Aluminum-lithium alloy powder as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of alloy powder preparation, and discloses aluminum-lithium alloy powder and a preparation method and application thereof. The preparation method of the aluminum-lithium alloy powder comprises the steps that metal lithium and elemental aluminum are heated to be molten, and molten aluminum-lithium alloy is obtained; and the molten aluminum-lithium alloy is sequentially atomized and graded, and the aluminum-lithium alloy powder is obtained. The aluminum-lithium alloy powder prepared through the preparation method is fine in granularity, D50 can be smaller than 70 microns, the prepared aluminum-lithium alloy powder is uniform in component and good in quality consistency, and higher specific power and specific energy can be provided for a thermal battery.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy powder preparation, and in particular to an aluminum-lithium alloy powder and a preparation method and application thereof. Background Art

[0002] Thermal batteries have the advantages of fast activation, high current density, strong pulse discharge capability, long storage life, wide operating temperature, compact structure, simple process, low cost and no maintenance required. They are ideal military power sources.

[0003] With the development of high-performance weapon systems, the performance of existing thermal batteries is insufficient to support their development needs. Aluminum-lithium alloy, as a new generation of lithium-based thermal battery negative electrode material after lithium-silicon alloy, has good electrochemical and physical properties. The use of aluminum-lithium alloy to make thermal battery negative electrode material will greatly improve the comprehensive performance of thermal batteries. Special battery-grade lithium-aluminum alloy powder is a light gray metal solid powder with fine particle size and high activity. It needs to be prepared under special atmosphere conditions in a glove box throughout the process, which makes production and processing difficult. At present, only a few scientific research institutes in China can develop small batches, but there are still problems such as uneven distribution of lithium-aluminum content, poor product quality consistency and low cycle stability. In terms of preparation process, there are also disadvantages such as low degree of automation, low production capacity, high risk and unsuitability for large-scale mass production.

[0004] Therefore, it is of great significance to study and obtain an aluminum-lithium alloy powder with uniform lithium-aluminum content distribution, good product quality consistency, fine particle size, and a preparation method with simple preparation process, high degree of automation and safety. Summary of the invention

[0005] In view of this, the present invention provides an aluminum-lithium alloy powder and a preparation method and application thereof, the purpose of which is to solve the problems of uneven distribution of lithium and aluminum content, poor consistency and stability of product quality in existing lithium-aluminum alloy powders, and low degree of automation, small production capacity, high risk and inability to scale up batch production in the lithium-aluminum alloy powder preparation process.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The present invention provides a method for preparing aluminum-lithium alloy powder, comprising the following steps:

[0008] 1) heating metallic lithium and elemental aluminum until they are melted to obtain a molten aluminum-lithium alloy;

[0009] 2) The molten aluminum-lithium alloy is atomized and classified in sequence to obtain aluminum-lithium alloy powder.

[0010] Preferably, in step 1), the mass ratio of metallic lithium to elemental aluminum is 1:3-5.

[0011] Preferably, in step 1), the heating is carried out in an inert atmosphere, the heating pressure is 0 to 0.05 MPa, and the heating rate from room temperature to the melting temperature is 8 to 12°C / min;

[0012] The melting is carried out under stirring, the stirring speed is 60-150 rpm, the melting temperature is ≥700° C., and the melting time is 3-5 hours.

[0013] Preferably, in the step 2), the atomization is carried out in a high-speed airflow, the injection pressure of the high-speed airflow is ≥4 MPa, and the gas of the high-speed airflow is argon or helium.

[0014] Preferably, in step 2), atomization is performed in an atomization chamber, and the molten aluminum-lithium alloy flows through the bottom valve of the reactor and enters the atomization chamber through a high-pressure pneumatic valve, and the nozzle angle of the high-pressure pneumatic valve is 0 to 60°;

[0015] The wall of the atomization bin is a hollow sandwich structure, and a cooling medium is passed into the hollow sandwich structure, and the cooling medium is white oil.

[0016] Preferably, in step 2), the classification is performed in a classification chamber located in a glove box, and the atomized alloy powder is transported into the classification chamber by airflow;

[0017] The gas transported by the airflow is an inert gas, which is argon or helium, and the airflow velocity of the airflow transport is 3 to 5 L / min.

[0018] Preferably, in step 2), the particle size of the aluminum-lithium alloy powder is controlled by adjusting the rotation speed of the grading wheel through a frequency conversion controller, and the frequency of the frequency conversion controller is 30 to 60 Hz.

[0019] The invention also provides aluminum-lithium alloy powder prepared by a method for preparing the aluminum-lithium alloy powder.

[0020] The present invention also provides an application of the aluminum-lithium alloy powder in the field of thermal batteries.

[0021] It can be seen from the above technical solutions that, compared with the prior art, the present invention has the following beneficial effects:

[0022] The aluminum-lithium alloy powder prepared by the preparation method of the present invention has fine particle size, D50 can be less than 70μm, and the prepared aluminum-lithium alloy powder has uniform components and good quality consistency, and can provide higher specific power and specific energy for thermal batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0024] Figure 1 This is a schematic diagram of the process of preparing aluminum-lithium alloy powder according to the present invention;

[0025] Figure 2 The particle size distribution diagram of the lithium aluminum alloy powder obtained by passing the aluminum-lithium alloy powder in the primary collection bin through a 100-mesh standard sieve in Example 1;

[0026] Figure 3 This is a particle size distribution diagram of the lithium aluminum alloy powder obtained by passing the aluminum-lithium alloy powder in the secondary collection bin through a 200-mesh standard sieve in Example 1. DETAILED DESCRIPTION

[0027] The present invention provides a method for preparing aluminum-lithium alloy powder, comprising the following steps:

[0028] 1) heating metallic lithium and elemental aluminum until they are melted to obtain a molten aluminum-lithium alloy;

[0029] 2) The molten aluminum-lithium alloy is atomized and classified in sequence to obtain aluminum-lithium alloy powder.

[0030] In the present invention, in the step 1), the mass ratio of metallic lithium to elemental aluminum is preferably 1:3-5, more preferably 1:3.5-4.5, and more preferably 1:4.

[0031] In the present invention, in the step 1), the heating is preferably carried out in an inert atmosphere, the heating pressure is preferably 0 to 0.05 MPa, more preferably 0.01 to 0.04 MPa, more preferably 0.02 to 0.03 MPa, and the heating rate from room temperature to the melting temperature is preferably 8 to 12°C / min, more preferably 9 to 11°C / min, more preferably 10°C / min;

[0032] The melting is preferably carried out under stirring, the stirring speed is preferably 60 to 150 rpm, more preferably 80 to 140 rpm, more preferably 100 to 120 rpm, the melting temperature is preferably ≥700°C, more preferably ≥720°C, more preferably ≥750°C, and the melting time is preferably 3 to 5 h, more preferably 3.5 to 4.5 h, more preferably 4 h;

[0033] The stirring is firstly carried out at the bottom of the reactor, and when the remaining melting time is 0.5 h, the stirring is switched to the upper part of the reactor.

[0034] In the present invention, the step 1) is carried out in a reaction kettle, and a stirring rod, a pull rod and a bottom valve are arranged inside the reaction kettle;

[0035] By lifting the pull rod, the molten aluminum-lithium alloy can flow through the bottom valve of the reactor and enter the atomization chamber through the high-pressure pneumatic valve. The lifting height of the pull rod can adjust the opening degree of the bottom valve. The higher the pull rod is lifted, the larger the opening of the bottom valve of the reactor. When the pull rod is fully lifted, the bottom valve of the reactor is fully opened.

[0036] In the present invention, the order of adding metallic lithium and elemental aluminum in the step 1) is to add metallic lithium first and then elemental aluminum, which can avoid the situation that the relative atomic mass of aluminum is greater than the relative atomic mass of lithium, resulting in the aluminum gradually settling to the bottom layer of the reactor after the metallic lithium and elemental aluminum are melted, thereby causing the aluminum to have an uneven composition of the aluminum-lithium alloy powder. Therefore, loading elemental aluminum into the upper layer of the reactor can delay the sedimentation of aluminum, which is beneficial to the homogenization of the composition of the aluminum-lithium alloy powder and can improve the quality consistency of the aluminum-lithium alloy powder.

[0037] In the present invention, in the step 1), after the addition of metallic lithium and elemental aluminum is completed, the reactor is evacuated and then filled with inert gas; the vacuum degree of the reactor after evacuation is preferably ≤-0.1MPa, more preferably ≤-0.15MPa, and more preferably ≤-0.2MPa.

[0038] In the present invention, in the step 2), the atomization is preferably carried out in a high-speed airflow, the injection pressure of the high-speed airflow is preferably ≥4MPa, more preferably ≥4.2MPa, and more preferably ≥4.5MPa, and the gas of the high-speed airflow is preferably argon or helium.

[0039] In the present invention, in the step 2), atomization is preferably carried out in an atomization bin, and the molten aluminum-lithium alloy flows through the bottom valve of the reactor and enters the atomization bin through a high-pressure pneumatic valve. The nozzle angle of the high-pressure pneumatic valve is preferably 0-60°, more preferably 10-50°, and more preferably 20-30°; when the high-speed airflow flows through the high-pressure pneumatic valve, low pressure is generated near the nozzle of the high-pressure pneumatic valve, so that the dripping speed of the molten aluminum-lithium alloy can be controlled by adjusting the nozzle angle.

[0040] In the present invention, the wall of the atomization bin is preferably a hollow sandwich structure, and a cooling medium is passed into the hollow sandwich structure, and the cooling medium is preferably white oil; during the atomization process, the high-speed airflow crushes the aluminum-lithium alloy into atomized alloy powders to the wall of the atomization bin, and the alloy powders are cooled along the wall to form atomized alloy powders, which fall to the collection port for collection.

[0041] In the present invention, in the step 2), the classification is performed in a classification chamber located in the glove box, and the atomized alloy powder is transported into the classification chamber by air flow;

[0042] The gas transported by the airflow is preferably an inert gas, and the inert gas is preferably argon or helium. The airflow velocity of the airflow transport is preferably 3 to 5 L / min, more preferably 3.5 to 4.5 L / min, and more preferably 4 L / min.

[0043] In the present invention, in the step 2), the particle size of the aluminum-lithium alloy powder is controlled by adjusting the rotation speed of the classifying wheel through a frequency conversion controller, and the frequency of the frequency conversion controller is preferably 30 to 60 Hz, more preferably 35 to 55 Hz, and more preferably 40 to 50 Hz.

[0044] In the present invention, the classification is multi-stage screening, and the multi-stage screening is to transport the atomized alloy powder by gas to a primary classifier, and the aluminum-lithium alloy powder with larger particle size falls into the primary collecting bin. The alloy powder that has passed the primary classifier and has not fallen into the primary collecting bin is transported to the secondary classifier by gas, and the alloy powder with smaller particles falls into the secondary collecting bin.

[0045] In the present invention, the purity of the helium or argon gas is independently preferably greater than or equal to 99.99%.

[0046] In the present invention, the gas passing through the secondary classifier is introduced into a dust collector for gas-solid separation, and the obtained gas enters a compressor for secondary pressurization and recycling, thereby reducing the use of inert gas and reducing production costs.

[0047] The invention also provides aluminum-lithium alloy powder prepared by a method for preparing the aluminum-lithium alloy powder.

[0048] The present invention also provides an application of the aluminum-lithium alloy powder in the field of thermal batteries.

[0049] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0050] In the embodiment of the present invention, the wall of the atomization bin has a 5 mm thick hollow sandwich structure, and white oil is introduced into the hollow sandwich structure as a cooling medium;

[0051] The purity of nitrogen is 99.99%, and the purity of argon is 99.99%;

[0052] The classification is carried out in a classification chamber located in a glove box, and the classification chamber is composed of a primary classifier and a secondary classifier connected to each other.

[0053] Example 1

[0054] 2kg of lithium metal ingot and 8kg of aluminum were placed in a reactor in sequence, and the reactor was evacuated to -0.11MPa, and then filled with argon gas until the pressure in the reactor was 0.01MPa. The temperature was raised to 720°C at a heating rate of 10°C min-1, and the mixture was stirred at the bottom of the reactor for 2.5h at a rate of 100rpm, and then moved to the upper part of the reactor and stirred for 0.5h to obtain a molten aluminum-lithium alloy.

[0055] Open the high-pressure pneumatic valve, adjust the nozzle angle to 30°, lift the reactor pull rod, and allow the molten aluminum-lithium alloy to flow through the bottom valve of the reactor and drip into the atomization chamber through the high-pressure pneumatic valve. Pass nitrogen with a spray pressure of 4MPa into the atomization chamber, and atomize the molten aluminum-lithium alloy dripping from the high-pressure pneumatic valve to the wall of the atomization chamber, cool along the chamber wall into aluminum-lithium alloy powder and fall to the collection port;

[0056] The atomized alloy powder is transported to a primary classifier (the frequency of the frequency converter is 30 Hz) with argon gas at a flow rate of 3 L / min as the airflow carrier, and the aluminum-lithium alloy powder with larger particle size falls into the primary collecting bin. The alloy powder that has passed through the primary classifier and has not fallen into the primary collecting bin is transported to a secondary classifier (the frequency of the frequency converter is 45 Hz) by gas, and the aluminum-lithium alloy powder with smaller particle size falls into the secondary collecting bin; the first and second collecting bins are taken out respectively, and the aluminum-lithium alloy powder in the first collecting bin is sieved through a 100-mesh standard sieve to obtain lithium-aluminum alloy powder with a particle size of D50=83.061 μm, and the aluminum-lithium alloy powder in the secondary collecting bin is sieved through a 200-mesh standard sieve to obtain aluminum-lithium alloy powder with a particle size of D50=69.462 μm.

[0057] The obtained lithium aluminum alloy powder was subjected to component detection, and the test results showed that the Li content was 19.93% and the Al content was 80.06%. It can be seen that the component detection of the obtained lithium aluminum alloy powder showed that the Al and Li contents were within 0.5% of the Al and Li ratio during smelting and feeding, that is, the components were uniform and the quality consistency was good.

[0058] Example 2

[0059] 5 kg of lithium metal ingot and 20 kg of aluminum were placed in a reactor in sequence, and the reactor was evacuated to -0.15 MPa, and then filled with argon gas until the pressure in the reactor was 0.04 MPa. The temperature was raised to 700 ° C at a heating rate of 10 ° C / min, and the mixture was stirred at the bottom of the reactor for 4.5 hours at a rate of 80 rpm, and then moved to the upper part of the reactor and stirred for 0.5 hours to obtain a molten aluminum-lithium alloy.

[0060] Open the high-pressure pneumatic valve, adjust the nozzle angle to 45°, lift the reactor pull rod, and allow the molten aluminum-lithium alloy to flow through the bottom valve of the reactor and drip into the atomization chamber through the high-pressure pneumatic valve. Pass nitrogen with a spray pressure of 4.2MPa into the atomization chamber, and atomize the molten aluminum-lithium alloy dripping from the high-pressure pneumatic valve to the wall of the atomization chamber, cool along the chamber wall into aluminum-lithium alloy powder and fall to the collection port;

[0061] The atomized alloy powder is transported to a primary classifier (the frequency of the frequency converter is 35 Hz) with argon gas at a flow rate of 4 L / min as the airflow carrier, and the aluminum-lithium alloy powder with larger particle size falls into the primary collecting bin. The alloy powder that has passed through the primary classifier and has not fallen into the primary collecting bin is transported to a secondary classifier (the frequency of the frequency converter is 50 Hz) by gas, and the aluminum-lithium alloy powder with smaller particle size falls into the secondary collecting bin; the first and second collecting bins are taken out respectively, and the aluminum-lithium alloy powder in the first collecting bin is sieved through a 100-mesh standard sieve to obtain lithium-aluminum alloy powder with a particle size of D50=86.057 μm, and the aluminum-lithium alloy powder in the secondary collecting bin is sieved through a 200-mesh standard sieve to obtain aluminum-lithium alloy powder with a particle size of D50=71.389 μm.

[0062] Example 3

[0063] 8 kg of lithium metal ingot and 32 kg of aluminum were placed in a reactor in sequence, and the reactor was evacuated to -0.2 MPa, and then filled with argon gas until the pressure in the reactor was 0.02 MPa. The temperature was raised to 750°C at a heating rate of 10°C / min, and the mixture was stirred at the bottom of the reactor for 3.5 hours at a rate of 140 rpm, and then moved to the upper part of the reactor and stirred for 0.5 hours to obtain a molten aluminum-lithium alloy.

[0064] Open the high-pressure pneumatic valve, adjust the nozzle angle to 60°, lift the reactor pull rod, and allow the molten aluminum-lithium alloy to flow through the bottom valve of the reactor and drip into the atomization chamber through the high-pressure pneumatic valve. Pass nitrogen with a spray pressure of 4.5 MPa into the atomization chamber, and atomize the molten aluminum-lithium alloy dripping from the high-pressure pneumatic valve to the wall of the atomization chamber, cool along the chamber wall into aluminum-lithium alloy powder and fall to the collection port;

[0065] The atomized alloy powder is transported to a primary classifier (the frequency of the frequency converter is 40 Hz) with argon gas at a flow rate of 5 L / min as the airflow carrier, and the aluminum-lithium alloy powder with larger particle size falls into the primary collecting bin. The alloy powder that has passed through the primary classifier and has not fallen into the primary collecting bin is transported to a secondary classifier (the frequency of the frequency converter is 60 Hz) by gas, and the aluminum-lithium alloy powder with smaller particle size falls into the secondary collecting bin; the first and second collecting bins are taken out respectively, and the aluminum-lithium alloy powder in the first collecting bin is sieved through a 100-mesh standard sieve to obtain lithium-aluminum alloy powder with a particle size of D50=88.125 μm, and the aluminum-lithium alloy powder in the secondary collecting bin is sieved through a 200-mesh standard sieve to obtain aluminum-lithium alloy powder with a particle size of D50=72.147 μm.

[0066] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing aluminum-lithium alloy powder, characterized in that: The steps include: 1) heating metallic lithium and elemental aluminum until they are melted to obtain a molten aluminum-lithium alloy; 2) The molten aluminum-lithium alloy is atomized and classified in sequence to obtain aluminum-lithium alloy powder.

2. The method for preparing aluminum-lithium alloy powder according to claim 1, characterized in that: In the step 1), the mass ratio of metallic lithium to elemental aluminum is 1:3-5.

3. The method for preparing aluminum-lithium alloy powder according to claim 2, characterized in that: In the step 1), the heating is carried out in an inert atmosphere, the heating pressure is 0 to 0.05 MPa, and the heating rate from room temperature to the melting temperature is 8 to 12°C / min; The melting is carried out under stirring, the stirring speed is 60-150 rpm, the melting temperature is ≥700° C., and the melting time is 3-5 hours.

4. The method for preparing aluminum-lithium alloy powder according to claim 2 or 3, characterized in that: In the step 2), the atomization is performed in a high-speed airflow, the injection pressure of the high-speed airflow is ≥4 MPa, and the gas of the high-speed airflow is argon or helium.

5. The method for preparing aluminum-lithium alloy powder according to claim 4, characterized in that: In the step 2), atomization is performed in an atomization chamber, and the molten aluminum-lithium alloy flows through the bottom valve of the reactor and enters the atomization chamber through a high-pressure pneumatic valve, and the nozzle angle of the high-pressure pneumatic valve is 0 to 60°; The wall of the atomization bin is a hollow sandwich structure, and a cooling medium is passed into the hollow sandwich structure, and the cooling medium is white oil.

6. The method for preparing aluminum-lithium alloy powder according to claim 5, characterized in that: In the step 2), the classification is performed in a classification chamber located in the glove box, and the atomized alloy powder is transported into the classification chamber by air flow; The gas transported by the airflow is an inert gas, which is argon or helium, and the airflow velocity of the airflow transport is 3 to 5 L / min.

7. The method for preparing aluminum-lithium alloy powder according to claim 5 or 6, characterized in that: In the step 2), the particle size of the aluminum-lithium alloy powder is controlled by adjusting the rotation speed of the classifying wheel through a frequency conversion controller, and the frequency of the frequency conversion controller is 30 to 60 Hz.

8. Aluminum-lithium alloy powder obtained by the method for preparing aluminum-lithium alloy powder according to any one of claims 1 to 7.

9. Application of the aluminum-lithium alloy powder according to claim 8 in the field of thermal batteries.

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