US4569886A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fabrication of novel whisker reinforced ceramics
Assignee: United States Department of the Navy
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Filing: 1984-06-18
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Granted: 1986-02-11
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Expires: 2004-06-18
Abstract
Abstract The method of coating ceramic whiskers selected from the group consisting SiC, graphite, boron carbide and alumina with magnesium by sublimation and finally by magnesium oxide (MgO) after oxidation comprising (a) heating powdered Mg and SiC w mixture in an oxygen free atmosphere to a temperature of 400° C. to 550° C. (b) igniting the mixture in air in the presence of O 2 (which may incidently cause the mixture to attain a temperature more than 1800° C.) that the desired end results in a coating of MgO on the whisker or particle surfaces, to obtain novel coated whiskers varying in length from 10-100 microns.
Inventors
- 👤 Amarnath P. Divecha
- 👤 Roger E. Wilson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:14
CPC Classifications
C; C30; C30B; C30B33/00; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; C04B35/117; C04B35/515; C04B35/56; C04B35/565; C04B35/575; C04B35/58; C04B35/584; C04B35/593; C04B35/622; C04B35/626; C04B35/62605; C04B35/62645; C04B35/6265; C04B35/6268; C04B35/628; C04B35/62802; C04B35/62805; C04B35/6281; C04B35/62842; C04B35/62844; C04B35/62847; C04B35/62876; C04B35/71; C04B35/78; C04B35/80; C30B29/00; C30B29/10; C30B29/16; C30B29/36; C30B29/60; C30B29/62; C04B2235/00; C04B2235/02; C04B2235/30; C04B2235/32; C04B2235/3217; C04B2235/38; C04B2235/3817; C04B2235/3826; C04B2235/50; C04B2235/52; C04B2235/5208; C04B2235/5216; C04B2235/522; C04B2235/5224; C04B2235/524; C04B2235/5244; C04B2235/526; C04B2235/5264; C04B2235/5276; C04B2235/54; C04B2235/5418; C04B2235/5427; C04B2235/5436; C04B2235/5463; Y; Y10; Y10T; Y10T428/00; Y10T428/29; Y10T428/2913; Y10T428/2933; Y10T428/294
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
121 words
A process for forming a protective coating on whiskers comprising the following steps in order: (a) coating whiskers which are form about 1 to about 100 microns in length and which are made of a material selected from the group consisting of SiC, Si 3 N 4 , Al 2 O 3 , and B 4 C with magnesium by exposing the whiskers to magnesium vapor which is produce by sublimating the magnesium at a temperature of from 400° C. to 550° C. in an inert, oxygen free atmosphere at a pressure of from 0.75 to 1.25 atmospheres; and then (b) igniting the magnesium coated whiskers in an oxygen containing environment to convert the magnesium coating to a magnesium oxide coating.
Claim 2
Dependent Claim
121 words
A process for forming a protective coating on whiskers comprising the following steps in order: (a) coating whiskers which are form about 1 to about 100 microns in length and which are made of a material selected from the group consisting of SiC, Si 3 N 4 , Al 2 O 3 , and B 4 C with magnesium by exposing the whiskers to magnesium vapor which is produce by sublimating the magnesium at a temperature of from 400° C. to 550° C. in an inert, oxygen free atmosphere at a pressure of from 0.75 to 1.25 atmospheres; and then (b) igniting the magnesium coated whiskers in an oxygen containing environment to convert the magnesium coating to a magnesium oxide coating.
Claim 3
Dependent Claim
13 words
A process according to claim 1 wherein the whiskers are made of SiC.
Claim 4
Dependent Claim
17 words
A process according to claim 1 wherein the whiskers are made of Si 3 N 4 .
Claim 5
Dependent Claim
24 words
A process according to claim 1 wherein the magnesium in step (a) is heated to a temperature of from 400° C. to 500° C.
Claim 6
Dependent Claim
18 words
A process according to claim 1 wherein the magnesium coated whiskers are ignited in air in step (b).
Claim 7
Dependent Claim
27 words
A process according to claim 1 wherein the magnesium coated whiskers are ignited in an atmosphere containing from 20 to 100 percent of oxygen in step (b).
Claim 8
Dependent Claim
19 words
A process according to claim 1 wherein the magnesium coated whiskers are ignited in pure oxygen in step (b).
Claim 9
Dependent Claim
17 words
The process of claim 1 wherein the whiskers are from about 1 to 25 microns in length.
Claim 10
Dependent Claim
17 words
The process of claim 1 wherein the whiskers are from 10 to about 100 microns in length.
Claim 11
Dependent Claim
16 words
The process of claim 9 wherein the whiskers are from 10 to 25 microns in length.
Claim 12
Dependent Claim
16 words
The process of claim 1 wherein the whiskers are from 0.4 to 0.9 microns in diameter.
Claim 13
Dependent Claim
15 words
A magnesium oxide coated whisker which is produced according to the process of claim 1.
Claim 14
Dependent Claim
15 words
A magnesium oxide coated whisker which is produced according to the process of claim 2.
Claim 15
Dependent Claim
15 words
A magnesium oxide coated whisker which is produced according to the process of claim 3.
Claim 16
Dependent Claim
15 words
A magnesium oxide coated whisker which is produced according to the process of claim 8.
Claim 17
Dependent Claim
15 words
A magnesium oxide coated whisker which is produced according to the process of claim 9.
Claim 18
Dependent Claim
15 words
A magnesium oxide coated whisker which is produced according to the process of claim 10.
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) | 1989-02-10 | 1989-08-12 | 1990-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-02-10 | 1993-08-12 | 1994-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-02-10 | 1997-08-12 | 1998-02-11 | $7700.00 | Window Closed / Lapsed |