EP0611141A1 - Giessbare zweibasige Treibstoffe mit Metallionen der Gruppe IIA enthaltenden Verbindungen als Ballistikmodifikatoren - Google Patents

Giessbare zweibasige Treibstoffe mit Metallionen der Gruppe IIA enthaltenden Verbindungen als Ballistikmodifikatoren Download PDF

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Publication number
EP0611141A1
EP0611141A1 EP94300922A EP94300922A EP0611141A1 EP 0611141 A1 EP0611141 A1 EP 0611141A1 EP 94300922 A EP94300922 A EP 94300922A EP 94300922 A EP94300922 A EP 94300922A EP 0611141 A1 EP0611141 A1 EP 0611141A1
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EP
European Patent Office
Prior art keywords
propellant
burn rate
group iia
propellants
solid propellant
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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EP94300922A
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English (en)
French (fr)
Inventor
Jamie B C/O Thiokol Corporation Neidert
Robert E Askins
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ATK Launch Systems LLC
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Thiokol Corp
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    • 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
    • C06B23/007—Ballistic modifiers, burning rate catalysts, burning rate depressing agents, e.g. for gas generating

Definitions

  • the present invention is related to methods and compositions for modifying the burn rate of solid rocket motor propellants, without the addition of expensive, toxic or polluting materials, such as lead or copper. More particularly, the present invention is related to the use of Group IIA metal ions, added in the form of Group IIA salts or similar materials, to modify the burn rate of solid rocket motor propellants.
  • the rocket motor case forms the exterior of the rocket motor and provides the essential structural integrity for the rocket motor.
  • the rocket motor case is conventionally manufactured from a rigid, yet durable, material such as steel or filament wound composite.
  • propellant grain Placed within the interior of the rocket motor case is the propellant grain.
  • the propellant forming the grain is conventionally burned to form thrust within the interior of the rocket motor case.
  • the formation of hot gases upon burning of the propellant, and the subsequent exit of those gases through the throat and nozzle of the case provide the thrust to propel the rocket motor.
  • Solid propellants are used extensively in the aerospace industry. Solid propellants have developed as the preferred method of powering most missiles and rockets for military, commercial, and space applications.
  • Solid rocket motor propellants have become widely accepted because of the fact that they are relatively simple to manufacture and use, and they have excellent performance characteristics. Furthermore, solid propellant rocket motors are generally more simple than liquid fuel rocket motors. For all of these reasons, it is found that solid rocket propellants are very reliable and economical.
  • the rocket motor perform with reduced or eliminated smoke output.
  • smoke causes a number of disadvantages.
  • the smoke produced may obscure the vision of pilots or drivers of a craft or vehicle firing the tactical rocket.
  • the production of smoke makes tracking the source of the motor easier, a serious disadvantage during military operations.
  • the pressure created within the casing may exceed the design capability of the casing, resulting in damage or destruction to the device. If the propellant does not develop a sufficient burn rate, there may not be sufficient thrust to propel the rocket motor over the desired course.
  • Burn rate modifiers are generally added in order to control the burning rate and pressure exponent of the propellant to lower the pressure exponent or to cause a "plateau" at an operable level.
  • Plateau burning behavior (sometimes referred to as platonization) is typified by a zero, or very low, exponent over a 700 to 3000 psig range in a logarithmic plot of the burning rate versus pressure.
  • a mesa burning is typified by a zero slope at some point, followed by a negative burning rate at some higher pressure.
  • pressure exponent means the slope of a curve plotted with burn rate in inches per second on the Y axis and pressure in pounds per square inch on the X axis.
  • the present invention is related to methods and compositions for modifying the burn rate of solid rocket motor propellants, without the addition of expensive, toxic, hazardous, or polluting materials, such as lead and copper. More particularly, the present invention is related to the use of Group IIA metal ions (generally added in the form of Group IIA metal salts), or similar materials, to modify the burn rate of a solid rocket motor propellant. Examples of such materials include calcium carbonate and strontium carbonate. The addition of such materials has been found to be effective in modifying the burn rate of certain propellants in order to provide a more usable and controllable propellant product.
  • the present invention has been found particularly effective in controlling the burn rate of propellants containing a combination of nitrocellulose/nitrate esters.
  • the propellants may also include ammonium nitrate.
  • Nitrocellulose for example, may comprise the binder component of such propellants.
  • Such propellants are widely used as solid rocket motor propellants.
  • a propellant of this general type may be formulated as follows: Material Percentage Range Ammonium Nitrate 0-25 Carbon (amorphous) 0.5-1.0 Nitrocellulose (NC) 15-20 BTTN 39-54 TMETN 13-17 HMX 0-10 MNA 1-2
  • BTTN and TMETN are nitrate esters.
  • BTTN is 1,2,4 butanetrioltrinitrate and TMETN is trimethylolethane trinitrate.
  • HMX is cyclotetramethylene tetranitramine, a solid ingredient used widely in explosives and propellants. This type of propellant is known to be relatively low in smoke output and, therefore, is desirable for uses where minimum smoke is a significant benefit.
  • formulations within the ranges set forth above are fqund to be relatively insensitive to accidental ignition (32 cards in the NOL card gap test).
  • the present invention is particularly adaptable to propellants of this type which are often referred to as "double base” propellants.
  • Double base propellants have been widely used for a long period of time.
  • the term “double base” merely indicates that two primary explosive ingredients are present (typically nitrocellulose (NC), nitroglycerin (NG), and/or other nitrate esters). Accordingly, the present invention is found to provide good results in double base propellants.
  • that term refers to propellants incorporating at least two nitrate esters.
  • One typical method of NG incorporation in this system is solventless, whereby the NG is mixed with an aqueous slurry of NC, filtered, then rolled or pasted into a powder while heating. Another method incorporates solvents such as acetone. A final method employs solid NC in a rocket chamber which is then swelled with NG or nitrate esters to then form the propellant grain.
  • the castable (pourable) double base discussed herein requires none of these difficult procedures.
  • the castable double base propellant is readily cast in any device after only one mix procedure or cycle.
  • the mix cycle involves the vacuum mixing of a preblend containing NC, TMETN, BTTN, and MNA (N-methylnitro aniline). Desired ballistic additives are incorporated, followed by the addition of curing agents, further mixing, and vacuum casting of samples.
  • the present invention teaches the addition of non-toxic, non-hazardous, and non-polluting burn rate modifiers to nitrate ester/ammonium nitrate propellants.
  • One such burn rate modifier is calcium carbonate, however, other Group IIA metal salts also fall within the scope of the present invention.
  • Such other salts include, for example, strontium carbonate.
  • burn rate modifiers which are not based on lead or similar toxic materials.
  • Figure 1 is a graph plotting burn rate data obtained from propellant compositions within the scope of the present invention.
  • Figure 2 is a graph plotting burn rate data obtained from propellant compositions within the scope of the present invention.
  • Figure 3 is a graph plotting burn rate data obtained from propellant compositions within the scope of the present invention.
  • Figure 4 is a graph plotting burn rate data obtained from propellant compositions within the scope of the present invention.
  • Figure 5 is a graph plotting burn rate data obtained from propellant compositions within the scope of the present invention.
  • Figure 6 is a graph plotting burn rate data obtained from propellant compositions within the scope of the present invention.
  • Figure 7 is a graph plotting burn rate data obtained from propellant compositions within the scope of the present invention.
  • Figure 8 is a graph plotting burn rate data obtained from propellant compositions within the scope of the present invention.
  • Figure 9 is a graph plotting burn rate data obtained from propellant compositions within the scope of the present invention.
  • Figure 10 is a graph plotting burn rate data obtained from propellant compositions within the scope of the present invention.
  • Figure 11 is a graph plotting burn rate data obtained from a propellant composition within the scope of the present invention.
  • Figure 12 is a graph plotting burn rate data obtained from a comparison of a propellant incorporating lead oxide with a propellant incorporating calcium carbonate.
  • Figure 13 is a motor pressure/time trace.
  • Figure 14 is a plot of smoke transmissivity.
  • the present invention is related to methods and compositions for modifying the burn rate of solid rocket motor propellants, without the addition of expensive, toxic, hazardous, or polluting materials, such as lead and copper and their related compounds.
  • the present invention is related to the use of Group IIA metal ions incorporated within the propellant matrix as burn rate modifiers.
  • Those ions are typically added in the form of Group IIA metal salts.
  • Examples of such salts include calcium carbonate and strontium carbonate.
  • the Group IIA metal salts, or other similar compounds, added to the propellant formulation may have a relatively wide range of particle sizes.
  • particle sizes in the range of from about 0.5 ⁇ to about 35 ⁇ fall within the scope of the present invention and produced the desired effect when incorporated into a propellant matrix. It has been discovered, however, that particle sizes in the range of from about 2 ⁇ to about 3 ⁇ results in a particularly acceptable formulations.
  • burn rate modifiers comprise from about 0.5% to about 5.0% of the overall propellant. More particularly, it is found that propellants having from about 1.0% to about 3.0% produce propellants having good burning rate characteristics. Particularly good performance has been observed with from about 1.5% to about 2.0% Group IIA metal salt added.
  • the present invention is particularly useful when used with propellant compositions based upon a combination of nitrate esters, optionally including ammonium nitrate or HMX. It should be appreciated, however, that the present invention is expected to produced beneficial results with other types of propellants, such as ammonium perchlorate-based propellants, cross-linked double base (“XLDB”), and extruded double base propellants, and minimum smoke (nitrato plasticized) propellants.
  • XLDB cross-linked double base
  • XLDB extruded double base propellants
  • minimum smoke (nitrato plasticized) propellants minimum smoke (nitrato plasticized) propellants.
  • Such exemplary formulations may have the following ingredients, in the following percentages (by weight): Material Percentage Range Ammonium Nitrate 0-25 Group IIA metal salt (such as CaCO3) 1.5-2.0 Carbon (amorphous) 0.5-1.0 Nitrocellulose 15-20 BTTN 39-54 TMETN 13-17 MNA 0-1.0 HMX 0-10 Material Percentage Range Nitrocellulose 20-25 BTTN 0-5 TMETN 16-20 MNA 0.7-1.2 Curative 1.5-2.5 Cure Catalyst 0.03-0.08 Group IIA metal salt 1.0-3.0 Carbon 0.3-0.7
  • Propellants falling within the scope of the present invention are found to provide excellent burn rate control.
  • such formulations result in burn rate v. pressure curves which exhibit a significant "plateau.”
  • the plateau effect provides the ability to control the pressure produced by burning the propellant, and allows one to construct a propellant grain which is suitable for use in a rocket motor casing.
  • the formulations of the present invention exhibit other beneficial characteristics.
  • the propellants of the present invention are generally low smoke. This is a significant benefit, especially when the propellant is to be used in a tactical rocket motor. Low smoke propellants make it more difficult to precisely locate the point from which the rocket motor was fired. In addition, low smoke characteristics assure that visibility is not obstructed at the point of firing.
  • these formulations are relatively insensitive. Indeed, sensitivities of ⁇ 70 cards in the NOL card gap test are achievable. This increases the safety of the propellants and provides the ability to use the propellants with confidence, even in hazardous environments such as military operations. Such insensitive propellants are much less likely to be accidently detonated.
  • compositions within the scope of the present invention where prepared, burned, and characterized.
  • the propellants had the following percentage compositions (by weight): Composition #1 Material Percentage NC 15.9 BTTN 40.53 TMETN 13.51 MNA 1.7 TMXDI 1.35 AN 24.80 Calcium Carbonate 1.50 Carbon 0.7 Triphenyl bismuth (TPB/MA) 0.02 Legend in Figure 1 ⁇ Composition #2 Material Percentage NC 15.9 BTTN 40.53 TMETN 13.51 MNA 1.7 TMXDI 1.35 AN 25.0 Calcium Carbonate 1.50 Carbon 0.5 Triphenyl bismuth 0.02 Legend in Figure 1 ⁇
  • Nitrocellulose used in these formulations as a binder as well as being one of the nitrate ester components
  • BTTN, TMETN, and MNA were incorporated into the propellant in the form of a preblend as described above.
  • the preblend was prepared by dissolving or swelling the NC in acetone. After thorough mixing of all of the ingredients, all of the solvents were removed. This resulted in a lacquer preblend.
  • TMXDI is employed in the composition as a curing agent to cross-link the NC binder. It was found that the formulations set forth above produced acceptable low-smoke propellants having good burn rate control.
  • the propellant formulations were burned and the burn rate of the propellant formulations was plotted against pressure produced. The results of that plot are set forth in Figure 1. It can be seen from Figure 1 that the slope of both plots plateaus, indicating that the burn rates of the propellants are modified by the addition of calcium carbonate.
  • the burn rate v. pressure is within the range required for a usable propellant formulation.
  • Example propellants within the scope of the present invention where prepared, burned, and characterized.
  • the propellants differed in that particle size of calcium carbonate varied.
  • Calcium carbonate with a 12 micron particle size is designated by the symbol ⁇
  • calcium carbonate having an 8 micron particle size is designated by the symbol ⁇
  • a composition having calcium carbonate with a 3.3 micron particle size is designated with a ⁇ .
  • Each of the compositions had the following weight percentage compositions: Material Percentage NC 15.81 BTTN 40.39 TMETN 13.43 MNA 2.00 TMXDI 1.35 AN 25.0 Calcium Carbonate 1.50 Carbon (22m2/g) 0.5 Triphenyl bismuth 0.02
  • carbon of varying particle sizes was used.
  • the carbon used included ELFTEX-8 carbon with a particle size (surface area) of 64 m2/g, ELFTEX-12 carbon with a particle size of 35 m2/g, and STERLING R carbon with a particle size of 21 m2/g.
  • propellants within the scope of the present invention where prepared, burned, and characterized.
  • the propellants had the following weight percentage compositions: Composition #1 Material Percentage NC 21.26 BTTN 54.22 TMETN 18.07 MNA 1.95 TMXDI/N-100 1.94 Calcium carbonate 2.0 Carbon 0.50 TPB/MA 0.05 Composition #2 Material Percentage NC 21.31 BTTN 54.34 TMETN 18.11 MNA 1.95
  • carbon are varying particle sizes was used.
  • the carbon used included ELFTEX-8 carbon with a particle size of 64 m2/g and ELFTEX-12 carbon with a particle size of 35 m2/g.
  • the propellant 0.5% ELFTEX-12 carbon is designated ⁇
  • 0.5% ELFTEX-8 carbon is designated ⁇
  • 0.3% ELFTEX-12 carbon is designated ⁇
  • 0.3% ELFTEX-8 carbon is designated ⁇ .
  • Example propellant within the scope of the present invention where prepared, burned, and characterized.
  • the composition had the following weight percentage compositions: Material Percentage NC 20.27 BTTN 51.70 TMETN 17.23 MNA 1.90 TMXDI 1.84 Calcium Carbonate 1.50 Carbon 0.5 TPB/MA 0.05 HMX 5.0
  • Example a minimum smoke composite propellant within the scope of the present invention where prepared, burned, and characterized.
  • the composition had the following weight percentage compositions: Material Percentage Binder (inert polymers and curing agents) 6.16 BTTN 15.23 TMETN 7.62 MNA 0.5 Calcium Carbonate 1.50 Carbon 0.5 Al2O3 1.0 HMX 20.26 RDX 47.24
  • Figure 13 illustrates 70-grain motor traces for a formulation with 1% calcium carbonate compared to a formulation containing LC-12-15, which is a lead-copper complex of beta-resorcyclic acid.
  • LC-12-15 which is a lead-copper complex of beta-resorcyclic acid.
  • Neither formulation contained a classic combustion stability additive (i.e. ZrC, or Al2O3 which have historically increased card gap sensitivity by 30 cards or more).
  • the motor with calcium carbonate exhibits smooth combustion, whereas the leaded version is erratic. This appears to indicate that calcium oxide is generated during combustion, which in turn stabilizes performance.
  • Figure 14 illustrates a comparison of smoke output from a propellant within the scope of the present invention with a lead-containing propellant. It will be appreciated that the smoke outputs are similar, indicating that the present invention provides a minimum smoke formulation without the need for the use of toxic burn rate modifiers. This formulation (1.5% calcium carbonate) was determined to be 50 cards in the NOL card gap test.
  • the present invention provides methods and compositions for controlling the burn rate of solid rocket motor propellants. More particularly, the burn rate of nitrate ester/ammonium nitrate/HMX propellants have been shown to be controlled by the addition of Group IIA metal ions, particularly in the form of calcium carbonate and strontium carbonate.
  • the present invention provides compositions and methods for modifying burn rate without the use of lead, copper, or similar materials.
  • the burn rate is modified by the addition of calcium carbonate, or similar materials, which are not toxic, hazardous, or polluting.
  • the propellant formulation produced is a minimum smoke propellant which is also generally insensitive.
  • the major objects of the present invention are met by the compositions and methods of the present invention.

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EP94300922A 1993-02-08 1994-02-08 Giessbare zweibasige Treibstoffe mit Metallionen der Gruppe IIA enthaltenden Verbindungen als Ballistikmodifikatoren Withdrawn EP0611141A1 (de)

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US16381 1993-02-08

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103333036A (zh) * 2013-06-21 2013-10-02 宜宾北方川安化工有限公司 一种低临界压力双基推进剂
EP2503135B1 (de) 2011-03-23 2016-03-16 ROXEL France Doppelimpuls- und Mehrfachimpuls-Schubgenerator

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3009796A (en) * 1951-03-08 1961-11-21 Ralph F Preckel Gas-producing compositions of smokeless powder and metal compound inhibitors
US3841929A (en) * 1963-07-12 1974-10-15 Rockwell International Corp Solid propellant containing strontium carbonate-calcium citrate burning rate depressant
US3873386A (en) * 1971-06-28 1975-03-25 Us Navy Double-base propellant containing poly (carboranyl lower alkyl acrylate)
US4216039A (en) * 1978-11-20 1980-08-05 The United States Of America As Represented By The Secretary Of The Army Smokeless propellant compositions having polyester or polybutadiene binder system crosslinked with nitrocellulose
JPH07504721A (ja) * 1993-01-28 1995-05-25 セルモ　ファイバーテック　インコーポレイテッド 製紙機の回転フェルト吸い込み管用の支持装置

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3009796A (en) * 1951-03-08 1961-11-21 Ralph F Preckel Gas-producing compositions of smokeless powder and metal compound inhibitors
US3841929A (en) * 1963-07-12 1974-10-15 Rockwell International Corp Solid propellant containing strontium carbonate-calcium citrate burning rate depressant
US3873386A (en) * 1971-06-28 1975-03-25 Us Navy Double-base propellant containing poly (carboranyl lower alkyl acrylate)
US4216039A (en) * 1978-11-20 1980-08-05 The United States Of America As Represented By The Secretary Of The Army Smokeless propellant compositions having polyester or polybutadiene binder system crosslinked with nitrocellulose
JPH07504721A (ja) * 1993-01-28 1995-05-25 セルモ　ファイバーテック　インコーポレイテッド 製紙機の回転フェルト吸い込み管用の支持装置

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
CHEMICAL ABSTRACTS, vol. 069, no. 18, 28 October 1968, Columbus, Ohio, US; abstract no. 68698p, S. DELI ET AL.: "Methane-proof and non-methane-proof industrial explosive of high brisance and increased storability." page 6426; *
CHEMICAL ABSTRACTS, vol. 083, no. 10, 8 September 1975, Columbus, Ohio, US; abstract no. 82295a, J. KANEKO ET AL.: "Solid propellant chemical composition containing smokeless explosive material." page 201; *
CHEMICAL ABSTRACTS, vol. 106, no. 20, 18 May 1987, Columbus, Ohio, US; abstract no. 158905r, Z. LAZIC ET AL.: "Multifactorial analysis of technological conditions for the manufacture of double-base rocket fuels with high combustion rates." page 150; *
CHEMICAL PATENTS INDEX, DOCUMENTATION ABSTRACTS JOURNAL Derwent World Patents Index; AN 75-20239W *
NAUCNO-TEH. PREGL., vol. 36, no. 8, 1986, pages 28 - 34 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2503135B1 (de) 2011-03-23 2016-03-16 ROXEL France Doppelimpuls- und Mehrfachimpuls-Schubgenerator
CN103333036A (zh) * 2013-06-21 2013-10-02 宜宾北方川安化工有限公司 一种低临界压力双基推进剂
CN103333036B (zh) * 2013-06-21 2016-06-29 宜宾北方川安化工有限公司 一种低临界压力双基推进剂

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