Metal fuel as well as preparation method and application thereof

Abstract

The invention provides a metal fuel as well as a preparation method and application thereof, and relates to the technical field of rocket fuels, and the metal fuel comprises the following components: fluorinated carbon nanotubes and metal particles. According to the metal fuel provided by the invention, the mixing uniformity of the metal fuel can be greatly improved, the ignition delay time is greatly shortened, the agglomeration size of a condensed-phase combustion product is remarkably reduced, the preparation method is simple, and the combustion performance of the high-energy metal fuel in a rocket engine containing a metal propellant is favorably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of rocket fuel, and in particular to a metal fuel and a preparation method and application thereof. Background Art

[0002] Metal fuels are widely used as high-energy fuels for various propellants in the field of aerospace propulsion due to their high energy density, low cost and low carbon emissions, in order to increase the energy level and specific impulse of the propellants. However, metal particles burn slowly and incompletely, which hinders their more complete energy release and limits their further application in propellants. Metal particles such as boron (B) and aluminum (Al) have natural oxide shells on their surfaces, which are not conducive to the diffusion of oxygen, resulting in metal particles having a higher ignition threshold.

[0003] Related studies have shown that the above problems can be effectively improved by compounding and modifying fluorinated oxidants with micron-sized Al and B particles. Polytetrafluoroethylene (PTFE) is the most studied fluorinated oxidant at present, and its powder usually has a larger particle size (D>200μm). However, the scale of the mixture of spherical aluminum and block PTFE is relatively coarse, and the surface of most fuels only indirectly contacts the PTFE particles. This may lead to component separation and reduced mixing uniformity, resulting in limited actual effect of Al / PTFE mixed powder in fuel formulation. Considering the gaseous nature of PTFE intermediates / decomposition products, at lower heating rates, it may escape from the system without fully reacting with the fuel powder. The incompatibility between metal particles and polymers leads to relatively poor combustion performance of composite materials composed of metal / fluorinated oxidants.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] One of the purposes of the present invention is to provide a metal fuel to at least solve one of the technical problems existing in the prior art. The components of the metal fuel include: fluorinated carbon nanotubes and metal particles. The metal fuel provided by the present invention has strong compatibility with the fluorinated carbon nanotubes and excellent ignition and combustion performance.

[0006] The second object of the present invention is to provide a method for preparing a metal fuel. The method for preparing a metal fuel comprises the following steps: mixing a formula amount of fluorinated carbon nanotubes and metal particles to prepare the metal fuel. The preparation method is simple to operate and has high mixing uniformity.

[0007] A third object of the present invention is to use a metal fuel in a rocket propulsion system.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0009] In a first aspect, the present invention provides a metal fuel, the components of which include: fluorinated carbon nanotubes and metal particles.

[0010] Furthermore, the components of the metal fuel include, by weight percentage: 1%-60% of fluorinated carbon nanotubes and the remainder of metal particles;

[0011] The metal particles include aluminum particles or boron particles.

[0012] Furthermore, the particle size of the aluminum particles is 0.1-100 μm.

[0013] Furthermore, the particle size of the boron particles is 0.1-100 μm.

[0014] Furthermore, the diameter of the fluorinated carbon nanotubes is 1-100 nm.

[0015] Furthermore, the length of the fluorinated carbon nanotubes is 0.1-100 μm.

[0016] In a second aspect, the present invention provides a method for preparing the metal fuel, the method for preparing the metal fuel comprising the following steps:

[0017] The metal fuel is prepared by mixing the fluorinated carbon nanotubes and metal particles in a prescribed amount.

[0018] Furthermore, the fluorinated carbon nanotubes and the metal particles are mixed using a vortex mixer.

[0019] Furthermore, the mixing time is at least 8 hours;

[0020] Preferably, the rotation speed during the mixing process is at least 2000 rpm.

[0021] In a third aspect, the present invention provides an application of the metal fuel in a rocket propulsion system.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The metal fuel provided by the present invention is a high-energy metal fuel. The advantages of the fluorinated carbon nanotubes (FCNTs) in the metal fuel over existing fluorinated modifiers such as metal fluorides are that they have a higher aspect ratio, better tensile modulus and strength, and can form an effective nanoscale reinforcement network, making it easier to disperse and adsorb in metal particles, thereby improving its reinforcement effect in composite materials. The metal and fluorinated carbon nanotubes in the metal fuel provided by the present invention are highly compatible and have excellent ignition and combustion properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 is the SEM image of Al particles;

[0026] Figure 2 is the SEM image of Al particles;

[0027] Figure 3 This is a SEM image of the Al / FCNT composite particles prepared in Example 12;

[0028] Figure 4 This is a SEM image of the Al / FCNT composite particles prepared in Example 12;

[0029] Figure 5 This is an EDS image of the Al element in the Al / FCNT composite particles prepared in Example 12;

[0030] Figure 6 This is the EDS image of the F element in the Al / FCNT composite particles prepared in Example 12. DETAILED DESCRIPTION

[0031] Unless otherwise defined herein, scientific and technical terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear, however, in the case of any potential ambiguity, the definitions provided herein take precedence over any dictionary or external definitions. In this application, unless otherwise stated, the use of "or" means "and / or". In addition, the use of the term "including" and other forms is non-limiting.

[0032] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] A first aspect of the present invention provides a metal fuel, the components of which include: fluorinated carbon nanotubes and metal particles.

[0034] In the present invention, the advantages of fluorinated carbon nanotubes (FCNTs) over existing fluorinated modifiers such as metal fluorides are: they have a higher aspect ratio, better tensile modulus and strength, can form an effective nanoscale reinforcement network, making them easier to disperse and adsorb in metal particles, thereby improving their reinforcement effect in composite materials; the metal and fluorinated carbon nanotubes in the metal fuel provided by the present invention are highly compatible, and have excellent ignition and combustion properties.

[0035] Furthermore, the components of the metal fuel include, by weight percentage: 1%-60% of fluorinated carbon nanotubes and the remainder of metal particles;

[0036] The metal particles include aluminum particles or boron particles.

[0037] Based on the total weight of the metal fuel as 100%, the added amount of fluorinated carbon nanotubes is 1%-60%, for example, it can be 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, etc.

[0038] In the present invention, the formula ratio is determined according to the theoretical calorific value, and the heat released by the reaction of metal with oxygen is slightly higher than that of the reaction with fluoride. Metal particles aluminum and boron are fuels used in different application scenarios, aluminum is mostly used in rocket engines, and boron is often used in ramjet engines.

[0039] Furthermore, the particle size of the aluminum particles is 0.1-100μm, for example, it can be 0.1μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, etc.

[0040] Furthermore, the particle size of the boron particles is 0.1-100μm, for example, it can be 0.1μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, etc.

[0041] Furthermore, the diameter of the fluorinated carbon nanotubes is 1-100 nm, for example, it can be 1 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, etc.

[0042] Furthermore, the tube length of the fluorinated carbon nanotubes is 0.1-100μm, for example, it can be 0.1μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, etc.

[0043] The second aspect of the present invention provides a method for preparing the metal fuel, the method for preparing the metal fuel comprising the following steps:

[0044] The metal fuel is prepared by mixing the fluorinated carbon nanotubes and metal particles in a prescribed amount.

[0045] In the present invention, a vortex mixer (Joanlab) is used to prepare metal / FCNT composite particles by mechanical mixing. In existing studies, fluorides that can achieve core-shell structure metal particle coating usually need to be prepared by dissolution-recrystallization and other methods in water, ethanol and other solutions. Not only is the process very complicated, but the reactivity of the metal particles will also be affected by the reagents and aqueous solutions; in addition, some impurities such as residual solvents, epoxides and epoxide by-products will inevitably be detected in the obtained composite, which greatly affects the combustion performance. The present invention can achieve the core-shell structure of FCNT coated metal through simple mechanical oscillation mixing.

[0046] Furthermore, the fluorinated carbon nanotubes and the metal particles are mixed using a vortex mixer.

[0047] Furthermore, the mixing time is more than 8 hours, for example, it can be 8 hours, 12 hours, 24 hours, 48 ​​hours, 50 hours, 55 hours, 60 hours, 65 hours, 70 hours, 72 hours, etc.;

[0048] Preferably, the rotation speed during the mixing process is above 2000 rpm, for example, it may be 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm, 4000 rpm, etc.

[0049] The third aspect of the present invention provides an application of the metal fuel in a rocket propulsion system.

[0050] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0051] Example 1

[0052] This embodiment provides a metal fuel, the components of which include, by weight percentage, 1% of fluorinated carbon nanotubes and 99% of aluminum particles.

[0053] The particle size of the aluminum particles is 0.1-100 μm; the diameter of the fluorinated carbon nanotubes is 1 nm, and the length of the tubes is 100 μm.

[0054] Example 2

[0055] This embodiment provides a metal fuel, which is different from Embodiment 1 in that the metal particles are boron particles.

[0056] The particle size of the boron particles is 0.1-100 μm.

[0057] The rest is consistent with Example 1.

[0058] Example 3

[0059] This embodiment provides a metal fuel, the components of which include, by weight percentage, 60% of fluorinated carbon nanotubes and 40% of aluminum particles.

[0060] The particle size of the aluminum particles is 0.1-100 μm; the diameter of the fluorinated carbon nanotubes is 100 nm, and the tube length is 0.1 μm.

[0061] Example 4

[0062] This embodiment provides a metal fuel, which is different from Embodiment 3 in that the metal particles are boron particles.

[0063] The particle size of the boron particles is 0.1-100 μm.

[0064] The rest is consistent with Example 3.

[0065] Example 5

[0066] This embodiment provides a metal fuel, the components of which include, by weight percentage, 10% of fluorinated carbon nanotubes and 90% of aluminum particles.

[0067] The particle size of the aluminum particles is 0.1-100 μm; the diameter of the fluorinated carbon nanotubes is 50 nm and the length is 50 μm.

[0068] Example 6

[0069] This embodiment provides a metal fuel, the components of which include, by weight percentage, 20% of fluorinated carbon nanotubes and 80% of aluminum particles.

[0070] The particle size of the aluminum particles is 0.1-100 μm; the diameter of the fluorinated carbon nanotubes is 50 nm and the length is 50 μm.

[0071] Example 7

[0072] This embodiment provides a metal fuel, which is different from the embodiment 6 in that the metal particles are boron particles, 30% of the fluorinated carbon nanotubes and 70% of the boron particles.

[0073] Wherein, the particle size of the boron particles is 0.1-100 μm;

[0074] The rest is consistent with Example 6.

[0075] Embodiment 8-14

[0076] This embodiment provides a method for preparing a metal fuel, comprising the following steps:

[0077] By vortex mixing, the fluorinated carbon nanotubes and metal particles in the amounts of Examples 1-7 were mixed in sequence for 8 hours to prepare the metal fuels of Examples 8-14 in sequence;

[0078] The rotation speed during the mixing process was 2000 rpm.

[0079] Comparative Example 1

[0080] This comparative example provides a metal fuel, which is different from Example 6 in that no fluorinated carbon nanotubes are added.

[0081] The metal fuel was prepared using the preparation method of Example 13.

[0082] Comparative Example 2

[0083] This comparative example provides a metal fuel, which is different from Example 7 in that no fluorinated carbon nanotubes are added.

[0084] The metal fuel was prepared using the preparation method of Example 14.

[0085] Comparative Example 3

[0086] This comparative example provides a metal fuel, which is different from Example 6 in that the components of the metal fuel include, by weight percentage, 20% polytetrafluoroethylene (PTFE) and 80% aluminum particles.

[0087] The metal fuel was prepared using the preparation method of Example 13.

[0088] Comparative Example 4

[0089] This comparative example provides a metal fuel, which is different from Example 7 in that the components of the metal fuel include, by weight percentage, 30% polytetrafluoroethylene (PTFE) and 70% boron particles.

[0090] The metal fuel was prepared using the preparation method of Example 14.

[0091] Test Example 1:

[0092] Test samples: the metal fuels prepared in Examples 8-14 and Comparative Examples 1-4.

[0093] Test method: The ignition delay measurement experiment is carried out at different laser powers to obtain the ignition delay data.

[0094] The test results are shown in Table 1.

[0095] Table 1

[0096]

[0097]

[0098] By comparing Example 13 with Comparative Example 3, it can be seen that in the ignition delay time test under different laser powers (laser powers correspond to: 10W, 12W, 14W, 16W, 18W, 20W, 30W, 40W), Example 13 is shortened by 84%, 77%, 83%, 83%, 82%, 83%, 70%, 71% compared with Comparative Example 3. By comparing Example 14 with Comparative Example 4, it can be seen that in the ignition delay time test under different laser powers (laser powers correspond to: 10W, 12W, 14W, 16W, 18W, 20W, 30W, 40W), Example 14 is shortened by 54%, 37%, 35%, 40%, 32%, 23%, 27%, 39% compared with Comparative Example 4. It can be seen from the data in Table 1 that the ignition delay time of the metal fuel of the embodiment of the present invention is much shorter than that of the comparative example.

[0099] The morphology of pure Al and Al / FCNT composite particles (taking Example 12 as an example) was characterized by SEM. The results are as follows: Figure 1-5 As shown. Among them, Figure 1 and Figure 2 This is the SEM image of Al particles. It can be seen that the surface of pure Al particles is smooth. Figure 3 and Figure 4 This is a SEM image of Al / FCNT composite particles. After Al particles are mixed with FCNT, FCNT is evenly coated on the surface of Al particles to form a core-shell structure. The outer shell is made of FCNT interwoven with each other. Figure 4 shown. Figure 5 This is the EDS image of Al element in Al / FCNT composite particles. Figure 6 This is the EDS image of the F element in the Al / FCNT composite particles. Using EDS analysis, it can be seen that the signals of the Al and F elements in the Al / FCNT composite particles are evenly distributed on the surface of the Al particles, indicating that their mixing effect is very good.

[0100] Test Example 2:

[0101] Test samples: the metal fuels prepared in Examples 13-14 and Comparative Examples 1-4.

[0102] Test method: After igniting the fuel under laser power, measure the data of the agglomeration size of the condensed phase combustion products at different volume percentages.

[0103] The test results are shown in Table 2.

[0104] Table 2

[0105]

[0106] As shown in Table 2, by comparing Example 13 with Comparative Example 3, in the condensed phase combustion product agglomeration size test, (corresponding to D 25 , D 50 , D 75 , D 97 ), the sizes of Example 13 are reduced by 18%, 59%, 23%, and 3% respectively compared with those of Comparative Example 3. It can be seen from the data in Table 2 that the agglomerate size of the condensed phase combustion products of the metal fuel in the examples of the present invention is significantly reduced compared with that in the control group.

[0107] The formula of the metal fuel provided by the present invention can not only greatly improve the mixing uniformity of the metal fuel, greatly shorten the ignition delay time, and significantly reduce the agglomeration size of the condensed phase combustion products, but also has a simple preparation method, which helps to improve the combustion performance of high-energy metal fuel in metal-propellant rocket engines.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention 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 replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A metal fuel, characterized in that: The components of the metal fuel include: fluorinated carbon nanotubes and metal particles.

2. The metal fuel according to claim 1, characterized in that: The components of the metal fuel include, by weight percentage: 1%-60% of fluorinated carbon nanotubes and the remainder of metal particles; The metal particles include aluminum particles or boron particles.

3. The metal fuel according to claim 2, characterized in that: The particle size of the aluminum particles is 0.1-100 μm.

4. The metal fuel according to claim 2, characterized in that: The particle size of the boron particles is 0.1-100 μm.

5. The metal fuel according to claim 2, characterized in that: The diameter of the fluorinated carbon nanotubes is 1-100 nm.

6. The metal fuel according to claim 2, characterized in that: The length of the fluorinated carbon nanotubes is 0.1-100 μm.

7. The method for preparing the metal fuel according to any one of claims 1 to 6, characterized in that: The method for preparing the metal fuel comprises the following steps: The metal fuel is prepared by mixing the fluorinated carbon nanotubes and metal particles in a prescribed amount.

8. The method for preparing the metal fuel according to claim 7, characterized in that: The fluorinated carbon nanotubes and the metal particles are mixed using a vortex mixer.

9. The method for preparing the metal fuel according to claim 7, characterized in that: The mixing time is at least 8 hours; Preferably, the rotation speed during the mixing process is at least 2000 rpm.

10. Use of the metal fuel according to any one of claims 1 to 6 in a rocket propulsion system.

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