US3288659A

US3288659A - Metallized rocket propellants containing azides

Info

Publication number: US3288659A
Application number: US169180A
Authority: US
Inventors: Douglas A Rausch
Original assignee: Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1962-01-24
Filing date: 1962-01-24
Publication date: 1966-11-29
Anticipated expiration: 1983-11-29

Description

United States Patent 3,288,659 METALLIZED ROCKET PROPELLANTS CONTAINING AZIDES Douglas A. Rausch, Midland, Mich., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware No Drawing. Filed Jan. 24, 1962, Ser. No. 169,180 3 Claims. (Cl. 14936) This invention relates to rocket propellants and more particularly is concerned with an improved rocket propellant based on a metallized-inorganic oxidizer system.

The use of metallic fuels in combination with inorganic oxidizers as solid propellants is Well known and widely used. For example, finely divided metals such as aluminum, magnesium, zirconium, beryllium, lithium and the like either alone, as mixtures or as alloys when admixed with ammonium nitrate, ammonium perchlorate, lithium perchlorate or other inorganic oxidizers provide solid propellants which upon burning give large amounts of heat. However, these systems have relatively small amounts of gaseous products and therefore the specific impulse of these propellant systems is relatively low.

The addition of enhancing materials to such systems to provide low molecular weight 'gaseous products has been disclosed generically in a copending application Serial No. 846,510, now Patent No. 3,151,445, filed October 14, 1959. Now, it has been found that the particular solid compounds, hydrazonium azide (N H -N H) and/ or hydrazonium azide hydrazide (N H -N H-N H are highly satisfactory driving fluids for use in conventional metallized propellant systems. These specific solid compounds serve to markedly increase the specific impulses of such system since they provide large amounts of low molecular weight gases upon combustion of the propellant.

The amount of the hydrazine based azide compound to be incorporated into the metallized propellant system is that quantity which utilizes and is expanded by the waste heat of combustion that ordinarily goes to produce undesirable phase changes and/ or dissociation of the propellant combustionproducts while maintaining the combustion flame temperature at a minimum of about 3000 K. However, depending upon the characteristics desired in a propellant system either larger or smaller amounts of the hydrazonium azide or hydrazonium azide hydrazide can be employed in the system. For example, with an aluminum-ammonium nitrate propellant for the optimum specific impulse the amount of hydrazine azide compound to be employed is from about 1 to about 1.25 moles per mole of aluminum oxide produced. With an aluminumammonium perchlorate propellant, from about 1 to about 2 moles of the azide compound preferably is to be employed per mole of aluminum oxide produced.

The azide gas formers, or driving fluids as they are called, can be used both with simple mixtures of the inorganic oxidizer and metal or with propellant formulations having binders and other components therein. Ordinarily, the metal-inorganic oxidizer solid propellants are stoichiometrically balanced for metal oxide formation although in certain instances these may be oxygen rich. The hydrazine azides can be added to the propellant during formation of the propellant grain as a part of the general blending procedure or can be added at the times during the propellant manufacture as is apparent to one skilled in the art.

The utility of the instance additives is shown further by the following examples. An aluminum-ammonium perchlorate solid propellant, stoichiometrically balanced 3,288,659 Patented Nov. 29, 1966 for conversion of all the aluminum into aluminum oxide according to the following tquation (I) has an undesirably high calcuated combustion temperature of about 5500 K and a specific impulse of about 261 seconds.

Adding hydrazonium azide hydrazide to this composition in an amount to provide a combustion temperature of about 3800 K. gives a calculated specific impulse of 285 seconds.

If hydrazonium azide is incorporated into a similar aluminum-ammonium perchlorate propellant to give a combustion temperature of about 3800 K. the calculated specific impulse is 283 seconds.

In a manner similar to that described for the foregoing examples hydrazonium azide can be incorporated into an aluminum-lithium perchlorate based propellant system. Hydrazonium azide hydrazide can be added to an aluminum-ammonium nitrate propellant having a polyurethane binder. Likewise the hydrazine based azides can be added to (1) magnesiumdithium perchlorate solid propellant, (2) lithium-ammonium perchlorate and (3) aluminum-ammonium nitrate-ammonium perchlorate systems.

Various modifications can be made in the present invention without departing from the spirit or scope thereof for it is understood that I limit myself only as defined in the appended claims.

I claim:

1. A solid rocket propellant composition consisting essentially of a finely divided light metal and an inorganic oxidizer selected from the group consisting of ammonium perchlorate, ammonium nitrate, lithium perchlorate and mixtures thereof, said light metal and inorganic oxidizer being present in stoichiometric amounts based on the conversion of said metal to the corresponding metal oxide, and in admixture therewith a gas producing member selected from the group consisting of hydrazonium azide, hydrazonium azide hydrazide and mixtures thereof, said gas producing member being present in amount which utilizes and is expanded by the waste heat of combustion of said propellant while maintaining the combustion flame temperature of said propellant at a minimum of about 3000 K.

2. A solid rocket propellant composition consisting essentially of a stoichiometric mixture of finely divided aluminum and ammonium perchlorate and having hydrazonium azide in combination therewith, the amount of said hydrazonium azide in said composition ranging from about 1 to about 2 moles per mole of aluminum oxide produced by combustion of said propellant.

3. A solid rocket propellant composition consisting essentially of a stoichiometric mixture of finely divided aluminum and ammonium perchlorate and having hydrazonium azide hydrozide in combination therewith, the amount of said hydrazonium azide hydrazide in said composition ranging from about 1 to about 2 moles per mole of aluminum oxide produced by combustion of said propellant.

References Cited by the Examiner UNITED STATES PATENTS 4/1961 Boyer 149--35 8/1961 McMillan et al. 149-22 X BENJAMIN R. PADGETT, Primary Examiner.

Claims

1. A SOLID ROCKET PROPELLANT COMPOSITION CONSISTING ESSENTIALLY OF A FINELY DIVIDED LIGHT METAL AND AN INORGANIC OXIDIZER SELECTED FROM THE GROUP CONSISTING OF AMMONIUM PERCHLORATE, AMMONIUM NITRATE, LITHIUM PERCHLORATE AND MIXTURES THEREOF, SAID LIGHT METAL AND INORGANIC OXIDIZER BEING PRESENT IN STOICHIOMETRIC AMOUNTS BASED ON THE CONVERSION OF SAID METAL TO THE CORRESPONDING METAL OXIDE, AND IN ADMIXTURE THEREWITH A GAS PRODUCING MEMBER SELECTED FROM THE GROUP CONSISTING OF HYDRAZONIUM AZIDE, HYDRAZONIUM AZIDE HYDRAZIDE AND MIXTURES THEREOF, SAID GAS PRODUCING MEMBER BEING PRESENT IN AMOUNT WHICH UTILIZES AND IS EXPANDED BY THE WASTE HEAT OF COMBUSTION OF SAID PROPELLANT WHILE MAINTAINING THE COMBUSTION FLAME TEMPERATURE OF SAID PROPELLANT AT A MINIMUM OF ABOUT 3000*K.