CN111774579A - A kind of Al/Ni composite particle and preparation method thereof - Google Patents

Abstract

The invention discloses a preparation method of Al/Ni composite particles. The method is specifically as follows: mixing nanometer or micron aluminum powder, nickel salt and ethanol to form a suspension, mixing sodium hydroxide and ethanol to form a transparent solution; under the conditions of required ambient temperature and pH value, mixing the sodium hydroxide solution When added dropwise to the suspension, sodium hydroxide reacts with the aluminum oxide on the surface of the aluminum powder, so that the aluminum core inside the aluminum powder is exposed, and then the exposed aluminum core undergoes a displacement reaction with nickel ions, and the nano-nickel particles generated by the reaction are deposited on the surface. The surface of the aluminum powder is filtered and vacuum dried to finally obtain Al/Ni composite particles with a core-shell structure. In the preparation process, the preparation method of the invention has little environmental pollution, simple process and low cost.

Description

A kind of Al/Ni composite particle and preparation method thereof

technical field

The invention belongs to the technical field of micro-nano energetic materials, and provides an Al/Ni composite particle and a preparation method thereof.

Background technique

Micro-nano aluminum powder is one of the most commonly used high-activity metal powders in the field of energetic materials. It is of great significance for the development of high-performance weapons and ammunition. Small-particle aluminum powder, especially for nano-aluminum powder, is very easy to react with oxygen, water, etc. to form a dense and chemically stable compound Al ₂ O ₃ , which hinders the reaction of remaining active aluminum and oxidants, and greatly limits its use. Energy release efficiency; at the same time, aluminum powder often occurs agglomeration and sintering during combustion, generating larger particles, which reduces the activity of aluminum powder and the reaction is incomplete. For example, for aluminum powder particles with an average particle size of 80 nm, the active aluminum content is only about 75%, the chemically inert Al ₂ O ₃ accounts for a very high mass, and the average size of agglomerates and sintered bodies can reach 3 μm to 6 μm. In the meantime, all the advantages of nano-effect of aluminum powder are lost, and the characteristics of high reactivity and high reaction rate cannot be brought into full play.

The study found that nano-nickel particles, as the coating material of aluminum powder, have many advantages in improving the reaction characteristics of aluminum powder. First of all, compared with aluminum, nickel has lower reactivity in the natural state, and it is not easy to chemically react with oxygen or water. Therefore, using a certain thickness of nickel coating to replace aluminum oxide on the surface of aluminum powder can be very To a large extent, the core of aluminum powder is prevented from being oxidized, and the dispersibility of nano-aluminum powder is improved at the same time; secondly, nickel will also undergo redox reaction under certain conditions, and replacing Al ₂ O ₃ with nickel makes the aluminum powder system change from Al/Al ₂ O ₃ was changed to Al/Ni/Al ₂ O ₃ , and the total active material content of the system was improved; in addition, it was reported in other literatures that coating the surface of aluminum powder with nickel can also improve the ignition performance and combustion performance of nano-aluminum powder. Further improve the energy release efficiency of nano aluminum powder.

At present, the methods for preparing nickel-coated aluminum powder mainly include vapor deposition method and chemical plating method. Patent CN201210180759.3 (application date June 5, 2012, publication date October 10, 2012) discloses a vapor deposition method to prepare The method for coating micron aluminum powder with nickel, the aluminum powder particles form a countercurrent in the fluidized bed reactor with the carbonyl nickel steam/carbon monoxide mixed gas injected by the nozzle at the lower side of the fluidized bed reactor. During the countercurrent process, the carbonyl nickel gas Metal nickel is formed by thermal decomposition on the surface of the aluminum powder, and the metal nickel is deposited on the surface of the aluminum powder, thereby realizing the coating of the micron aluminum powder. The method has complex process parameters, the preparation process is not under very high temperature and normal pressure conditions, there are certain safety hazards, the equipment cost is high, and strict requirements are placed on the performance of the equipment in all aspects. Patent CN201310359074.X (application date August 16, 2013, publication date December 11, 2013) introduces a method for preparing nickel-coated micron aluminum powder by chemical plating method, firstly, the aluminum powder is alkali-washed with NaOH aqueous solution , then the alkali-washed aluminum powder is added to the first main salt solution composed of nickel sulfate and citric acid, and a surfactant is added, and then NH ₄ F solution is added dropwise to the plating solution at a constant speed to initiate a replacement reaction. The two main salt solution, sodium hypophosphite solution, ammonia water, ammonium sulfate solution, etc. reprocess the above-mentioned plating solution, after suction filtration, alternately wash with water and absolute ethanol for many times, and then vacuum dry to obtain the final product. The technical process of this method is relatively complicated. The aluminum powder is coated with nickel plating in two steps. Each nickel plating process will leave a lot of chemical waste liquid, resulting in waste of raw materials. In the final treatment, a lot of ammonia water is used. It will also cause serious pollution to the environment; in addition, the entire nickel plating process adopts an aqueous environment, and the redox reaction between aluminum powder and water is not considered, resulting in a large loss of active aluminum. Patent CN200710056768.0 (application date February 9, 2007, publication date August 13, 2008) discloses a method for nickel coating on nano aluminum powder, adding nano aluminum powder to ethylene glycol dimethyl ether In the liquid, it is dispersed evenly by stirring; the nickel acetylacetonate is added to the ethylene glycol dimethyl ether liquid, and it is completely dissolved by stirring to form a uniformly mixed liquid; the above two liquids are mixed to make the nickel acetylacetonate. The nano-aluminum powder is spontaneously adsorbed on the nano-aluminum powder in the ethylene glycol dimethyl ether liquid; the nano-aluminum powder which has been adsorbed is taken out after being dried by natural volatilization, and the core-shell structure nickel-coated nano-aluminum powder is prepared. In this method, a highly volatile organic solvent is used in the whole process. In order to obtain the final product, all the organic solvents are finally discharged into the atmosphere by volatilization, which causes environmental pollution. At the same time, the use of a large amount of organic solvents also makes the preparation cost relatively high. In addition, ethylene glycol dimethyl ether has flammable and explosive characteristics and strong toxicity, which increases the probability of dangerous accidents during sample preparation.

Summarizing the above research on the preparation method of nickel-coated micro-nano aluminum powder, it is found that the existing preparation method is not simple and convenient, not green and safe, and has high economic cost, so it is not suitable for large-scale application and production to prepare Al/Ni composite particles.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an Al/Ni composite particle and a preparation method thereof, so as to prevent the oxidative deactivation of the aluminum powder in the air, reduce the ignition delay of the aluminum powder, improve the combustion reaction rate of the aluminum powder, and solve the problem of the energy release of the aluminum powder. Incomplete and so on.

The technical scheme that realizes the object of the present invention is:

An Al/Ni composite particle is composed of 3.6%-14.8% mass fraction of nickel, 68.7%-96.0% mass fraction of active aluminum and 0.4%-16.5% mass fraction of alumina.

Further, the composite particles have a core-shell structure, the nano-aluminum powder is a core, and the nickel is coated on the surface of the nano-aluminum powder.

The preparation method of the above-mentioned Al/Ni composite particles comprises the following steps: (1) weighing sodium hydroxide, adding it to absolute ethanol to form a transparent solution; (2) weighing aluminum powder and nickel salt, adding them to into absolute ethanol, then ultrasonically dispersed for 30min to form a uniform suspension; (3) transfer the transparent solution and suspension configured in steps (1) and (2) to a constant temperature water bath, and set the water bath temperature to be 35 ℃～45℃, make the temperature of the transparent solution and the suspension reach the set temperature; (4) drop the transparent solution configured in step (1) into the suspension configured in step (2), and vigorously stir and suspend during the dropping process liquid, and the total reaction time is controlled to be 5 min to 10 min; (5) after the reaction is completed, suction filtration and vacuum drying are performed to collect the composite particles.

Compared with the prior art, the present invention has the following significant advantages: 1. Al/Ni composite particles have good corrosion resistance in the natural environment, can maintain the active aluminum content in the nano aluminum powder for a long time, and prevent the active aluminum from being oxidized; 2. .Al/Ni composite particles are ignited by the ignition wire in the air atmosphere, and the burning speed is fast. The total burning time of the 50mg sample placed in a cone is only about 450ms.

Description of drawings

FIG. 1 is a 100 nm transmission electron microscope image of Al/Ni composite particles.

FIG. 2 is a scanning electron microscope image of 500 nm of Al/Ni composite particles.

FIG. 3 is a high-speed video image of the combustion process of Al/Ni composite particles in an air atmosphere.

Detailed ways

The present invention is further illustrated by the following examples.

Example 1

Weigh 1.0g of nano aluminum powder, measure 40mL of absolute ethanol, and configure it into a suspension; weigh 0.5g of nickel chloride hexahydrate, weigh 50mL of absolute ethanol, and configure it into a transparent solution; add the above suspension to the transparent solution Stir to form a mixed turbid solution; weigh 0.12 g of sodium hydroxide, measure 15.0 mL of anhydrous ethanol, and prepare a sodium hydroxide ethanol solution; add the sodium hydroxide ethanol solution dropwise to the mixed turbid solution at 40 °C, vigorously After stirring for 10 min, vacuum drying at 50°C was performed to obtain the final product. It is found that the Al/Ni composite particles have good dispersibility. The total burning time of the 50 mg sample placed as a cone is only 471 ms, and the nano-aluminum powder of the same specification is not ignited under the same conditions.

Example 2

Weigh 0.5g of nano-aluminum powder, measure 20mL of absolute ethanol, and configure it into a suspension; weigh 0.25g of nickel sulfate, measure 25mL of absolute ethanol, and configure it into a transparent solution; add the above suspension to the transparent solution and stir to form Mix the turbid liquid; weigh 0.06 g of sodium hydroxide, measure 7.5 mL of anhydrous ethanol, and prepare a sodium hydroxide ethanol solution; add the sodium hydroxide ethanol solution dropwise to the mixed turbid solution at 25 °C, stir vigorously for 10 min, After suction filtration, vacuum drying at 50°C was performed to obtain the final product. It was found that the Al/Ni composite particles prepared at low temperature, the total burning time of 50mg sample placed as a cone was 753ms.

Example 3

Weigh 1.0g of nano aluminum powder, measure 40mL of absolute ethanol, and configure it into a suspension; weigh 0.5g of nickel chloride hexahydrate, weigh 50mL of absolute ethanol, and configure it into a transparent solution; add the above suspension to the transparent solution Stir to form a mixed turbid solution; weigh 0.12 g of sodium hydroxide, measure 15.0 mL of anhydrous ethanol, and prepare a sodium hydroxide ethanol solution; add the sodium hydroxide ethanol solution dropwise to the mixed turbid solution at 55 °C, vigorously After stirring for 10 min, vacuum drying at 50°C was performed to obtain the final product. It was found that the Al/Ni composite particles prepared at high temperature, the total burning time of 50mg sample placed as a cone was 697ms.

Example 4

Weigh 0.5g of nano-aluminum powder, measure 20mL of absolute ethanol, and configure it into a suspension; weigh 0.25g of nickel sulfate, measure 25mL of absolute ethanol, and configure it into a transparent solution; add the above suspension to the transparent solution and stir to form Mix the turbid liquid; weigh 0.2 g of sodium hydroxide, measure 7.5 mL of anhydrous ethanol, and prepare a sodium hydroxide ethanol solution; add the sodium hydroxide ethanol solution dropwise to the mixed turbid solution at 40 °C, stir vigorously for 10 min, After suction filtration, vacuum drying at 50°C was performed to obtain the final product. It was found that the Al/Ni composite particles prepared under the condition of higher sodium hydroxide content, the 50 mg sample placed as a cone, were not ignited under the same experimental conditions.

Example 5

Weigh 1.0g of nano aluminum powder, measure 40mL of absolute ethanol, and configure it into a suspension; weigh 0.8g of nickel chloride hexahydrate, weigh 50mL of absolute ethanol, and configure it into a transparent solution; add the above suspension to the transparent solution Stir to form a mixed turbid solution; weigh 0.12 g of sodium hydroxide, measure 15.0 mL of anhydrous ethanol, and prepare a sodium hydroxide ethanol solution; add the sodium hydroxide ethanol solution dropwise to the mixed turbid solution at 40 °C, vigorously After stirring for 10 min, vacuum drying at 50°C was performed to obtain the final product. It was found that the Al/Ni composite particles prepared under the condition of high nickel salt content, the total burning time of 50mg sample placed as a cone was 766ms.

Figure 1 is a transmission electron microscope image of the Al/Ni composite particles, and it can be seen from the figure that the composite particles have a typical core-shell structure.

Figure 2 is a scanning electron microscope photo of the Al/Ni composite particles. It can be seen from the figure that the composite particles have a good microscopic morphology.

Figure 3 is a high-speed video of the combustion process of Al/Ni composite particles in an air atmosphere taken at a shooting rate of 2000 frames per second. It can be seen from the figure that the composite particles have good combustion performance and a fast combustion rate.

Summarizing the above examples, it is found that the present invention controls the conditions: an ambient temperature of 35°C to 45°C, a mass ratio of sodium hydroxide to aluminum powder of 1:50 to 1:5, and a nickel salt to aluminum powder of 1:10 to 1:2. The powder mass ratio is a reasonable condition for the preparation of Al/Ni composite particles. Changing the ambient temperature and the mass ratio of sodium hydroxide/aluminum powder/nickel salt will lead to poor combustion performance of the final prepared composite particles, which is reflected in the 50mg cone sample. Burn time becomes longer.

Claims (6)

1. An Al/Ni composite particle, characterized in that the composite particle is composed of 3.6%-14.8% mass fraction of nickel, 68.7%-96.0% mass fraction of active aluminum and 0.4%-16.5% mass fraction of alumina . 2 . The Al/Ni composite particle according to claim 1 , wherein the composite particle has a core-shell structure, the micro-nano aluminum powder is the core, and the surface of the aluminum powder is coated with nickel. 3 . 3. according to the preparation method of the Al/Ni composite particle described in any one of claim 1-2, it is characterized in that: may further comprise the steps: (1) weigh sodium hydroxide, be added to dehydrated alcohol (2) Weigh aluminum powder and nickel salt, add them to absolute ethanol, and ultrasonically disperse them for 30 min to form a uniform suspension; (3) combine step (1) with step (2) The configured transparent solution and suspension are transferred to a constant temperature water bath, and the temperature of the water bath is set to be 35°C to 45°C, so that the temperature of the transparent solution and the suspension both reach the set temperature; (4) The transparent solution configured in step (1) is Add dropwise to the suspension prepared in step (2), vigorously stir the suspension during the dropwise addition, and control the total reaction time to be 5 min to 10 min; (5) after the reaction is completed, perform suction filtration and vacuum drying to collect composite particles. 4. Al/Ni composite particle preparation method according to claim 3, is characterized in that: the mass ratio of sodium hydroxide and aluminium powder is 1:50～1:5; The mass ratio of nickel salt and aluminium powder is 1: 10 to 1:2. 5 . The method for preparing Al/Ni composite particles according to claim 3 , wherein the purity of the nickel salt is more than 99.9%. 6 . 6 . The preparation method of Al/Ni composite particles according to claim 3 , wherein the solvent used in the preparation process is anhydrous ethanol, and the purity is above 99.9. 7 .

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