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US4720362A
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Transparent aluminum oxynitride and method of manufacture
Assignee: Surmet Corp
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Filing: 1985-03-20
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Granted: 1988-01-19
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Expires: 2005-03-20
Abstract
Abstract An article of manufacture is provided comprising a polycrystalline cubic aluminum oxynitride having a density of at least 98% of theoretical density, and being transparent to electromagnetic radiation in the wavelength range from 0.3 to 5 micrometers with an in-line transmission of at least 20% in this range. A method of preparing the optically transparent aluminum oxynitride is also provided comprising the steps of forming a green body of substantially homogeneous aluminum oxynitride powder and pressureless sintering said green body in a nitrogen atmosphere and in the presence of predetermined additives which enhance the sintering process. Preferred additives are boron and yttrium in elemental or compound form.
Inventors
- 👤 Richard L. Gentilman
- 👤 Edward A. Maguire
- 👤 Leonard E. Dolhert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 14:28
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/581; Y; Y10; Y10S; Y10S501/00; Y10S501/90; Y10S501/904
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
41 words
A method of manufacturing a dense aluminum oxynitride body comprising the steps of: forming a single phase aluminum oxynitride powder; pressing said powder into a green body of predetermined shape; and sintering said green aluminum oxynitride body in a nitrogen atmosphere.
Claim 2
Independent Claim
41 words
A method of manufacturing a dense aluminum oxynitride body comprising the steps of: forming a single phase aluminum oxynitride powder; pressing said powder into a green body of predetermined shape; and sintering said green aluminum oxynitride body in a nitrogen atmosphere.
Claim 3
Dependent Claim
19 words
The method of claim 1 wherein: said sintering step takes place in the presence of a plurality of dopants.
Claim 4
Dependent Claim
39 words
The method of claim 2 wherein: said sintering step is carried out at a temperature and for a length of time sufficient to eliminate porosity by diffusion of said solid single phase aluminum oxynitride while preventing excessive grain growth.
Claim 5
Independent Claim
45 words
A method of manufacturing a substantially transparent aluminum oxynitride body comprising the steps of: forming a homogeneous single phase aluminum oxynitride powder; pressing said powder into a green body of predetermined shape; and sintering in a nitrogen atmosphere said body in the presence of dopants.
Claim 6
Independent Claim
45 words
A method of manufacturing a substantially transparent aluminum oxynitride body comprising the steps of: forming a homogeneous single phase aluminum oxynitride powder; pressing said powder into a green body of predetermined shape; and sintering in a nitrogen atmosphere said body in the presence of dopants.
Claim 7
Dependent Claim
39 words
The method of claim 4 wherein: said sintering step is carried out at a temperature and for a length of time sufficient to eliminate porosity by diffusion of said solid single phase aluminum oxynitride while preventing excessive grain growth.
Claim 8
Dependent Claim
21 words
The method of claim 4 wherein: said single phase aluminum oxynitride powder has an average particle size smaller than 1.0 microns.
Claim 9
Dependent Claim
64 words
The method of claim 4 wherein said aluminum oxynitride forming step comprises the steps of: preparing an homogeneous mixture of aluminum nitride and aluminum oxide, said aluminum oxide forming 63 to 70 mole percent of said mixture; calcining said mixture until substantially changed to single phase aluminum oxynitride powder; and reducing said aluminum oxynitride powder to an average particle size less than 1.0 microns.
Claim 10
Dependent Claim
55 words
The method of claim 7 wherein: said homogeneous mixture preparing step comprises admixing aluminum nitride and aluminum oxide powders having a purity of at least 97% and 99%, respectively, and a particle size smaller than 74 microns, and ball milling the mixture until fully mixed with an average particle size reduced to approximately 1.0 microns.
Claim 11
Dependent Claim
29 words
The method of claim 7 further comprising the step of: adding yttrium oxide to the mixture of aluminum nitride and aluminum oxide in amounts up to 0.5 weight percent.
Claim 12
Dependent Claim
37 words
The method of claim 4 wherein: said sintering step is at a temperature higher than 1900° C. but lower than the solidus temperature of aluminum oxynitride and for a period of time of at least 20 hours.
Claim 13
Dependent Claim
15 words
The method of claim 4 wherein: said dopants comprise yttrium and boron or compounds thereof.
Claim 14
Dependent Claim
17 words
The method of claim 4 wherein: said dopants are present in the sintered body in trace amounts.
Claim 15
Dependent Claim
20 words
The method of claim 11 wherein: said dopants are in a vapor phase during a portion of said sintering step.
Claim 16
Dependent Claim
20 words
The method of claim 13 wherein: in said sintering step, the dopant vapor transport to and diffuse throughout said body.
Claim 17
Dependent Claim
19 words
The method of claim 14 wherein: said sintered body comprises not more than 0.5 weight percent of said dopants.
Claim 18
Dependent Claim
19 words
The method of claim 14 wherein: said dopants produce a liquid phase at grain boundaries during said sintering step.
Claim 19
Independent Claim
87 words
The method of manufacturing a substantially transparent aluminum oxynitride body comprising the steps of: forming a substantially homogeneous single phase aluminum oxynitride powder having an average particle size not greater than 1.0 microns; forming a green body of predetermined shape from said single phase powder; and sintering said body in the presence of yttrium and boron dopants and in a nitrogen atmosphere at a temperature and for a length of time sufficient to achieve substantial densification of said aluminum oxynitride body while in its solid single phase.
Claim 20
Independent Claim
87 words
The method of manufacturing a substantially transparent aluminum oxynitride body comprising the steps of: forming a substantially homogeneous single phase aluminum oxynitride powder having an average particle size not greater than 1.0 microns; forming a green body of predetermined shape from said single phase powder; and sintering said body in the presence of yttrium and boron dopants and in a nitrogen atmosphere at a temperature and for a length of time sufficient to achieve substantial densification of said aluminum oxynitride body while in its solid single phase.
Claim 21
Dependent Claim
17 words
The method of claim 17 wherein: said dopants are present in said sintered body in trace amounts.
Claim 22
Dependent Claim
25 words
The method of claim 17 wherein: said dopants are present in the sintered body in amounts less than 0.5 weight percent of said green body.
Claim 23
Dependent Claim
6 words
The method of claim 17 wherein:
Claim 24
Dependent Claim
32 words
said sintering is done at a temperature in the range from 1900° C. to the solidus temperature of aluminum oxynitride, and for a duration in the range of 20 to 100 hours.
Claim 25
Dependent Claim
32 words
said sintering is done at a temperature in the range from 1900° C. to the solidus temperature of aluminum oxynitride, and for a duration in the range of 20 to 100 hours.
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) | 1991-01-18 | 1991-07-20 | 1992-01-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-01-18 | 1995-07-20 | 1996-01-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-01-18 | 1999-07-20 | 2000-01-19 | $7700.00 | Window Closed / Lapsed |