Method for removing surface oxide layer of amorphous boron powder and amorphous boron powder for propellant

Abstract

The present application provides a kind of amorphous boron powder surface oxide layer removal method and propellant for amorphous boron powder, and amorphous boron powder surface oxide layer removal method includes the following contents: amorphous boron powder with surface coated with oxide layer is added to strong polar solvent, and amorphous boron powder suspension liquid is obtained;In the temperature range of 80-100 ℃, amorphous boron powder suspension liquid is ultrasonically dispersed for 4-6 h, and mechanical stirring is continuously carried out during ultrasonic dispersion, and amorphous boron powder dispersion liquid is obtained;After amorphous boron powder dispersion liquid is filtered, filter cake is obtained, filter cake is washed with low boiling point solution for 1-3 times, and then vacuum drying is carried out in vacuum drying apparatus at room temperature for 24-48 h, and amorphous boron powder removed surface oxide layer is obtained;The method of the present application is simple and controllable, and can be applied to large-scale preparation.The present application can effectively remove most of the oxide layer on the surface of boron powder, improve the purity of boron powder by more than 4%, and help to improve the charging process of boron powder in propellant system.

Description

Technical Field

[0001] This invention belongs to the field of energetic materials technology, specifically relating to a method for removing the oxide layer on the surface of amorphous boron powder and amorphous boron powder. Background Technology

[0002] Metallic fuels have long been of interest to researchers of solid rocket propellants and explosives due to their high energy density and high thermal energy release during combustion. Boron (B) is particularly valuable due to its high calorific value (58.30 MJ·kg⁻¹). -1 ) and high volumetric calorific value (137.70 MJ·m -3 With its advantages, HTPB has become the most promising high-energy fuel in the defense industry, including solid propellants, high-energy explosives, and pyrotechnics. However, amorphous or commercially available boron powder is usually covered with a B2O3 oxide layer with a thickness of about 2-5 nm. This surface oxide layer is prone to polymerization with the hydroxyl groups (-OH) in HTPB molecules to form a gel, which deteriorates the propellant preparation process. During combustion, the surface oxide layer also forms a viscous liquid that hinders the complete combustion of boron particles, severely limiting its application.

[0003] Currently, the most common approach to addressing the problems of boron powder as a component of metallic fuels is purification or surface modification. Due to the inherent properties of boron oxide, conventional wet purification methods (such as acid washing) are difficult to use to remove it from boron powder, resulting in low efficiency and high cost. Some literature suggests using fluorides to aid in the removal of the boron oxide layer; the reaction of fluoropolymers with boron oxide can generate gas that accelerates the removal rate of the surface oxide layer, thereby improving the ignition and combustion performance of boron. However, this method is complex, difficult to scale up, and the introduction of fluoropolymers can reduce the boron powder content, potentially lowering the overall energy of the system. Summary of the Invention

[0004] In view of the defects and deficiencies of the existing technology, the purpose of this invention is to provide a method for removing the oxide layer on the surface of amorphous boron powder and amorphous boron powder, so as to solve the technical problems that the oxide layer on the surface of boron powder is prone to polymerization reaction with the hydroxyl groups in HTPB molecules to form a gel, and that the oxide layer on the surface of boron powder will form a viscous liquid during combustion, which will affect the complete combustion of boron particles.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A method for removing the oxide layer from the surface of amorphous boron powder includes the following steps:

[0007] Step 1: Add amorphous boron powder with an oxide layer on its surface to a strongly polar solvent to obtain an amorphous boron powder suspension.

[0008] Step 2: The amorphous boron powder suspension is ultrasonically dispersed for 4-6 hours within a temperature range of 80-100℃, and mechanical stirring is continuously performed during the ultrasonic dispersion process to obtain an amorphous boron powder dispersion.

[0009] Step 3: After filtering the amorphous boron powder dispersion, a filter cake is obtained. The filter cake is washed 1 to 3 times with a low-boiling-point solution and then vacuum dried in a vacuum dryer at room temperature for 24 to 48 hours to obtain amorphous boron powder with the surface oxide layer removed.

[0010] The ratio of the amorphous boron powder to the highly polar solvent is (1-4g): (40-140g).

[0011] The present invention also has the following technical features:

[0012] Specifically, the highly polar solvent is any one of N,N-dimethylformamide, dimethyl sulfoxide, and acetonitrile.

[0013] Furthermore, the low-boiling-point solution is any one of methanol, ethanol, diethyl ether, and acetone.

[0014] Furthermore, the ultrasonic dispersion power described in step 2 is 300-400W.

[0015] Furthermore, the mechanical stirring speed described in step 2 is 200–300 rpm.

[0016] Furthermore, the method includes the following specific steps:

[0017] Step 1: Add 2.0g of amorphous boron powder with an oxide layer on its surface to 60g of N,N-dimethylformamide to obtain an amorphous boron powder suspension;

[0018] Step 2: At 80°C, the amorphous boron powder suspension is ultrasonically dispersed at a power of 300W for 6 hours, and during the ultrasonic dispersion process, it is continuously mechanically stirred at a speed of 250rpm to obtain an amorphous boron powder dispersion.

[0019] Step 3: After filtering the amorphous boron powder dispersion, a filter cake is obtained. The filter cake is washed three times with ether and then vacuum dried in a vacuum dryer at room temperature for 24 hours to obtain 1.9g of amorphous boron powder with the surface oxide layer removed.

[0020] This invention also protects an amorphous boron powder for propellants, wherein the amorphous boron powder is prepared by the above-described method for removing the oxide layer on the surface of amorphous boron powder.

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

[0022] The method of this invention is simple and controllable, and can be applied to large-scale preparation. This invention can effectively remove most of the oxide layer on the surface of boron powder, increasing the purity of boron powder by more than 4%, and improving the loading process of boron powder in propellant systems. Furthermore, the heat of combustion of boron powder after removing the surface oxide layer can be increased by 14.89%, which is beneficial for its application in solid propellants and explosives. Attached Figure Description

[0023] Figure 1 This is a SEM image of the amorphous boron powder with an oxide layer on its surface in Example 1;

[0024] Figure 2 This is a SEM image of the amorphous boron powder with the surface oxide layer removed in Example 1;

[0025] Figure 3 This is an XPS image of the amorphous boron powder with an oxide layer on its surface in Example 1;

[0026] Figure 4 This is an XPS image of the amorphous boron powder with the surface oxide layer removed in Example 1;

[0027] Figure 5 This is an EDS image of the amorphous boron powder with an oxide layer on its surface in Example 1;

[0028] Figure 6 This is the EDS image of the amorphous boron powder with the surface oxide layer removed in Example 1;

[0029] Figure 7 This is a picture of amorphous boron powder with an oxide layer on its surface.

[0030] Figure 8 This is a picture of amorphous boron powder with the surface oxide layer removed.

[0031] The technical solution of the present invention will be further described below with reference to the embodiments. Detailed Implementation

[0032] Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0033] The technical concept of this invention is as follows: Utilizing the principle that polar solutes are readily soluble in polar solvents, a highly polar solvent free of oxygen (hydroxyl groups) is selected. Under heating conditions, the boron oxide and boric acid on the boron surface are dissolved, thereby removing the surface oxide layer. The hydroxyl-free solution avoids secondary oxidation during the film removal process. Finally, a low-boiling-point solution that is easy to remove further improves the purity of the boron powder.

[0034] A method for removing the oxide layer from the surface of amorphous boron powder includes the following steps:

[0035] Step 1: Add amorphous boron powder with an oxide layer on its surface to a strongly polar solvent to obtain an amorphous boron powder suspension.

[0036] Preferably, the ratio of the amorphous boron powder to the strongly polar solvent is (1-4g):(40-140g).

[0037] Preferably, the highly polar solvent is any one of N,N-dimethylformamide, dimethyl sulfoxide, and acetonitrile.

[0038] Step 2: The amorphous boron powder suspension is ultrasonically dispersed for 4-6 hours within a temperature range of 80-100℃, and mechanical stirring is continuously performed during the ultrasonic dispersion process to obtain an amorphous boron powder dispersion.

[0039] Preferably, the power of ultrasonic dispersion is 300-400W.

[0040] Preferably, the mechanical stirring speed is 200-300 rpm.

[0041] Step 3: After filtering the amorphous boron powder dispersion, a filter cake is obtained. The filter cake is washed 1 to 3 times with a low-boiling-point solution and then vacuum dried in a vacuum dryer at room temperature for 24 to 48 hours to obtain amorphous boron powder with the surface oxide layer removed.

[0042] Preferably, the low-boiling-point solution is any one of methanol, ethanol, diethyl ether, and acetone.

[0043] Example 1

[0044] Following the above technical solution, this embodiment discloses a method for removing the oxide layer on the surface of amorphous boron powder, including the following steps:

[0045] Step 1: Add 2.0g of amorphous boron powder with an oxide layer on its surface to 60g of N,N-dimethylformamide to obtain an amorphous boron powder suspension;

[0046] Step 2: At 80°C, the amorphous boron powder suspension is ultrasonically dispersed at a power of 300W for 6 hours, and during the ultrasonic dispersion process, it is continuously mechanically stirred at a speed of 250rpm to obtain an amorphous boron powder dispersion.

[0047] Step 3: After filtering the amorphous boron powder dispersion, a filter cake is obtained. The filter cake is washed three times with ether and then vacuum dried in a vacuum dryer at room temperature for 24 hours to obtain 1.9g of amorphous boron powder with the surface oxide layer removed.

[0048] Morphological analysis:

[0049] from Figure 1 and Figure 2 It can be seen that the amorphous boron powder with an oxide layer on the surface suffers from severe agglomeration due to the presence of the surface oxide layer and boric acid. After removing the surface oxide layer, the agglomeration phenomenon is significantly improved, and the boron particles have a more uniform particle size.

[0050] EDS analysis

[0051] like Figure 5 and Figure 6 As shown, the amorphous boron powder with an oxide layer on its surface contains 85.4% boron and 2.9% oxygen; the boron powder obtained after removing the surface oxide layer contains 89.9% boron and 1.7% oxygen. This indicates that the method of the present invention partially and successfully removes the oxide layer on the surface of the boron powder, reducing the oxygen content in the amorphous boron powder and increasing the boron content.

[0052] XPS Analysis

[0053] like Figure 3 and Figure 4 As shown, obvious B2O2 can be observed in the XPS spectra of both amorphous boron powder with an oxide layer on its surface and clean boron powder with the surface oxide layer removed. 0 The peak is produced by elemental boron. Furthermore, B peaks also appeared on the amorphous boron powder with an oxide layer on its surface. 3+ The peak is caused by the oxide layer on the surface of the boron powder. After removing the surface oxide layer, the boron powder's B... 3+ The peaks have largely disappeared, indicating that the surface of the obtained clean boron powder is basically free of oxide layer.

[0054] 4. Heat of combustion

[0055] Table 1 shows the heat of combustion measured for the amorphous boron powder (raw material) with an oxide layer on its surface used in Example 1 and the amorphous boron powder (product) with the surface oxide layer removed.

[0056]

[0057] As can be seen from the table above, the average heat of combustion of the raw materials is 15.83 kJ·g. -1 The average heat of combustion of the products is 18.03 kJ·g. -1 The heat of combustion of the product increased by 14.89%. This indicates that the method of the present invention can significantly increase the heat of combustion of boron powder, thereby improving its combustion efficiency.

[0058] The amorphous boron powder prepared in this embodiment can be used to prepare propellants.

[0059] Example 2

[0060] The steps of the method for removing the oxide layer on the surface of amorphous boron powder disclosed in this embodiment are the same as those in Embodiment 1, except that the ratio of amorphous boron powder to a strongly polar solvent is different. In this embodiment, 2.5g of amorphous boron powder with an oxide layer on its surface is added to 69g of N,N-dimethylformamide, and finally 2.4g of amorphous boron powder with the surface oxide layer removed is obtained.

[0061] Example 3

[0062] The steps of the method for removing the oxide layer on the surface of amorphous boron powder disclosed in this embodiment are the same as those in Embodiment 1, except that the ratio of amorphous boron powder to a strongly polar solvent is different. In this embodiment, 1.5g of amorphous boron powder with an oxide layer on its surface is added to 60g of N,N-dimethylformamide, and finally 1.3g of amorphous boron powder with the surface oxide layer removed is obtained.

[0063] Example 4

[0064] The steps of the method for removing the oxide layer on the surface of amorphous boron powder disclosed in this embodiment are the same as those in Embodiment 1, except that the ratio of amorphous boron powder to a strongly polar solvent is different. In this embodiment, 4g of amorphous boron powder with an oxide layer on its surface is added to 140g of N,N-dimethylformamide, and finally 3.8g of amorphous boron powder with the surface oxide layer removed is obtained.

[0065] Example 5

[0066] The steps of the method for removing the oxide layer on the surface of amorphous boron powder disclosed in this embodiment are the same as those in Embodiment 1, except that the ratio of amorphous boron powder to a strongly polar solvent is different. In this embodiment, 2.5g of amorphous boron powder with an oxide layer on its surface is added to 69g of N,N-dimethylformamide, and finally 2.4g of amorphous boron powder with the surface oxide layer removed is obtained.

[0067] Example 6

[0068] The steps of the method for removing the oxide layer on the surface of amorphous boron powder disclosed in this embodiment are the same as those in Embodiment 1, except that the choice of strong polar solvent is different. In this embodiment, 2.0g of amorphous boron powder with an oxide layer on its surface is added to 60g of acetonitrile, and finally 1.9g of amorphous boron powder with the surface oxide layer removed is obtained.

[0069] Example 7

[0070] The steps of the method for removing the oxide layer on the surface of amorphous boron powder disclosed in this embodiment are the same as those in Embodiment 1, except that the selection of a strongly polar solvent is different. In this embodiment, 2.0g of amorphous boron powder with an oxide layer on its surface is added to 60g of dimethyl sulfoxide, and finally 1.7g of amorphous boron powder with the surface oxide layer removed is obtained.

[0071] Example 8

[0072] The steps of the method for removing the surface oxide layer of amorphous boron powder disclosed in this embodiment are the same as those in Embodiment 1, except that the ultrasonic dispersion power is different. In this embodiment, 1.8g of amorphous boron powder with the surface oxide layer removed was finally obtained under an ultrasonic power of 400W.

[0073] Example 9

[0074] The steps of the method for removing the surface oxide layer of amorphous boron powder disclosed in this embodiment are the same as those in Embodiment 1, except that the mechanical stirring speed is different. In this embodiment, 1.8g of amorphous boron powder with the surface oxide layer removed was finally obtained at a stirring speed of 200rpm.

[0075] Example 10

[0076] The steps of the method for removing the surface oxide layer of amorphous boron powder disclosed in this embodiment are the same as those in Embodiment 1, except that the mechanical stirring speed is different. In this embodiment, 1.9g of amorphous boron powder with the surface oxide layer removed was finally obtained at a stirring speed of 300rpm.

[0077] Example 11

[0078] The steps of the method for removing the surface oxide layer of amorphous boron powder disclosed in this embodiment are the same as those in Embodiment 1, except that the temperature during ultrasonic dispersion is different. In this embodiment, ultrasonic dispersion is performed at 90°C, and 1.8g of amorphous boron powder with the surface oxide layer removed is finally obtained.

[0079] Example 12

[0080] The steps of the method for removing the surface oxide layer of amorphous boron powder disclosed in this embodiment are the same as those in Embodiment 1, except that the ultrasonic dispersion temperature is different. In this embodiment, ultrasonic dispersion is performed at 100°C, and 1.8g of amorphous boron powder with the surface oxide layer removed is finally obtained.

[0081] Example 13

[0082] The steps of the method for removing the surface oxide layer of amorphous boron powder disclosed in this embodiment are the same as those in Embodiment 1, except that the ultrasonic dispersion time is different. In this embodiment, the ultrasonic dispersion time is 4 hours, and 1.9g of amorphous boron powder with the surface oxide layer removed is finally obtained.

[0083] Example 14

[0084] The steps of the method for removing the oxide layer on the surface of amorphous boron powder disclosed in this embodiment are the same as those in Embodiment 1, except that the selected low-boiling-point solution is different. In this embodiment, acetone solution is used to wash the powder three times, and finally 1.9g of amorphous boron powder with the surface oxide layer removed is obtained.

[0085] Example 15

[0086] The steps of the method for removing the oxide layer on the surface of amorphous boron powder disclosed in this embodiment are the same as those in Embodiment 1, except that the selected low-boiling-point solution is different. In this embodiment, methanol solution is used for washing three times, and finally 1.7g of amorphous boron powder with the surface oxide layer removed is obtained.

[0087] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0088] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0089] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. An amorphous boron powder surface oxide layer removal method characterized by, The method comprises the following steps: Step 1, adding amorphous boron powder coated with an oxide layer into a strong polar solvent to obtain an amorphous boron powder suspension; Step 2, ultrasonic dispersing the amorphous boron powder suspension at a temperature of 80-100 ℃ for 4-6 h, and continuously performing mechanical stirring during the ultrasonic dispersion to obtain an amorphous boron powder dispersion; Step 3, filtering the amorphous boron powder dispersion to obtain a filter cake, washing the filter cake with a low-boiling-point solution for 1-3 times, and then vacuum drying the filter cake in a vacuum dryer at room temperature for 24-48 h to obtain amorphous boron powder from which the surface oxide layer is removed; The ratio of the amorphous boron powder to the strong polar solvent is (1-4 g) : (40-140 g); the strong polar solvent is any one of N, N-dimethylformamide, dimethyl sulfoxide and acetonitrile; The low-boiling-point solution is any one of methanol, ethanol, diethyl ether and acetone; The power of the ultrasonic dispersion in Step 2 is 300-400 W. The rotating speed of the mechanical stirring in Step 2 is 200-300 rpm.

2. The method of claim 1, wherein the boron powder is amorphous boron powder. The method comprises the following specific steps:

3. The method of claim 1, wherein the boron powder is amorphous boron powder. Step 1, adding 2.0 g of amorphous boron powder coated with an oxide layer into 60 g of N, N-dimethylformamide to obtain an amorphous boron powder suspension; Step 2, ultrasonic dispersing the amorphous boron powder suspension at 80 ℃ for 6 h at a power of 300 W, and continuously performing mechanical stirring at a rotating speed of 250 rpm during the ultrasonic dispersion to obtain an amorphous boron powder dispersion; Step 3, filtering the amorphous boron powder dispersion to obtain a filter cake, washing the filter cake with diethyl ether for 3 times, and then vacuum drying the filter cake in a vacuum dryer at room temperature for 24 h to obtain 1.9 g of amorphous boron powder from which the surface oxide layer is removed. The amorphous boron powder is prepared by the method for removing the surface oxide layer of the amorphous boron powder according to any one of claims 1-3.

4. An amorphous boron powder for propellant, characterized by comprising: ​

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