INVENTOR. MYRON H. BOYER BY (2=4 AGEN United States Patent Office is and x represents the valency of M, and (2) at least one oxidizing compound selected from the class consisting of metal peroxides, inorganic perchlorates and metal ni 2,981,616 trates; said azides and said oxidizing compounds being present in amounts expressed by the equation n/my, GAS GENERATOR GRAN wherein in represents the number of azide nitrogenatoms, Myron H. Boyer, Puente, Calif., assignor to m represents the number of equivalents of oxidizing comi North American Aviation, Inc. pounds, and y has a numerical value of from about 23 to about 3.6. |- Filed Oct. 1, 1956, Ser. No. 613,327 10 An example of the gas generator grain of this inven 8 Claims. (CI.52-5) tion is a composition comprising calcium azide and pos tassium perchlorate in amounts such that the “equatiòn n/n has the value 3. The azides, M(Na), that can be used in the prepara This invention relates to a novel composition of matter 5 tion of the compositions of this invention can be any suitable for generating gases. More particularly, this azide which has suitable stability to permit grinding and invention relates to a composition which upon ignition handling in the preparation of the composition, and also generates an inert gas useful for pressurizing rocket pro will burn at a satisfactory rate without exploding. A pellant tanks. class of metal azides which satisfy these requirements In a rocket or missile which is operated on liquid fuel, 20 are the alkali and alkaline earth azides. Nonlimiting it is necessary to provide a means for Supplying the fuel examples of these include lithium azide, sodium azide, to the engine at a predetermined rate. This rate must potassium azide, rubidium azide, and cesium azide which be of a magnitude sufficient to sustain uninterrupted constitute the alkali metal azides having the general-for combustion from which power is derived to operate the mula M(Na). Since the valence, x, of M, the alkali rocket. The use of pumps is one method for Supplying 25 metal is unity, the symbol x is omitted from the formula. the fuel to the rocket engine. To obviate the use of The alkaline earth azides include the calcium azide, weighty pumping equipment, a method of feeding the strontium azide, and barium azide. The metal M in the fuel to the combustion chamber by the development of formula M(N) in this case is divalent and, therefore, gas pressure in the fuel tank has been employed. The the symbol x has a numerical value of 2. The alkaline gas developing the pressure may be obtained from the 30 earth metals of which the azides are composed have combustion product of a composition of matter called a atomic weights varying from 40 to 138 inclusive. When gas generator grain. The gas generator grain is ignited a hydrazine azide and ammonium azide are used, it is at the time the motor is put into operation and as com advisable to employ - an explosion : inhibitor such as di bustion consumes the grain, the resulting gaseous prod atomaceous earth in order to reduce the hazard of spon ucts exert a pressure inside the fuel compartment causing taneous decomposition. - the fuel to flow through feed lines to the rocket motor. The alkali metal azides are found to be particularly One gas generator grain employed in the past was com suited to the preparation of gas generator grains and come posed of a mixture of ammonium perchlorate and a hydro positions containing them constitute a preferred embodi carbon and sulfur-containing polymer. Among the com ment of this invention. The alkali metals of which the bustion products of the gas generatorg rain were, there 40 alkali metal azides are composed have atomic weights of fore, hydrogen, carbon monoxide and hydrocarbon gases. from 6 to 133 inclusive. These are reducing gases and, consequently, cannot be The oxidizing compounds of which the composition of used with certain types of propellants such as, for ex matter of this invention are prepared include metal perox ample, nitric acid, as they would destroy the oxidizing ides, inorganic perchlorates and metal nitrates. The characteristic of the fuel prior to its introduction into 45 metal peroxides have the general formula XOs wherein the combustion chamber of the motor. Also, the gases X is a metal having an atomic weight of from 6 to about inay form explosive vapor mixtures with fuels and/or 138 inclusive, r is the number of metal atoms in the perox oxidizer. Other combustion products of the sulfur-con ide compound and varies from 1 to 2. The value of s vars taining polymers are oxides of sulfur. These are very ies from 1 to 2 and represents the number of oxygen atoms corrosive and cause damage to the motor. This not only 5 in the peroxide molecule. Nonlimiting examples of metal reduces the period of serviceability but also impairs the peroxides employed in the manufacture of the composi operation of the motor during flight. The result is that tions of this invention include peroxides of group I-A the missile or rocket is more difficult to control and metals such as sodium peroxide, Na2O, potassium per increases the hazard of loss due to motor failure. A oxide, K2O, rubidium peroxide, Rb50, and cesium per need, therefore, existed for the development of a gas 55 oxide, Cs2O2; peroxides of group II-A. metals such as generator grain which, upon combustion, would give of calcium peroxide, CaO2; strontiumperoxide, SrO2; barium inert gases only so as to affect neither the properties of peroxide, BaO. Examples of the inorganic perchlorates the rocket fuel nor the operability of the motor. having the general formula Y(CIO), wherein Y is se It is therefore an object of this invention to provide lected from the class consisting of a metal and the a composition of matter suitable for use as a gas gen 60 ammonium radical, v represents the valence of Y and erator grain. It is also an object of this invention to has a numerical value of 1 to 3 inclusive, include am provide a composition of matter which, upon combustion, monium perchlorate; group I-A metal perchlorates such produces only inert gaseous products. Another object as lithium perchlorate, LiCIO, sodium perchlorate, of this invention is to provide a method for pressurizing NaClO4, potassium perchlorate, KCIO, and rubidium propellant or fuel chambers of rockets and missiles. Other 65 perchlorate, RbClO4; group II-A metal perchlorates such objects will become apparent from the discussion that as magnesium perchlorate, Mg(ClO4)2, calcium perchlo follows. v rate, Ca(ClO4)2, strontium perchlorate, Sr(CIO), and The above and other objects of this invention are ac barium perchlorate, Ba(ClO4)2; group VIII perchlorates complished by a composition of matter comprising (1) such as ferric perchlorate, Fe(ClO4)3, and cobalt per an azidehaving the general formula M(N): wherein chlorate, CO(CIO); and group III-A metal perchlora M. is selected from the class consisting of a metal, a hy such as In(ClO4)3. Non-limiting examples of metal ni drazino radical and an ammonium radical; N is nitrogen; trates having the general formula f(NO), wherein T ?? ? ?? ? ?? ... ............... ???? ????? 2,981,616 ??. ? 4 is a metal and z is the valence of T having a numerical the equation n/m=y wherein in represents the number value of from i to 4 inclusive, include group I-A metal of azide nitrogen atoms, in represents the number of nitrates such as lithium nitrate, LiNOs, sodium nitrate, equivalents i of oxidizing compounds, and y ... has a nu NaNO3, and potassium nitrate KNO; group I-B metal merical value of from about 2.3 to about 3.6. -nitrates such as copper nitrate, Cu (NO), and silver 5 In addition, the compositions of this invention may nitrate, Ag(NO3); group II-A metal nitrates such as also contain minor amounts of metal and metalloid pow magnesium nitrate, Mg(NO3), and barium nitrate, ders and their oxides as burning catalysts. Powdered Ba(NO3)2; group II-B metal nitrates such as zinc nitrate; or comminuted carbon, phosphorus and sulfur, also serve group III-A metal nitrates such as aluminum nitrate, as burning catalysts. The amounts can range from less Al(NO3)3, and thalium nitrate, Til (NO); group IV-A O than 0.1 weight percent to about 3 weight percent based metal nitrates such as stannic nitrate, Sn (NO); group on the weight of the combined azide and oxidizing com V-A metal nitrate such as bismuth nitrate, Bi(NO); pound. The particle size of the burning catalyst can group VII-B metal nitrates such as manganese nitrate, vary from about 10 to 100 microns. Nonlimiting ex Mn(NO3)3; and group VIII. metal nitrates such as ferric amples of metal and metalloid powders and their oxides Initrate, ferrous nitrate and nickel nitrate. Methods for 15 that can be used as burning catalysts are copper, mag the preparation of metal, peroxides, metal nitrates and nesium, boron, aluminum, zirconium, vanadium, anti inorganic perchlorates are given in volumes I and II of mony, manganese, iron, cobalt, nickel, ferric oxide, silica, the text "Chemical Elements and Their Compounds' by etc. N.V. Sidgwick, 1950 edition, published by the Clarendon In the preparation of the compositions of this inven Press. tion the metal azide and the oxidizing compound are each : The metal perchlorates and the metal peroxides are comminuted separately to a particle size ranging from founi to be particularly suited for preparing gas generator 10 to about i 250 i microns.