Low temperature autoignition composition

• US 6,749,702 B1
• Filed: 01/22/1998
• Issued: 06/15/2004
• Est. Priority Date: 05/14/1996
• Status: Expired due to Fees

• Current Assignee: Nammo Talley, Inc. (Nammo AS)
• Original Assignee: Nammo Talley, Inc. (Nammo AS)
• Inventors: Ludwig, Christopher P., Knowlton, Gregory D.
• Primary Examiner(s): FELTON, AILEEN BAKER
• Application Number:
  US09/010,822
• Time in Patent Office: 2,336 Days
• Field of Search: 102/205, 149/37, 149/38, 149/43, 149/45, 149/41, 149/40
• US Class Current: 149/38
• CPC Class Codes: C06B 33/00 Compositions containing particulate metal, alloy, boron, silicon, selenium or tellurium with at least one oxygen supplying material which is either a metal oxide or a salt, organic or inorganic, capable of yielding a metal oxide
• CPC Class Codes: C06C 9/00 Chemical contact igniters; Chemical lighters

Abstract

The present invention relates to a low temperature autoignition composition for safely initiating combustion of a main pyrotechnic charge in a gas generator or pyrotechnic device exposed to flame or a high temperature environment. The low temperature autoignition compositions of the invention include a mixture of an oxidizer and a powdered metal, wherein the oxidizer includes silver nitrate or a comelt or mixture comprising silver nitrate and at least one of an alkali metal nitrate, an alkaline earth metal nitrate, a complex salt nitrate, a dried, hydrated nitrate, an alkali metal chlorate, an alkali metal perchlorate, an alkaline earth metal chlorate, an alkaline earth metal perchlorate, ammonium perchlorate, sodium nitrite, potassium nitrite, silver nitrite, a complex salt nitrite, a solid organic nitrate, a solid organic nitrite, or a solid organic amine, and where the metal fuel and oxidizer are present in amounts sufficient to provide an autoignition composition having an autoignition temperature of no more than about 232° C. The present invention also relates to a method for initiating a gas generator or pyrotechnic composition in a gas generator or pyrotechnic device exposed to flame or a high temperature environment. In the method of the invention, the gas generator or pyrotechnic composition is placed in thermal contact with a low temperature autoignition composition of the invention.

Claims

1. A low temperature autoignition composition for safely initiating combustion of a main pyrotechnic charge in a gas generator or pyrotechnic device exposed to flame or a high temperature environment, consisting essentially of:

a mixture of a silver nitrate oxidizer composition and a powdered metal fuel, the silver nitrate oxidizer composition consisting essentially of one of;

(a) silver nitrate;

or

(b) a comelt or mixture consisting essentially of silver nitrate and at least one additional component selected from the group consisting of an alkali metal nitrate, an alkaline earth metal nitrate, a complex salt nitrate, a dried hydrated nitrate, an alkali metal chlorate, an alkali metal perchlorate, an alkaline earth metal chlorate, an alkaline earth metal perchlorate, ammonium perchlorate, sodium nitrite, potassium nitrite, silver nitrite, a complex salt nitrite, a solid organic nitrate, and a solid organic nitrite;

wherein

the powdered metal fuel is selected from the group consisting of molybdenum, calcium, strontium, barium, titanium, zirconium, vanadium, niobium, tantalum, chromium, tungsten, manganese, iron, cobalt, nickel, copper, zinc, cadmium, tin, antimony, bismuth, aluminum, silicon, and mixtures thereof;

the silver nitrate oxidizer composition has at least one of a crystalline phase transition, a melting point, a eutectic point, or a peritectic point at a temperature of no more than about 250°

C.;

the metal fuel is present in an amount at least substantially stoichiometric relative to the silver nitrate oxidizer composition; and

the mixture of metal fuel and silver nitrate oxidizer composition has a mix intimacy and homogeneity sufficient between the silver nitrate oxidizer composition and the metal fuel to react in an autoignition reaction of metal fuel and silver nitrate oxidizer composition at an autoignition temperature of no more than about 232°

C., thereby providing an autoignition composition having the autoignition temperature of no more than about 232°

C.;

wherein

heating the autoignition composition to the autoignition temperature results in a reaction between the silver nitrate and the metal fuel, thereby initiating the autoignition reaction.

2. The low temperature autoignition composition of claim 1, wherein the silver nitrate oxidizer composition is a comelt consisting essentially of silver nitrate and at least one of an alkali metal nitrate, alkali metal nitrite, alkali metal chlorate, alkali metal perchlorate, alkaline metal nitrate, alkaline metal nitrite, alkaline metal chlorate, alkaline metal perchlorate, sodium nitrite, potassium nitrite, or silver nitrite.

3. The low temperature autoignition composition of claim 2, wherein the powdered metal fuel is selected from the group consisting of molybdenum, titanium, zirconium, niobium, nickel, chromium, zinc, aluminum, and cerium.

4. The low temperature autoignition composition of claim 3, wherein the powdered metal fuel is selected from the group consisting of molybdenum, titanium, zirconium, zinc, and cerium.

5. The low temperature autoignition composition of claim 4, wherein the powdered metal fuel is molybdenum.

6. The low temperature autoignition composition of claim 4, wherein the silver nitrate oxidizer composition is selected from the group consisting of silver nitrate and comelts consisting essentially of silver nitrate and potassium nitrate, silver nitrate and sodium nitrate, and silver nitrate and lithium nitrate.

7. The low temperature autoignition composition of claim 4, wherein the silver nitrate oxidizer composition is a comelt consisting essentially of silver nitrate and potassium nitrate.

8. The low temperature autoignition composition of claim 6, wherein the powdered metal fuel is molybdenum.

9. The low temperature autoignition composition of claim 8, wherein the comelt is ground to a particle size of about 10 to about 30 microns, and the molybdenum powder has a particle size of less than about 6 microns.

10. The low temperature autoignition composition of claim 6, wherein

the mole fraction of silver nitrate in the comelt is about 0.4 to about 0.6;

the mole fraction of potassium nitrate in the comelt is about 0.6 to 0.4; and

the comelt is mixed with at least a stoichiometric amount of molybdenum powder fuel.

11. The low temperature autoignition composition of claim 10, wherein the autoignition temperature is about 130-135°

C.

12. The low temperature autoignition composition of claim 1, wherein the silver nitrate oxidizer composition consists essentially of a mixture of silver nitrate and a solid organic nitrate or a solid organic nitrite.

13. The low temperature autoignition composition of claim 12, wherein the silver nitrate oxidizer composition consists essentially of a mixture of silver nitrate and guanidine nitrate.

14. The low temperature autoignition composition of claim 12, wherein the powdered metal fuel is selected from the group consisting of molybdenum, titanium, zirconium, niobium, nickel, chromium, zinc, aluminum, and cerium.

15. The low temperature autoignition composition of claim 12, wherein the powdered metal fuel is selected fuel from the group consisting of molybdenum, titanium, zirconium, zinc, and cerium.

16. The low temperature autoignition composition of claim 12, wherein the powdered metal fuel is molybdenum.

17. The low temperature autoignition composition of claim 16, wherein the molybdenum fuel is present in an amount greater than that required to form a mixture in which the amount of molybdenum fuel is stoichiometric relative to the silver nitrate oxidizer composition, thereby providing an autoignition composition having an autoignition temperature that is less than the autoignition temperature of a similar composition in which the amount of molybdenum fuel is stoichiometric relative to the silver nitrate oxidizer composition.

18. The low temperature autoignition composition of claim 1, further consisting essentially of an alkali metal chloride, alkali metal fluoride, alkali metal bromide, alkaline earth metal chloride, alkaline earth metal fluoride, or alkaline earth metal bromide.

19. The low temperature autoignition composition of claim 1, further consisting essentially of an output augmenting composition, consisting essentially of a metal in combination with an energetic oxidizer selected from the group consisting of ammonium perchlorate, alkali metal chlorates, alkali metal perchlorates, and alkali metal nitrates.

20. The low temperature autoignition composition of claim 1, wherein the silver nitrate oxidizer composition consists essentially of silver nitrate and a complex salt nitrate of at least one of Ce(NH₄)₂(NO₃)₆ and ZrO(NO₃)₂.

21. The low temperature autoignition composition of claim 1, wherein the silver nitrate oxidizer composition consists essentially of silver nitrate and a dried hydrated metal nitrate of Ca(NO₃)₂·

4H₂O or Cu(NO₃)₂·

2.5H₂O.

22. The low temperature autoignition composition of claim 1, further consisting essentially of a metal oxide catalyst.

23. The low temperature autoignition composition of claim 22, wherein the metal oxide catalyst is selected from the group consisting of Al₂O₃, SiO₂, CeO₂, V₂O₅, CrO₃, Cr₂O₃, MnO₂, Fe₂O₃, CO₃O₄, NiO, CuO, ZnO, ZrO₂, Nb₂O₅, MoO₃, and Ag₂O.

24. The low temperature autoignition composition of claim 1, wherein the fuel consists essentially of molybdenum and the silver nitrate oxidizer composition consists essentially of a mixture of silver nitrate, potassium nitrate, and guanidine nitrate.

29. The low temperature autoignition composition of claim 1, further consisting essentially of a solid organic amine.

30. The low temperature autoignition composition of claim 12, further consisting essentially of a solid organic amine.

25. A low temperature autoignition composition for safely initiating combustion of a main pyrotechnic charge in a gas generator or pyrotechnic device exposed to flame or a high temperature environment comprising:

a mixture of a silver nitrate oxidizer composition and a powdered metal fuel;

wherein

the silver nitrate oxidizer composition comprises a mixture or a comelt comprising silver nitrate and at least one additional component selected from the group consisting of an alkali metal nitrate, an alkaline earth metal nitrate, a complex salt nitrate, a dried hydrated nitrate, silver nitrate, an alkali metal chlorate, an alkali metal perchlorate, an alkaline earth metal chlorate, an alkaline earth metal perchlorate, ammonium perchlorate, sodium nitrite, potassium nitrite, silver nitrite, a complex salt nitrite, a solid organic nitrate, and a solid organic nitrite;

the metal fuel is present in an amount at least substantially stoichiometric relative to the silver nitrate oxidizer composition; and

the mixture of metal fuel and silver nitrate oxidizer composition has a mix intimacy and homogeneity sufficient in the composition between the silver nitrate oxidizer composition and the metal fuel to react in an autoignition reaction of metal fuel and silver nitrate oxidizer composition at an autoignition temperature of no more than about 232°

C., thereby providing an autoignition composition having the autoignition temperature of no more than about 232°

C.;

wherein

heating the autoignition composition to the autoignition temperature results in a reaction between silver nitrate and the metal fuel, thereby initiating the autoignition reaction.

26. The low temperature autoignition composition of claim 25, wherein the metal fuel is present in an amount sufficient to form a fuel rich composition, thereby providing an autoignition composition having an autoignition temperature that is less than the autoignition temperature of a similar composition having a stoichiometric amount of metal fuel.

27. The low temperature autoignition composition of claim 26, wherein the powdered metal fuel is chosen form the group consisting of molybdenum, magnesium, calcium, strontium, barium, titanium, zirconium, vanadium, niobium, tantalum, chromium, tungsten, manganese, iron, cobalt, nickel, copper, zinc, cadmium, tin, antimony, bismuth, aluminum, and silicon.

28. The low temperature autoignition composition of claim 26, wherein the fuel comprises molybdenum and the silver nitrate oxidizer composition comprises silver nitrate, potassium nitrate, and guanidine nitrate.

31. The low temperature autoignition composition of claim 25, further comprising a solid organic amine.