CN115889760A - Device and method for rapidly preparing carbon nanotube coated superfine high-entropy alloy composite powder - Google Patents

Abstract

The invention discloses a device and a method for rapidly preparing carbon nanotube-coated high-entropy alloy composite powder (CNT @ HEA), which relate to the growth of carbon nanotubes and high-entropy alloy, wherein a certain amount of nitrate hydrate containing iron, cobalt, nickel and other metals which are easy to catalyze and grow the carbon nanotubes is weighed and added into an ethanol solution, argon is used for driving an independently designed gas atomization device to spray micron-sized fog beads, the ethanol and the nitrate are subjected to high-temperature cracking at the temperature of over 1100 ℃ through a vacuum tube furnace, and a carbon source and H are generated ₂ And reducing to obtain fine high-entropy alloy particles, and growing the carbon nano tubes on the surfaces of the high-entropy alloy particles in situ under the catalysis of iron, cobalt and nickel. The invention utilizes the independently designed device to be fastAnd rapidly preparing the superfine high-entropy alloy, and growing the carbon nano tube on the surface of the superfine high-entropy alloy particle in situ to obtain the nano tube-coated superfine high-entropy alloy composite powder. The invention has simple process and low cost, and is suitable for the fields of energy catalysis, composite materials and the like.

Description

A device and method for rapidly preparing carbon nanotube-coated ultrafine high-entropy alloy composite powder

technical field

The invention belongs to the technical field of high-entropy alloy preparation, and specifically relates to a device and method for rapidly preparing carbon nanotube-coated ultrafine high-entropy alloy composite powder.

Background technique

High-entropy alloys (HEAs) possess unique properties with rich possibilities for atomic-scale tuning. For bulk HEA, its special mechanical properties (yield strength, ductility, and hardness) have been predicted and demonstrated, and the concepts of hydrogen storage capacity, thermoelectric properties, superconductivity, and pseudoelements have also been explored.

In recent years, high-entropy nanoparticles (HEA-NPs) have attracted extensive attention due to their multi-element composition (usually five or more elements) and uniformly mixed solid solution state, which not only provide a large number of combinations for materials discovery, but also have Unique microstructure for performance optimization. Recent advances in ultrafast synthetic methods, such as those based on non-equilibrium thermal shock, have enabled a variety of high-entropy nanoparticles without phase separation problems, even in immiscible element combinations. High-entropy alloy nanoparticles simultaneously possess superior physicochemical properties, including a wide selection of elements, high corrosion resistance, high thermal and chemical stability, enhanced mechanical strength, and enhanced catalytic activity due to synergistic catalytic reactions of elements, and in recent years It has received extensive attention in energy and catalytic applications.

Metal elements such as Fe, Co, Ni, and Cu are used to catalyze the growth of carbon nanotubes. Carbon nanotubes have good electrical conductivity. At the same time, carbon nanotubes (CNT) are one-dimensional quantum materials with a special structure (the radial dimension is on the order of nanometers, the axial dimension is on the order of microns, and both ends of the tube are basically sealed). Growth on the surface of high-entropy alloy nanoparticles makes the nanoparticles have a larger surface area and excellent electrical conductivity, which can make the nanoparticles more widely used in energy and catalysis.

Contents of the invention

Aiming at the technical problems of difficult preparation of high-entropy alloy ultrafine particles, complex process and low yield, the present invention proposes a device and method for rapidly preparing carbon nanotube-coated ultrafine high-entropy alloy composite powder. The device is simple, and at the same time, it can produce a large amount of CNT@HEA ultrafine particles.

To achieve the above object, the present invention adopts the following technical solutions:

A device for rapidly preparing carbon nanotube-coated ultrafine high-entropy alloy composite powder includes: a flow control device, a gas atomization generating device, a high-temperature device, a collecting device and a tail gas treatment device.

Further, the flow control device, the gas atomization generating device, the high temperature device, the collecting device and the exhaust gas treatment device are sequentially connected according to the air flow direction; sealing rings, vacuum clamps, etc. are used to ensure the sealing.

Further, the flow control device is a glass rotameter with a range of 600mL~6L, preferably greater than 4L/min, and the gas flow can be adjusted, and the Ar gas source and the gas atomization generating device are connected through a hose.

Further, the gas atomization generating device is an atomic absorption nebulizer, the left side of the atomic absorption nebulizer is provided with a pipeline connected to the precursor solution, the lower part is provided with a pipeline passing through Ar gas, and the right side is provided with an aerosol An atomization nozzle, the gas atomization nozzle is connected with the inlet of the high temperature device.

Further, the high-temperature device is a vacuum tube furnace, the right side of which is connected to the inlet of the collecting device; the collecting device is composed of a container containing filter paper, wherein the filter paper is located at the outlet of the collecting device for intercepting the product in the airflow, to achieve Collect effects. The outlet of the collection device is connected to the inlet of the tail gas treatment device, and the tail gas treatment device is composed of a container containing NaOH solution, through which the generated NO, NO ₂ and other gases are processed.

The present invention also provides a method for rapidly preparing carbon nanotube-coated ultrafine high-entropy alloy composite powder by using the above-mentioned device, comprising the following steps:

1) Preparation of precursor solution: Weigh the five metals of Fe, Co, Ni, Cr and Al (the three elements that mainly play a catalytic role are Fe, Co and Ni, and other elements such as Al, Ti, V, Mn, Cr, Cu, etc. can all be used.), add the nitrate hydrate into the ethanol solution, ultrasonic, stir to make it evenly mixed, and obtain the precursor mixed solution;

2) Preparation of carbon nanotube-coated ultrafine high-entropy alloy composite powder (CNT@HEA): the precursor mixed solution prepared in step (1) is driven into the aerosolization device by Ar gas Atomized nozzle, put together with Ar gas into a vacuum tube furnace above 1000°C, after rapid heating of the tube furnace, ethanol is cracked at high temperature to produce carbon source and hydrogen gas, and quickly reduce nitrate to obtain FeCoNiCrAl high-entropy alloy, in Fe, Under the catalysis of Co and Ni elements, CNTs are produced on the surface of the high-entropy alloy, and the carbon nanotube-coated high-entropy alloy is obtained. After the product exits the vacuum tube furnace, it is cooled rapidly in the pipeline and reaches the collection device to be intercepted and collected by filter paper. The generated tail gas is absorbed in the NaOH solution of the tail gas treatment device through the collection device.

As a preferred solution of the present invention, the concentration range of each metal nitrate in the ethanol solution is 0.01-0.2M.

As a preferred solution of the present invention, the ultrasonic time in step 1) is 1-3 hours, and the stirring time is 4-6 hours.

As a preferred solution of the present invention, the flow rate of Ar gas in step 2) is 2-6 L/min.

Compared with prior art, the present invention has following advantage:

1. Through the self-assembly device, the preparation process and preparation cost are greatly simplified. Compared with the original carbon thermal shock method, the high-entropy alloy nanoparticles prepared by the present invention do not contain carrier and can be directly applied.

2. The present invention does not need to add reducing gases such as H ₂ , which reduces the danger of H ₂ and the use cost to a certain extent.

3. The present invention can control the size of high-entropy alloy particles. By adjusting the concentration of each metal nitrate in ethanol, the particle size of the finished product can be controlled.

4. The present invention can change the type of high-entropy alloy by changing the composition of metal nitrate.

Description of drawings

Figure 1 is a schematic diagram of a simple device for preparing carbon nanotube-coated ultrafine high-entropy alloys; in the figure, 1 is a precursor solution container; 2 is a gas atomization device, 3 is a high-temperature device; 4 is a collection device; 5 is an exhaust gas processing device; 6 is a flow control device;

2 is a schematic diagram of an atomic absorption atomizer in a simple device for preparing carbon nanotube-coated ultrafine high-entropy alloys; 201 is a gas atomization nozzle in the figure;

Figure 3 is a schematic diagram of the structure of the collection device in the simple device for preparing carbon nanotube-coated ultrafine high-entropy alloys; in the figure, a is the sealing ring to ensure the sealing of the device, and b is the filter paper, which is used to intercept the generated CNT@HEA powder;

Figure 4 is the XRD pattern of CNT@HEA prepared by the simple device of carbon nanotube-coated ultrafine high-entropy alloy;

Figure 5 is the SEM image of CNT@HEA prepared by the simple device of carbon nanotube-coated ultrafine high-entropy alloy; (a), (c), and (d) are the morphology images of CNT@HEA particles with different multiples, (b ) is the particle size distribution diagram of CNT@HEA;

Figure 6 is the Raman spectrum of CNT@HEA prepared by the simple device of carbon nanotube-coated ultrafine high-entropy alloy.

Detailed ways

The specific implementation manner of the present invention will be further described below in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited thereto, and any technical concepts defined in the claims of the present invention and other simple transformations based on them are within the protection scope of the present invention.

As shown in Figure 1, the simple device for rapidly preparing carbon nanotube-coated ultrafine high-entropy alloy composite powder in this embodiment includes: flow control device 6, gas atomization device 2, high-temperature device 3, collection device 4 and tail gas Processing device 5.

The gas atomization generating device 2 described in this embodiment is an atomic absorption nebulizer. The left side of the atomic absorption nebulizer is provided with a pipeline connected to the precursor solution, the lower part is provided with a pipeline through which Ar gas passes, and the right side is provided with a gas atomization pipeline. An atomizing nozzle 201, the gas atomizing nozzle 201 is connected to the inlet of the high-temperature device 3; the right side of the high-temperature device 3 is connected to the inlet of the collecting device 4, and the collecting device 4 is composed of a container containing filter paper b, wherein The filter paper b is located at the outlet of the collecting device 5 and is used to intercept the product in the airflow to achieve the collection effect. The outlet of the collection device 4 is connected to the inlet of the tail gas treatment device 5, and the tail gas treatment device 5 is composed of a container containing NaOH solution, through which the generated NO, NO ₂ and other gases are processed.

The flow control device 6 used in this embodiment is a glass rotameter with a range of 600mL~6L, which is connected to the Ar gas source and the gas atomization generator through a hose.

Driven by the Ar gas flow, the gas atomization generating device 2 in this embodiment absorbs and atomizes the solution by using the Bernoulli principle, and connects with the high-temperature device (quartz tube) using designed accessories. Use screws to connect the atomizer with accessories, and the intermediate sealing ring ensures its tightness. It is then connected to the quartz tubing with a vacuum-tight clamp.

The high-temperature device 3 used in this embodiment is a vacuum tube furnace whose temperature can reach 1200° C., and the inner diameter of the quartz tube used is 20 mm.

The collection device 4 described in this embodiment is 500mm away from the high temperature zone of the tube furnace, and the product can be cooled by a sufficient distance.

Example 1: Weigh 0.005 mol of Fe(NO ₃ ) ₃ 9H ₂ O, Co(NO ₃ ) ₂ 6H ₂ O, Ni(NO ₃ ) ₂ 6H ₂ O, Al(NO ₃ ) ₃ ·9H ₂ O and Cr(NO ₃ ) ₃ ·9H ₂ O were added to 100 mL of ethanol solution, ultrasonicated for 2 hours and magnetically stirred for 6 hours to obtain a precursor solution.

Assemble the device, feed argon gas to ensure that the device is an inert gas, insert the precursor solution into the suction tube of the atomic absorption nebulizer 2, and feed the Ar gas at 4 L/min when the vacuum tube furnace 3 is heated to 1100 °C , the precursor solution is driven by Ar gas to reach the tip of the atomizer nozzle 201, so that it is atomized and enters the vacuum tube furnace 3. At 1100°C, ethanol is preferentially cracked to generate C and H ₂ . Synchronously with the high temperature, the metal nitrate rapidly Cracking and reduction into high-entropy alloys, nitrogen monoxide and nitrogen dioxide. At the same time, under the catalysis of Fe, Co, and Ni elements produced by reduction, C grows CNTs on the surface of high-entropy alloys, and finally CNT@HEA powder is obtained, namely Carbon nanotube-coated ultrafine high-entropy alloy composite powder. After the product exits the vacuum tube furnace 3, it cools rapidly in the pipeline, and reaches the collection device 4 to be intercepted and collected by filter paper. The generated tail gas is absorbed in the NaOH solution of the tail gas treatment device 5 through the collection device 4 .

The XRD image of CNT@HEA, the product of Example 1, is shown in Figure 4. It can be seen that the peaks of AlCrFeCoNi high-entropy alloys with a relatively pure FCC structure were detected, indicating that high-entropy alloys were produced.

The SEM of the CNT@HEA product of Example 1 is shown in Figure 5. Under the scanning electron microscope, it can be seen that the size of the ultrafine CNT@HEA particles is between 100nm and 8μm, the average size is about 2μm, and a large number of particles grow on the surface of the particles. Carbon nanotubes with a diameter of about 25 nm.

The Raman spectrum of the product CNT@HEA of Example 1 is shown in Figure 6. The Raman spectrum shows that the _ID / _IG ratio of CNTs is 0.56, and the low ID/IG ratio indicates that the original CNTs have a complete structure and fewer surface structural defects. .

It can be seen that the present invention can rapidly prepare a high-entropy alloy composite powder (CNT@HEA) with a complete surface-coated structure of CNTs and high crystallinity (CNT@HEA), while simplifying the preparation process and reducing the preparation cost.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements without departing from the spirit and scope of the technical solution of the present invention shall be covered by the claims of the present invention.

Claims (10)

1. A device for rapidly preparing carbon nanotube-coated ultrafine high-entropy alloy composite powder, characterized in that: comprising: flow control device, gas atomization generating device, high-temperature device, collecting device and tail gas treatment device; The flow control device, the gas atomization generating device, the high temperature device, the collecting device and the tail gas treatment device are connected in sequence according to the air flow direction. 2. The device for rapidly preparing carbon nanotube-coated ultrafine high-entropy alloy composite powder according to claim 1, characterized in that: the flow control device, gas atomization generating device, high-temperature device, collecting device and tail gas The processing device ensures the tightness through the sealing ring and the vacuum clamp. 3. The device for rapidly preparing carbon nanotube-coated ultrafine high-entropy alloy composite powder according to claim 1, characterized in that: the flow control device is a glass rotameter with a range of 600mL~6L connected to Ar Gas source and gas atomization generating device. 4. The device for rapidly preparing carbon nanotube-coated ultrafine high-entropy alloy composite powder according to claim 1, characterized in that: the gas atomization generating device is an atomic absorption atomizer, and its right side is equipped with A gas atomization nozzle, the gas atomization nozzle is connected with the inlet of the high temperature device. 5. The device for rapidly preparing carbon nanotube-coated ultrafine high-entropy alloy composite powder according to claim 1, characterized in that: the high-temperature device is a vacuum tube furnace. 6. A method for rapidly preparing carbon nanotube-coated ultrafine high-entropy alloy composite powders using the device described in any one of claims 1-5, characterized in that it comprises the following steps: 1) Preparation of precursor solution: Weigh five or more metal element nitrate hydrates alone, add them to the ethanol solution, ultrasonicate, stir, and mix them evenly to obtain a precursor mixed solution; 2) Preparation of CNT@HEA composite powder: The precursor mixed solution prepared in step (1) is driven by Ar gas to the gas atomization nozzle for atomization, and then passed into a vacuum tube furnace with a temperature above 1000 °C together with Ar gas In the process, after rapid heating in a vacuum tube furnace, ethanol is pyrolyzed to produce carbon sources and hydrogen, and the nitrate is rapidly reduced to obtain a FeCoNi high-entropy alloy. Under the catalysis of Fe, Co or Ni, CNTs are generated on the surface of the high-entropy alloy to obtain Carbon nanotubes are coated with high-entropy alloys, and the Ar gas enters the collection device to be collected, and the tail gas enters the tail gas treatment device through the collection device, and is filtered by NaOH solution. 7 . The method according to claim 6 , wherein the concentration of each metal in the precursor mixed solution in step 1) is 0.01-0.2M. 8. The method according to claim 6, characterized in that: in step 1), the ultrasonic time is 1~3h, and the stirring time is 4~6h. 9. The method according to claim 6, characterized in that: in step 1), five or more metal elements include Fe, Co, and Ni, and also include Al, Ti, V, Mn, Cr, and C Two or more elements in . 10. The method according to claim 6, characterized in that the flow rate of Ar gas in step 2) is 2-6 L/min.

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