US3172793A - Temperature xc - Google Patents
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- US3172793A US3172793A US3172793DA US3172793A US 3172793 A US3172793 A US 3172793A US 3172793D A US3172793D A US 3172793DA US 3172793 A US3172793 A US 3172793A
- Authority
- US
- United States
- Prior art keywords
- ammonium perchlorate
- ammonium
- perchlorate
- propellant
- temperature
- Prior art date
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- HHEFNVCDPLQQTP-UHFFFAOYSA-N Ammonium perchlorate Chemical compound [NH4+].[O-]Cl(=O)(=O)=O HHEFNVCDPLQQTP-UHFFFAOYSA-N 0.000 claims description 192
- 239000000203 mixture Substances 0.000 claims description 102
- 239000003380 propellant Substances 0.000 claims description 68
- 150000001875 compounds Chemical class 0.000 claims description 62
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 54
- PRKQVKDSMLBJBJ-UHFFFAOYSA-N Ammonium carbonate Chemical compound N.N.OC(O)=O PRKQVKDSMLBJBJ-UHFFFAOYSA-N 0.000 claims description 42
- 239000001099 ammonium carbonate Substances 0.000 claims description 42
- 239000007787 solid Substances 0.000 claims description 32
- 235000012501 ammonium carbonate Nutrition 0.000 claims description 24
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 claims description 18
- 235000012538 ammonium bicarbonate Nutrition 0.000 claims description 18
- PPBAJDRXASKAGH-UHFFFAOYSA-O azanium;urea Chemical compound [NH4+].NC(N)=O PPBAJDRXASKAGH-UHFFFAOYSA-O 0.000 claims description 16
- 239000000446 fuel Substances 0.000 claims description 14
- 239000011230 binding agent Substances 0.000 claims description 10
- QGZKDVFQNNGYKY-UHFFFAOYSA-O ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 claims description 8
- 238000000354 decomposition reaction Methods 0.000 description 46
- 239000007800 oxidant agent Substances 0.000 description 36
- 230000000087 stabilizing Effects 0.000 description 32
- 238000000034 method Methods 0.000 description 30
- 239000000463 material Substances 0.000 description 26
- 239000002360 explosive Substances 0.000 description 22
- 239000011159 matrix material Substances 0.000 description 20
- VLTRZXGMWDSKGL-UHFFFAOYSA-M Perchlorate Chemical compound [O-]Cl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-M 0.000 description 18
- 238000004455 differential thermal analysis Methods 0.000 description 18
- 239000007788 liquid Substances 0.000 description 16
- 229920000642 polymer Polymers 0.000 description 16
- XSQUKJJJFZCRTK-UHFFFAOYSA-N urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 16
- 239000000126 substance Substances 0.000 description 14
- VLTRZXGMWDSKGL-UHFFFAOYSA-N Perchloric acid Chemical compound OCl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-N 0.000 description 12
- 239000007789 gas Substances 0.000 description 12
- 239000012535 impurity Substances 0.000 description 12
- FAPWRFPIFSIZLT-UHFFFAOYSA-M sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 12
- 238000001035 drying Methods 0.000 description 10
- 239000004449 solid propellant Substances 0.000 description 10
- 239000004202 carbamide Substances 0.000 description 8
- 239000002131 composite material Substances 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 8
- 238000002844 melting Methods 0.000 description 8
- 238000002156 mixing Methods 0.000 description 8
- 229920005596 polymer binder Polymers 0.000 description 8
- 239000002491 polymer binding agent Substances 0.000 description 8
- 230000000717 retained Effects 0.000 description 8
- 239000003381 stabilizer Substances 0.000 description 8
- MHCFAGZWMAWTNR-UHFFFAOYSA-M Lithium perchlorate Chemical compound [Li+].[O-]Cl(=O)(=O)=O MHCFAGZWMAWTNR-UHFFFAOYSA-M 0.000 description 6
- YLMGFJXSLBMXHK-UHFFFAOYSA-M Potassium perchlorate Chemical compound [K+].[O-]Cl(=O)(=O)=O YLMGFJXSLBMXHK-UHFFFAOYSA-M 0.000 description 6
- 230000002411 adverse Effects 0.000 description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N al2o3 Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 230000002708 enhancing Effects 0.000 description 6
- 150000002484 inorganic compounds Chemical class 0.000 description 6
- 229910010272 inorganic material Inorganic materials 0.000 description 6
- 229910001486 lithium perchlorate Inorganic materials 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 229910001487 potassium perchlorate Inorganic materials 0.000 description 6
- 239000011780 sodium chloride Substances 0.000 description 6
- KRVSOGSZCMJSLX-UHFFFAOYSA-L Chromic acid Chemical compound O[Cr](O)(=O)=O KRVSOGSZCMJSLX-UHFFFAOYSA-L 0.000 description 4
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitrogen oxide Substances O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 4
- BAZAXWOYCMUHIX-UHFFFAOYSA-M Sodium perchlorate Chemical compound [Na+].[O-]Cl(=O)(=O)=O BAZAXWOYCMUHIX-UHFFFAOYSA-M 0.000 description 4
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid Chemical compound OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 4
- 239000000654 additive Substances 0.000 description 4
- 230000015556 catabolic process Effects 0.000 description 4
- 239000003054 catalyst Substances 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 4
- 238000004132 cross linking Methods 0.000 description 4
- 239000003431 cross linking reagent Substances 0.000 description 4
- 230000003247 decreasing Effects 0.000 description 4
- 230000004059 degradation Effects 0.000 description 4
- 238000006731 degradation reaction Methods 0.000 description 4
- 239000011521 glass Substances 0.000 description 4
- MHAJPDPJQMAIIY-UHFFFAOYSA-N hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 4
- 238000011065 in-situ storage Methods 0.000 description 4
- RRHGJUQNOFWUDK-UHFFFAOYSA-N isoprene Chemical compound CC(=C)C=C RRHGJUQNOFWUDK-UHFFFAOYSA-N 0.000 description 4
- 239000000320 mechanical mixture Substances 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 230000001590 oxidative Effects 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 230000000704 physical effect Effects 0.000 description 4
- 230000036314 physical performance Effects 0.000 description 4
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 4
- 229910001488 sodium perchlorate Inorganic materials 0.000 description 4
- 229910001220 stainless steel Inorganic materials 0.000 description 4
- 239000010935 stainless steel Substances 0.000 description 4
- 238000003860 storage Methods 0.000 description 4
- PPBRXRYQALVLMV-UHFFFAOYSA-N styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 4
- LGXVIGDEPROXKC-UHFFFAOYSA-N 1,1-Dichloroethene Chemical compound ClC(Cl)=C LGXVIGDEPROXKC-UHFFFAOYSA-N 0.000 description 2
- SDJHPPZKZZWAKF-UHFFFAOYSA-N 2,3-dimethylbuta-1,3-diene Chemical compound CC(=C)C(C)=C SDJHPPZKZZWAKF-UHFFFAOYSA-N 0.000 description 2
- GYCMBHHDWRMZGG-UHFFFAOYSA-N 2-cyanopropene-1 Chemical compound CC(=C)C#N GYCMBHHDWRMZGG-UHFFFAOYSA-N 0.000 description 2
- GJIIAJVOYIPUPY-UHFFFAOYSA-N 2-methylidenebut-3-enoic acid Chemical compound OC(=O)C(=C)C=C GJIIAJVOYIPUPY-UHFFFAOYSA-N 0.000 description 2
- SWLVFNYSXGMGBS-UHFFFAOYSA-N Ammonium bromide Chemical compound [NH4+].[Br-] SWLVFNYSXGMGBS-UHFFFAOYSA-N 0.000 description 2
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 2
- DVARTQFDIMZBAA-UHFFFAOYSA-O Ammonium nitrate Chemical compound [NH4+].[O-][N+]([O-])=O DVARTQFDIMZBAA-UHFFFAOYSA-O 0.000 description 2
- VBIXEXWLHSRNKB-UHFFFAOYSA-N Ammonium oxalate Chemical compound [NH4+].[NH4+].[O-]C(=O)C([O-])=O VBIXEXWLHSRNKB-UHFFFAOYSA-N 0.000 description 2
- YACLQRRMGMJLJV-UHFFFAOYSA-N Chloroprene Chemical compound ClC(=C)C=C YACLQRRMGMJLJV-UHFFFAOYSA-N 0.000 description 2
- JGDFBJMWFLXCLJ-UHFFFAOYSA-N Copper chromite Chemical compound [Cu]=O.[Cu]=O.O=[Cr]O[Cr]=O JGDFBJMWFLXCLJ-UHFFFAOYSA-N 0.000 description 2
- KTWOOEGAPBSYNW-UHFFFAOYSA-N Ferrocene Chemical compound [Fe+2].C=1C=C[CH-]C=1.C=1C=C[CH-]C=1 KTWOOEGAPBSYNW-UHFFFAOYSA-N 0.000 description 2
- 239000000020 Nitrocellulose Substances 0.000 description 2
- 239000004952 Polyamide Substances 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 2
- NLHHRLWOUZZQLW-UHFFFAOYSA-N acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 2
- 238000007792 addition Methods 0.000 description 2
- 150000001336 alkenes Chemical class 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminum Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229940077484 ammonium bromide Drugs 0.000 description 2
- 235000019270 ammonium chloride Nutrition 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- SATZVFKUEAMFPB-UHFFFAOYSA-N azanium;sodium;chloride Chemical compound [NH4+].[Na].[Cl-] SATZVFKUEAMFPB-UHFFFAOYSA-N 0.000 description 2
- 230000001588 bifunctional Effects 0.000 description 2
- 230000000903 blocking Effects 0.000 description 2
- KAKZBPTYRLMSJV-UHFFFAOYSA-N butadiene Chemical compound C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 239000006229 carbon black Substances 0.000 description 2
- 150000001735 carboxylic acids Chemical class 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000009833 condensation Methods 0.000 description 2
- 230000005494 condensation Effects 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 229920001577 copolymer Polymers 0.000 description 2
- 230000000875 corresponding Effects 0.000 description 2
- 125000004122 cyclic group Chemical group 0.000 description 2
- 230000002939 deleterious Effects 0.000 description 2
- 230000001419 dependent Effects 0.000 description 2
- 230000000881 depressing Effects 0.000 description 2
- 150000001993 dienes Chemical class 0.000 description 2
- GIRZNGMZUXTPTL-UHFFFAOYSA-N disodium;iron(3+);nitroxyl;pentacyanide;dihydrate Chemical compound O.O.[Na+].[Na+].[Fe+3].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].O=N GIRZNGMZUXTPTL-UHFFFAOYSA-N 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000001640 fractional crystallisation Methods 0.000 description 2
- 238000010952 in-situ formation Methods 0.000 description 2
- 238000010348 incorporation Methods 0.000 description 2
- 239000004615 ingredient Substances 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 239000011872 intimate mixture Substances 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- -1 lithium perchlorate Chemical class 0.000 description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- CERQOIWHTDAKMF-UHFFFAOYSA-N methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 235000010755 mineral Nutrition 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000006011 modification reaction Methods 0.000 description 2
- 239000003607 modifier Substances 0.000 description 2
- QDHHCQZDFGDHMP-UHFFFAOYSA-N monochloramine Chemical compound ClN QDHHCQZDFGDHMP-UHFFFAOYSA-N 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N nitric acid Chemical class O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- 229920001220 nitrocellulos Polymers 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 229910052813 nitrogen oxide Inorganic materials 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N oxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 230000036961 partial Effects 0.000 description 2
- 239000011236 particulate material Substances 0.000 description 2
- 229920002647 polyamide Polymers 0.000 description 2
- 229920000728 polyester Polymers 0.000 description 2
- 229920000570 polyether Polymers 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- 239000001103 potassium chloride Substances 0.000 description 2
- 235000011164 potassium chloride Nutrition 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- 238000009877 rendering Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 238000004513 sizing Methods 0.000 description 2
- 239000000779 smoke Substances 0.000 description 2
- 239000011343 solid material Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000011105 stabilization Methods 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- 229920001897 terpolymer Polymers 0.000 description 2
- 238000002076 thermal analysis method Methods 0.000 description 2
- 238000005979 thermal decomposition reaction Methods 0.000 description 2
- 150000003673 urethanes Chemical class 0.000 description 2
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B23/00—Compositions characterised by non-explosive or non-thermic constituents
- C06B23/006—Stabilisers (e.g. thermal stabilisers)
-
- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B29/00—Compositions containing an inorganic oxygen-halogen salt, e.g. chlorate, perchlorate
- C06B29/22—Compositions containing an inorganic oxygen-halogen salt, e.g. chlorate, perchlorate the salt being ammonium perchlorate
Definitions
- This invention relates to a process for improving the stability of ammonium perchlorate and to ammonium perchlorate-containin g compositions having improved stability. More particularly, this invention is directed to a process whereby the thermal stability of ammonium perchlorate is improved and to mixtures containing ammonium perchlorate having improved thermal stability.
- ammonium perchlorate of high purity for use as an oxidizer in solid rocket propellants and various explosives.
- Ammonium perchlorate oxidizing agents are particularly attrative in propellants and explosives because of their low hygroscopicity and high density, the latter property resulting in propellant compositions having attractive density and bulk strength properties.
- Ammonium perchlorate is inherently unstable at elevated temperatures. This undesirable stability characteristic has severely limited the range of utility of materials containing ammonium perchlorate to fairly low temperature applications. It is extremely important that propellants maintain a predetermined burning rate; this rate is in part dependent upon accurately controlling the stability of the oxidizer employed. It is further essential that the ballistic potential of a propellant be maintained within critical limits even during rolonged exposure to extreme variations in thermal conditions.
- composite solid propellants containing an ammonium perchlorate oxidizer have been susceptible to decomposition during storage when exposed to rises in temperature. Similarly such compositions tend to decompose during use when exposed to temperature rises due to aerodynamic heating.
- Such decomposition of the ammonium perchlorate oxidizer results in changes in the ballistic properties of the composition.
- ballistic deficiencies such as decreased total energy, sporadic burning rates and the like result which tend to produce propellant compositions having unreliable ballistic properties.
- the crystals thereof will generally contain water, either occluded therein or absorbed thereon. This water tends to cause caking of the product during storage and processing difiiculties during manufacture of ammonium perchlorate containing compositions.
- the presence of Water in ammonium perchlorate crystals tends to cause blocking of the orifices of pulverizing and sizing equipment used to comminute the oxidizer to the desired particle size, thus impeding control of the particle size.
- solid propellant compositions usually contain polymerizable components and any water associated with the ammonium perchlorate would interfere with such polymerization.
- the presence of water in any form in a solid propellant represents an unattractive weight addition to the propellant.
- ammonium perchlorate compositions it is accepted practice in the propellant and explosive industry to subject ammonium perchlorate compositions to relatively low temperature drying processes wherein drying conditions below the decomposition temperature of the ammonium perchlorate are maintained for prolonged periods to produce a substantially waterfree crystalline product suitable for use in explosives and propellants.
- ammonium perchlorate is exposed to temperatures near its decomposition temperature it is essential that it be essentially free from such impurities and low melting point inorganic compounds to avoid decomposition. In order to avoid such effects, exhaustive purifying processes are employed to produce an essentially pure ammonium perchlorate product.
- Composite solid rocket propellant grains normally consist of at least one solid oxidizing agent such as ammonium perchlorate uniformly distributed throughout a matrix of a fuel-binder material.
- the propellant grains are generally made by mixing the solid oxidizing agent, and other particulate materials used to enhance the ballistic and physical performance of the product, with a liquid linear polymer binder.
- the propellant mixture is solidified by curing the polymer binder at a temperature below the decomposition temperature of ammonium perchlorate. Even in the presence of various curing promoters such as cross-linking agents and the like, this curing process is time consuming and diflicult because of the low operating temperature restrictions imposed on the process by the thermal instability of the ammonium perchlorate oxidizing agent present.
- a further object of the invention is to provide a propellant containing an ammonium perchlorate oxidizer which can be used and stored without degradation throughout a fairly broad temperature range.
- Still another object of the invention is to provide an improved method of drying ammonium perchlorate.
- Another object of the invention is to provide an improved method of curing compositions containing ammonium perchlorate.
- ammonium perchlorate, propellants, and other compositions containing ammonium perchlorate can be stabilized at high temperatures without degradation of the ammonium perchlorate by providing an atmosphere of ammonia, said gas obtained from the decomposition of certain substances having a decomposition temperature below that of ammonium perchlorate.
- Examples of solid compounds, which decompose, forming ammonia gas at a temperature below about 200 C. include ammonium carbonate, ammonium bicarbonate and urea.
- ammonium carbonate, ammonium bicarbonate and urea examples include ammonium carbonate, ammonium bicarbonate and urea.
- compositions capable of producing ammonia produce a stabilizing effect on ammoniurn perchlorate at elevated temperatures, for example ammonium nitrate, ammonium chloride and ammonium bromide do not have satisfactory decomposition temperatures and do not stabilize ammonium perchlorate at elevated temperatures.
- the solid compounds which are capable of producing ammonia at the requisite temperature are used in a closed system, wherein the stabilizing ammonia gas once produced is retained within the confines of the system.
- the stabilizing compounds suitable for use in a closed system can have decomposition temperatures substantially below 200 C.
- the decomposition products of these stabilizers will be retained in the closed system to impart their stabilizing effect on the ammonium perchlorate at elevated temperatures.
- the stabilizing compounds impart an unexpected stabilizing effect to am monium perchlorate compositions containing impurities. That is, it has been found that the adverse effects on the thermal stability of ammonium perchlorate compositions produced by certain impurities such as perchloric acid and lithium perchlorate which were discussed above, are unexpectedly suppressed by the instantly described stabilizing compounds. Such impurities can be tolerated in ammonium perchlorate compositions which are subjected to high temperatures if the composition is maintained in the presence of the stabilizers, therefore, extensive purifying and processing of ammonium perchlorate is rendered unnecessary.
- the present invention can advantageously be utilized to remove water from water contaminated ammonium perchlorate by means of high-temperature drying meth ods, while avoiding the hazard of decomposition of the oxidizer.
- the rate of drying ammonium perchlorate can be increased significantly.
- the increased thermal stability achieved by the stabilizers of the invention can be utilized in producing ammonium perchloratecontaining explosives wherein the oxidizer is included in the explosive grain during curing of the liquid polymer fuel composition. By means of the present invention curing of the liquid polymer fuel can be achieved at significantly higher temperatures.
- FIGURE I is a conventional differential thermal analysis curve obtained with pure ammonium perchlorate under an atmosphere of flowing air.
- FIGURE II is a differential thermal analysis curve obtained with a mixture of ammonium perchlorate and urea.
- solid stabilizing agents could be employed, and mixtures of such solids with ammonia gas could be combined in either open or closed systems to produce satisfactory stabilizing results. That is, for example, a mixture of ammonium carbonate, urea and ammonia gas in a closed system would have satisfactory stabilizing properties.
- ammonia producing composition compound employed is that the amount of ammonia gas produced thereby be sufficient to effect thermal stability of the ammonium perchlorate at elevated temperatures.
- excessive amounts of such gas producing agents are not required and would not be employed particularly in explosive and propellant compositions.
- Forming the ammonia gas in situ in a closed system is particularly attractive in certain solid propellant compositions and explosive compositions having a relatively high density.
- ammonia gas in situ eliminates the need for diffusional passages and the like, for if such a gas producing compound is intermixed throughout the propellant, upon decomposition the ammonia gas produced would be entrapped in the propellant grain itself, thereby exerting its stabilizing effect on the ammonium perchlorate present in the immediate area defined by the propellant grain.
- the propellant grain therefore would serve as the container for the gaseous ammonia, exerting the necessary mechanical forces to retain the gas within the grain.
- the ammonia producing stabilizing compounds can be employed in open systems, loss of some of the ammonia gas produced cannot be avoided, thus rendering this approach economically less attractive.
- the rate of flow of the ammonia produced by decomposition of the ammonia producing compound will be sufficient to maintain a partial pressure of ammonia sufficient to stabilize the ammonium perchlorate at the environmental temperature.
- the rate of flow of the ammonia can range from about 1 to about 500 cc. (measured at room temperature and atmospheric pressure) per 1% g. or" amomnium perchlorate per minute.
- the rate of flow of the ammonia gas is from about 5 to about 100 cc. per 100 g. ammonium perchlorate per minute.
- Ammonium perchlorate is usually prepared by reacting sodium perchlorate and ammonium chloride in aqueous solution to produce ammonium perchlorate and sodium chloride.
- Ammonium perchlorate has a temperature gradient of solubility that is substantially greater than that of sodium chloride and this difference in solubility has been utilized in a number of known processes for separating these two products. Usually a cyclic process is employed and often multiple separation steps or even fractional crystallization are required to produce an ammonium perchlorate product having the requisite purity.
- the composite propellant explosives containing ammonium perchlorate are generally composed of from about 10 to about 30% of a linear polymeric binder and a curing agent and from about 70 to about ammonium perchlorate oxidizing agent, ballistic modifiers and other suitable additives necessary to achieve the desired performance of the propellant or explosive.
- the propellant contains less than about 10% matrix, it has undesirable physical properties, exhibits deficiencies in physical strength and is difficult to process.
- the physical properties of the propellant improve as the matrix content is increased. However, when this value exceeds about 30%, the propellant again exhibits unsatisfactory ballistic properties such as lack of strength to withstand field handling, acceleration, and the like and difficulty in ignition, decreased total energy, smoke or carbonaceous exhaust products, etc.
- any solid ino r ganic or organic oxidizing agent compatible with ammonium perchlorate and thermally stable under the conditions imposed and capable of reacting with the matrix and other fuel ingredients in combustion processes can be used.
- an additional oxidizing agent such as lithium perchlorate, ammonium nitriate and potassium perchlorate can be tolerated within certain concentration limitations even through these materials heretofore had adverse elfects on the thermal stability of the ammonium perchlorate.
- the stabilizing compounds depress the adverse effects such oxidizing compounds have on ammonium perchlorate thereby allowing their use as oxidizing agents along with ammonium perchlorate or, for that matter, as impurities in the ammonium perchlorate.
- certain organic derivatives of nitric acid, hydrogen peroxide, chromic acid and perchloric acid can be tolerated due to this depressing effect of the herein defined stabilizing compounds.
- the propellant may also contain various components to enhance its ballistic properties, thus various oxidizer decomposition catalysts can be employed as well as materials such as ammonium oxalate and the like which serve to cool the gases generated by the propellant.
- composition can be provided with different ballistic potential by the incorporation of carbon black, copper chromite, ferrocene or other suitable rate catalysts.
- the propellant can also contain finely divided metallic components such as aluminum, magnesium, berryllium and the like.
- Composite, solid propellant grains normally consist of ammonium perchlorate uniformly distributed through a matrix of fuel binder material.
- the propellant grains are usually made by mixing the solid oxidizing agent and other solid additives which may be present to enhance the ballistic and physical performance of the product with the liquid matrix which is solidified after uniform dispersion of the solid materials has been obtained.
- the liquid linear polymer binder employed for the matrix of the propellant grain includes those polymerized products resulting from the reaction of one or more types of monomers and in the stricter sense, copolymers of two monomers, terpolymers of three monomers, etc.
- liquid linear polymer binder materials have active centers for cross-linking and curing of the linear polymers is effected in the presence of the various cross linking agents reacted with these active centers.
- the cross-linking is accomplished by a reaction of a bifunctional compound with active centers in the linear chain polymer and is accompanied by marked increase in the viscosity of the solution.
- Polymers particularly well suited to use in developing the matrix of the propellant include the class of polymers derived from unsaturated carboxylic acids of the acrylic acid type such as acrylic acid, methacrylic acid and vinyl acrylic acid.
- Polymers derived from various ethylenically unsaturated olefins and diolefins such as styrene, acrylonitrile, methacrylonitrile, vinylidene chloride, butadiene, isoprene, 2,3-dimethylbutadiene, chloroprene and the like are particularly preferred a as source of fuel.
- various other materials can be used in forming the matrix, for example, various polysulfidm and urethanes are often employed.
- Other materials such as nitrocellulose, polyesters, polyethers and various polyamides can also be satisfactorily employed as a matrix for the propellant or explosive compositions.
- the vessel containing the ammonium perchlorate contained in the closed system should be capable of withstanding the pressures imposed thereon either initially or by the in situ formation of the stabilizing ammonia gas.
- Various conventional pressure vessels capable of withstanding such pressures as are encountered in the instant invention would be suitable and are well known in the art.
- the differential thermal analysis method referred to in the drawings is a convenient method used for determining the thermal stability of substances such as ammonium perchlorate.
- the sample under study is heated simultaneously with, but separately from, a material known to undergo no thermal changes over the temperature range. That is, a substance which is thermally inert and undergoes no physical or chemical changes over the temperature range of interest.
- thermally stable substances as aluminum oxide, potassium chloride and sodium chloride are often used as reference materials in differential thermal analysis.
- the temperature of the ammonium perchlorate is measured continuously as Well as the temperature difference between the ammonium perchlorate and the inert reference material.
- Example A This example illustrates the thermal instability of am monium perchlorate at elevated temperatures under an atmosphere of flowing air.
- FIGURE I is the differential thermal analysis curve obtained for ammonium perchlorate by means of the differential thermal analysis method described above. It is apparent from the curve in FIGURE I that at about 240 C. an endotherm corresponding to a crystallographic transition occurs, immediately followed by an exothermic break. Decomposition is evident at this exothermic break by the condensation of liquids and solids above the cooler portions of the sample test tube. The exotherm was found to peak at about 307 C. Between about 310 C. and about 400 C. there is a gradual change in the temperature differential value and at about 400 C. a large exotherm starts. Upon the completion of this exotherm, the decomposition of the ammonium perchlorate was complete.
- the following example illustrates the differential thermal analysis obtained for a mechanical mixture of ammonium perchlorate and urea.
- Example B A mechanical mixture of weight percent ammonium perchlorate and 10 weight percent urea is subjected to thermal analysis. It is found that the heating together of the components of this mixture results in the internal generation of ammonia gas and the consequent increase of thermal stability of ammonium perchlorate. This result is illustrated in FIGURE II of the drawing wherein it is evident that no exotherm occurs following the endotherm at 240 C. and it is also noted that no condensate or liquid is observed above the sample. Only at about 300 C. is there evidence of the onset of decomposition as seen by the presence of condensate. However, decomposition becomes rapid at about 380 C. as evidenced by the small exotherm and finally at about 400 C. the large exotherm starts to form with subsequent complete decomposition of the ammonium perchlorate content.
- Example C Ammonium perchlorate (50 grams) is placed on a glass liner in a 500 cc. stainless steel bomb. The bomb is then heated and maintained at a temperature of 200 C. for 16 hours. During this period a substantial increase in pressure in the bomb is observed. This increase in pressure is attributed to the accumulation of ammonium perchlorate decomposition products such as oxygen, nitrogen, nitrogen oxides, hydrochloric gas, water vapor and the like.
- Example D An intimate mixture of ammonium perchlorate (50 grams and ammonium carbonate (2 grams) is placed on a glass liner in a 500 cc. stainless steel bomb. The bomb is heated and maintained at a temperature of 200 C. for 16 hours. No substantial increase in the total pressure is observed beyond that attributable to the presence of ammonium carbonate; thus indicating that the ammonium perchlorate is retained in a condition substantially free from decomposition.
- ammonium bicarbonate can be used in a closed system to produce results comparable to those achieved in Example D.
- a process of improving the thermal stability of compositions containing ammonium perchlorate which comprises mixing with said ammonium perchlorate at least one solid compound capable of decomposing into ammonia at a temperature below 200 C. selected from the group consisting of ammonium carbonate, ammonium bicarbonate and urea.
- An ammonium perchlorate-containing propellant composition having improved thermal stability at elevatcd temperatures comprising a mixture of major proportion of ammonium perchlorate, a minor proportion of a polymeric fuel binder composition and at least one solid compound capable of decomposing into ammonia at a temperature below 200 C. selected from the group consisting of ammonium carbonate, ammonium bicarbonate and urea.
- composition of claim 5 wherein said compound comprises ammonium carbonate.
- composition of claim 5 wherein said compound comprises ammonium bicarbonate.
- composition of claim 5 wherein said compound comprises urea.
- An ammonium perchlorate composition having improved thermal stability at elevated temperatures comprising a mixture of ammonium perchlorate and at least one solid compound capable of decomposing into ammonia at a temperature below 200 C. selected from the group consisting of ammonium carbonate, ammonium bicarbonate and urea.
- composition of claim 9 wherein said compound comprises ammonium carbonate.
- composition of claim 9 wherein said compound comprises ammonium bicarbonate.
- composition of claim 9 wherein said compound comprises urea.
Description
March 9, 1965 M. M. MARKOWITZ PROPELLANT COMPOSITIONS CONTAINING STABILIZED AMMONIUM PERCHLORATE Filed Oct. 12 1962 I 300 TEM PERATUR E PURE NH4CLO4 IN AIR 5 INVENT M EYER M. MARKOW l T BY ATTYS R A m 1 0 A U E 1 T R M I U I E P I W l M T E W J T O -w 4 w I I H i N O L I M l O -m N19 United States Patent 3,172,793 PROEELLANT (IGMPQSITEQNS CGNTAENENG STABTLEZED AMYMQN Meyer M. Marlrowitz, Ardnrore, Ra, assignor to Foote Mineral Company, Philadelphia, Pin, a corporation of Pennsylvania Filed Get. 12, 1962, Ser. No. 2.302% 12 Claims. (Cl. 149-19) This invention relates to a process for improving the stability of ammonium perchlorate and to ammonium perchlorate-containin g compositions having improved stability. More particularly, this invention is directed to a process whereby the thermal stability of ammonium perchlorate is improved and to mixtures containing ammonium perchlorate having improved thermal stability.
There is at present a considerable demand for ammonium perchlorate of high purity for use as an oxidizer in solid rocket propellants and various explosives. Ammonium perchlorate oxidizing agents are particularly attrative in propellants and explosives because of their low hygroscopicity and high density, the latter property resulting in propellant compositions having attractive density and bulk strength properties.
Ammonium perchlorate, however, is inherently unstable at elevated temperatures. This undesirable stability characteristic has severely limited the range of utility of materials containing ammonium perchlorate to fairly low temperature applications. It is extremely important that propellants maintain a predetermined burning rate; this rate is in part dependent upon accurately controlling the stability of the oxidizer employed. It is further essential that the ballistic potential of a propellant be maintained within critical limits even during rolonged exposure to extreme variations in thermal conditions. However, composite solid propellants containing an ammonium perchlorate oxidizer have been susceptible to decomposition during storage when exposed to rises in temperature. Similarly such compositions tend to decompose during use when exposed to temperature rises due to aerodynamic heating. Such decomposition of the ammonium perchlorate oxidizer results in changes in the ballistic properties of the composition. For example, ballistic deficiencies such as decreased total energy, sporadic burning rates and the like result which tend to produce propellant compositions having unreliable ballistic properties.
Unless precautions are taken in manufacturing and storing ammonium perchlorate, the crystals thereof will generally contain water, either occluded therein or absorbed thereon. This water tends to cause caking of the product during storage and processing difiiculties during manufacture of ammonium perchlorate containing compositions. For example, the presence of Water in ammonium perchlorate crystals tends to cause blocking of the orifices of pulverizing and sizing equipment used to comminute the oxidizer to the desired particle size, thus impeding control of the particle size. Moreover, solid propellant compositions usually contain polymerizable components and any water associated with the ammonium perchlorate would interfere with such polymerization. Of course, the presence of water in any form in a solid propellant represents an unattractive weight addition to the propellant.
Therefore, it is accepted practice in the propellant and explosive industry to subject ammonium perchlorate compositions to relatively low temperature drying processes wherein drying conditions below the decomposition temperature of the ammonium perchlorate are maintained for prolonged periods to produce a substantially waterfree crystalline product suitable for use in explosives and propellants.
"ice
It is known that certain compounds which are present during the production of ammonium perchlorate, often are retained in the finished product. It is further known that when these compounds such as perchloric acid and potassium perchlorate are present in the ammonium perchlorate product in even trace amounts, they have a deleterious effect on ammonium perchlorate, particularly with respect to its thermal stability. Additionally, certain low melting point, inorganic compounds, such as lithium perchlorate, adversely afiect the thermal stability of ammonium perchlorate by forming a low melting point liquid phase. E tectic mixtures of low melting point inorganic compounds and ammonium perchlorate have considerably less thermal stability than the pure ammo nium perchlorate. Therefore, if ammonium perchlorate is exposed to temperatures near its decomposition temperature it is essential that it be essentially free from such impurities and low melting point inorganic compounds to avoid decomposition. In order to avoid such effects, exhaustive purifying processes are employed to produce an essentially pure ammonium perchlorate product.
Composite solid rocket propellant grains normally consist of at least one solid oxidizing agent such as ammonium perchlorate uniformly distributed throughout a matrix of a fuel-binder material. The propellant grains are generally made by mixing the solid oxidizing agent, and other particulate materials used to enhance the ballistic and physical performance of the product, with a liquid linear polymer binder. Generally, the propellant mixture is solidified by curing the polymer binder at a temperature below the decomposition temperature of ammonium perchlorate. Even in the presence of various curing promoters such as cross-linking agents and the like, this curing process is time consuming and diflicult because of the low operating temperature restrictions imposed on the process by the thermal instability of the ammonium perchlorate oxidizing agent present.
It is therefore an object of this invention to provide a process for the stabilization of ammonium perchlorate at elevated temperatures.
It is also an object of this invention to provide an improved composition containing ammonium perchlorate, said composition being stable at elevated temperatures.
It is another object of this invention to provide a process whereby ammonium perchlorate and mixtures containing ammonium perchlorate can be stored and used at relatively high temperatures without adversely affecting the stability of the ammonium perchlorate or of the mixture in which it is contained.
A further object of the invention is to provide a propellant containing an ammonium perchlorate oxidizer which can be used and stored without degradation throughout a fairly broad temperature range.
Still another object of the invention is to provide an improved method of drying ammonium perchlorate.
It is also an object of the invention to provide an ammonium perchlorate composition which can tolerate various impurities while maintaining a satisfactory thermal stability.
Another object of the invention is to provide an improved method of curing compositions containing ammonium perchlorate.
Other objects of the invention will become apparent from a consideration of the following specification, drawing and the claims.
It has been discovered that the thermal stability of ammonium perchlorate at elevated temperatures can be unexpectedly improved by mixing with the ammonium perchlorate a compound capable of producing an atmosphere of ammonia at a temperature below the decom:
position temperature of the ammonium perchlorate. That is, it has now been discovered that ammonium perchlorate, propellants, and other compositions containing ammonium perchlorate can be stabilized at high temperatures without degradation of the ammonium perchlorate by providing an atmosphere of ammonia, said gas obtained from the decomposition of certain substances having a decomposition temperature below that of ammonium perchlorate.
Examples of solid compounds, which decompose, forming ammonia gas at a temperature below about 200 C. include ammonium carbonate, ammonium bicarbonate and urea. However, not all compositions capable of producing ammonia produce a stabilizing effect on ammoniurn perchlorate at elevated temperatures, for example ammonium nitrate, ammonium chloride and ammonium bromide do not have satisfactory decomposition temperatures and do not stabilize ammonium perchlorate at elevated temperatures.
In a preferred embodiment the solid compounds which are capable of producing ammonia at the requisite temperature are used in a closed system, wherein the stabilizing ammonia gas once produced is retained within the confines of the system.
It is understood that the stabilizing compounds suitable for use in a closed system can have decomposition temperatures substantially below 200 C. The decomposition products of these stabilizers will be retained in the closed system to impart their stabilizing effect on the ammonium perchlorate at elevated temperatures.
It has been found that the unexpected thermal stabilizing effects of the stated compounds are apparently limited to ammonium perchlorate. That is, other perchlorates used as oxidizing substances, for example, potassium perchlorate and sodium perchlorate which are similarly sensitive to elevated temperatures substantially decom pose at their decomposition temperature in the presence of the compounds in open and/ or closed systems.
It has further been discovered that the stabilizing compounds impart an unexpected stabilizing effect to am monium perchlorate compositions containing impurities. That is, it has been found that the adverse effects on the thermal stability of ammonium perchlorate compositions produced by certain impurities such as perchloric acid and lithium perchlorate which were discussed above, are unexpectedly suppressed by the instantly described stabilizing compounds. Such impurities can be tolerated in ammonium perchlorate compositions which are subjected to high temperatures if the composition is maintained in the presence of the stabilizers, therefore, extensive purifying and processing of ammonium perchlorate is rendered unnecessary.
The present invention can advantageously be utilized to remove water from water contaminated ammonium perchlorate by means of high-temperature drying meth ods, while avoiding the hazard of decomposition of the oxidizer. Thus, the rate of drying ammonium perchlorate can be increased significantly. Moreover, the increased thermal stability achieved by the stabilizers of the invention can be utilized in producing ammonium perchloratecontaining explosives wherein the oxidizer is included in the explosive grain during curing of the liquid polymer fuel composition. By means of the present invention curing of the liquid polymer fuel can be achieved at significantly higher temperatures.
The present invention will be more readily understood from a consideration of the drawings in which:
FIGURE I is a conventional differential thermal analysis curve obtained with pure ammonium perchlorate under an atmosphere of flowing air; and
FIGURE II is a differential thermal analysis curve obtained with a mixture of ammonium perchlorate and urea.
Mixtures of the solid stabilizing agents could be employed, and mixtures of such solids with ammonia gas could be combined in either open or closed systems to produce satisfactory stabilizing results. That is, for example, a mixture of ammonium carbonate, urea and ammonia gas in a closed system would have satisfactory stabilizing properties.
The only significant limitation on the amount of ammonia producing composition compound employed is that the amount of ammonia gas produced thereby be sufficient to effect thermal stability of the ammonium perchlorate at elevated temperatures. On the other hand, excessive amounts of such gas producing agents are not required and would not be employed particularly in explosive and propellant compositions.
Forming the ammonia gas in situ in a closed system is particularly attractive in certain solid propellant compositions and explosive compositions having a relatively high density.
Forming the ammonia gas in situ eliminates the need for diffusional passages and the like, for if such a gas producing compound is intermixed throughout the propellant, upon decomposition the ammonia gas produced would be entrapped in the propellant grain itself, thereby exerting its stabilizing effect on the ammonium perchlorate present in the immediate area defined by the propellant grain. The propellant grain therefore would serve as the container for the gaseous ammonia, exerting the necessary mechanical forces to retain the gas within the grain. Although the ammonia producing stabilizing compounds can be employed in open systems, loss of some of the ammonia gas produced cannot be avoided, thus rendering this approach economically less attractive.
The rate of flow of the ammonia produced by decomposition of the ammonia producing compound will be sufficient to maintain a partial pressure of ammonia sufficient to stabilize the ammonium perchlorate at the environmental temperature. For example, the rate of flow of the ammonia can range from about 1 to about 500 cc. (measured at room temperature and atmospheric pressure) per 1% g. or" amomnium perchlorate per minute. Preferably the rate of flow of the ammonia gas is from about 5 to about 100 cc. per 100 g. ammonium perchlorate per minute.
Ammonium perchlorate is usually prepared by reacting sodium perchlorate and ammonium chloride in aqueous solution to produce ammonium perchlorate and sodium chloride. Ammonium perchlorate has a temperature gradient of solubility that is substantially greater than that of sodium chloride and this difference in solubility has been utilized in a number of known processes for separating these two products. Usually a cyclic process is employed and often multiple separation steps or even fractional crystallization are required to produce an ammonium perchlorate product having the requisite purity.
The composite propellant explosives containing ammonium perchlorate are generally composed of from about 10 to about 30% of a linear polymeric binder and a curing agent and from about 70 to about ammonium perchlorate oxidizing agent, ballistic modifiers and other suitable additives necessary to achieve the desired performance of the propellant or explosive. When the propellant contains less than about 10% matrix, it has undesirable physical properties, exhibits deficiencies in physical strength and is difficult to process. The physical properties of the propellant improve as the matrix content is increased. However, when this value exceeds about 30%, the propellant again exhibits unsatisfactory ballistic properties such as lack of strength to withstand field handling, acceleration, and the like and difficulty in ignition, decreased total energy, smoke or carbonaceous exhaust products, etc.
In addition to ammonium perchlorate, any solid ino r ganic or organic oxidizing agent compatible with ammonium perchlorate and thermally stable under the conditions imposed and capable of reacting with the matrix and other fuel ingredients in combustion processes can be used. Moreover, by means of the present invention the use of an additional oxidizing agent such as lithium perchlorate, ammonium nitriate and potassium perchlorate can be tolerated within certain concentration limitations even through these materials heretofore had adverse elfects on the thermal stability of the ammonium perchlorate. That is, it will be recalled that the stabilizing compounds depress the adverse effects such oxidizing compounds have on ammonium perchlorate thereby allowing their use as oxidizing agents along with ammonium perchlorate or, for that matter, as impurities in the ammonium perchlorate. In addition, certain organic derivatives of nitric acid, hydrogen peroxide, chromic acid and perchloric acid can be tolerated due to this depressing effect of the herein defined stabilizing compounds. The propellant may also contain various components to enhance its ballistic properties, thus various oxidizer decomposition catalysts can be employed as well as materials such as ammonium oxalate and the like which serve to cool the gases generated by the propellant. Moreover, the composition can be provided with different ballistic potential by the incorporation of carbon black, copper chromite, ferrocene or other suitable rate catalysts. The propellant can also contain finely divided metallic components such as aluminum, magnesium, berryllium and the like.
Composite, solid propellant grains normally consist of ammonium perchlorate uniformly distributed through a matrix of fuel binder material. The propellant grains are usually made by mixing the solid oxidizing agent and other solid additives which may be present to enhance the ballistic and physical performance of the product with the liquid matrix which is solidified after uniform dispersion of the solid materials has been obtained. The liquid linear polymer binder employed for the matrix of the propellant grain includes those polymerized products resulting from the reaction of one or more types of monomers and in the stricter sense, copolymers of two monomers, terpolymers of three monomers, etc. Usually these liquid linear polymer binder materials have active centers for cross-linking and curing of the linear polymers is effected in the presence of the various cross linking agents reacted with these active centers. The cross-linking is accomplished by a reaction of a bifunctional compound with active centers in the linear chain polymer and is accompanied by marked increase in the viscosity of the solution. Polymers particularly well suited to use in developing the matrix of the propellant include the class of polymers derived from unsaturated carboxylic acids of the acrylic acid type such as acrylic acid, methacrylic acid and vinyl acrylic acid. Polymers derived from various ethylenically unsaturated olefins and diolefins such as styrene, acrylonitrile, methacrylonitrile, vinylidene chloride, butadiene, isoprene, 2,3-dimethylbutadiene, chloroprene and the like are particularly preferred a as source of fuel. In addition to these polymers, various other materials can be used in forming the matrix, for example, various polysulfidm and urethanes are often employed. Other materials such as nitrocellulose, polyesters, polyethers and various polyamides can also be satisfactorily employed as a matrix for the propellant or explosive compositions.
When a closed system is employed it is understood that the vessel containing the ammonium perchlorate contained in the closed system should be capable of withstanding the pressures imposed thereon either initially or by the in situ formation of the stabilizing ammonia gas. Various conventional pressure vessels capable of withstanding such pressures as are encountered in the instant invention would be suitable and are well known in the art.
The differential thermal analysis method referred to in the drawings is a convenient method used for determining the thermal stability of substances such as ammonium perchlorate. According to this method, the sample under study is heated simultaneously with, but separately from, a material known to undergo no thermal changes over the temperature range. That is, a substance which is thermally inert and undergoes no physical or chemical changes over the temperature range of interest. Such thermally stable substances as aluminum oxide, potassium chloride and sodium chloride are often used as reference materials in differential thermal analysis. During heating, the temperature of the ammonium perchlorate is measured continuously as Well as the temperature difference between the ammonium perchlorate and the inert reference material. By plotting the results of heating the two samples, a curve of sample temperature versus temperature difference is obtained, where changes in the slope and discontinuities of the curve indicate the occurrence of chemical or physical changes in the ammonium perchlorate. Thermal decomposition of ammonium perchlorate proceeds by virtue of an exothermic oxidation/reduction reaction and therefore readily lends itself to study by the differential thermal analysis method.
The present invention will be more readily understood from a consideration of the following examples which are given for the purpose of illustration only and are not intended to limit the scope of the invention in any way.
Example A This example illustrates the thermal instability of am monium perchlorate at elevated temperatures under an atmosphere of flowing air.
One gram samples of ammonium perchlorate and aluminum oxide are separately, but simultaneously, heated from about 50 C. to about 500 C. in the presence of 50 cc./min. of flowing air. The aluminum oxide reference material exposed to similar conditions is essentially inert throughout this temperature range. Therefore, any changes in the slope of the differential thermal analysis curve would indicate endothermic or exothermic changes occurring in the ammonium perchlorate material.
FIGURE I is the differential thermal analysis curve obtained for ammonium perchlorate by means of the differential thermal analysis method described above. It is apparent from the curve in FIGURE I that at about 240 C. an endotherm corresponding to a crystallographic transition occurs, immediately followed by an exothermic break. Decomposition is evident at this exothermic break by the condensation of liquids and solids above the cooler portions of the sample test tube. The exotherm was found to peak at about 307 C. Between about 310 C. and about 400 C. there is a gradual change in the temperature differential value and at about 400 C. a large exotherm starts. Upon the completion of this exotherm, the decomposition of the ammonium perchlorate was complete.
The following example illustrates the differential thermal analysis obtained for a mechanical mixture of ammonium perchlorate and urea.
Example B A mechanical mixture of weight percent ammonium perchlorate and 10 weight percent urea is subjected to thermal analysis. It is found that the heating together of the components of this mixture results in the internal generation of ammonia gas and the consequent increase of thermal stability of ammonium perchlorate. This result is illustrated in FIGURE II of the drawing wherein it is evident that no exotherm occurs following the endotherm at 240 C. and it is also noted that no condensate or liquid is observed above the sample. Only at about 300 C. is there evidence of the onset of decomposition as seen by the presence of condensate. However, decomposition becomes rapid at about 380 C. as evidenced by the small exotherm and finally at about 400 C. the large exotherm starts to form with subsequent complete decomposition of the ammonium perchlorate content.
7' The following examples (C and D) illustrate the stabilizing effect of ammonium carbonate on ammonium perchlorate at elevated temperatures in a closed system.
Example C Ammonium perchlorate (50 grams) is placed on a glass liner in a 500 cc. stainless steel bomb. The bomb is then heated and maintained at a temperature of 200 C. for 16 hours. During this period a substantial increase in pressure in the bomb is observed. This increase in pressure is attributed to the accumulation of ammonium perchlorate decomposition products such as oxygen, nitrogen, nitrogen oxides, hydrochloric gas, water vapor and the like.
Example D An intimate mixture of ammonium perchlorate (50 grams and ammonium carbonate (2 grams) is placed on a glass liner in a 500 cc. stainless steel bomb. The bomb is heated and maintained at a temperature of 200 C. for 16 hours. No substantial increase in the total pressure is observed beyond that attributable to the presence of ammonium carbonate; thus indicating that the ammonium perchlorate is retained in a condition substantially free from decomposition.
It is further understood that ammonium bicarbonate can be used in a closed system to produce results comparable to those achieved in Example D.
From the foregoing description it will be evident that numerous variations and modifications can be made in the present process without departure from the invention.
The claims:
1. A process of improving the thermal stability of compositions containing ammonium perchlorate which comprises mixing with said ammonium perchlorate at least one solid compound capable of decomposing into ammonia at a temperature below 200 C. selected from the group consisting of ammonium carbonate, ammonium bicarbonate and urea.
2. The process according to claim 1 wherein said compound comprises ammonium carbonate.
3. The process according to claim 1 wherein said compound comprises ammonium bicarbonate.
4. The process according to claim 1 wherein said compound comprises urea.
5. An ammonium perchlorate-containing propellant composition having improved thermal stability at elevatcd temperatures comprising a mixture of major proportion of ammonium perchlorate, a minor proportion of a polymeric fuel binder composition and at least one solid compound capable of decomposing into ammonia at a temperature below 200 C. selected from the group consisting of ammonium carbonate, ammonium bicarbonate and urea.
6. The composition of claim 5 wherein said compound comprises ammonium carbonate.
7. The composition of claim 5 wherein said compound comprises ammonium bicarbonate.
8. The composition of claim 5 wherein said compound comprises urea.
9. An ammonium perchlorate composition having improved thermal stability at elevated temperatures comprising a mixture of ammonium perchlorate and at least one solid compound capable of decomposing into ammonia at a temperature below 200 C. selected from the group consisting of ammonium carbonate, ammonium bicarbonate and urea.
10. The composition of claim 9 wherein said compound comprises ammonium carbonate.
11. The composition of claim 9 wherein said compound comprises ammonium bicarbonate.
12. The composition of claim 9 wherein said compound comprises urea.
References Cited in the file of this patent UNITED STATES PATENTS 792,511 Frank June 13, 1905 1,273,477 Given July 23, 1916 2,997,501 Shino et a1. Aug. 22, 1961 3,002,830 Barr Oct. 3, 1961 3,024,595 Helvenston et al Mar. 13, 1962
Claims (1)
- 5. AN AMMONIUM PERCHLORATE-CONTAINING PROPELLANT COMPOSITION HAVING IMPROVED THERMAL STABILTIY AT ELEVATED TEMPERATURES COMPRISING A MIXTURE OF MAJOR PROPORTION OF AMMONIUM PERCHLORATE, A MINOR PROPORTION OF A POLYMERIC FUEL BINDER COMPOSITION AND AT LEAST ONE SOLID COMPOUND CAPABLE OF DECOMPOSING INTO AMMONIA AT A TEMPERATURE BELOW 200*C. SELECTED FROM THE GROUP CONSISTING OF AMMONIUM CARBONATE, AMMONIUM BICARBONATE AND UREA.
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US3172793D Expired - Lifetime US3172793A (en) | Temperature xc |
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Cited By (9)
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US3770527A (en) * | 1969-11-20 | 1973-11-06 | Martin Marietta Corp | Nitranium perchlorate reaction rate alteration |
US3770526A (en) * | 1971-11-26 | 1973-11-06 | Us Army | Combustion composition containing a ferrocenyl or carboramyl derivative |
US3798088A (en) * | 1973-03-05 | 1974-03-19 | Us Navy | Cocrystallization of ammonium perchlorate and stabilization of solid propellants |
US3870577A (en) * | 1970-10-09 | 1975-03-11 | Us Navy | Process for making whisker-like crystals of ammonium perchlorate |
US4201605A (en) * | 1978-07-31 | 1980-05-06 | The United States Of America As Represented By The Secretary Of The Navy | Gas generator propellant for airbreathing missiles |
US5346512A (en) * | 1993-08-05 | 1994-09-13 | Thiokol Corporation | Carbon treatment of reclaimed ammonium perchlorate |
US20040231765A1 (en) * | 2001-05-28 | 2004-11-25 | Kjell Anflo | Ammonium dinitrimide based liquid monopropelants exhibiting improved combustion stability and storage life |
FR2863608A1 (en) * | 2003-12-10 | 2005-06-17 | Snpe Materiaux Energetiques | New composite solid propergol based on a polyether with hydroxyl terminations with reduced sensitivity to impact or heating useful in the preparation of insensitive munitions |
WO2017131840A3 (en) * | 2015-11-18 | 2017-09-28 | Aerojet Rocketdyne, Inc. | Additive for solid rocket motor having perchlorate oxidizer |
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US1273477A (en) * | 1917-09-10 | 1918-07-23 | Atlas Powder Co | Method of producing ammonium perchlorate. |
US2997501A (en) * | 1958-08-04 | 1961-08-22 | Shiino Kazuo | 1, 3-dinitro-1, 3-dimethyl urea |
US3002830A (en) * | 1959-01-02 | 1961-10-03 | Olin Mathieson | Method of manufacturing solid propellants having a polymeric fuel-binder using a plurality of crosslinking agents |
US3024595A (en) * | 1959-01-07 | 1962-03-13 | Pittsburgh Plate Glass Co | Method of rocket propulsion using liquid ammonia and ammonium perchlorate |
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US792511A (en) * | 1904-08-10 | 1905-06-13 | Adolph Frank | Explosive composition. |
US1273477A (en) * | 1917-09-10 | 1918-07-23 | Atlas Powder Co | Method of producing ammonium perchlorate. |
US2997501A (en) * | 1958-08-04 | 1961-08-22 | Shiino Kazuo | 1, 3-dinitro-1, 3-dimethyl urea |
US3002830A (en) * | 1959-01-02 | 1961-10-03 | Olin Mathieson | Method of manufacturing solid propellants having a polymeric fuel-binder using a plurality of crosslinking agents |
US3024595A (en) * | 1959-01-07 | 1962-03-13 | Pittsburgh Plate Glass Co | Method of rocket propulsion using liquid ammonia and ammonium perchlorate |
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3770527A (en) * | 1969-11-20 | 1973-11-06 | Martin Marietta Corp | Nitranium perchlorate reaction rate alteration |
US3870577A (en) * | 1970-10-09 | 1975-03-11 | Us Navy | Process for making whisker-like crystals of ammonium perchlorate |
US3770526A (en) * | 1971-11-26 | 1973-11-06 | Us Army | Combustion composition containing a ferrocenyl or carboramyl derivative |
US3798088A (en) * | 1973-03-05 | 1974-03-19 | Us Navy | Cocrystallization of ammonium perchlorate and stabilization of solid propellants |
US4201605A (en) * | 1978-07-31 | 1980-05-06 | The United States Of America As Represented By The Secretary Of The Navy | Gas generator propellant for airbreathing missiles |
US5346512A (en) * | 1993-08-05 | 1994-09-13 | Thiokol Corporation | Carbon treatment of reclaimed ammonium perchlorate |
US20040231765A1 (en) * | 2001-05-28 | 2004-11-25 | Kjell Anflo | Ammonium dinitrimide based liquid monopropelants exhibiting improved combustion stability and storage life |
US7976653B2 (en) * | 2001-05-28 | 2011-07-12 | Svenska Rymdaktiebolaget | Ammonium dinitrimide based liquid monopropelants exhibiting improved combustion stability and storage life |
FR2863608A1 (en) * | 2003-12-10 | 2005-06-17 | Snpe Materiaux Energetiques | New composite solid propergol based on a polyether with hydroxyl terminations with reduced sensitivity to impact or heating useful in the preparation of insensitive munitions |
WO2017131840A3 (en) * | 2015-11-18 | 2017-09-28 | Aerojet Rocketdyne, Inc. | Additive for solid rocket motor having perchlorate oxidizer |
US11023884B2 (en) | 2015-11-18 | 2021-06-01 | Aerojet Rocketdyne, Inc. | Additive for solid rocket motor having perchlorate oxidizer |
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