U.S. patent application number 11/339079 was filed with the patent office on 2007-07-26 for energetic thin-film initiator.
This patent application is currently assigned to Lockheed Martin Corporation. Invention is credited to Jon A. Amos, George D. Hugus, Edward W. Sheridan.
Application Number | 20070169862 11/339079 |
Document ID | / |
Family ID | 37909530 |
Filed Date | 2007-07-26 |
United States Patent
Application |
20070169862 |
Kind Code |
A1 |
Hugus; George D. ; et
al. |
July 26, 2007 |
Energetic thin-film initiator
Abstract
An energetic thin film initiator and a method of making same
comprising providing a plurality of thin film layers of fuel,
providing a plurality of thin film layers of oxidizer, at least one
interposed between two of the thin layers of fuel, and providing an
electrical input to the thin film layers that upon receipt of an
electrical pulse causes ignition of layers of fuel and
oxidizer.
Inventors: |
Hugus; George D.; (Chuluota,
FL) ; Sheridan; Edward W.; (Orlando, FL) ;
Amos; Jon A.; (Ocoee, FL) |
Correspondence
Address: |
PEACOCK MYERS, P.C.
201 THIRD STREET, N.W.
SUITE 1340
ALBUQUERQUE
NM
87102
US
|
Assignee: |
Lockheed Martin Corporation
Bethesda
MD
|
Family ID: |
37909530 |
Appl. No.: |
11/339079 |
Filed: |
January 24, 2006 |
Current U.S.
Class: |
149/14 ;
149/15 |
Current CPC
Class: |
F42B 3/11 20130101 |
Class at
Publication: |
149/014 ;
149/015 |
International
Class: |
C06B 45/12 20060101
C06B045/12 |
Claims
1. An energetic thin film initiator comprising: a plurality of thin
film layers of fuel; a plurality of thin film layers of oxidizer,
at least one interposed between two of said thin layers of fuel;
and an electrical input to the thin film layers that upon receipt
of an electrical pulse causes ignition of layers of fuel and
oxidizer.
2. The initiator of claim 1 wherein said electrical input comprises
a pair of conductive electrical leads.
3. The initiator of claim 1 additionally comprising a silicon wafer
substrate for said thin film layers.
4. The initiator of claim 1 wherein an electrical pulse of less
than or equal to approximately 2 watts causes ignition.
5. The initiator of claim 1 wherein a resultant temperature of said
ignition is at least approximately 4600 degrees F.
6. The initiator of claim 1 wherein said thin film layers are
tailored for one or more properties selected from the group
consisting of stored chemical energy content, maximum achievable
reaction temperature, maximum reaction rate, deposition thickness,
and required deposition area.
7. The initiator of claim 1 wherein said thin film layers have a
thickness of less than approximately 100 micrometers.
8. The initiator of claim 7 wherein said thin film layers have a
thickness of less than approximately 100 nanometers.
9. The initiator of claim 1 wherein said ignition primarily results
from free energy release associated with intermetallic
reactions.
10. The initiator of claim 1 wherein said ignition primarily
results from free energy release associated with
oxidation-reduction reactions.
11. A method of making an energetic thin film initiator, the method
comprising: providing a plurality of thin film layers of fuel;
providing a plurality of thin film layers of oxidizer, at least one
interposed between two of the thin layers of fuel; and providing an
electrical input to the thin film layers that upon receipt of an
electrical pulse causes ignition of layers of fuel and
oxidizer.
12. The method of claim 11 wherein the electrical input comprises a
pair of conductive electrical leads.
13. The method of claim 11 additionally comprising the step of
providing a silicon wafer substrate for the thin film layers.
14. The method of claim 11 wherein an electrical pulse of less than
or equal to approximately 2 watts causes ignition.
15. The method of claim 11 wherein a resultant temperature of the
ignition is at least approximately 4600 degrees F.
16. The method of claim 11 additionally comprising the step of
tailoring the thin film layers for one or more properties selected
from the group consisting of stored chemical energy content,
maximum achievable reaction temperature, maximum reaction rate,
deposition thickness, and required deposition area.
17. The method of claim 11 wherein the thin film layers have a
thickness of less than approximately 100 micrometers.
18. The method of claim 17 wherein the thin film layers have a
thickness of less than approximately 100 nanometers.
19. The method of claim 11 wherein the ignition primarily results
from free energy release associated with intermetallic
reactions.
20. The method of claim 11 wherein the ignition primarily results
from free energy release associated with oxidation-reduction
reactions.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable.
INCORPORATION BY REFERENCE OF MATERIAL SUBMITTED ON A COMPACT
DISC
[0003] Not Applicable.
COPYRIGHTED MATERIAL
[0004] Not Applicable.
BACKGROUND OF THE INVENTION
[0005] 1. Field of the Invention (Technical Field)
[0006] The present invention relates to energetic material
initiators.
[0007] 2. Description of Related Art
[0008] The initiation of an energetic material requires that a
stable and reliable fuze mechanism activate the chemical reaction
at a desired time. Fuzes are often used in conjunction with a safe
and arm mechanism. Electronic Safe and Arm Fuze (ESAF) designs are
increasingly being used due to their flexibility in state sensing,
response logic and use of electricity as the initiating power
source. The initiator is the component of the ESAF that converts
the electrical energy to a form that can initiate the energetic
material. The finished initiator package volume, the cost of
initiator fabrication, the repeatability of initiator fabrication,
and the required power to initiate an energetic chemical reaction
must be minimized while reliability, resistance to misfire, and
durability must be maximized for optimum service.
[0009] Electro-Explosive Devices (EEDs) typically incorporate hot
wire, semiconductor bridge, or exploding foil type initiators.
Existing types of EEDs involve resistance heating (and relatively
high power) to produce a high temperature used to trigger a fuze
chain or energetic material. Existing devices that employ thin
films include the following references.
[0010] J. M. Boyd, "Thin-Film Electric Initiator--Application Of
Explosives And Performance Tests", Defense Technical Information
Center Report No. HDL-TR-1414 (1969), discloses a thin film
deposited chemically that does not comprise a reactive material.
The film produces a high temperature when a relatively high
electrical current is applied across it.
[0011] U.S. Pat. No. 5,732,634, titled "Thin Film Bridge Initiators
and Method of Manufacture", to Flickinger, et al., discloses a
vapor deposited thin film that produces a high temperature when a
relatively high current is passed through it. Again, the film does
not comprise a reactive material.
[0012] U.S. Pat. No. 6,276,276, titled "Thin-Film Optical
Initiator", to Erickson, discloses a film used in conjunction with
an optical power input (laser). The laser heats a thin-film
material which produces a high temperature which then initiates an
output charge.
[0013] The use of the multilayered thin film Exploding Film
Initiator (EFI) of the invention provides a greater initial energy
output then a conventional EFI for an equivalent input energy and
can be tailored for initiation sensitivity and maximum achievable
temperature. Once initiated, relatively high temperatures can be
reached by the EFI through the release of chemically stored energy
upon reaction of the EFI component materials.
BRIEF SUMMARY OF THE INVENTION
[0014] The present invention is of an energetic thin film initiator
and a method of making same, comprising: providing a plurality of
thin film layers of fuel; providing a plurality of thin film layers
of oxidizer, at least one interposed between two of the thin layers
of fuel; and providing an electrical input to the thin film layers
that upon receipt of an electrical pulse causes ignition of layers
of fuel and oxidizer. In the preferred embodiment, the electrical
input comprises a pair of conductive electrical leads. A silicon
wafer substrate is preferred for the thin film layers. An
electrical pulse of less than or equal to approximately 2 watts
causes ignition. A resultant temperature of the ignition is
preferably at least approximately 4600 degrees F. The thin film
layers are tailored for one or more properties selected from stored
chemical energy content, maximum achievable reaction temperature,
maximum reaction rate, deposition thickness, and required
deposition area. The thin film layers have a thickness of less than
approximately 100 micrometers for appropriate applications and less
than approximately 100 nanometers for others. The ignition
primarily results from free energy release associated with
intermetallic reactions or from free energy release associated with
oxidation-reduction reactions.
[0015] Objects, advantages and novel features, and further scope of
applicability of the present invention will be set forth in part in
the detailed description to follow, taken in conjunction with the
accompanying drawings, and in part will become apparent to those
skilled in the art upon examination of the following, or may be
learned by practice of the invention. The objects and advantages of
the invention may be realized and attained by means of the
instrumentalities and combinations particularly pointed out in the
appended claims.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0016] The accompanying drawings, which are incorporated into and
form a part of the specification, illustrate one or more
embodiments of the present invention and, together with the
description, serve to explain the principles of the invention. The
drawings are only for the purpose of illustrating one or more
preferred embodiments of the invention and are not to be construed
as limiting the invention. In the drawings:
[0017] FIG. 1 is a schematic diagram of a first embodiment of the
invention; and
[0018] FIG. 2 is a schematic diagram of a second embodiment of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0019] The present invention relates to the production of an
electro-explosive device (EED) utilizing an exploding film
initiator (EFI). In particular this invention relates to the
production of an EED by the application of a multilayered thin-film
EFI. Using developed and highly repeatable batch processing
approaches involving thin-film deposition, an energetic structure
is fabricated by depositing layers of reactants onto a selected
substrate. The adjacent reactants form a repeating unit that is
duplicated multiple times during the thin-film deposition process
until sufficient quantity of material is accumulated on the
substrate to function as an energetic initiator. Among other
possible initiation methods, a pair of electrical leads can supply
a relatively low voltage to the thin-film structure resulting in
ohmic heating and reaction of the initiator. This reaction is rapid
and produces a high-temperature that, when placed in contact with a
fuze chain or another energetic material, results in the triggering
of another event. Relatively low power is required to produce
sufficient heat within the energetic material to release the
chemical energy within this type of initiator, and the fabrication
process can be fully automated to produce structures that have
consistent reaction properties. Thin film deposition processes
permit precise control over the deposited structure geometry in
such a way that the initiator can be tailored for a variety of
applications. Thin-film deposition processes also permit the
deposition of insulating structures to electrically, thermally, or
physically isolate the initiator from its surrounding
environment.
[0020] FIGS. 1-2 show the preferred embodiments 10,30 of the
invention, albeit not to scale. In FIG. 1, the energetic thin film
initiator of the invention comprises a pair of layers 16,18
preferably on substrate 12, one layer of which comprises fuel and
the other oxidizer. Electrical conductors 14,14' carry electrical
impulses. The initiator ignites secondary energetic material 20. In
FIG. 2, a plurality of pairs of layers of fuel/oxidizer are
employed.
[0021] For example, a thin-film initiator can be deposited on a
silicon wafer substrate. The substrate is in part used to
retain/protect thin-film initiator during handling. After
experiencing an electrical impulse (on the order of 2 watts or
less) or other sufficiently initiating stimulus, the deposited
material reaction begins. The resultant temperature of the
thin-film reaction might be, for example, about 4600 degrees F.;
but again, can be tailored by design the thin film deposition
thickness of the various layers and the selected deposition
materials.
[0022] The deposited materials are selected for tailored
performance regarding properties such as stored chemical energy
content, maximum achievable reaction temperature, and maximum
reaction rate, traded against deposition thickness and required
deposition area. Exothermic reaction of deposited materials result
from the free energy release associated with intermetallic
reactions, or from oxidation-reduction reactions. The selected
reactive materials are deposited such that reactants are positioned
in close proximity (nanometer (i.e., thin films of thickness less
than approximately 100 nanometers) or micrometer (i.e., thin films
of thickness less than approximately 100 micrometers) scale).
Repeated deposition of reactants in a layered structure increases
the stored energy content per unit area.
[0023] A great multitude of intermetallic reactants and
oxidation-reduction reactants are capable of producing energy once
initiated. For a partial review of these reactions and the energy
content (per unit mass, and volume), maximum adiabatic temperature
rise using thermodynamic approaches to analysis, refer to S. H.
Fischer and M. C. Grubelich, "A Survey of Combustible Metals,
Thermites, and Intermetallics for Pyrotechnic Applications,"
American Institute of Aeronautics and Astronautics Paper
AIM-96-3018 (1996).
[0024] To reiterate, the initiator of the invention produces high
thermal energy when a relatively low electrical input is applied to
the material releasing stored chemical energy. The device can be
fabricated using a variety of thin-film deposition techniques to
tailor the input (activation) requirements for initiation, and the
resultant output properties to suit the application. When an
electrical impulse is applied to the initiator material, it starts
a chemical reaction that releases stored chemical energy producing
a high temperature. This resultant high temperature is much greater
than the electrical impulse could have produced by itself.
[0025] Although the invention has been described in detail with
particular reference to these preferred embodiments, other
embodiments can achieve the same results. Variations and
modifications of the present invention will be obvious to those
skilled in the art and it is intended to cover in the appended
claims all such modifications and equivalents. The entire
disclosures of all references, applications, patents, and
publications cited above are hereby incorporated by reference.
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