Fluorine-containing solvent assisted organic silicone oil surface coating modified aluminum powder and preparation method thereof

Abstract

The invention relates to fluorine-containing solvent assisted organic silicone oil surface coating modified aluminum powder and a preparation method thereof, and the preparation method comprises the following steps: S1, adding a fluorine-containing solvent into organic silicone oil to obtain a mixed solution; and S2, adding aluminum powder into the mixed solution obtained in the step S1, stirring and mixing to generate a silicone oil coating layer on the surface of the aluminum powder, and drying to obtain the fluorine-containing solvent assisted organic silicone oil surface coating modified aluminum powder. Compared with the prior art, the low-surface-energy fluorine-containing solvent is used for assisting the organic silicone oil to modify the surface of the aluminum powder, and a uniform, compact and stable coating layer is formed on the surface of the aluminum powder, so that the combustion performance of the aluminum powder and the thermal stability during storage are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of energetic materials, and in particular to an aluminum powder with a surface coated and modified by fluorinated solvent-assisted organosilicon oil and a preparation method thereof. Background Art

[0002] Due to the relatively high combustion energy of aluminum powder, solid propellants usually use aluminum powder as a component of high-energy metal fuel. However, if the aluminum content in the fuel is relatively high, incomplete combustion of aluminum powder particles or agglomeration of aluminum powder during combustion will occur, which leads to an increase in ignition energy, a decrease in the combustion performance of aluminum powder, and ultimately affects the energy release and propulsion efficiency of the propellant fuel. In addition, the agglomeration of aluminum powder particles will also cause potential safety problems. When alumina particles melt to form larger solid alumina particles during combustion, it will damage the combustion equipment. Therefore, it is of great practical significance to develop an aluminum powder with good combustion performance as a solid propellant.

[0003] There have been many studies on the modification of aluminum powder in existing literature and patents. By preparing an inert coating layer on the surface of micron-sized or nano-sized aluminum powder, the stability of aluminum powder in a high-temperature environment is improved. When the aluminum powder burns, the coating layer on the surface can prevent the aluminum powder from agglomerating into large particles after melting, will not cause an increase in ignition energy, thereby improving the combustion performance of aluminum powder, and can also improve the combustion safety of aluminum powder.

[0004] Patent CN110508802A discloses a preparation method of polyvinylidene fluoride-coated micro / nano aluminum powder. By coating the PVDF polymer on the surface of aluminum powder, it can hinder the oxidation of aluminum powder in the air, and at the same time can reduce the energy barrier of aluminum powder combustion and improve the combustion performance of aluminum powder. Patent CN103254025A discloses a high-combustion-performance aluminum powder composition and a preparation method thereof. Mix aluminum powder and boron powder in a certain proportion, add a solvent and then perform colloidal mill mixing treatment. The prepared aluminum powder composition has a relatively high energy density. Patent CN110590483A discloses a preparation method of a fluorinated compound-coated micro / nano aluminum powder. By dissolving the fluorinated compound in an organic solvent and then adding micro / nano aluminum powder and stirring, a fluorinated compound-coated micro / nano aluminum powder is prepared, which can improve the combustion heat and combustion performance of aluminum powder. Patent CN111217652A discloses a composite solid propellant based on fluoropolymer-modified aluminum powder and a preparation method thereof. By inducing with polydopamine, fluoropolymer-coated aluminum powder is prepared. Its structural particles and composition are easy to adjust, the activity is adjustable, the combustion performance is easy to control, and the combustion efficiency is high.

[0005] However, although there are many reports in the current literature and patents on modifying aluminum powder to improve its combustion performance, most of these methods cannot enhance the stability of aluminum powder during storage. The high activity of micro-nano aluminum powder itself easily leads to the oxidation of aluminum powder in high-temperature and high-humidity environments, thereby reducing the combustion performance and even causing safety accidents during storage. In addition, when surface-treating and modifying aluminum powder, problems often occur where the solvents used react with the aluminum powder. Therefore, it is crucial to solve the above problems.

[0006] Silicone oil has attracted people's attention due to its unique properties, such as resistance to high and low temperatures, anti-oxidation, good insulation, small surface tension, and small temperature-viscosity coefficient. It has been applied in many aspects, such as defoaming, damping, and shock absorption, and has excellent effects. The special surface properties of silicone oil can also be used in surface modification coatings, such as release agents, waterproof, and anti-mildew coatings. However, due to the relatively high viscosity of silicone oil, it cannot be used directly, nor can it directly form a uniform coating layer on the surface of aluminum powder. Summary of the Invention

[0007] The purpose of the present invention is to provide an aluminum powder surface-coated and modified with fluorinated solvent-assisted organosilicone oil and a preparation method thereof to overcome the defects existing in the prior art.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] One of the technical solutions of the present invention is to provide a preparation method for an aluminum powder surface-coated and modified with fluorinated solvent-assisted organosilicone oil, including the following steps:

[0010] S1. Add a fluorinated solvent to the organosilicone oil to obtain a mixed solution;

[0011] S2. Add aluminum powder to the mixed solution obtained in step S1, stir and mix to form a silicone oil coating layer on the surface of the aluminum powder, and after drying, obtain an aluminum powder surface-coated and modified with fluorinated solvent-assisted organosilicone oil.

[0012] In some specific embodiments, in step S1, the fluorinated solvent is selected from any one or more of 1,1,2,2,3,3-hexafluorocyclopentane, 1,1,2,2,3,3,4-heptafluorocyclopentane, 1-chloro-2,3,3,4,4,5,5-heptafluorocyclopentene, 3,3,4,4,5,5-hexafluorocyclopentene, and 1,3,3,4,4,5,5-heptafluorocyclopentene.

[0013] In some specific embodiments, in step S1, the organosilicone oil is selected from any one or more of methylphenyl silicone oil, methylchlorophenyl silicone oil, methylethoxysilicone oil, methyltrifluoropropyl silicone oil, methylvinyl silicone oil, and methylhydroxy silicone oil.

[0014] In some specific embodiments, in step S1, the concentration of the organosilicon oil in the fluorinated solvent is 0.1-50 wt.%.

[0015] In some specific embodiments, in step S2, the aluminum powder is selected from any one or more of nano-aluminum powder and micro-aluminum powder.

[0016] In some specific embodiments, in step S2, the mass ratio of the aluminum powder to the organosilicon oil is 10000:1-10:1.

[0017] In some specific embodiments, in step S2, the temperature of the stirring and mixing is room temperature, and the time of the stirring and mixing is 20 min-3 h.

[0018] In some specific embodiments, in step S2, the drying conditions are vacuum drying at 30-100 °C.

[0019] In some specific embodiments, in step S2, the thickness of the silicone oil coating layer is 1-100 nm.

[0020] The second technical solution of the present invention is to provide an aluminum powder with a surface coated and modified by an organosilicon oil assisted by a fluorinated solvent, based on the preparation method described in the above technical solution one.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention uses a fluorinated solvent with a low surface energy to assist in modifying the surface of the aluminum powder with an organosilicon oil, forming a uniform, dense and stable coating layer on the surface of the aluminum powder to improve the combustion performance of the aluminum powder and the thermal stability during storage. On the one hand, through the surface silicification treatment of the silicone oil, the aluminum powder shows good non-sticking characteristics, which can greatly reduce the caking and agglomeration phenomena of nano-scale and micro-scale aluminum powders during combustion, improve the combustion efficiency, and reduce the average particle size of the combustion products. On the other hand, by using the low surface energy, chemical inertness and easy volatility of the fluorinated solvent, a uniform ultra-thin silicone oil coating layer is formed on the surface of the aluminum powder, which can improve the combustion performance of the aluminum powder and avoid phenomena such as incomplete combustion of the aluminum powder, agglomeration of combustion intermediate products resulting in poor combustion performance and damage to combustion equipment.

[0023] (2) The preparation method of the present invention is simple, the solvent in the reaction process does not react with the aluminum powder, the material cost is low, and it has a significant effect on the practical application of the aluminum powder as a high-energy solid propellant. Description of the Drawings

[0024] Figure 1 It is a transmission electron microscope image of the organosilicon oil surface-modified nano-aluminum powder prepared in Example 1 at a scale of 50 nanometers.

[0025] Figure 2It is the transmission electron microscopy image of the organosilicon oil surface-modified nano-aluminum powder prepared in Example 1 at the 20-nanometer scale.

[0026] Figure 3 It is the transmission electron microscopy image of the un-surface-modified aluminum powder.

[0027] Figure 4 It is the infrared test spectrum of the organosilicon oil surface-modified aluminum powder prepared in Example 1 and the un-surface-modified aluminum powder in Comparative Example 1.

[0028] Figure 5 It is the transmission electron microscopy image of the organosilicon oil surface-modified aluminum powder prepared in Comparative Example 2. Detailed implementation mode

[0029] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and the detailed implementation mode and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

[0030] In the following examples and comparative examples, unless otherwise specified, the raw materials or treatment techniques are all conventional commercially available raw material products or conventional treatment techniques in the art.

[0031] Example 1:

[0032] At normal temperature and pressure, 0.5 g of methyl ethoxy silicone oil was added to 20 mL of 1,1,2,2,3,3-hexafluorocyclopentane solvent, and ultrasonically dispersed for 0.5 min to obtain an aluminum powder dispersion; then 10 g of nano-aluminum powder was added to the dispersion, and stirred at room temperature for 20 min to form a dense organosilicon oil coating layer on the surface of the aluminum powder. The mixed solution was vacuum dried at 80 °C to remove the 1,1,2,2,3,3-hexafluorocyclopentane solvent, and the organosilicon oil surface-modified aluminum powder was obtained, marked as Lv-1. The content of the coating layer was 5.2 wt.% of the mass of the aluminum powder, and the thickness of the coating layer was 4.21 nm.

[0033] Example 2:

[0034] Compared with Example 1, most of them are the same, except that "1,1,2,2,3,3-hexafluorocyclopentane solvent" is replaced with "1,1,2,2,3,3,4-heptafluorocyclopentane solvent".

[0035] At normal temperature and pressure, 0.5 g of methyl ethoxy silicone oil was added to 20 mL of 1,1,2,2,3,3,4-heptafluorocyclopentane solvent, and ultrasonic dispersion was carried out for 0.5 min to obtain an aluminum powder dispersion; then 10 g of nano-aluminum powder was added to the dispersion, and stirring reaction was carried out at normal temperature for 20 min to form a dense organic silicone oil coating layer on the surface of the aluminum powder. The mixed solution was vacuum dried at 80 °C to remove the 1,1,2,2,3,3,4-heptafluorocyclopentane solvent, and surface-modified aluminum powder, labeled as Lv-2, was obtained. The content of the coating layer was 5.2 wt.% of the mass of the aluminum powder. The thickness of the coating layer on the surface of the modified aluminum powder was 4 nm.

[0036] Example 3:

[0037] Compared with Example 1, most of them are the same. The difference is that "methyl ethoxy silicone oil" is replaced by "methyltrifluoropropyl silicone oil".

[0038] At normal temperature and pressure, 0.5 g of methyltrifluoropropyl silicone oil was added to 20 mL of 1,1,2,2,3,3-hexafluorocyclopentane solvent, and ultrasonic dispersion was carried out for 0.5 min to obtain an aluminum powder dispersion; then 10 g of nano-aluminum powder was added to the dispersion, and stirring reaction was carried out at normal temperature for 20 min to form a dense organic silicone oil coating layer on the surface of the aluminum powder. The mixed solution was vacuum dried at 80 °C to remove the 1,2,2,3,3-hexafluorocyclopentane solvent, and surface-modified aluminum powder, labeled as Lv-3, was obtained. The content of the coating layer was 5.3 wt.% of the mass of the aluminum powder, and the thickness of the coating layer on the surface of the modified aluminum powder was 5 nm.

[0039] Example 4:

[0040] Compared with Example 1, most of them are the same. The difference is that "methyl ethoxy silicone oil" is replaced by "methyltrifluoropropyl silicone oil", and "1,1,2,2,3,3-hexafluorocyclopentane solvent" is replaced by "1,1,2,2,3,3,4-heptafluorocyclopentane solvent".

[0041] At normal temperature and pressure, 0.5 g of methyltrifluoropropyl silicone oil was added to 20 mL of 1,1,2,2,3,3,4-heptafluorocyclopentane solvent, and ultrasonic dispersion was carried out for 0.5 min to obtain an aluminum powder dispersion; then 10 g of nano-aluminum powder was added to the dispersion, and stirring reaction was carried out at normal temperature for 20 min to form a dense organic silicone oil coating layer on the surface of the aluminum powder. The mixed solution was vacuum dried at 80 °C to remove the 1,1,2,2,3,3,4-heptafluorocyclopentane solvent, and surface-modified aluminum powder, labeled as Lv-4, was obtained. The content of the coating layer was 5.3 wt.% of the mass of the aluminum powder, and the thickness of the coating layer on the surface of the modified aluminum powder was about 5.2 nm.

[0042] Example 5:

[0043] Compared with Example 1, most of them are the same. The differences are that "methyl ethoxy silicone oil" is replaced with "methyl phenyl silicone oil", and "1,1,2,2,3,3-hexafluorocyclopentane solvent" is replaced with "1,1,2,2,3,3,4-heptafluorocyclopentane solvent".

[0044] At normal temperature and pressure, 0.5 g of methyl phenyl silicone oil was added to 20 mL of 1,1,2,2,3,3,4-heptafluorocyclopentane solvent, and ultrasonically dispersed for 0.5 min to obtain an aluminum powder dispersion; then 10 g of nano-aluminum powder was added to the dispersion, and stirred at room temperature for 20 min to form a dense organic silicone oil coating layer on the surface of the aluminum powder. The mixed solution was vacuum dried at 80 °C to remove the 1,1,2,2,3,3,4-heptafluorocyclopentane solvent, and surface-modified aluminum powder was obtained, labeled as Lv-5. The content of the coating layer was 4.8 wt.% of the mass of the aluminum powder, and the thickness of the coating layer on the surface of the modified aluminum powder was 5 nm.

[0045] Comparative Example 1: Nano-aluminum powder with an unmodified surface.

[0046] Comparative Example 2: Modified nano-aluminum powder prepared by using a common non-fluorinated organic solvent as a diluent and organic silicone oil as a coating material. Compared with Example 1, most of them are the same. The difference is that "1,1,2,2,3,3-hexafluorocyclopentane" is replaced with "ethyl methyl carbonate".

[0047] At normal temperature and pressure, 0.5 g of methyl ethoxy silicone oil was added to 20 mL of ethyl methyl carbonate solvent, and ultrasonically dispersed for 0.5 min to obtain an aluminum powder dispersion; then 10 g of nano-aluminum powder was added to the dispersion, and stirred at room temperature for 20 min to form a dense organic silicone oil coating layer on the surface of the aluminum powder. The mixed solution was vacuum dried at 80 °C to remove the ethyl methyl carbonate solvent, and silicone oil surface-modified aluminum powder was obtained, labeled as Pr-1. The content of the coating layer was 5.1 wt.% of the mass of the aluminum powder, and the thickness of the coating layer was 5 nm.

[0048] Table 1 shows the performance test data of the surface-modified aluminum powder prepared according to Examples 1-5 and Comparative Examples 1-2 for stability in hot water. The surface-modified aluminum powder was immersed in hot water at 80 °C and stirred at a constant temperature, and the time when bubbles appeared on the surface of the aluminum powder was recorded.

[0049] Table 1

[0050]

[0051]

[0052] As shown in Table 1, the time for the surface-modified aluminum powder prepared according to Examples 1-5 to produce bubbles in hot water was greater than 24 hours. In Comparative Example 1, the unmodified nano-aluminum powder produced bubbles after only 15 minutes of soaking and heating. In Comparative Example 2, the modified nano-aluminum powder prepared using a common fluorine-free organic solvent as a diluent and silicone oil as a coating material produced bubbles after 50 minutes of soaking and heating. This experiment demonstrated that the silicone oil surface-modified aluminum powder prepared by the method of the present invention has good thermal stability in hot water.

[0053] Figure 1 , Figure 2 Figure (a) is a transmission electron microscope image of the silicone oil surface-modified aluminum powder prepared in Example 1 at different scales. Figure 3 Figure (b) is a transmission electron microscope image of the unmodified aluminum powder surface in Comparative Example 1. Figure 5 Figure (c) is a transmission electron microscope image of the surface-modified aluminum powder prepared in Comparative Example 2. Figure 1 Figure (d) shows the silicone oil-modified nano-aluminum powder prepared in Example 1 observed at a scale of 50 nm, indicating that a dense coating layer has formed on the surface of the silicone oil-modified nano-aluminum powder prepared in Example 1, which can improve the stability of the aluminum powder in the storage environment. Figure 2 Figure (e) shows the silicone oil-modified nano-aluminum powder prepared in Example 1 observed at a scale of 20 nm after magnification, indicating that the thickness of the coating layer on the aluminum powder surface is approximately 5 nm, uniform and dense. Figure 3 Figure (f) shows that there is no coating layer on the surface of the unmodified aluminum powder particles. Figure 5 Figure (g) is a transmission electron microscope image of the silicone oil surface-modified aluminum powder prepared in Comparative Example 2 by using a non-fluorinated solvent as a diluent and keeping the rest of the preparation method unchanged. It can be observed that a partial coating can be formed on the surface of the nano-aluminum powder, but the coating layer cannot completely cover the surface of the aluminum powder particles, and the coating thickness is uneven at the coated areas. This is because the surface energy of the common solvent is much lower than that of the fluorinated solvent, and its wettability on the surface of the nano-material is poor, so it cannot achieve the effect of completely coating the nano-particles.

[0054] Figure 4 Figure (h) is an infrared test spectrum of the silicone oil surface-modified aluminum powder prepared in Example 1 and the unmodified aluminum powder surface in Comparative Example 1. Figure 4 As shown in Figure (h), there are absorption peaks of carbon-hydrogen bonds at 1380, 1460, 2850, and 2920 cm -1 , and there is an absorption peak of silicon-oxygen bonds at 1150 cm -1 , further proving the presence of silicone oil on the surface of the coated aluminum powder.

[0055] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A preparation method of aluminum powder with a fluorinated solvent-assisted surface coating modification of organosilicone oil, characterized in that, It includes the following steps: S1. Add a fluorinated solvent to the organosilicone oil to obtain a mixed solution; S2. Add aluminum powder to the mixed solution obtained in step S1, stir and mix to form a silicone oil coating layer on the surface of the aluminum powder, and after drying, obtain aluminum powder with a fluorinated solvent-assisted surface coating modification of the organosilicone oil.

2. The preparation method of aluminum powder with a fluorinated solvent-assisted surface coating modification of organosilicone oil according to claim 1, characterized in that, In step S1, the fluorinated solvent is selected from any one or more of 1,1,2,2,3,3-hexafluorocyclopentane, 1,1,2,2,3,3,4-heptafluorocyclopentane, 1-chloro-2,3,3,4,4,5,5-heptafluorocyclopentene, 3,3,4,4,5,5-hexafluorocyclopentene, 1,3,3,4,4,5,5-heptafluorocyclopentene.

3. The preparation method of aluminum powder with a fluorinated solvent-assisted surface coating modification of organosilicone oil according to claim 1, characterized in that, In step S1, the organosilicone oil is selected from any one or more of methylphenyl silicone oil, methyl chlorophenyl silicone oil, methyl ethoxy silicone oil, methyl trifluoropropyl silicone oil, methyl vinyl silicone oil, methyl hydroxy silicone oil.

4. The preparation method of aluminum powder with a fluorinated solvent-assisted surface coating modification of organosilicone oil according to claim 1, characterized in that, In step S1, the concentration of the organosilicone oil in the fluorinated solvent is 0.1-50 wt.%.

5. The preparation method of aluminum powder with a fluorinated solvent-assisted surface coating modification of organosilicone oil according to claim 1, wherein, In step S2, the aluminum powder is selected from any one or more of nano-aluminum powder and micro-aluminum powder.

6. The preparation method of aluminum powder with a fluorine-containing solvent-assisted surface coating modification of organosilicone oil according to claim 1, characterized in that, In step S2, the mass ratio of the aluminum powder to the organosilicone oil is 10000:1-10:

1.

7. The preparation method of aluminum powder with a fluorine-containing solvent-assisted surface coating modification of organosilicone oil according to claim 1, characterized in that, In step S2, the temperature of the stirring and mixing is room temperature, and the time of the stirring and mixing is 20 min-3 h.

8. The preparation method of aluminum powder with a fluorinated solvent-assisted surface coating modification of organosilicone oil according to claim 1, characterized in that, In step S2, the drying condition is vacuum drying at 30-100 °C.

9. The preparation method of aluminum powder with a fluorine-containing solvent-assisted surface coating modification of organosilicone oil according to claim 1, characterized in that, In step S2, the thickness of the silicone oil coating layer is 1-100 nm.

10. An aluminum powder with a surface-coated modification of organosilicon oil assisted by a fluorinated solvent, characterized in that, Based on the preparation method according to any one of claims 1-9.

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