US 3122462 A
Description (OCR text may contain errors)
as we 3,122,462 NOVEL PYROTECHNICS Martin H. Kaufman, 411-A Nimitz, China Lake, Calif.,
(Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
The present invention relates to novel pyrotechnics, and more particularly a pyrotechnic composition utiliz ing safe-to-handle azides.
In the field of pyrotechnics two criteria, rate of reaction and energy liberated per unit weight or volume, are generally of great importance in devising new pyro technics. Although many elements are and have been used as essential ingredients of various pyrotechnics, the use of many reactive elements such as lithium, sodium, potassium, rubidium and cesium has been severly limited because their reactivities are often too great. The present invention is for novel pyrotechnics the composition of which will provide reactive species.
The general purpose of this invention is to provide a pyrotechnic composition which has improved intensity, burning rate, color value and efficiency in light production. Also because pyrotechnic compositions are low explosives and must withstand loading operations, handling, and storage, other important characteristics which this invention provides are insensitivity to static, low impact and friction sensitivity, igniti bility, stability, and low hygroscopicity.
An object of the present invention is the provision of a pyrotechnic composition which has low sensitivity to impact and is therefore safe to prepare and handle.
Another object is to provide a pyrotechnic composition which may be used at high altitude, e.g., as an igniter or flare.
A further object of the invention'is the provision of a pyrotechnic composition which will produce hot metallic compounds that react easily with oxygen or a halogen.
Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description.
The initial work which led to the present invention was done with purified sodium azide (NaN and potassium azide (KN intimately mixed with various elements including silicon, boron, aluminum, titanium, zirconium, magnesium. All ignited when touched with a hot wire. Silicon mixtures were found to ignite easily and the reaction sustained itself to apparent completion. Aluminum and sodium azide mixtures, containing as low as 5% sodium azide ignited easier than aluminum alone and the burning sustained itself. The reaction continued at a faster rate than that of aluminum powder alone. As increasing quantities of sodium azide were incorporated, faster ignition and reaction rates were realized. To test the action in the presence of a minimum of air, a mixture of fine aluminum powder and sodium azide in the ratio of 81 to 65 was packed in an open end cardboard tube 3,122,462 Patented Feb. 25, 1964 Similar reactions may be postulated for other elements. Substituting boron for aluminum in reaction (1) 186 kcal. would be produced or 1.9 kcaL/ gram compared with 1.2 kcal./ gram for aluminum.
As a result of this work it was found feasible to prepare mixtures which when ignited, would produce alkali metal vapors simply by using an excess of alkali azide, e.g., lithium, sodium or potassium azides, and that it was possible to produce an atmosphere of hot oxygen simply by adding to the mixture an excess of oxygen in the form ofa solid oxygen containing oxidizer which decomposes easily at the temperatures reached by these reactions. Oxidizers other than the oxygen containing variety may be incorporated, e.g., halogen containing materials. The oxygen oxidizer or halogen oxidizer may be part of a polymer or plastic material like Kel-F or Teflon, polyvinylidine fluoride, or copolymer of vinylidine fluoride and perfluoropropylene or other halogen containing polymers. Polymers containing oxidizer groups such as polynitroethylene may be used. Examples of typical pyrotechnic formulations of those investigated are as follows:
Example 1 Percent Aluminum (Al) 49.9 Sodium azide (NaN 40.0 Potassium permanganate (KMnO 10.1
This mixture showed fast ignition withhot wire.
Example ll Boron (B) 29.9 Potassium azide (KN 60.1 Potassium permanganate (KMnO 10.0
This mixture showed rapid ignition.
Example Ill Zirconium (Zr) 68.5 Sodium azide.(NaN 16.4 Potassium permanganate (KMnO 15.1
This mixture exhibited rapid ignition.
Example IV Boron (B) 63.75 Sodium azide (NaN 21.25 Barium nitrate [Ba(NO 15.00
, This mixture exhibited very rapid ignition.
Example V Boron (B) 71.25 Sodium azide (NaN 23.75 Potassium perchlorate (KClO 5.0
This mixture exhibited very rapid ignition.
Example VI This mixture was almost immediately explosive.
Example VIII Silicon (Si) 45 Sodium azide (NaN 45 Barium nitrate [Ba(NO This mixture is difficult to sustain burning.
Example IX Magnesium (Mg) 45 Potassium azide (KN 45 Potassium perchlorate (KCIO 10 This mixture is difficult to sustain burning.
Example X Boron (B) 32 Sodium azide (NaN 58 Potassium nitrate (KNO 10 This mixture is fast burning.
Example XI Aluminum (Al) 45 Sodium azide (NaN 45 Potassium perchlorate (KCIO 10 This mixture is fast burning. Examples I-XI were tested at an initial pressure of 705 mm. Hg and at ambient temperatures.
Example XII Boron (B) 27 Potassium perchlorate (KClO 10.1 Sodium azide (NaN 54.9 Binder (Viton A) 8 Example XIII Boron (B) 28.7 Potassium perchlorate (KClO 10.7 Potassium azide (KN 57.3 Binder (Kel-F elastomer) 3.3
Example XIV Boron (B) 19.0 Potassium perchlorate 6.9 Sodium azide (NaN 56.1 Kel-F (powder) 12.5 Binder (Fluorel) 5.5
Example XV Magnesium (Mg) 9.6 Sodium azide (NaN 48.0 Kel-F (powder) 38.5 Binder (Kel-F elastomer) 3.9
Example XVI Aluminum (Al) 38.4 Sodium azide (NaN 38.4 Kel-F (powder) 19.2 Binder (Viton A) 4.0
Example XVII Boron (B) 38 Potassium azide (KN 38 Teflon powder 24 It is postulated that the above reaction may be illustrated by the following equation:
4 Example XVIII Percent Aluminum (Al) 38.4 Sodium azide (NaN 38.4 Binder (fluorocarbon) 23.2 Example XIX Boron (B) 26.5 Sodium azide (NaN 53.1 Teflon (powder) 20.4 Example XX Zirconium (Zr) 75.1 Sodium azide (NaN 18.0 Viton 6.9 Example XXI Aluminum (Al) 47.4 Sodium azide (NaN 38.0 Teflon 100 9.0 Kel-F wax 5.6
In Examples XII through XXI a number of fluorocarbons were used. Among those found satisfactory were Viton A and AHV, Kel-F wax, Kel-F elastomer, Fluorel, Teflon, and Teflon 100.
Viton is the tradename for a rubbery copolymer of vinylidene fluoride and perfluoropropylene. Fluorel is asimilar copolymer of perfluoropropylene and vinylidene fluoride. Teflon is the tradename for a homopolymer of tetrafluoroethylene and the same as polytetrafluoroethylene, while Teflon 100 is a copolymer of tetrafluoroethylene and perfluoropropylene. Kel-F wax is a homopolymer of chlorotrifluoroethylene and Kel-F elastomer is a copolymer of chlorotrifluoroethylene and vinylidene fluoride.
Examples XII-XXI not only ignited very rapidly, but burned very rapidly as well. These mixtures are stable to fairly high temperatures, (at least 250 C.) which increases handling safely.
An additional advantage to safety is the relative stability to impact exhibited by all the mixtures. Examples IV and VI when struck with the flat end of a hammer on a flat piece of steel were almost completely insensitive to such treatment. Example XV which contains no oxygen oxidizer, would not ignite or explode at all regardless of hammer force.
All these pyrotechnic samples (I-XXI) were handmixed by means of mortar and pestle. Only high temperatures above 250 C. set them olf.
Various modifications are contemplated and may obviously be resorted to by those skilled in the art without departing from the spirit and scope of the invention as hereinafter defined by the appended claims.
What is claimed is:
1. A pyrotechnic composition consisting essentially of about 9.6 percent by weight magnesium, about 48 percent by weight sodium azide, about 38.5 percent by 5 weight of a homopolymer of chlorotrifluoroethylene and about 3.9 percent by weight of a copolymer of chlorotrifiuoroethylene and vinylidene fluoride.
2. A pyrotechnic composition consisting essentially of about 26.5 percent by weight boron, about 53.1 percent by weight sodium azide, and about 20.4 percent by weight of a homopolymer of tetrafluoroethylene.
3. A pyrotechnic composition consisting essentially of about 75.1 percent by weight zirconium, about 18 percent by weight sodium azide, and about 6.9 percent by weight of a copolymer of vinylidene fluoride and perfluoropropylene.
4. A pyrotechnic composition consisting essentially of about 47.4 percent by weight aluminum, about 38 percent by weight sodium azide, about 9 percent by weight of the copolymer of tetralluoroethylcne and perfluoropropylenc and about 5.6 percent of a homopolymer ot' chlorolrifiuoroethylene.
5. A pyrotechnic composition consisting essentially of about 26 to about 75 percent by weight of an element selected from the group consisting of silicon, boron, aluminum, titanium, zirconium and magnesium; about 18 to about 54 percent by weight alkali azide selected from the group consisting of lithium, sodium and potassium azides; and about 14 to about 42 percent by weight of a member selected from the group consisting of a copolymer of vinylidene fluoride and perfluoropropylene, a homopolymer of tetrafiuoroethylene, a copolymer of tetrafluoroethylene and perfluoropropylene; a homopolymer of chlorotrifiuoroethylene, and a copolymer of chlorotrifluoroethylene and vinylidene fluoride and mixtures thereof.
References Cited in the file of this patent UNITED STATES PATENTS 1,174,669 Buell Mar. 7, 1916 2,105,674 Sosson Jan. 18, 1938 2,900,242 Williams et al Aug. 18, 1959 2,968,917 Whaley Jan. 24, 1961 2,981,616 Boyer Apr. 25, 1961 2,995,431 Bice Aug. 8, 1961 3,027,283 Bice Mar. 27, 1962