (b).
Claim 22
Dependent Claim
37 words
A process as defined by claim 1 wherein said seeding component is in the form of an oxylate, a carbonate, a carbide, a nitrate, an oxide, a boride, a silicate, a sulfate, a phosphide or a halide.
Claim 23
Dependent Claim
24 words
A process as defined by claim 1 wherein a portion of the product recovered in step (d) of said process comprises said seeding component.
Claim 24
Dependent Claim
136 words
A process for producing silicon carbide whiskers which comprises: (a) suspending particles of silica in a petroleum residual oil; (b) heating said suspension of silica particles in said residual oil in a substantially nonoxidizing atmosphere at temperatures below about 1200° C. but sufficiently high to carbonize the residual oil and thereby form an intimate mixture of carbon and silica; (c) heating said intimate mixture of carbon and silica in a nonoxidizing atmosphere in the presence of a seeding component comprising an element selected from the group consisting of lithium, potassium, sodium, rubidium, neodymium, niobium, tantalum, boron, cobalt, vanadium, iron, nickel, chromium, molybdenum, manganese, ruthenium, rhodium, palladium and copper at temperatures sufficiently above about 1200° C. to induce the reaction between carbon and silica to form silicon carbide; and (d) recovering a product containing silicon carbide whiskers.
Claim 25
Dependent Claim
136 words
A process for producing silicon carbide whiskers which comprises: (a) suspending particles of silica in a petroleum residual oil; (b) heating said suspension of silica particles in said residual oil in a substantially nonoxidizing atmosphere at temperatures below about 1200° C. but sufficiently high to carbonize the residual oil and thereby form an intimate mixture of carbon and silica; (c) heating said intimate mixture of carbon and silica in a nonoxidizing atmosphere in the presence of a seeding component comprising an element selected from the group consisting of lithium, potassium, sodium, rubidium, neodymium, niobium, tantalum, boron, cobalt, vanadium, iron, nickel, chromium, molybdenum, manganese, ruthenium, rhodium, palladium and copper at temperatures sufficiently above about 1200° C. to induce the reaction between carbon and silica to form silicon carbide; and (d) recovering a product containing silicon carbide whiskers.
Claim 26
Dependent Claim
12 words
A process as defined by claim 23 wherein said element is cobalt.
Claim 27
Dependent Claim
12 words
A process as defined by claim 23 wherein said element is vanadium.
Claim 28
Dependent Claim
12 words
A process as defined by claim 23 wherein said element is iron.
Claim 29
Dependent Claim
12 words
A process as defined by claim 23 wherein said element is boron.
Claim 30
Dependent Claim
12 words
A process as defined by claim 23 wherein said element is nickel.
Claim 31
Dependent Claim
14 words
A process as defined by claim 23 wherein said seeding component is vanadium carbide.
Claim 32
Dependent Claim
14 words
A process as defined by claim 23 wherein said seeding component is vanadium oxide.
Claim 33
Dependent Claim
14 words
A process as defined by claim 23 wherein said seeding component is cobalt carbonate.
Claim 34
Dependent Claim
14 words
A process as defined by claim 23 wherein said seeding component is cobalt nitrate.
Claim 35
Dependent Claim
28 words
A process as defined by claim 23 wherein said residual oil is produced by removing components boiling below about 350° C. at atmospheric pressure from a crude petroleum.
Claim 36
Dependent Claim
24 words
A process as defined by claim 23 wherein step (b) is carried out at a temperature between about 500° C. and about 750° C.
Claim 37
Dependent Claim
24 words
A process as defined by claim 23 wherein step (c) is carried out at a temperature between about 1300° C. and about 2000° C.
Claim 38
Dependent Claim
35 words
A process as defined by claim 23 wherein said silica particles are suspended in said residual oil in the absence of an added solvent which will dissolve both the silica particles and the residual oil.
Claim 39
Dependent Claim
14 words
A process as defined by claim 23 wherein said seeding component is boric oxide.
Claim 40
Dependent Claim
14 words
A process as defined by claim 23 wherein said seeding component is boron carbide.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-08-05 | 1995-02-04 | 1995-08-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-08-05 | 1999-02-04 | 1999-08-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-08-05 | 2003-02-04 | 2003-08-06 | $7700.00 | Window Closed / Lapsed |