US4461750A
Expired / Lapsed
US
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Infrared window materials and their fabrication
Assignee: United States Department of the Navy
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Filing: 1982-08-23
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Granted: 1984-07-24
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Expires: 2002-08-23
Abstract
Abstract Process for making densified ternary sulfide ceramics as infrared window materials using sulfide compounds MLn2S4 belonging to the Th3P4, CaFe2O4 and spinel structure types. These refractory sulfides show good sinterability especially when fired in flowing hydrogen sulfide, and they can be densified by a combination of hot-pressing and hot-isostatic pressing into ceramic pieces approaching their theoretical density with closed pores and which have good transmission characteristics in the infrared region.
Inventors
- 👤 Daniel L. Chess
- 👤 William B. White
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 17:41
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/547; C01; C01F; C01F17/00; C01F17/30; C01F17/38; C01P; C01P2006/00; C01P2006/10; C01P2006/32; C01P2006/33; C01P2006/60; Y; Y10; Y10S; Y10S501/00; Y10S501/90; Y10S501/904
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
56 words
Densified ternary alkaline earth-rare earth sulfides having relatively low porosity and density equal to the theoretical density thereof for infrared windows represented by a formula: MLn.sub.2 S.sub.4 wherein M, Ln and S are a member of the group consisting of Ba +2 , Sr +2 and Ca +2 , light lanthanide ion and sulfide ion respectively.
Claim 2
Dependent Claim
56 words
Densified ternary alkaline earth-rare earth sulfides having relatively low porosity and density equal to the theoretical density thereof for infrared windows represented by a formula: MLn.sub.2 S.sub.4 wherein M, Ln and S are a member of the group consisting of Ba +2 , Sr +2 and Ca +2 , light lanthanide ion and sulfide ion respectively.
Claim 3
Dependent Claim
18 words
The densified ternary sulfides of claim 1 wherein said sulfides exhibit cubic Th 3 P 4 like structure.
Claim 4
Dependent Claim
26 words
The densified ternary sulfides of claim 2 wherein said light lanthanide ion is a member of a group consisting of rare earths from La to Gd.
Claim 5
Dependent Claim
17 words
The densified ternary sulfides of claim 1 wherein CaLa 2 S 4 is a representative member thereof.
Claim 6
Dependent Claim
16 words
The densified ternary sulfides of claim 1 wherein SrLa 2 S 4 is another member thereof.
Claim 7
Dependent Claim
20 words
The densified ternary sulfides of claim 2 which have about 50% transmission of infrared radiation in the 8-14 micrometer region.
Claim 8
Dependent Claim
97 words
A process for densifying to the theoretical limit ternary alkaline earth-rare earth sulfides represented by MLn 2 S 4 , wherein M, Ln and S representing alkaline earth, light lanthanide and sulfide ions respectively, which includes the steps of: obtaining said ternary alkaline earth-rare earth sulfides by reacting carbonates of the alkaline earth elements with oxides of lanthanide elements in an atmosphere of flowing hydrogen sulfide; hot pressing said ternary alkaline earth-rare earth sulfides for densification thereof; and hot-isostatic pressing the densified ternary alkaline earth-rare earth sulfides resulting from said step of hot-pressing for further densification thereof.
Claim 9
Dependent Claim
97 words
A process for densifying to the theoretical limit ternary alkaline earth-rare earth sulfides represented by MLn 2 S 4 , wherein M, Ln and S representing alkaline earth, light lanthanide and sulfide ions respectively, which includes the steps of: obtaining said ternary alkaline earth-rare earth sulfides by reacting carbonates of the alkaline earth elements with oxides of lanthanide elements in an atmosphere of flowing hydrogen sulfide; hot pressing said ternary alkaline earth-rare earth sulfides for densification thereof; and hot-isostatic pressing the densified ternary alkaline earth-rare earth sulfides resulting from said step of hot-pressing for further densification thereof.
Claim 10
Dependent Claim
34 words
The process of claim 7 wherein the step of obtaining ternary alkaline earth-rare earth sulfides includes reacting carbonates of alkaline earth elements with hydroxides of lanthanide elements in an atmosphere of flowing hydrogen sulfide.
Claim 11
Dependent Claim
20 words
The process of claim 7 wherein the step of obtaining said ternary alkaline earth-rare earth sulfides includes grinding and milling.
Claim 12
Dependent Claim
24 words
The process of claim 8 wherein said step of hot pressing of said ternary sulfides is accomplished uniaxially by applying pressure along an axis.
Claim 13
Dependent Claim
23 words
The process of claim 9 wherein said step of isostatic-pressing of said ternary sulfides is accomplished in an atmosphere of an inert gas.
Claim 14
Dependent Claim
13 words
The process of claim 11 which involves using argon as said inert gas.
References Cited (Backward Citations)
FR2139620A2
Cited
JPS4955593A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-07-24 | 1988-01-23 | 1988-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-07-24 | 1992-01-23 | 1992-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-07-24 | 1996-01-23 | 1996-07-24 | $7700.00 | Window Closed / Lapsed |