US3793920A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for making a conductive-mix electrical initiator
Assignee: ETI EXPLOSIVES TECHNOLOGIES INTE
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Filing: 1972-11-16
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Granted: 1974-02-26
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Expires: 1992-11-16
Abstract
Abstract A conductive-mix electrical initiator is made more energysensitive by applying to at least one electrode surface therein which is to be adjacent the conductive ignition charge, e.g., the end surface of the electrode seated within the initiator body, a coating which increases the resistance of the initiator. Preferably, the coating is applied by chemical or electrochemical conversion coating of the surface, e.g., by acid chromate treatment or a light anodic oxidation.
Inventors
- 👤 C Sheran
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 20:57
CPC Classifications
F; F42; F42B; F42B3/00; F42B3/10; F42B3/14
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
82 words
A method of claim 1 wherein the composition and thickness of said coating are such that the resistance of the conductive path from one of said electrodes to the other through said electrically conductive explosive charge is within the range of about from 0.4 to 110 ohms when measured at 10 milliamperes of test current with a conductive charge comprising 70 percent by weight of lead azide and 30 percent by weight of silver within one hour of contact with the coating.
Claim 2
Dependent Claim
16 words
A method of claim 1 wherein said coating is about from 0.00002 to 0.0001 inch thick.
Claim 3
Dependent Claim
154 words
In a method of making a conductive-mix electrical initiator wherein a solid metal body is seated within the mouth of a metal shell in a manner such that one end surface thereof is exposed and the other end surface thereof is within said shell adjacent an electrically conductive explosive charge comprising a mixture of a finely divided heat-sensitive explosive and a finely divided electrically conductive material, said explosive charge being adjacent the inner wall of said shell, and adjacent surfaces of said metal body and said metal shell being electrically insulated from one another, the improvement which comprises applying to at least one of the metal surfaces which is to be positioned adjacent said explosive charge a coating which is less electrically conductive than said solid metal body, said shell, and said conductive material in said explosive charge, and thereafter bringing the intact coating on said metal surface into contact with said explosive charge.
Claim 4
Dependent Claim
19 words
A method of claim 4 wherein said coating is applied to the end surface of said solid metal body.
Claim 5
Dependent Claim
17 words
A method of claim 4 wherein said coating is applied to the inner wall of said shell.
Claim 6
Dependent Claim
18 words
A method of claim 5 wherein said end surface to which said coating is applied is substantially flat.
Claim 7
Dependent Claim
48 words
A method of claim 1 wherein said electrically conductive explosive charge is comprised of about from 45 to 90 percent by weight of a metallic azide and 55 to 10 percent by weight of a conductive material selected from the group consisting of the noble metals and carbon.
Claim 8
Dependent Claim
22 words
A method of claim 8 wherein said electrically conductive explosive charge is in a continuous reaction train with a secondary high explosive.
Claim 9
Dependent Claim
11 words
A method of claim 8 wherein said conductive material is silver.
Claim 10
Dependent Claim
15 words
A method of claim 2 wherein said coating is applied by a conversion coating process.
Claim 11
Dependent Claim
37 words
A method of claim 11 wherein said electrode is made of aluminum and said coating is applied by treatment of said electrode surface with a solution containing a source of hexavalent chromium and a source of fluoride.
Claim 12
Dependent Claim
29 words
A method of claim 5 wherein said solid metal body is made of aluminum and said coating is applied by anodic oxidation of the end surface of said body.
Claim 13
Dependent Claim
200 words
In a method of making a conductive-mix electrical initiator wherein a solid metal body is seated within the mouth of a metal shell in a manner such that one end surface thereof is exposed and the other end surface thereof is witin said shell adjacent an electrically conductive explosive charge comprising a mixture of finely divided heat-sensitive explosive and a finely divided electrically conductive material, said explosive charge being adjacent the inner wall of said shell, and adjacent surfaces of said cylindrical body and said shell being electrically insulated from one another, the improvement which comprises employing a conductive explosive charge comprising 45 to 90 percent by weight of lead azide and 55 to 10 percent by weight silver and applying to at least one of the metal surfaces which is to be positioned adjacent said explosive charge a coating which is less electrically conductive than said solid metal body, said shell, and silver, and thereafter bringing the intact coating on said metal surface into contact with said explosive charge, said charge having been prepared bY contacting a silver nitrate with an aqueous suspension of finely divided lead azide and magnesium powder, whereby silver is precipitated, and separating the solids.
Claim 14
Dependent Claim
24 words
A method of claim 14 wherein said coating is applied to the end surface of said solid metal body by a conversion coating process.
References Cited (Backward Citations)
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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) | 1977-02-25 | 1977-08-27 | 1978-02-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-25 | 1981-08-27 | 1982-02-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-25 | 1985-08-27 | 1986-02-26 | $7700.00 | Window Closed / Lapsed |