PYROTECHNIC THERMITE COMPOSITION AND TORCH BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a thermite composition, more particularly, this invention relates to a thermite composition for pyrotechnics, and even more particularly, this invention relates to a thermite composition for pyrotechnics having characteristics of a controllable burn rate and gas production and having an extremely high rate of heat transfer which can be suitable as a fuel for a hand held metal-cutting pyrotechnic torch.

Description of the Prior Art Thermite compositions are very well known and consist generally of a mixture of a finely divided, strongly reducible metal oxide, typically consisting of ferrous oxide, and a finely divided strong reducing agent, typically consisting of aluminum. Once ignited, the composition reacts highly exothermically as the strong reducing agent has negative free energy, typically above 90,000 calories per gram atom of oxygen at a reference of 25° C. and the strongly reducible metal oxide has a negative free energy as high as about 60,000 calories per gram atom of oxygen at a reference of 25o C.

Consequently, 750 kilocalories is released thereby raising the temperature of the products to about 3000° C. under favorable conditions as it produces little or no permanent gas and yields aluminum oxide and molten iron. The heat from the molten iron and aluminum oxide is used for various purposes, such as destruction of military targets and munitions, incendiary weapons, cutting and welding torches, igniter for other reactions such as activation of air bags, plating of metals upon substrates, cutting or plugging oil well conduits, and the like.

Other types of thermite compositions containing metals and the oxides of other metals other than iron oxide are known. The metal oxides include FeO, Fie203, CoO, NiO, Cu20, CuO, Sb203, Mn02, MoO2, MoO3 Cr2 03, Pb02, WO2, W03 and others. The Oxidizable metals include Al, Si, Zr, Be, Mg, Ba, Ti, B and-others.

For many of these applications, it is desirable to optimize the transfer of heat and gas from the thermite reaction to a target or substrate or workpiece. To some of these thermite compositions were added gas producing compounds such as carbides to produce high pressure and high velocity gases such as is taught by Halcomb, et. al. in U. S. Patent 4,963, 203. This composition, in its preferred embodiment consist of 79. 5% CuO and 17. 5% Al and 3% SiC, was designed to be thermally stable to a temperature of about 500° C.

While this composition may be suitable for some applications, it is not designed to optimize temperature and heat transfer when the products of the reaction contact a target or workpiece, rather it is designed for high pressure and high velocity. In another application, into a flame spray, a thermite composition is introduced containing a reducible metal oxide and a strong oxidizing agent thereby enabling the production of a one-step coating of substantial thickness.

In U. S. Patent 4,202, 691 issued to Yurasko, Jr. an example of an agglomerate of 50% by weight each of NiO and Al in a binder of sodium silicate was mixed and dried.. This agglomerate was mixed with nickel powder and sprayed upon a steel substrate using an oxyacetylene torch. The steel substrate was thereby coated using this process. Atomizing the metal and depositing them upon a substrate is excellent for coating metals but is not designed to maximize the transfer of the heat of the reaction to the substrate.

U. S. Patent 4,349, 396 discloses a metal-cutting pyrotechnic- composition. This composition utilizes a oxidizer selected from the group consisting of calcium sulfate hemihydrate, anhydrous calcium sulfate, magnesium monohydrate, anhydrous magnesium sulfate, anhydrous strontium sulfate, and mixtures thereof, a metal fuel, a halopolymeric binder; and sulfur. In this application an appreciable amount of heat per unit volume of composition is produced without generating an appreciable amount of gas. The patent teaches that gas generation, as an incident of oxygen reactions absorbs the heat of the reaction and removes it from the reaction system. The patent further teaches that the oxidizer reacts primarily with the metal fuel, secondarily with any carbon of hydrogen present in the composition, and with the workpiece, and consequently the best composition has an excess of oxidizer up to about 80% by weight. While this composition is effective in that it uses by conduction the heat of the reaction and supply an excess of oxygen for the workpiece after it is heated wherein the oxygen comes from the oxidizers selected. It specifically reduces gas production which can be desirable to transfer heat. Consequently, this composition does not take advantage of optimum heat transfer.

The earliest effective technique for cutting metal utilizes an oxyacetylene flame to heat an area on a metal surface after which a gas stream of acetylene and mostly oxygen is directed to the heated area thereby oxidizing the metal surface. The force of the gas stream removes the oxide products of the combustion. For some applications this method is relatively fast and efficient if the use of large amounts of oxygen and acetylene under high pressure in heavy metal bottles does not present an impediment. However, this method is not efficient for cutting copper and aluminum and their alloys. Further, it is not efficient for cutting where high temperatures are required nor where underwater metal-cutting is to be done. In addition, the heavy bottles and hoses present a hazard for military operations during wartime. Consequently, the portability of this system is very limited and cumbersome.

Underwater use is extremely sophisticated and require specialized equipment and high pressure air sources. This equipment is not practical to be carried by first responders and require some skill in use. Use of this equipment require special eye protection which limits visiblity.

U. S. Patent 2, 836, 172 issued to Ginsburgh et al. describes a hand held torch for welding, soldering, burning and brazing metals.

It employs a solid fuel comprising a mixture of a solid oxidizing salt dispersed in a solid combustible fuel enclosed inside the torch. The torch is also equipped with a convergent nozzle and a means for urging the solid fuel toward the nozzle. However, this patent does not suggest the use of a torch which does not require a nozzle, nor does it suggest the use of a slow burning thermite fuel which reaches a higher temperature and creates a thrust for metal-cutting operations.

SUMMARY OF THE INVENTION These disadvantages are overcome as well as novel advantages realized in the present invention. Applicant has found that an optimal temperature and gas production of the thermite reaction can be optimally controlled when a combination and a ratio of at least two multi-covalent metallic oxides is utilized. Further the reaction products can be adapted for certain desired properties such as excellent transfer of heat to a target, substrate or workpiece.

Controllability is achieved by adjusting the ratio of the combination of multi-covalent metallic oxides. It is believed that controlablilty is related to the multi-covalence of the metallic oxides. These advantages are realized by a thermite composition for pyrotechnics which comprises a combination of and ratio of at least two of the metallic oxides taken from the group consisting of FeO, Fe203, Cu20, CuO, MnO, Mn02, MoO2, MoO3, WO2, and W03 and a strong reducing agent. The addition of a strong oxidizing agent further enhances the controllability of the thermite composition. The composition is controllable to achieve a desired gas production and temperature combination. The ingredients that may be added to the composition are modulators, accelerators, gas generating compounds, binders, and diluents. By"modulator", it is meant an agent that slows down the rate of the reaction or otherwise reduce the intensity of the reaction. By"accelerator"it is meant an agent that increases the intensity of the reaction. Certain of these compositions can be-environmentally safe, can be made from readily available and relatively inexpensive materials, can be burned in a simple hand held torch, does not produce a light harmful to the eyes and can be adapted so as not to produce an excessive amount of smoke or harmful fumes.

Applicants invention can be used as a fuel for a hand held torch which comprises a solid relataively slow burning thermite fuel composition according to the present invention, an igniter, a tubular body which burns away with the composition and a thermally non conducting handle.

BRIEF DESCRIPTION OF THE DRAWINGS The invention used as fuel in a hand held torch is more readily understood by reference to the following drawings in which: FIG. 1 is a drawing of a hand held cutting torch having a cylindrical body.

FIG. 2 is a cross sectional drawing of a hand held cutting torch having a solid thermite charge with a polymeric binder.

FIG. 3 is a cross sectional drawing of a hand held cutting torch having a solid thermite charge with a cylindrical body to contain the charge.

DETAILED DESCRIPTION OF THE INVENTION The thermite composition for pyrotechnics of the present invention preferably includes a combination and a ratio of about 41%-51% by weight of the higher covalent metal oxide and about 26%- 36% by weight of the lower covalent metallic oxide, and a strong reducing agent. The metal oxides of the present invention are taken from the group consisting of FeO, Fe203, Fe30d, Cu20, CuO, MnO, MnO, MoO2, MoO3, WO2, and W03, The preferred metal oxides are the oxides of iron, copper and manganese. The copper oxides are even more preferred. While a combination of oxides of the same metal is preferred, oxides of different metals can be utilized.

The thermite compound is preferably further enhanced by a strong oxidizing agent which is preferably stronger acting than the metal oxides and are taken from the group consisting of chlorates, perchlorates, peroxides, nitrites and nitrates or a combination thereof. The strong oxidizing agent is provided in an amount of about 5%-20% by weight. The strong oxidizing agent is preferably NaCl03, NaNO3 and Fe203. The strong oxidizing agent is more preferably NaCl03.

The strong reducing agent is taken from the group consisting of Al, Si, Zr, Be, Mg, Ba, Ti, and B and is provided in an amount of about 5-20% by weight. It is preferred that the strong reducing agent is taken from the group consisting of Al, Mg, Si and Be. It is even more preferred that the strong reducing agent is Al.

The burning rate of the thermite composition of this invention can be modulated by the addition of an agent taken from the group consisting of KN03, B, borates (such as NaB407), and other compounds containing boron or a combination thereof. By"modulator", it is meant an agent that slows down the rate of the thermite reaction of this invention. The modulator is provided in an amount of about 0%- 5%. It is preferred that the modulator is taken from the group consisting of B or Borates and the reducing metal is other than B.

While it is most preferred that the modulator is B, other compounds containing B could be more economical.

The potential of the thermite reaction to reach its optimal temperature at a faster rate can be increased by an accelerating agent. By"accelerating agent"it is meant an agent that cause the thermite reaction of this invention to achieve higher temperatures at faster rates. It has been found that the oxide of one metal can act as an excellent accelerator for the oxide of another metal. It is believed that the ability of the agent to easily give up oxygen without otherwise adversely affecting the reaction makes it a good accelerator. It has been found that MnO is an excellent accelerator for the combination of CuO and CuO and is provided in an amount of about 0%-2% by weight..

Other ingredients that may be added are gas generating compounds taken from the group consisting of metal carbides and metal nitrides and nitrates provided in the range of about 0-5% by weight. A preferred gas generating compound is KNO3. This compound is preferred because it can also act as a modulator.

Diluents that may be added are taken from the group consisting of LiF, NiF3, FeCl3, AlF3, NiF2, CaF2, CrF2, CrCl3, CaO, Na2SO4, SiO2, KC1, TiO2, CrF3, MgC12, CaCl2, NiF3, FeCl3, MgF2, MnO, Fe203, B203, Mgo, and A1203 or a combination thereof. The diluent is added in an amount to decrease the rate of the reaction simply by diluting or causing the reactants to be more spacially separated or less concentrated. Typically, the diluent will be provided in small amounts in the range of 0-2% by weight. It is preferred that the diluent is provided in the range of about 0-1. 5% by weight. While diluents in some respect is intended to reduce the intensity of the reaction, it may otherwise enhance the reaction of the invention.

In this regard, it should be understood that oxidizing agents, gas generating agents and rate modulating agents can also act as diluents.

The binder is used in limited applications and is a thermally fugitive agent which is decomposable or vaporizable during drying or during the reaction. The binder is provided in the range of about 0-2% by weight. These binders are well known in the art. A preferred binder would is a polyethylene glycol polymer. Other binders are well known in the art.

It is preferred that all of the components are provided in an average grain size under 80 microns, It is more preferred that the average grain size is under 20 microns. It is further preferred that the strong reducing agent is provided in an average grain size smaller than the other components.

In a preferred embodiment of the invention, the composition is made by mixing the combination of CuO and Cu2O with Al, MaC303, and b within the range mentioned above by means well known in the art.

The mixture is then dried and degassed to minimize moisture and gas therefrom and then formed into a means-in which the mixture will be ignited. Ignition means may be by electric arc, heated wire, laser, electromagnetic radiation, chemical reaction, blasting cap, detonator and the like. Upon ignition, it is thought that the NaCl03 reacts primarily with the Al to produce the exothermic thermite reaction. While some of the CuO and Cu2O reacts in the thermite reaction, it is primarily heated and decomposed at about 1800° C. by the reaction products of the redox reaction. Thereby, copper metal, substantially in the gaseous state, and oxygen is released in the form of a gases propagating from the burning mixture. The resultant gaseous copper and oxygen is available to heat a target, substrate or workpiece and supply oxygen for maintenance of the high temperature. When the products of the reaction are impinged upon an object, intense heat is transferred instantly from the gaseous copper in terms of latent heat of fusion, latent heat of crystallization and sensible heat through thermal conductivity. The oxygen from the reaction is available for further oxidation to intensify the rate and heat of reaction.

It is well known in the art that by further adjusting parameters such as blend ratios, density, particle size and forming techniques, the composition of the present invention may be modified in terms of burn rate, gas production and heat transfer intensity.

For example, the exothermic reaction proceeds at a slower rate as composition density is decreased. Heat transfer rate is slower where lesser thermally conductive compounds are u-sed. While the invention is intended primarily for a relatively slow burn rate, it-is envisioned that the invention may be used in explosive applications.

Reference is made to the drawing, Figure 1. Handle 5 can be made of any thermally insulating material. It is also preferably non-combustible. It is preferable that the handle 5 is removably attached to body 1 so that it can fit on either end of the Body 1 either as a cover over striker 3 or a handle fitted on the opposite end. As shown in Figure 2 and Figure 3, Handle 1 has disposed within a Plug 4 which is secured in Handle 1 by an adhesive. The distance A from the end of Handle 5 to Plug 4 is sufficient that the handle can be hand held and away from the burning Body 1. The Handle 5 may be of various designs and attached to Body 2 by means well known in the art.

Reference is now made to Figure 2 wherein a preferred embodiment of applicant's torch, applicant chooses to use a thermite charge using the composition comprising the CuO as the strongly reducible metal oxide provided in the amount of 44% by weight, Al as the strong reducing agent provided in the amount of 10% by weight, Cu2O is the thermally decomposable heat transfer agent provided in the amount of 29% by weight, NaClO3 as the supplemental strong oxidizing agent provided in the amount of 11% by weight and a binder consisting of polyurethane polymer provided in the amount of 5% by weight and an epoxy curing agent in the amount of 1%. All of the ingredients are provided in an average size of less than 10 microns.

This thermite charge making up Body 1 is chosen because when ignited, it releases a stream of gaseous products, which includes the heat transfer agent and oxygen, at a force sufficient to instantaneously heat a metal surface, cause combustion of the metal surface and remove combustion products of that metal surface.

Thereby, this torch is capable of cutting metal in the same manner as an acetylene torch, but with greater ease because of the superior heat transfer characteristics of the thermite composition.

The polymeric binder is mixed with a curing agent to form a slurry as is well known in the art. The CuO, Cu2O, Al and NaClO3 is added and mixed into a homogeneous mixture. Care must be taken that the mixture is a homogeneous mixture thereby avoiding cracks which result in discontinuities between fuel and oxidizer with the matrix resulting in an irregular burn and burn rate. The mixture is poured into a cylindrical mold. 750 inch in diameter and 12 inches long.

The diameter of the torch body is determined by the thickness of metal needed to be cut. A. 750 diameter torch can cut metal. 50 inch thick with ease. A larger diameter torch can cut metal thicker. The mixture is heated to an elevated temperature to effect polymerization. The ingredients in this embodiment is limited to those which do not react at ambient or at the elevated temperatures for polymerization. This molded composition comprise Body 1 in Figure 2.

The igniter may be an electric arc, heated wire, laser, electromagnetic radiation, chemical reaction, blasting cap, detonator and the like. In this embodiment of the invention, the Igniter 2 is that which is the solid chemical type capable of reaching a temperature of at least 1000° F. as commonly used for fusees. An inflammable igniter compound of the solid hard variety commonly known as a"hard head"is affixed to an end of the cylindrical molded thermite composition by a combustible adhesive compound known in the art. The strike button 3, which is a chemical solid ignitable by abrasion, is inserted on the end of the Igniter 2 by methods well known in the art of making fusees.

On the other end of the molded thermite compound is fitted a thermally non-conducting and preferably non-combustible handle 4 such as one made of sheet of paper rolled into a cylindrical shape of a size to force fit on body 1. By thermally non-conducting, it is meant that it can be held by hand preferably with protection while the thermite composition is burning. The handle is long enough so that the hand is far removed from the end of the thermite mold indicated by distance A. While the aforementioned embodiment is a preferred embodiment, it is not the most preferred embodiment as the solid body of the thermite mold and the"hard head"may be subject to impact causing breakage which could reduce the utility of the torch.

Reference is now made to Figure 3. In that most preferred embodiment of the invention, applicant chooses to use a thermite charge 1 of the composition comprising the CuO as the strongly reducible metal oxide provided in the amount of 46% by weight, Al as the strong reducing agent provided in the amount of 10% by weight, Cu2O is the thermally decomposable heat transfer agent provided in the amount of 31% by weight, NaClO3 as the supplemental strong oxidizing agent provided in the amount of 15% by weight and a binder consisting of polyethylene glycol provided in the amount of 1% by weight, All of the ingredients are provided in an average size of less than 10 microns.

A body 6 in Figure 3, made to contain the thermite charge 1, may be made of any material suitable for containing the thermite charge, such as metal, plastic, fabric, paper and the like. It is preferred, however, that the body is made of a material such a paper that burns away as the thermite charge is burned. Accordingly, a preferred Body 6 is prepared for the thermite charge by rolling a sheet of paper into a tubular form with walls formed of several layers of the sheet. The tube is. 75 inch in diameter and 14.0 inches long. Again, the diameter is determined by intended use.

A thin end formed of a single layer is folded down to close the end and fastened by cement or glue as well known in the art of making cylindrical bodies for fusees. The paper is a type that is easily burned away with the composition. The paper may actually burn a short distance behind the burning of the molded thermite charge.

The thermite charge is mixed with the binder by conventional means until the mixture is homogeneous. Homogeneity, again is important so that all of the ingredients are in intimate contact in a uniform mixture with all of the other ingredients. The charge is dried and degassed by conventional means care being taken not to heat the mixture to near the ignition temperature. After drying and degassing, the mixture is pressed into the paper Body 6 to a depth of 12.0 inches with a predetermined density based upon experimental burning rates. It is desired that the thermite charge burn at a rate of about 30 seconds per two inches, resulting in a four minute burn for a 8.0 inch torch. After the tube is packed with the thermite charge, an Igniter 2 is then inserted in the end of the paper body and caused to be adhered to the thermite charge by a combustible adhesive, glue or cement. A strike button 3 is inserted on the end of the igniter.

On the closed end of the body is fitted a thermally non- conducting Handle 5 which is made of a sheet of paper rolled into tubular shape and having disposed therein a Plug 4 which is secured within Handle 5 by an adhesive. By thermally non-conducting, as above, it is meant that it can be held by hand, preferably with protection while the thermite composition is burning. The handle is long enough, distance A, so that the hand is far removed from the end of the thermite mold.

This invention has been described with regard to specific embodiments and preferred combinations, however it is understood that modifications and adjustments and uses of the invention may be made without departing from the inventive intent herein. For example, it is envisioned that a thermite reacion with CuO and Cu2O can be accelerated with compounds other than MnO2. Other thermally conductive compounds that decompose at the reaction temperature or otherwise freely give up oxygen may be used. Compounds other than B may be used as modulators. It is believed that the modulation is related to the oxygen made available by the metallic oxide compounds. These modifications or adjustments or varying uses made by combining the invention with known and customary practices in the art falls within the scope of this invention and the claims herein.