Multi-component synergistically coated active metal composite boron powder and preparation method thereof

Abstract

The invention provides multi-component synergistically coated active metal composite boron powder and a preparation method thereof, and relates to the field of boron / rare earth metal compounds. The preparation method comprises the following steps: mixing a fluorine-containing coating agent, an organic solvent and active metal composite boron powder, reacting under a heating condition, and performing vacuum drying to obtain primary activated metal composite boron powder; the preparation method comprises the following steps: mixing a boron-containing organic ligand, a metal zirconium salt and a polar solvent, reacting under a heating condition to obtain a crystalline boron-based MOF precursor, then adding a nano rare earth element catalyst REO, and reacting to obtain an MOF-REO compound; and mixing the primarily activated metal composite boron powder with the MOF-REO compound, and reacting under a heating condition to obtain the synergistically coated active metal composite boron powder. According to the preparation method provided by the invention, the active metal composite boron powder is synergistically coated with the fluorine-containing coating agent, the metal organic framework and the rare earth element catalyst, so that the active metal composite boron powder with high combustion efficiency and good compatibility is obtained.

Description

Technical Field

[0001] The present application relates to the field of boron / rare earth metal composites, and in particular to a multi-component synergistically coated active metal composite boron powder and a preparation method thereof. Background Art

[0002] Boron powder is widely used in propellants due to its high combustion calorific value, but boron has low combustion efficiency, high oxygen consumption, and incomplete combustion. In addition, its surface oxide film (B2O3) also hinders combustion efficiency.

[0003] In existing technologies, the removal of oxide films on the surface of boron particles is generally achieved by coating with a single coating material. However, while a single coating material can partially improve performance, it suffers from problems such as uneven coating and insufficient synergistic effects, resulting in limited performance improvements. Summary of the Invention

[0004] The purpose of this application is to provide a multi-component synergistically coated active metal composite boron powder and a preparation method thereof to solve the above problems.

[0005] To achieve the above objectives, this application adopts the following technical solutions:

[0006] A method for preparing multi-component synergistically coated active metal composite boron powder comprises:

[0007] A fluorine-containing coating agent, an organic solvent, and an active metal composite boron powder are mixed, subjected to a first reaction under heating conditions, and then vacuum dried to obtain a primary activated metal composite boron powder;

[0008] A boron-containing organic ligand, a metal zirconium salt, and a polar solvent are mixed and subjected to a second reaction under heating conditions to obtain a crystalline boron-based MOF (metal-organic framework) precursor. A nano-rare earth element catalyst REO is then added and subjected to a third reaction to obtain a MOF-REO complex.

[0009] The primary activated metal composite boron powder and the MOF-REO complex are mixed, and a fourth reaction is carried out under heating conditions to obtain the synergistically coated active metal composite boron powder.

[0010] Preferably, the preparation method of the multi-component synergistically coated active metal composite boron powder meets one or more of the following conditions:

[0011] (1) The fluorine-containing coating agent includes one or more of lithium fluoride, fluororubber, and fluorographite;

[0012] (2) The organic solvent includes one or more of dichloromethane, tetrahydrofuran, anhydrous ethanol, and ethyl acetate;

[0013] (3) The active metal composite boron powder includes boron-aluminum composite powder and / or boron-magnesium composite powder;

[0014] (4) The boron content of the active metal composite boron powder is 95-97 wt%;

[0015] (5) The molar ratio of the fluorine-containing coating agent to the boron in the active metal composite boron powder is 1:8-12;

[0016] (6) The active metal composite boron powder is dispersed in a dispersant before use, and the dispersant includes one or more of ethanol, ethylene glycol, and n-butanol.

[0017] Preferably, the preparation method of the multi-component synergistically coated active metal composite boron powder meets one or more of the following conditions:

[0018] (1) The temperature of the first reaction is 40-60°C;

[0019] (2) The first reaction is carried out under stirring.

[0020] Preferably, the preparation method of the multi-component synergistically coated active metal composite boron powder meets one or more of the following conditions:

[0021] (1) The boron-containing organic ligand comprises borate ester and / or phenylboronic acid;

[0022] (2) The metal zirconium salt includes ZrCl4 and / or Zr(NO3)4;

[0023] (3) The molar ratio of the boron-containing organic ligand to the metal zirconium salt is 1-4:1.

[0024] Preferably, the polar solvent includes one or more of N,N-dimethylformamide, N,N-diethylformamide, and dimethyl sulfoxide.

[0025] Preferably, the preparation method of the multi-component synergistically coated active metal composite boron powder meets one or more of the following conditions:

[0026] (1) The nano rare earth element catalyst REO includes one or more of CeO2, La2O3, and Gd2O3;

[0027] (2) The particle size of the nano rare earth element catalyst REO is 10-30 nm;

[0028] (3) The mass ratio of the nano rare earth element catalyst REO to the crystalline boron-based MOF precursor is 1:3-10;

[0029] (4) The molar ratio of the nano rare earth element catalyst REO to the boron in the active metal composite boron powder is 1:5-8.

[0030] Preferably, the temperature of the second reaction is 80-120° C., and the time is 24-72 hours.

[0031] Preferably, the preparation method of the multi-component synergistically coated active metal composite boron powder meets one or more of the following conditions:

[0032] (1) The third reaction time is 2-5 hours;

[0033] (2) The third reaction is carried out under stirring.

[0034] Preferably, the preparation method of the multi-component synergistically coated active metal composite boron powder meets one or more of the following conditions:

[0035] (1) The temperature of the fourth reaction is 40-60°C;

[0036] (2) When the primary activated metal composite boron powder and the MOF-REO composite are mixed, a dispersant is added, and the dispersant includes one or more of ethanol, ethylene glycol, and n-butanol.

[0037] The present application also provides a multi-component synergistically coated active metal composite boron powder, which is prepared using the preparation method of the multi-component synergistically coated active metal composite boron powder.

[0038] Compared with the prior art, the advantages of this application include:

[0039] The present application provides a method for preparing multi-component synergistically coated active metal composite boron powder, which uses a fluorine-containing coating agent to coat the active metal composite boron powder once. The fluorine-containing coating agent can react chemically with B2O3 on the surface of the active metal composite boron powder to generate a gaseous product (easily volatile BOF gas), thereby improving the ignition and combustion performance of the boron particles and significantly reducing the particle size of the boron powder condensed phase combustion product; a crystalline boron-based MOF precursor is prepared by combining a boron-containing organic ligand and a metal zirconium salt to obtain a pore structure capable of accommodating a nano-rare earth element catalyst REO, thereby providing a physical adsorption space for the nano-rare earth element catalyst, and the crystalline boron-based The high specific surface area and adjustable pore structure characteristics of the MOF precursor enhance the adsorption capacity of the nano rare earth element catalyst REO. At the same time, as a carrier, it can also enhance the dispersibility of the nano rare earth element catalyst REO; and the surface of the nano rare earth element catalyst REO is rich in oxygen vacancies, and forms a chemical bond with the ligand of the crystalline boron-based MOF precursor to enhance the binding force; the resulting MOF-REO complex can carry oxygen and increase the oxygen uptake of the boron particles in the ignition stage, which can promote the ignition of the boron particles and effectively shorten the ignition delay time, and can catalyze the reaction of hydrocarbons around the boron particles to a certain extent, thereby helping the combustion of the boron particles. Therefore, the preparation method provided by the present application can effectively inhibit the combustion and agglomeration of boron powder through a synergistic coating effect.

[0040] The multi-component synergistically coated active metal composite boron powder provided in the present application has high combustion efficiency and good compatibility, and meets the compatibility and high energy release requirements of the pharmaceutical process of boron-containing propellant. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0042] Figure 1 This is a transmission electron microscope image of the multi-component synergistically coated active metal composite boron powder obtained in Example 1;

[0043] Figure 2 This is a transmission electron microscope image of the product obtained in Comparative Example 9. DETAILED DESCRIPTION

[0044] In order to better illustrate the technical solution provided by this application, before the embodiments, an overall description of the technical solution is first given, as follows:

[0045] A method for preparing multi-component synergistically coated active metal composite boron powder comprises:

[0046] A fluorine-containing coating agent, an organic solvent, and an active metal composite boron powder are mixed, subjected to a first reaction under heating conditions, and then vacuum dried to obtain a primary activated metal composite boron powder;

[0047] A boron-containing organic ligand, a metal zirconium salt, and a polar solvent are mixed and subjected to a second reaction under heating conditions to obtain a crystalline boron-based MOF precursor. A nano-rare earth element catalyst REO is then added and subjected to a third reaction to obtain a MOF-REO complex.

[0048] The primary activated metal composite boron powder and the MOF-REO complex are mixed, and a fourth reaction is carried out under heating conditions to obtain the synergistically coated active metal composite boron powder.

[0049] It should be emphasized that it is not possible to coat the MOF-REO complex first and then the fluorine-containing coating agent, nor can the MOF-REO complex and the fluorine-containing coating agent be coated in a "one-step method". The reason is that the fluorine-containing coating agent mainly acts on the surface of the activated metal composite boron powder. If the MOF-REO complex is coated first and then the fluorine-containing coating agent, the MOF-REO complex will affect the function of the fluorine-containing coating agent; and if the "one-step method" is used for coating, there is a problem that the MOF-REO complex affects the function of the fluorine-containing coating agent, and the fluorine-containing coating agent negatively affects the MOF-REO complex to play a dominant role. In addition, if MOF is not used to load REO, and REO is coated directly after coating the fluorine-containing coating agent, there will be problems such as insufficient REO coating strength and inability to maximize the catalytic effect; and if the "one-step method" is used to coat the fluorine-containing coating agent and REO, there will be problems such as mutual negative impact. Furthermore, when using the one-step coating method, some fluorine-containing coating agents can be randomly embedded within the MOF pores, causing REO to fall off and the MOF-REO framework to collapse, resulting in uneven and incomplete coating. During combustion, the fluorine-containing coating agents embedded within the MOF cannot reach the boron oxide, thus failing to promote the combustion of the boron particles.

[0050] In an optional embodiment, the preparation method of the multi-component synergistically coated active metal composite boron powder meets one or more of the following conditions:

[0051] (1) The fluorine-containing coating agent includes one or more of lithium fluoride, fluororubber (such as Viton A), and fluorine graphite;

[0052] (2) The organic solvent includes one or more of dichloromethane, tetrahydrofuran, anhydrous ethanol, and ethyl acetate;

[0053] (3) The active metal composite boron powder includes boron-aluminum composite powder and / or boron-magnesium composite powder;

[0054] (4) The boron content of the active metal composite boron powder is 95-97 wt%;

[0055] Optionally, the boron content in the active metal composite boron powder may be 95wt%, 96wt%, 97wt% or any value between 95-97wt%;

[0056] (5) The molar ratio of the fluorine-containing coating agent to the boron in the active metal composite boron powder is 1:8-12;

[0057] If the amount of fluorine-containing coating agent used is too little, the surface film removal effect of the active metal composite boron powder will be poor; the fluorine-containing coating agent itself is a non-flammable component or a self-extinguishing component during combustion. If the amount of fluorine-containing coating agent used is too little, it will be detrimental to the release of combustion energy of the active metal composite boron powder.

[0058] Optionally, the molar ratio of the fluorine-containing coating agent to the active metal composite boron powder can be 1:8, 1:9, 1:10, 1:11, 1:12 or any value between 1:8 and 12;

[0059] (6) The active metal composite boron powder is dispersed in a dispersant before use, and the dispersant includes one or more of ethanol, ethylene glycol, and n-butanol.

[0060] In an optional embodiment, the preparation method of the multi-component synergistically coated active metal composite boron powder meets one or more of the following conditions:

[0061] (1) The temperature of the first reaction is 40-60°C;

[0062] Heating and stirring at 40-60°C is conducive to full contact between the surface of the boron particles and the coating agent. Below 40°C, the solvent volatilization efficiency is low, and above 60°C, the solvent evaporates too quickly and the coating agent cannot be evenly coated. During this process, the organic solvent evaporates, and the coating agent undergoes a process similar to recrystallization, and then is coated on the surface of the boron particles.

[0063] Optionally, the temperature of the first reaction can be 40°C, 50°C, 60°C or any value between 40-60°C;

[0064] (2) The first reaction is carried out under stirring.

[0065] In an optional embodiment, the preparation method of the multi-component synergistically coated active metal composite boron powder meets one or more of the following conditions:

[0066] (1) The boron-containing organic ligand comprises borate ester and / or phenylboronic acid;

[0067] (2) The metal zirconium salt includes ZrCl4 and / or Zr(NO3)4;

[0068] The pore size of the crystalline boron-based MOF precursor, obtained by combining zirconium salts with organic ligands, is well matched to that of nano-rare earth oxides. Furthermore, the zirconium-based MOF framework is rigid, stable, and resistant to collapse, allowing it to withstand higher loadings. MOFs derived from other metal salts generally have smaller pore sizes, which places higher demands on the size of nano-rare earth oxides. Nano-rare earth oxides below 10 nm are difficult to achieve, necessitating the selection of appropriate ligands and metal salts.

[0069] (3) The molar ratio of the boron-containing organic ligand to the metal zirconium salt is 1-4:1.

[0070] Optionally, the molar ratio of the boron-containing organic ligand to the metal zirconium salt can be 1:1, 2:1, 3:1, 4:1 or any value between 1 and 4:1.

[0071] In an optional embodiment, the polar solvent includes one or more of N,N-dimethylformamide, N,N-diethylformamide, and dimethyl sulfoxide.

[0072] In an optional embodiment, the preparation method of the multi-component synergistically coated active metal composite boron powder meets one or more of the following conditions:

[0073] (1) The nano rare earth element catalyst REO includes one or more of CeO2, La2O3, and Gd2O3;

[0074] (2) The particle size of the nano rare earth element catalyst REO is 10-30 nm;

[0075] Optionally, the particle size of the nano rare earth element catalyst REO can be 10 nm, 20 nm, 30 nm or any value between 10-30 nm;

[0076] (3) The mass ratio of the nano rare earth element catalyst REO to the crystalline boron-based MOF precursor is 1:3-10;

[0077] Optionally, the mass ratio of the nano rare earth element catalyst REO to the crystalline boron-based MOF precursor can be 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10 or any value between 1:3 and 10.

[0078] (4) The molar ratio of the nano rare earth element catalyst REO to the boron in the active metal composite boron powder is 1:5-8.

[0079] When the dosage of nano rare earth element catalyst REO is low, the effect of increasing the oxygen uptake of boron particles in the ignition stage is not obvious. The rare earth element catalyst will limit the diffusion of oxygen in the boron particles, which is not conducive to the ignition and combustion of the boron particles.

[0080] Optionally, the molar ratio of the nano rare earth element catalyst REO to the active metal composite boron powder can be 1:5, 1:6, 1:7, 1:8 or any value between 1:5-8.

[0081] In an optional embodiment, the temperature of the second reaction is 80-120° C., and the time is 24-72 hours.

[0082] Optionally, the temperature of the second reaction can be 80°C, 90°C, 100°C, 110°C, 120°C or any value between 80-120°C, and the time can be 24h, 36h, 48h, 60h, 72h or any value between 24-72h.

[0083] In an optional embodiment, the preparation method of the multi-component synergistically coated active metal composite boron powder meets one or more of the following conditions:

[0084] (1) The third reaction time is 2-5 hours;

[0085] The third reaction is carried out after the second reaction is completed. The temperature change of the system first undergoes a cooling process and then proceeds at room temperature.

[0086] Optionally, the time of the third reaction can be 2h, 3h, 4h, 5h or any value between 2-5h;

[0087] (2) The third reaction is carried out under stirring.

[0088] In an optional embodiment, the preparation method of the multi-component synergistically coated active metal composite boron powder meets one or more of the following conditions:

[0089] (1) The temperature of the fourth reaction is 40-60°C;

[0090] Optionally, the temperature of the fourth reaction may be 40°C, 50°C, 60°C or any value between 40-60°C;

[0091] (2) When the primary activated metal composite boron powder and the MOF-REO composite are mixed, a dispersant is added, and the dispersant includes one or more of ethanol, ethylene glycol, and n-butanol.

[0092] The present application also provides a multi-component synergistically coated active metal composite boron powder, which is prepared using the preparation method of the multi-component synergistically coated active metal composite boron powder.

[0093] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, the conditions are carried out according to conventional conditions or manufacturer recommendations. The reagents or instruments used are not specified by the manufacturer and are conventional products that can be purchased commercially.

[0094] Example 1

[0095] This embodiment provides a multi-component synergistically coated active metal composite boron powder, the preparation method of which is as follows:

[0096] (1) dissolving a fluorine-containing coating agent LiF in a solvent ethyl acetate to prepare a solution, adding active metal composite boron powder (boron-aluminum composite powder, boron content of 95 wt%) ultrasonically dispersed using an alcohol solvent ethylene glycol, wherein the molar ratio of the fluorine-containing coating agent to the active metal composite boron powder is 1:10; heating and stirring at 60°C, coating the fluorine-containing coating agent on the surface of the active composite boron powder by a recrystallization method, and vacuum drying to obtain a once-activated metal composite boron powder;

[0097] (2) The boron-containing organic ligand borate ester and the metal salt Zr(NO3)4 were mixed in dimethyl sulfoxide, wherein the molar ratio of the boron-containing organic ligand to the metal zirconium salt was 2:1; the mixture was reacted at 120°C for 72 hours to form a crystalline boron-based MOF precursor, and a nano rare earth element catalyst CeO2 with a particle size of 10 nm was added. The mass ratio of REO to the crystalline boron-based MOF precursor was 1:5, and the mixture was stirred for 2 hours. The mixture was filtered and dried to obtain a MOF-REO composite.

[0098] (3) The primary activated metal composite boron powder is ultrasonically dispersed in ethylene glycol, MOF-REO (the molar ratio of REO to boron in the active metal composite boron powder is 1:6) is added, and the mixture is heated and stirred at 60°C. The secondary coating is achieved by solvent evaporation to obtain the secondary activated metal composite boron powder, that is, the active metal composite boron powder with multi-component synergistic coating.

[0099] The transmission electron microscopy image of the obtained product is as follows Figure 1 shown.

[0100] Example 2

[0101] This embodiment provides a multi-component synergistically coated active metal composite boron powder, the preparation method of which is as follows:

[0102] (1) A fluorine-containing coating agent Viton A (fluororubber, produced by DuPont) is dissolved in tetrahydrofuran to prepare a solution, and active metal composite boron powder (boron-aluminum composite powder, boron content of 97 wt%) is added after ultrasonic dispersion using alcohol solvent ethanol, wherein the molar ratio of the fluorine-containing coating agent to the active metal composite boron powder is 1:8; heating and stirring at 60°C, the fluorine-containing coating agent is coated on the surface of the active composite boron powder by recrystallization, and vacuum drying is performed to obtain a once-activated metal composite boron powder;

[0103] (2) The boron-containing organic ligand phenylboric acid and the metal salt ZrCl4 were mixed in N,N-dimethylformamide, wherein the molar ratio of the boron-containing organic ligand to the metal zirconium salt was 2:1; the mixture was reacted at 100°C for 48 hours to form a crystalline boron-based MOF precursor, and a nano rare earth element catalyst (Gd2O3, particle size of 20 nm, mass ratio of REO to crystalline boron-based MOF precursor of 1:3) was added, stirred for 3 hours, filtered, and dried to obtain a MOF-REO composite.

[0104] (3) The primary activated metal composite boron powder was ultrasonically dispersed in ethanol, MOF-REO (the molar ratio of REO to boron in the active metal composite boron powder was 1:5) was added, and the mixture was heated and stirred at 60°C. The secondary coating was achieved by evaporation of the solvent to obtain the secondary activated metal composite boron powder, that is, the active metal composite boron powder with multi-component synergistic coating.

[0105] Example 3

[0106] This embodiment provides a multi-component synergistically coated active metal composite boron powder, the preparation method of which is as follows:

[0107] (1) dissolving a fluorine-containing coating agent LiF in dichloromethane to prepare a solution, adding active metal composite boron powder (boron-magnesium composite powder, boron content of 96 wt%) ultrasonically dispersed using an alcohol solvent n-butanol, wherein the molar ratio of the fluorine-containing coating agent to the active metal composite boron powder is 1:12; heating and stirring at 40°C, coating the fluorine-containing coating agent on the surface of the active composite boron powder by a recrystallization method, and vacuum drying to obtain a primary activated metal composite boron powder;

[0108] (2) The boron-containing organic ligand phenylboronic acid and the metal salt Zr(NO3)4 were mixed in N,N-diethylformamide, wherein the molar ratio of the boron-containing organic ligand to the metal zirconium salt was 2:1; the mixture was reacted at 120°C for 72 hours to form a crystalline boron-based MOF precursor, and a nano rare earth element catalyst (REO was a mixture of CeO2 and La2O with a molar ratio of 2:1 and a particle size of 10 nm, and the mass ratio of REO to the crystalline boron-based MOF precursor was 1:3) was added, stirred for 3 hours, filtered, and dried to obtain a MOF-REO complex.

[0109] (3) The primary activated metal composite boron powder was ultrasonically dispersed in n-butanol, MOF-REO (the molar ratio of REO to boron in the active metal composite boron powder was 1:7) was added, and the mixture was heated and stirred at 50°C. The secondary coating was achieved by solvent evaporation to obtain the secondary activated metal composite boron powder, that is, the active metal composite boron powder with multi-component synergistic coating.

[0110] Comparative Example 1

[0111] The difference from Example 1 is that only the fluorine-containing coating agent is coated.

[0112] Comparative Example 2

[0113] The difference from Example 1 is that only the MOF-REO composite is coated.

[0114] Comparative Example 3

[0115] The difference from Example 1 is that only REO is coated (active metal composite boron powder and REO are dispersed in a dispersant, and the solvent is evaporated at the same temperature).

[0116] Comparative Example 4

[0117] The difference from Example 1 is that after coating with the fluorine-containing coating agent, only REO is coated, and no MOF-REO composite is prepared.

[0118] Comparative Example 5

[0119] The difference from Example 1 is that the MOF-REO composite is coated first and then the fluorine-containing coating agent is coated.

[0120] Comparative Example 6

[0121] The difference from Example 1 is that triphenylboron is selected as the boron-containing organic ligand.

[0122] Triphenylboron lacks active sites (such as hydroxyl groups, carboxyl groups, etc.) for coordinating with metal ions, and therefore cannot construct a stable MOF skeleton.

[0123] Comparative Example 7

[0124] The difference from Example 1 is that the metal salt is Zn(NO3)2.

[0125] Zn-based MOF has weak coordination ability and low loading capacity, and the structure is prone to collapse when it exceeds 5%.

[0126] Comparative Example 8

[0127] The difference from Example 1 is that the rare earth metal oxide is dysprosium oxide (Dy2O3).

[0128] If the density is too high, it is easy to aggregate due to gravity during the loading process, forming unevenly dispersed clusters and destroying the periodic structure of MOF.

[0129] Comparative Example 9

[0130] The difference from Example 1 is that the molar ratio of the fluorine-containing coating agent to the boron in the active metal composite boron powder is 1:15.

[0131] The amount of fluorine-containing coating agent used is small, and the coating is incomplete and uneven.

[0132] The transmission electron microscopy image of the obtained product is as follows Figure 2 shown.

[0133] Comparative Example 10

[0134] The difference from Example 1 is that the molar ratio of the fluorine-containing coating agent to the boron in the active metal composite boron powder is 1:5.

[0135] The amount of fluorine-containing coating agent used is too large, and the coating amount is too much, which reduces the combustion calorific value.

[0136] Comparative Example 11

[0137] The difference from Example 1 is that the molar ratio of REO to boron in the active metal composite boron powder is 1:10.

[0138] The amount of REO used is small and cannot effectively shorten the ignition delay time of boron particles.

[0139] Comparative Example 12

[0140] The difference from Example 1 is that the molar ratio of REO to boron in the active metal composite boron powder is 1:4.

[0141] A large amount of REO will limit the diffusion of oxygen in the boron particles, which is not conducive to the ignition and combustion of the boron particles.

[0142] The active metal composite boron powder used in Example 1, the once-activated metal composite boron powder, the finally obtained multi-component synergistically coated active metal composite boron powder, and the product of the comparative example were subjected to combustion tests (sampling was carried out using an oxygen bomb calorimeter). The calorific value results are shown in Table 1. The particle size of the obtained condensed phase combustion products was tested, and the results are shown in Table 2:

[0143] Table 1 Combustion calorific value

[0144] sample <![CDATA[Calorific value / (MJ·kg -1 )]]> Active metal composite boron powder Al-B 39.73 Example 1 46.21 Comparative Example 1 41.26 Comparative Example 2 43.94 Comparative Example 3 40.66 Comparative Example 4 44.01 Comparative Example 5 41.20 Comparative Example 6 42.43 Comparative Example 7 42.11 Comparative Example 8 41.79 Comparative Example 9 42.87 Comparative Example 10 40.92 Comparative Example 11 41.43 Comparative Example 12 40.12

[0145] The combustion calorific value can reflect the combustion efficiency of the active boron powder. The theoretical calorific value of boron is 58.28 MJ / kg. As shown in Table 1 above, the product obtained in Example 1 has the highest combustion efficiency.

[0146] Table 2 Particle size of combustion residues

[0147]

[0148]

[0149] As shown in Table 2, the particle size of the condensed phase combustion product of the multi-component synergistically coated active metal composite boron powder obtained in Example 1 is the smallest and the combustion is the most complete.

[0150] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing multi-component synergistically coated active metal composite boron powder, characterized in that: include: A fluorine-containing coating agent, an organic solvent, and an active metal composite boron powder are mixed, subjected to a first reaction under heating conditions, and then vacuum dried to obtain a primary activated metal composite boron powder; A boron-containing organic ligand, a metal zirconium salt, and a polar solvent are mixed and subjected to a second reaction under heating conditions to obtain a crystalline boron-based MOF precursor. A nano-rare earth element catalyst REO is then added and subjected to a third reaction to obtain a MOF-REO complex. The primary activated metal composite boron powder and the MOF-REO complex are mixed, and a fourth reaction is carried out under heating conditions to obtain the synergistically coated active metal composite boron powder.

2. The method for preparing multi-component synergistically coated active metal composite boron powder according to claim 1, characterized in that: One or more of the following conditions are met: (1) The fluorine-containing coating agent includes one or more of lithium fluoride, fluororubber, and fluorographite; (2) The organic solvent includes one or more of dichloromethane, tetrahydrofuran, anhydrous ethanol, and ethyl acetate; (3) The active metal composite boron powder includes boron-aluminum composite powder and / or boron-magnesium composite powder; (4) The boron content of the active metal composite boron powder is 95-97 wt%; (5) The molar ratio of the fluorine-containing coating agent to the boron in the active metal composite boron powder is 1:8-12; (6) The active metal composite boron powder is dispersed in a dispersant before use, and the dispersant includes one or more of ethanol, ethylene glycol, and n-butanol.

3. The method for preparing multi-component synergistically coated active metal composite boron powder according to claim 1, characterized in that: One or more of the following conditions are met: (1) The temperature of the first reaction is 40-60°C; (2) The first reaction is carried out under stirring.

4. The method for preparing multi-component synergistically coated active metal composite boron powder according to claim 1, characterized in that: One or more of the following conditions are met: (1) The boron-containing organic ligand comprises borate ester and / or phenylboronic acid; (2) The metal zirconium salt includes ZrCl4 and / or Zr(NO3)4; (3) The molar ratio of the boron-containing organic ligand to the metal zirconium salt is 1-4:

1.

5. The method for preparing multi-component synergistically coated active metal composite boron powder according to claim 1, characterized in that: The polar solvent includes one or more of N,N-dimethylformamide, N,N-diethylformamide, and dimethyl sulfoxide.

6. The method for preparing multi-component synergistically coated active metal composite boron powder according to claim 1, characterized in that: One or more of the following conditions are met: (1) The nano rare earth element catalyst REO includes one or more of CeO2, La2O3, and Gd2O3; (2) The particle size of the nano rare earth element catalyst REO is 10-30 nm; (3) The mass ratio of the nano rare earth element catalyst REO to the crystalline boron-based MOF precursor is 1:3-10; (4) The molar ratio of the nano rare earth element catalyst REO to the boron in the active metal composite boron powder is 1:5-8.

7. The method for preparing multi-component synergistically coated active metal composite boron powder according to claim 1, characterized in that: The temperature of the second reaction is 80-120° C., and the time is 24-72 hours.

8. The method for preparing the synergistically coated active metal composite boron powder according to claim 1, characterized in that: One or more of the following conditions are met: (1) The time of the third reaction is 2-5 hours; (2) The third reaction is carried out under stirring.

9. The method for preparing multi-component synergistically coated active metal composite boron powder according to claim 1, characterized in that: One or more of the following conditions are met: (1) The temperature of the fourth reaction is 40-60°C; (2) When the primary activated metal composite boron powder and the MOF-REO composite are mixed, a dispersant is added, and the dispersant includes one or more of ethanol, ethylene glycol, and n-butanol.

10. A multi-component synergistically coated active metal composite boron powder, characterized in that: The active metal composite boron powder is prepared by the preparation method of multi-component synergistically coated active metal composite boron powder according to any one of claims 1 to 9.

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