Reactive composite material structures with electrostatic discharge protection and applications thereof
Applicants have discovered that electrostatic discharge (ESD) may, in some circumstances, result in current densities sufficient to ignite unprotected reactive composite materials. They have further discovered that a reactive composite material (RCM) can be protected from ESD ignition without adversely affecting the desirable properties of the RCM by the application of conducting and/or insulating materials at appropriate locations on the RCM. Thus ESD-protected RCM structures can be designed for such sensitive applications as ignition of propellants, generation of light bursts, and structural materials for equipment that may require controlled self-destruction.
1. A body of nano-structured reactive composite material subject to ignition by a self-propagating exothermic chemical reaction, having one or more edges, surfaces, or corners protected against unwanted electrical ignition by at least one applied layer of electrically insulating material, electrically conducting material, or a combination of electrically insulating material and electrically conducting material.
2. The body of reactive composite material of claim 1 wherein the at least one layer is chosen and configured to provide an alternative path to electrostatic discharge current that does not pass through the body.
3. The body of reactive composite material of claim 1 wherein the at least one layer is chosen and configured to reduce the electrostatic discharge current density in the body.
4. The body of reactive composite material of claim 1 wherein the at least one layer is chosen and configured to increase the threshold for electrostatic discharge arcing.
5. The body of reactive composite material of claim 1 wherein the at least one layer comprises a conducting layer having a thickness greater than about one micrometer.
6. The body of reactive composite material of claim 1 wherein the at least one layer comprises a layer of insulating material.
7. The body of claim 6 wherein the layer of insulating material overlies at least one surface of the body.
8. The body of claim 6 wherein the layer of insulating material overlies at least one edge of the body.
9. The body of claim 6 wherein the layer of insulating material overlies at least one corner of the body.
10. The body of claim 6 wherein the layer of insulating material overlies at least one surface and at least one edge of the body.
11. The body of claim 6 wherein the layer of insulating material overlies at least one surface, at least one edge and at least one corner of the body.
12. The body of claim 6 wherein the layer of insulating material overlies substantially the entire body.
13. The body of reactive composite material of claim 1 wherein the at least one layer comprises conducting material.
14. The body of claim 13 wherein the conducting layer overlies at least one surface of the body.
15. The body of claim 13 wherein the conducting layer overlies at least one edge of the body.
16. The body of claim 13 wherein the conducting layer overlies at least one surface and at least one edge of the body.
17. The body of claim 13 wherein the conducting layer overlies at least one corner of the body.
18. The body of claim 13 wherein the conducting layer overlies at least one surface, at least one edge and at least one corner of the body.
19. The body of claim 13 wherein the body with the conducting layer exhibits the degree of electrostatic discharge protection designated class 3B using the Human Body Model specified in ANSI-STM5.1-2001.
20. The body of claim 13 wherein the conducting layer overlies substantially the entire body.
21. The body of claim 13 wherein the conducting layer is flammable in air.
22. The body of reactive composite material of claim 1 wherein the at least one layer comprises a combination of insulating material and conducting material.
23. The body of claim 22 wherein the combination layer overlies at least one surface of the body.
24. The body of claim 22 wherein the combination layer overlies at least one edge of the body.
25. The body of claim 22 wherein the combination layer overlies at least one surface and one edge of the body.
26. The body of claim 22 wherein the combination layer overlies at least one corner of the body.
27. The body of claim 22 wherein the combination layer overlies at least one surface, one edge and one corner of the body.
28. The body of claim 22 wherein the combination layer overlies substantially the entire body.
29. The body of reactive composite material of claim 1 wherein the at least one layer comprises an insulating ceramic or polymer.
30. The body of reactive composite material of claim 1 wherein the at least one layer comprises a ceramic selected from the group consisting of oxides, nitrides, carbides, and insulating ceramics.
31. The body of reactive composite material of claim 1 wherein the at least one layer comprises anodized aluminum oxide.
32. The body of reactive composite material of claim 1 wherein the at least one layer comprises an insulating polymer selected from the group consisting of polyethylene terephthalate, polytetrafluoroethylene, polyethylene naphthalate, insulating epoxy, insulating anti-static coatings, and polymer tape.
33. The body of reactive composite material of claim 1 wherein the at least one layer comprises a metal foil or tape.
34. The body of reactive composite material of claim 1 wherein the at least one layer comprises a sputtered metal layer greater than 1 μm thick.
35. A method of protecting from unwanted ignition a body of nano-structured reactive composite material subject to ignition comprising the steps of:
providing a body of nano-structured reactive composite material comprising two or more solid materials with large negative heats of mixing which are spaced throughout a composite and which are ignitable to support self-propagating exothermic chemical reactions, having one or more edges, surfaces and corners; and
disposing on one or more of the edges, surfaces or corners at least one layer of electrically insulating material, electrically conducting material or a combination of electrically insulating material and electrically conducting material.
36. The method of claim 35 wherein the at least one layer comprises a layer of insulating material.
37. The method of claim 35 wherein the at least one layer comprises a layer of conducting material.
38. The method of claim 35 wherein the at least one layer comprises a composite layer of conducting material and insulating material.
39. The method of claim 35 wherein the at least one layer is disposed on the body by a method selected from the group consisting of vapor deposition, sputtering, thermal oxidation, chemical oxidation, chemical reaction, electrochemical oxidation and electrochemical deposition.
40. The method of claim 35 wherein the at least one layer is disposed on the body by a method selected from the group consisting of cladding, pressing, spraying or painting.