FR2877334A1 - Composition, useful e.g. to propel a vehicle, comprises three types of principal constitutive ingredients: a binder; a pulverulent oxidant; and a solid metal powder; and presenting a balance out of oxygen less than 50 percentage - Google Patents

Abstract

Composition (I) of composite solid propellant type, comprises three types of principal constitutive ingredients: a binder (10-15 mass %); a pulverulent oxidant (15-25 mass %); and a solid metal (aluminum, magnesium, silicon, boron, titanium and/or zirconium) powder (60-75 mass %); and presenting a balance out of oxygen less than 50% (preferably 70%). An independent claim is also included for production of energy comprising: combustion of (I) (generating metal gases charged with the state vapor and/or liquid); and reaction of the metal gases charged with water.

Description

2877334 1

  The present invention relates to a composition of the composite solid propellant type and a method of producing energy. More specifically, it relates to: a composition of the solid composite propellant type, which has adequate ballistic properties and is capable of generating (by combustion) pressurized hot gases charged with metals in the vapor and / or liquid state. Said composition is very strongly oxygenated to prevent the formation of metal oxide and thus be able to generate charged gases in the maximum of metals in the vapor and / or liquid state. Said gases are, in the presence of water (oxidizing reagent), very reactive; a method of producing energy, based on the use of said composite solid propellant type composition, based on the reactivity with water of the gases generated during the combustion of said composition, pressurized hot gases charged with metals to the vapor and / or liquid state.

  The present invention has more particularly been developed in the context of the propulsion of (underwater) vehicles and the propulsion of torpedoes. In such a context, in order to limit the volume of reagents to be loaded, seawater is advantageously used as an oxidizing reagent.

  According to the prior art, the reaction energy of water with substances reacting with said water has already been used in the propulsion of marine vehicles. Thus: US Pat. No. 2,461,797 describes the injection into water of a metal borohydride reacting strongly with said water; said metal borohydride, however, being phlegmatized in a suitable gel or liquid; US-A-3 044 252 discloses a water pulsator system in which a device pushes in a combustion chamber a wire of a substance reacting with water (called "hydrofuel"), for example a lithium or sodium wire; US Pat. No. 5,421,153 describes the injection of liquid Na-K ("hydrofuel") into a reaction chamber.

  US-A-5 139 589 discloses a process for phlegmatizing metal hydrides reacting with water.

  The systems described have numerous drawbacks: they generally use products which are very reactive with water and therefore very difficult to handle and store; they comprise pumps and other auxiliary devices for supplying the reaction chamber with water and reactive product ("hydrofuel"); - The combustion chamber must have a very sophisticated geometry, to optimize its operation.

  According to the invention, new compositions of the composite solid propellant type are proposed, capable of generating, by combustion, reactive gases (loaded with liquid and / or gaseous metals), themselves capable of reacting with water to produce water. energy and this, in devices with simple configuration. In fact, a new concept of reagents is proposed: gas charged with metal in vapor and / or liquid state, generated from a propellant and therefore a new concept of reaction: water / metal (aux) in gaseous state and / or liquid.

  Thus, according to its first object, the present invention relates to said new compositions of the composite solid propellant type.

  A composite solid propellant comprises, in a manner known per se, a solid polymeric matrix or binder, containing pulverulent solid charges: oxidizing, possibly reducing and / or energetic as well as various additives of feasibility, performance.

  The binder is generally prepared from a liquid resin, having chemically reactive terminations, capable of being crosslinked under the joint action of heat and at least one curing agent also liquid.

  For the preparation of the propellant is introduced into the liquid resin, in an appropriate order, its various constituent ingredients and the crosslinking agent. The resin, by hardening, by baking at a temperature compatible with the presence of pyrotechnic materials, coats said ingredients and in particular the powdery solid charges, to form a solid body.

  The novel compositions of the invention, of the composite solid propellant type, capable of generating (by combustion) gases loaded with metals in the vapor and / or liquid state, comprise the three main types of main constitutive ingredients hereafter. in the following relative proportions: a) 10 to 15% by weight of a binder, b) 15 to 25% by weight of a powdery oxidant; and c) 60 to 75%, by weight, of at least one pulverulent solid metal, said at least one metal being selected from aluminum, magnesium, silicon, boron, titanium, zirconium and mixtures of these metals; and have an oxygen balance of less than -50%, preferably less than -70%.

  Said compositions are very strongly oxygenated to prevent the formation, during their combustion, of metal oxide and thus to generate, during said combustion, the maximum of metals. The qualifier "very strongly under oxygenated" is quantified by the values given above of oxygen balance ("O) rygen Balance = OB = equilibrium in oxygen"). This parameter is familiar to those skilled in the art. It is particularly specified by J. Quinchon in "powders, propellants and explosives", Volume 1, Ed. Technique and Documentation Lavoisier (1982): "the equilibrium is called oxygen, the comparison between the amount of oxygen present in a molecule and the one necessary to completely oxidize in the state of H20, CO2, SO3, AI203 ... the fuel elements of said molecule If this balance is positive, that is to say if there is a surplus in oxygen, the product is "superoxygenated", and therefore in general more powerful than a product "under oxygenated" (with negative balance) ".

  The oxygen balance (the oxidizing power) for each element is calculated in the following way: OB_ valence (element). molar mass (oxygen) 100 valence (oxygen). molar mass (element) 'taking, when the element has several possible valences, the most usual or an average. For a composition: OBcomposition = E xi. OBi, with xi the mass fraction of the element i in said composition.

  The intervening binder is chosen from the binders usually used, advantageously from binders, which are at the same time not or little oxygenated 2877334 4 (the aim is to minimize or even avoid any formation of metal oxide) and not or little nitrogen (the aim is to minimize even avoid any formation of metal nitride, to minimize or even avoid any deposit of nitrogen on the metal). Said binder can be a hydrocarbon binder, for example of the polyether type. It can also be of the polydiene type. Thus, said binder can in particular be prepared from a polybutadiene with hydroxytelechelic terminations (PBHT). Said polybutadiene with hydroxytelechelic terminations (PBHT) is preferably at the functionality 2, 4. For purely illustrative purposes, it may be mentioned here that the product sold under the name R45HT by the company ATOFINA is suitable.

  Binder has been mentioned in that it generally involves a single compound capable of performing this binder function. However, it is not entirely excluded from the scope of the invention to mix at least two such compounds.

  The oxidant that can be used in the compositions of the invention (in the same way, it is not totally excluded to involve at least two oxidants in a mixture) is not particularly limited to a particular type. It may especially be chosen from ammonium perchlorate, ammonium dinitramide, hexogen and hexanitrohexaazaisowurtzitane. The compositions of the invention advantageously contain, as oxidant, ammonium perchlorate. The oxidant level is: defined so as to give the propellant the ballistic properties required. It is not currently a real optimization of said properties.

  The third main constituent of the compositions of the invention is a solid metal or a mixture of solid metals. It is selected from aluminum, magnesium, silicon, boron, titanium, zirconium and mixtures of these metals. These metals were selected in view of the desired result, especially in view of their low propensity to react with oxygen. The compositions of the invention advantageously contain magnesium or a mixture of magnesium and aluminum in a weight ratio equal to or substantially equal to 1.

  Oxidants) and solid metal (s) are present in powder form. The skilled person is able to optimize their granulometry. They intervene advantageously to a fine particle size of a few tens of microns. They can even intervene at a submicron granulometry.

  The preparation of the compositions of the invention does not pose any particular difficulty. Said compositions are prepared as specified upstream, according to a method analogous to the preparation of composite solid propellants. The method comprises mixing the main constituents: a) the binder, b) the powdery oxidant and c) the at least one powdery solid metal. This mixture is conventionally used in a kneader, at a temperature of between about 40 ° C. and about 70 ° C., under low pressure to facilitate degassing. In a way that is in no way limitative, an embodiment variant of this process for preparing the compositions of the invention is specified below.

  In the liquid binder, the possible various additives (except the crosslinking agent and the crosslinking catalyst) and the powdery metallic filler are introduced. The resulting mixture is homogenized and degassed. Then, the oxidizing charge is introduced. The resulting new mixture is thoroughly homogenized. Finally, in said homogenized mixture, the crosslinking agent and the crosslinking catalyst are introduced. The homogenized final mixture is poured by the effect of gravity or injected into a suitable structure where it is heated to a temperature sufficient for the binder to be crosslinked.

  It is understood that in addition to their three types of main constituents specified above, the compositions of the invention contain effective but minimal quantities of optional additives, crosslinking catalyst (s) and crosslinking agent (s) ( the crosslinker (s) is found in the structure of the crosslinked binder).

  By way of additives, the following may in particular be used: plasticizers, binder / filler adhesion additives, antioxidant ("anti-aging") agents, combustion catalysts, and additives facilitating the implementation.

  Such additives, crosslinking catalyst (s) and crosslinking (s) generally represent at most 5% by weight, very generally at most 2% by weight, of the compositions of the invention. Thus, the three types of constituent ingredients; The main oxidant (s), oxidant (s), metal (s) of the compositions of the invention generally represent at least 95% by weight, very generally at least 98% by weight of said compositions.

  Those skilled in the art have already understood all the advantages of the compositions of the invention, very strongly oxygenated, capable of generating a combustion gas, containing little metal oxide (s), loaded with metals to the metal. vapor state and / or liquid, a fuel gas per very reactive. Said gas is also generated at high pressure with propulsion energy.

  The use of the compositions of the invention as a precursor of such a fuel gas for supplying a combustion chamber with said metals in the liquid and / or vapor state is particularly suitable. Such a chamber is thus fed with said metals, in the liquid and / or vapor state, in a propelled gas flow. It is also supplied with water, advantageously seawater collected outside.

  Such technology, to compare with those described in the US patents cited in the introduction of this text, is particularly interesting. It allows in particular to solve the following difficulties: E the control of the injection of the metal ("hydrofuel"), E the obtaining of a good combustion efficiency, E the simplification of the configuration of the combustion chamber of the metal.

  It is quite naturally the second object of the present invention, i.e., a method of producing energy. Such a process comprises: the combustion of a composition, as described above, which composition constitutes the first object of the present invention; and the reaction of the gases generated containing little metal oxide (s) and loaded with metals in the vapor and / or liquid state, with water.

  Advantageously, such a method is implemented in two contiguous chambers so that the gases generated in the first chamber are reacted in the second, the passage of said gases from said first to said second chamber operating under the single effect of 2877334 7 their pressure. It is thus exempted from the intervention of any device of the injector type, pump ... because of the released propulsive energy.

  Advantageously, the energy production method of the invention therefore comprises: the combustion of a composition, as described above, in a combustion chamber; said combustion generating pressurized hot gases charged with metals in the vapor and / or liquid state; injecting, under their own pressure, said gases into an auxiliary chamber contiguous to said combustion chamber; - the admission of water into said auxiliary chamber; and - reacting, in said auxiliary chamber, said gases and said water.

  Whatever the exact context of carrying out the process of the invention, the gas / water reaction advantageously involves water at 20 to 90% by weight of the gas mass.

  The water in question, in a context of propulsion of (under) marine vehicles and torpedoes, is generally sea water. It thus contributes to limiting the volume to be loaded.

  The gas / water reaction produces energy in the form of a mixture of water vapor and gas, optionally charged with particles. This energy is recovered in a manner known per se, in particular for actuating a turbine or for producing a thrust, by expansion in a nozzle of said mixture.

  The method of the invention for producing energy is thus advantageously used for the use of the energy produced in these contexts: for actuating a turbine or for producing a thrust, in particular for propelling (under) marine vehicles, to propel torpedoes. The method of the invention is advantageously used in the context of the propulsion of very fast torpedoes, in particular those operating in supercavitant condition. In such a context, discretion is not required and it is therefore advantageous to use a solid propellant rocket engine to provide propulsion.

  According to the invention, it is therefore proposed new solid propellants whose composition is optimized so that they generate, by combustion, the maximum of metals, in the vapor and / or liquid state (thus avoiding the formation of metal oxide). Said metals, propelled 2877334 8 in a gas stream, are then perfectly suitable for reacting with water and producing energy. The concept of the invention is summarized in these two sentences.

  The invention is now illustrated, in its various aspects, in no way limiting, by the examples below.

  EXAMPLE 1 Composition according to the procedure previously described: The powdery aluminum has a particle size of less than 30 μm, the magnesium powder a particle size distribution. less than 40 μm.

  Composition A has an oxygen balance of -82.19%.

  A thermochemical calculation from the ingredients gives the combustion temperature as well as the majority components of the gases.

  The results are shown in Table 1 for combustion at a pressure of 7 MPa.

Table 1

  Tc (K) 2313 Majority Products (% mass) 19 Mg (liq) Mg (gas) MgO (sol) 12.9 Al (liq) 22 AIN (soil) 7 It is interesting to note that the combustion of this composition produces more 40% Mg and Al in the liquid or gaseous state.

  PBHT-based binder 12% by weight E Ammonium perchlorate 20% by weight Al Al 34% by weight E Mg 34% by weight Density = 1.801.

  Example 2: Composition_B _;> elon the inv_ention, _EvaluatioD.

  Composition B was prepared from the following components, according to the procedure previously described: PBHT-based binder 12% by mass E Ammonium perchlorate 20% by mass Mg 68% by weight Density = 1.607 The powdered magnesium has a particle size of less than 40 μm.

  Composition B has an oxygen balance of -74.32%.

  A thermochemical calculation from the ingredients gives the combustion temperature as well as the majority components of the gases.

  The results are presented in Table 2 for combustion at a pressure of 7 MPa.

Table 2

  The combustion of this composition produces 45% of liquid or gaseous Mg.

  Evaluation of the Propulsive Performance To illustrate the second aspect of the present invention, the performances of a rocket engine operating with the gases produced by the compositions A and B of the invention, generators of reactive gas, are evaluated by calculation. with water.

  Table 3 shows the results of specific impulse calculation (Isp) in a 100 to 4 expansion for the products of the gas / water reaction for different mixing ratios (% by weight). The pulse Tc (K) Majority Products (% mass) Mg (Liq) Mg (gas) MgO (sol) 28 17 29 2877334 10 is the thrust supplied per mass flow unit of reactive products, it is evaluated in seconds .

Table 3

  % water 30 50 65 80 Ex. 1,292.1 404 478 576 Ex. 2 295.1 385.4 452.3 571 For each of the compositions A and B, it can be seen that in the interval considered here the Isp increases very strongly when the percentage of water increases and for water rates below 30 Io composition B is more efficient.

  A propellant conventionally currently used and containing 12% of binder, 68% of ammonium perchlorate and 20% of aluminum has under the same conditions a specific impulse volume of 428.2 sg / cm-3. The concept described herein The invention therefore allows a very significant gain in energy performance.

  Table 4 presents the calculations of the specific volume impulse, expressed in s.g. cm-3; it is the product (in the mathematical sense) of the specific impulse by the specific mass of the gas-generating propellant. The density of the composition A being greater than that of the composition B, the advantage in Isp low water (here 30%) of the composition B on the composition A is gummed.

Table 4

  water 30 50 65 80 Ex. 1 526.1 727.6 860.9 1 037.4 Ex. 2 472.5 617.0 724, 1 914.2

Claims (1)

11 CLAIMS   1. Composition of the solid composite propellant type, comprising the following three types of main constituent ingredients, in the following relative proportions: a) 10 to 15%, by weight of a binder, b) 15 to 25 %, by mass, of a powdery oxidant; and c) 60 to 75%, by weight, of at least one pulverulent solid metal, said at least one metal being selected from aluminum, magnesium, silicon, boron, titanium, zirconium and mixtures of these metals; and having an oxygen balance of less than -50%, preferably less than -70%.   2. Composition according to claim 1, characterized in that the binder is produced from a polybutadiene with hydroxytelechelic terminations.   3. Composition according to one of claims 1 or 2, characterized in that the oxidant is selected from ammonium perchlorate, ammonium dinitramide, hexogen and hexanitrohexaazaisowurtzitane.   4. Composition according to any one of claims 1 to 3, characterized in that the oxidant is ammonium perchlorate.   5. Composition according to any one of claims 1 to 4, characterized in that the at least one solid metal is selected from magnesium and a mixture of magnesium and aluminum in a mass ratio equal to or substantially equal to 1.   6. A method of producing energy, characterized in that it comprises: the combustion of a composition according to any one of claims 1 to 5, said combustion generating gasses charged with metals in the vapor state and / or liquid; and reacting said metal-laden gases with water.   7. Process according to claim 6, characterized in that it comprises: said combustion, in a combustion chamber; Injecting the gases generated, under their own pressure, into an auxiliary chamber contiguous to said combustion chamber; - the admission of water into said auxiliary chamber; and - reacting, in said auxiliary chamber, said gases and said water.   8. The method of claim 6 or 7, characterized in that said gas / water reaction is carried out with the water involved at a rate of 20 to 90% by weight of the mass of gas.   9. Method according to any one of claims 6 to 8, characterized in that it is implemented to actuate a turbine.   10. Process according to any one of claims 6 to 8, characterized in that it is used to produce a thrust, by expanding the reaction products in a nozzle.   11. Method according to any one of claims 6 to 10, characterized in that it is implemented to propel a vehicle (underwater) or a torpedo.