A method for preparing high-calorific-value boron composite powder
Nanoscale molybdenum oxide was prepared by mixing ammonium molybdate and aluminum powder and using hydrogen reduction, which solved the problems of boron powder being difficult to ignite and having low combustion efficiency. This enabled the preparation of high-calorific-value boron composite powder, improving combustion performance and efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGSU ZHIREN JINGXING NEW MATERIALS RES INST CO LTD
- Filing Date
- 2023-12-21
- Publication Date
- 2026-05-26
AI Technical Summary
Boron powder in existing high-energy metallic fuels is difficult to ignite, and the boron oxide liquid film generated during combustion hinders further oxidation, resulting in low combustion efficiency. The high proportion of aluminum makes it easy to melt and clump.
Nanoscale molybdenum oxide and molybdenum-boron composite powder were prepared by mixing ammonium molybdate and boron powder, evaporating and drying them, adding aluminum powder, and then reducing and alloying them with hydrogen. The combustion performance of boron was improved by hydrogen reduction, and aluminum powder was used as a reducing agent and binder to promote the combustion of boron powder.
The combustion calorific value of boron composite powder was improved, combustion efficiency was enhanced, aluminum loading was reduced, and problems of aluminum melting and agglomeration were avoided, thus realizing the preparation of high-calorific-value boron composite powder.
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Figure CN117756587B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of high-energy metallic fuels, specifically relating to a method for preparing high-calorific-value boron composite powder. Background Technology
[0002] Boron powder possesses high quality and high volumetric calorific value, theoretically making it the optimal fuel choice for ramjet engines. High-energy boron-containing rich-fuel propellants are fundamental to maximizing the performance advantages of rocket ramjet engines. However, boron powder itself is difficult to ignite due to its high melting and boiling points, high oxygen consumption, and the presence of an initial oxide layer on its surface. Furthermore, the boron oxide generated during combustion forms a liquid film on the surface of the boron particles, hindering further oxidation. Therefore, the preparation of high-calorific-value boron powder is essential to improve its application in propellants.
[0003] CN113929547A discloses a high-calorific-value boron-based composite powder and its preparation method. The high-calorific-value boron-based composite powder is obtained by multi-step ball milling of amorphous boron powder, micron-sized aluminum powder, and an oxidant in an anhydrous ethanol environment, resulting in a boron-based ternary metal fuel with a combustion calorific value >32 kJ / g. The oxidant is PTFE, Fe2O3, CuO, or MoO3. CN114702362A discloses a metal fuel with internal catalytic energy release characteristics. This metal fuel includes aluminum, boron, and molybdenum, wherein aluminum is used as the matrix, boron accounts for 0.5% to 10% of the total mass of the metal fuel, and molybdenum accounts for 0.5% to 3% of the total mass of the metal fuel. The above fuels have good calorific value, but the proportion of aluminum is relatively high. Aluminum has a low melting point, which easily leads to melting and agglomeration during combustion, reducing the fuel's combustion efficiency. Summary of the Invention
[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing high calorific value boron composite powder with low aluminum loading.
[0005] The technical solution adopted by the present invention to achieve the above objectives is as follows:
[0006] A method for preparing a high-calorific-value boron composite powder includes the following steps:
[0007] (1) Mix ammonium molybdate and boron powder evenly in water, then evaporate and dry;
[0008] (2) Mix the mixture obtained after drying in step (1) with aluminum powder to obtain a precursor;
[0009] (3) The precursor is heated and then reduced and alloyed with hydrogen to obtain the high calorific value boron composite powder.
[0010] The high-calorific-value boron composite powder contains 3-10 wt% Mo and 0.1-3 wt% Al.
[0011] Preferably, the temperature for hydrogen reduction is 500–850°C.
[0012] More preferably, during hydrogen reduction, the temperature is first maintained at 500°C for a certain period of time, and then maintained at 850°C for a certain period of time.
[0013] Preferably, the alloying temperature is above 1000°C.
[0014] Reaction Mechanism: At 500℃, ammonium molybdate decomposes into molybdenum oxide, while trace amounts of aluminum powder promote the formation of molybdenum oxide, generating nano-sized molybdenum oxide particles. At 850℃, aluminum powder may undergo an aluminothermic reaction with molybdenum oxide, while also promoting the reduction of molybdenum oxide by hydrogen. At 1000℃, unreacted aluminum acts as a binder for molybdenum and boron powder, increasing the bonding force between molybdenum and boron and promoting the combustion of boron powder.
[0015] More preferably, alloying is carried out in an inert atmosphere.
[0016] A high-calorific-value boron composite powder prepared by the above preparation method.
[0017] Preferably, the high-calorific-value boron composite powder has a combustion calorific value of 35 kJ / g or higher.
[0018] The application of the above-mentioned high-calorific-value boron composite powder in the preparation of fuel-rich propellants.
[0019] Nanoscale molybdenum or molybdenum alloys were prepared by high-temperature hydrogen reduction to improve the combustion performance of boron. At the same time, a small amount of aluminum powder was used as a reducing agent and binder. The two worked together to improve the combustion efficiency of boron powder at low loading. Attached Figure Description
[0020] Figure 1 Scanning electron microscope (SEM) image of the high-calorific-value boron composite powder prepared in Example 1. Detailed Implementation
[0021] The technical solution of the present invention will be further described in detail below with reference to the embodiments.
[0022] Unless otherwise specified, the percentage of aluminum powder used in the following embodiments is relative to the mass of boron powder.
[0023] Example 1
[0024] 1.24 g of ammonium molybdate and 19.5 g of boron powder were weighed and placed in a 500 mL beaker. 200 mL of pure water was added and stirred until homogeneous. The mixture was stirred and evaporated to dryness at 80 °C to obtain a dry mixture. The mixture was then placed in a vacuum drying oven at 100 °C for 10 h to obtain a solid mixture. The solid mixture was ground and then mixed with 1% aluminum powder to obtain a precursor.
[0025] The precursor powder was placed in a crucible, which was then placed in a hydrogen furnace. The hydrogen furnace was first evacuated, and then the air inside the furnace was replaced with argon. This process was repeated three times before switching to hydrogen. The heating program was set as follows: from 30°C to 500°C at a rate of 8°C / min and held for 4 hours, then heated to 850°C at a rate of 5°C / min and held for 2 hours. After switching to argon, the temperature was raised to 1000°C and held for 1 hour before cooling to obtain sample A.
[0026] Comparative Example 1
[0027] Weigh 1.24 g of ammonium molybdate and 19.5 g of boron powder into a 500 mL beaker, add 200 mL of pure water and stir until homogeneous. Stir and evaporate to dryness at 80 °C to obtain a mixture, place it in a vacuum drying oven at 100 °C for 10 h, and grind the resulting solid mixture for later use.
[0028] The powder was placed in a crucible, which was then placed in a hydrogen furnace. The hydrogen furnace was first evacuated, and then the air inside the furnace was replaced with argon. This process was repeated three times before switching to hydrogen. The heating program was set as follows: from 30°C to 500°C at a rate of 8°C / min and held for 4 hours, then heated to 850°C at a rate of 5°C / min and held for 2 hours. After switching to argon, the temperature was raised to 1000°C and held for 1 hour before cooling to obtain sample B.
[0029] Comparative Example 2
[0030] Weigh 20.0g of boron powder and mix with 1% aluminum powder to obtain the precursor.
[0031] The powder was placed in a crucible, which was then placed in a hydrogen furnace. The hydrogen furnace was first evacuated, and then the air inside the furnace was replaced with argon. This process was repeated three times before switching to hydrogen. The heating program was set as follows: from 30°C to 500°C at a rate of 8°C / min and held for 4 hours, then the temperature was increased to 850°C at a rate of 5°C / min and held for 2 hours. After switching to argon, the temperature was increased to 1000°C and held for 1 hour before cooling to obtain sample C.
[0032] Comparative Example 3
[0033] 1.24 g of ammonium molybdate and 19.5 g of boron powder were weighed and placed in a 500 mL beaker. 200 mL of pure water was added and stirred until homogeneous. The mixture was stirred and evaporated to dryness at 80 °C to obtain a dry mixture. The mixture was then placed in a vacuum drying oven at 100 °C for 10 h to obtain a solid mixture. The solid mixture was ground and then mixed with 1% aluminum powder to obtain a precursor.
[0034] The powder was placed in a crucible, which was then placed in a hydrogen furnace. The hydrogen furnace was first evacuated, and then the air inside the furnace was replaced with argon. This process was repeated three times before switching to hydrogen. The heating program was set to increase the temperature from 30°C to 500°C at a rate of 8°C / min and hold for 4 hours. Then, argon was switched back to argon and the temperature was increased to 1000°C and held for 1 hour before cooling to obtain sample D.
[0035] Comparative Example 4
[0036] 1.24 g of ammonium molybdate and 19.5 g of boron powder were weighed and placed in a 500 mL beaker. 200 mL of pure water was added and stirred until homogeneous. The mixture was stirred and evaporated to dryness at 80 °C to obtain a dry mixture. The mixture was then placed in a vacuum drying oven at 100 °C for 10 h to obtain a solid mixture. The solid mixture was ground and then mixed with 1% aluminum powder to obtain a precursor.
[0037] The powder was placed in a crucible, which was then placed in a hydrogen furnace. The hydrogen furnace was first evacuated, and then the air inside the furnace was replaced with argon. This process was repeated three times before switching to hydrogen. The heating program was set as follows: from 30°C to 500°C at a rate of 8°C / min, then to 850°C at a rate of 5°C / min and held for 2 hours. After switching to argon, the temperature was raised to 1000°C and held for 1 hour before cooling to obtain sample E.
[0038] Comparative Example 5
[0039] 1.24 g of ammonium molybdate and 19.5 g of boron powder were weighed and placed in a 500 mL beaker. 200 mL of pure water was added and stirred until homogeneous. The mixture was stirred and evaporated to dryness at 80 °C to obtain a dry mixture. The mixture was then placed in a vacuum drying oven at 100 °C for 10 h to obtain a solid mixture. The solid mixture was ground and then mixed with 1% aluminum powder to obtain a precursor.
[0040] The powder was placed in a crucible, which was then placed in a hydrogen furnace. The hydrogen furnace was first evacuated, and then the air inside the furnace was replaced with argon. This process was repeated three times before switching to hydrogen. The heating program was set as follows: from 30°C to 500°C at a rate of 8°C / min and held for 4 hours, then the temperature was increased to 850°C at a rate of 5°C / min and held for 2 hours. After switching to argon and cooling, sample F was obtained.
[0041] Example 2
[0042] 1.24 g of ammonium molybdate and 19.5 g of boron powder were weighed and placed in a 500 mL beaker. 200 mL of pure water was added and stirred until homogeneous. The mixture was stirred and evaporated to dryness at 80 °C to obtain a dry mixture. The mixture was then placed in a vacuum drying oven at 100 °C for 10 h to obtain a solid mixture. The solid mixture was ground and then mixed with 0.1% aluminum powder to obtain a precursor.
[0043] The precursor powder was placed in a crucible, which was then placed in a hydrogen furnace. The hydrogen furnace was first evacuated, and then the air inside the furnace was replaced with argon. This process was repeated three times before switching to hydrogen. The heating program was set as follows: from 30°C to 500°C at a rate of 8°C / min and held for 4 hours, then heated to 850°C at a rate of 5°C / min and held for 2 hours. After switching to argon, the temperature was raised to 1000°C and held for 1 hour before cooling to obtain sample G.
[0044] Example 3
[0045] 4.0 g of ammonium molybdate and 19.0 g of boron powder were weighed and placed in a 500 mL beaker. 200 mL of pure water was added and stirred until homogeneous. The mixture was stirred and evaporated to dryness at 80 °C to obtain a dry mixture. The mixture was then placed in a vacuum drying oven at 100 °C for 10 h to obtain a solid mixture. The solid mixture was ground and then mixed with 3% aluminum powder to obtain a precursor.
[0046] The precursor powder was placed in a crucible, which was then placed in a hydrogen furnace. The hydrogen furnace was first evacuated, and then the air inside the furnace was replaced with argon. This process was repeated three times before switching to hydrogen. The heating program was set as follows: from 30°C to 500°C at a rate of 8°C / min and held for 4 hours, then heated to 850°C at a rate of 5°C / min and held for 2 hours. After switching to argon, the temperature was raised to 1000°C and held for 1 hour before cooling to obtain sample H.
[0047] This project uses an automatic calorimeter to test the heat of combustion of boron powder. The testing standard is in accordance with GB / T 213-2008.
[0048] Test data of the calorific value of the above samples:
[0049] Sample number Calorific value (kJ / g) Sample A 36 Sample B 17 Sample C 16 Sample D 17 Sample E 32 Sample F 30 Sample G 35 Sample H 38
[0050] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing a high-calorific-value boron composite powder, characterized in that: Includes the following steps: (1) Mix ammonium molybdate and boron powder evenly in water, then evaporate and dry; (2) Mix the mixture obtained after drying in step (1) with aluminum powder to obtain a precursor; (3) The precursor is heated and then reduced and alloyed with hydrogen to obtain the high calorific value boron composite powder; The high-calorific-value boron composite powder contains 3-10 wt% Mo and 0.1-3 wt% Al. The temperature for hydrogen reduction is 500~850℃; During hydrogen reduction, the temperature is first kept at 500℃ for a certain period of time, and then at 850℃ for a certain period of time. The alloying temperature is above 1000℃; Alloying is carried out in an inert atmosphere.
2. A high-calorific-value boron composite powder prepared according to the preparation method of claim 1.
3. The high calorific value boron composite powder according to claim 2, characterized in that: The calorific value of the high-calorific-value boron composite powder is above 35 kJ / g.
4. The application of the high calorific value boron composite powder according to any one of claims 2-3 in the preparation of fuel-rich propellants.