Preparation method and device of metal / metal oxide composite material with core-shell structure

Abstract

The invention provides a preparation method and device of a metal / metal oxide composite material with a core-shell structure, and relates to the technical field of composite material preparation. A preparation method of a metal / metal oxide composite material with a core-shell structure comprises the steps that surface oxides, impurities and oil stains of metal powder are cleaned and removed, and drying treatment is conducted; constraining the metal powder into an approximate block and immersing the approximate block into an electrolyte; the positive electrode and the negative electrode of a power source are connected with the metal powder and the electrolyte correspondingly, and the metal powder is subjected to an oxidation reaction through electrification; and filtering and washing the reacted metal powder, and drying to obtain the metal / metal oxide composite material with the shell-core structure and the oxidation film shell layer. According to the technical scheme, the metal / metal oxide composite material with the shell-core structure, which is controllable in shell thickness and uniform in coating, can be simply and quickly prepared.

Description

Technical Field

[0001] The invention relates to the technical field of composite material preparation, and in particular to a method and device for preparing a metal / metal oxide composite material with a core-shell structure. Background Art

[0002] Metal / metal oxide composite materials with core-shell structures have the advantages of both core and shell materials, avoiding the disadvantages of both materials, and are the focus of development in the field of composite materials. Specifically, the composite materials can be used for the preparation of corrosion-resistant coatings, for photocatalysis or for chemical catalysis, and the corrosion resistance, photocatalytic performance or chemical catalytic performance of the composite materials can be adjusted by adjusting the ratio of shell to core in the metal / metal oxide composite materials.

[0003] The current preparation methods for metal / metal oxide composite materials with shell-core structure include: heat treatment method, hydrothermal method, sol-gel method, and chemical plating method. These preparation methods all have certain defects. Among them, the heat treatment method is to obtain metal / metal oxide composite materials by annealing in an oxygen atmosphere. This method easily leads to uneven surface oxidation, which is not conducive to the uniformity control of the thickness of the oxide film shell structure, and the density of the oxide film shell prepared by it is low; the hydrothermal method uses hot water method to prepare metal / metal oxide composite materials, the oxidation time is long, and the steps are cumbersome, which is not conducive to large-scale production; the sol-gel method requires more process and there are also cumbersome steps; in the process of preparing metal / metal oxide composite materials by chemical plating, it is necessary to use a reducing agent to reduce metal ions to metals. This method has the disadvantages of long reaction time and easy decomposition of the plating solution.

[0004] Therefore, a new method for preparing metal / metal oxide composite materials is urgently needed to solve the above technical problems. Summary of the invention

[0005] The purpose of the embodiments of the present application is to provide a method for preparing a metal / metal oxide composite material with a core-shell structure, so as to simply and quickly prepare a metal / metal oxide composite material with a core-shell structure with controllable shell thickness and uniform coating.

[0006] In order to solve the above technical problems, the embodiments of the present application provide the following technical solutions:

[0007] The first aspect of the present application provides a method for preparing a metal / metal oxide composite material having a core-shell structure:

[0008] Clean and remove surface oxides, impurities and oil stains from metal powders, and dry them;

[0009] constraining the metal powder into a near-block and immersing the block in an electrolyte;

[0010] Connecting the positive electrode and the negative electrode of the power supply to the metal powder and the electrolyte respectively, and applying power to cause the metal powder to undergo an oxidation reaction;

[0011] The metal powder after the reaction is filtered, rinsed and dried to obtain the metal / metal oxide composite material with a core-shell structure having an oxide film shell layer.

[0012] In some embodiments, in the aforementioned preparation method, the metal powder is one of nickel, tantalum, copper, iron, aluminum, aluminum alloy, magnesium alloy, titanium alloy, and nickel alloy;

[0013] The particle size of the metal powder is 50 μm-1000 μm.

[0014] In some embodiments, in the aforementioned preparation method, the method for cleaning and removing surface oxides, impurities and oil stains of the metal powder is:

[0015] Pickling to remove oxides and impurities, the pickling immersion temperature is 25-80°C, and the time is 5min-60min;

[0016] The oil stains are removed by ultrasonic cleaning with alcohol solution or ultrasonic cleaning with organic solvent, and the time of ultrasonic cleaning with alcohol solution or ultrasonic cleaning with organic solvent is 5min-30min.

[0017] In some embodiments, in the aforementioned preparation method, the method of constraining the metal powder into a near-block and immersing the block in an electrolyte comprises:

[0018] The metal powder is placed in a container with an isolation net at the bottom and immersed in an electrolyte, and pressure is applied to the metal powder in the container to make the metal powder approximate a block.

[0019] In some embodiments, in the aforementioned preparation method, the electrolyte used according to the different oxidation properties and activity levels of the metal powder is one or more of sulfuric acid, hydrofluoric acid, phosphoric acid, oxalic acid, and nitric acid, or the electrolyte is any one of potassium hydroxide and sodium hydroxide.

[0020] In some embodiments, in the aforementioned preparation method, the power supply is a DC regulated power supply, and the power supply voltage amplitude is 0.1v-50v during the oxidation reaction.

[0021] The second aspect of the present application provides a device for preparing a metal / metal oxide composite material having a core-shell structure, comprising:

[0022] An electrolytic cell, the electrolytic cell being used to contain an electrolyte;

[0023] A container, wherein the top and the bottom of the container are both open, and an isolation net is arranged at the bottom of the container, and the isolation net is used to prevent the metal powder from leaking out;

[0024] A pressure piece, the pressure piece is in the shape of an elongated strip, the first end of the pressure piece extends into the container from the top opening, the pressure piece is in gap fit with the inner wall of the container, the pressure piece is used to apply pressure to the metal powder in the container, and is used as a positive electrode;

[0025] A power source, wherein the positive electrode of the power source is connected to the pressurizing member, and the negative electrode of the power source extends into the electrolytic cell.

[0026] In some embodiments, in the aforementioned preparation device, the container is cylindrical and made of resin material.

[0027] In some embodiments, the aforementioned preparation device further includes: a loading piece, the second end of the pressurizing piece is provided with a card slot, and the loading piece is detachably connected to the card slot.

[0028] In some embodiments, the aforementioned preparation device further includes: a support member, wherein the support frame member is detachably connected to the electrolytic cell and the container, respectively, and is used to fix the container in the electrolytic cell.

[0029] Compared with the prior art, the method and device for preparing a metal / metal oxide composite material with a shell-core structure provided by the present application, by constraining the metal powder into a form approximate to a block and immersing it in an electrolyte for anodization, realizes the preparation of a metal oxide shell on the surface of the metal powder, breaks through the existing technical prejudice, and realizes the preparation of a metal / metal oxide composite material with a shell-core structure by anodization; in addition, the method and device for preparing a metal / metal oxide composite material with a shell-core structure provided by the present application not only has a simple preparation method and quick steps, but also can adjust the uniformity of the metal oxide shell by controlling the magnitude of the current and the concentration of the electrolyte, and adjust the thickness of the metal oxide shell by controlling the power-on oxidation time, thereby achieving good control; in general, the method and device for preparing a metal / metal oxide composite material with a shell-core structure of the present application have simple processes and low costs, and are easy to form industrial conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] By reading the detailed description below with reference to the accompanying drawings, the above and other purposes, features and advantages of the exemplary embodiments of the present application will become easy to understand. In the accompanying drawings, several embodiments of the present application are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0031] Figure 1 The flowchart of the preparation method provided by the embodiment of the present invention is schematically shown;

[0032] Figure 2 The structural diagram of the preparation device provided by the embodiment of the present invention is schematically shown;

[0033] Figure 3 Schematically showing electron microscope scanning images of materials prepared using Examples 1-3 of the present invention and Comparative Example 1;

[0034] Figure 4 The electron microscope scanning images of the materials prepared using Example 4 of the present invention and Comparative Example 2 are schematically shown.

[0035] Description of Figure Numbers:

[0036] 1. Electrolytic cell; 2. Container; 21. Isolation net; 3. Pressurizing member; 4. Power source; 41 Negative electrode; 5. Loading member; 6. Metal powder. DETAILED DESCRIPTION

[0037] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0038] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by technicians in the field to which this application belongs.

[0039] like Figure 1 As shown, the present application embodiment provides a method for preparing a metal / metal oxide composite material having a core-shell structure, the method comprising:

[0040] 101. Clean and remove surface oxides, impurities and oil stains from metal powders, and dry them.

[0041] It should be noted that the preparation method provided in the embodiment of the present application is applicable to the preparation of metal / metal oxides from a variety of metals, such as nickel, tantalum, copper, iron, aluminum, aluminum alloy, magnesium alloy, titanium alloy, and nickel alloy, but not limited to these metals or alloys. As long as the metal or alloy can be used for anodization, the preparation method provided in the embodiment of the present application can be applied. In addition, the particle size of the metal powder suitable for the preparation method provided in the embodiment of the present application is 0.1 μm-1000 μm, preferably 50 μm-1000 μm, and the three-dimensional shape of the single metal particle of the metal powder is not limited, preferably approximately spherical.

[0042] In one embodiment, since the metal powder may contain some impurities, surface oxides and even oil stains, in order to ensure the smooth execution of subsequent preparation, it is necessary to first clean and dry it; wherein the cleaning method includes: acid cleaning + ultrasonic cleaning of alcohol solution or ultrasonic cleaning of organic solvent, wherein the acid solution can be selected according to the active characteristics and reaction characteristics of the metal powder, and the acid can be any one or more of sulfuric acid, hydrofluoric acid, phosphoric acid, and hydrochloric acid, but without specific limitation, acids other than the above examples can also be used; the alcohol solution can be ethanol, isopropanol, n-butanol, cyclohexanol, butanol, benzyl alcohol or polyether polyol, and the mass solubility of the alcohol solution can be 70%-90%.

[0043] The organic solvent may be acetone or methyl ethyl ketone, etc. Similarly, the alcohol and organic solvent are not specifically limited and may be alcohols and organic solvents other than those exemplified above. The pickling temperature may be 25°C-80°C, such as 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 60°C, 70°C, 80°C, and the pickling soaking time may be 5min-60min, such as 5min, 10min, 15min, 20min, 25min, 30min, 35min, 40min, 50min, 60min; the alcohol solution ultrasonic cleaning or organic solvent ultrasonic cleaning time may be 5min-30min, such as 5min, 8min, 10min, 12min, 15min, 18min, 20min, 25min, 30min.

[0044] For example, when the metal powder is iron powder, copper powder, or nickel powder, hydrochloric acid can be used for pickling, and acetone, ethanol, or a mixture of the two can be used for ultrasonic degreasing. When the metal powder is tantalum powder, due to its characteristics, it needs to be pickled with mixed sulfuric acid and hydrofluoric acid, and acetone and ethanol mixture can be used for ultrasonic degreasing.

[0045] The metal powder after cleaning can be dried at a temperature adjusted according to the oxidation temperature of different metals in the air. It can be dried in a vacuum drying oven at 60°C-80°C for 1h-3h. For example, the metal powder can be dried in a vacuum drying oven at 80°C for 1h, or in a vacuum drying oven at 60°C for 2h.

[0046] 102. Constrain the metal powder into a near-block and immerse it in an electrolyte.

[0047] In one embodiment, constraining the metal powder into a block-like structure can facilitate the simultaneous electrification of all metal powders for subsequent anodization reaction. The block-like structure can be understood as all metal powders being constrained and tightly pressed together to form a block structure in which all metal powders are tightly fitted together. However, since it is not an integral structure, it is called a block-like structure. At this time, although the metal powders are not an integral block, all powders are tightly fitted together to achieve current conduction.

[0048] There are many ways to achieve the constraint of metal powders. For example, a corrosion-resistant mesh can be used to tightly mesh all metal powders to achieve close fit between metal powders; or the metal powders can be placed in a container with an isolation mesh at the bottom and pressure can be applied to the metal powders in the container to achieve the constraint of the metal powders. Among them, both the mesh and the container with an isolation mesh at the bottom can achieve full infiltration of the metal powders with the electrolyte after being immersed in the electrolyte.

[0049] The electrolyte needs to be selected according to the oxidation properties and activity of the metal powder. It can be one or more of sulfuric acid, hydrofluoric acid, phosphoric acid, oxalic acid, and nitric acid, or the electrolyte can be any one of potassium hydroxide and sodium hydroxide. If the metal is more active, phosphoric acid or dilute hydrochloric acid can be used. If the metal is less active, concentrated sulfuric acid can be used. For example: phosphoric acid or hydrochloric acid can be selected as the electrolyte for iron metal powder; sulfuric acid can be selected as the electrolyte for copper metal powder; potassium hydroxide can be selected as the electrolyte for nickel metal powder; and a mixture of sulfuric acid and hydrofluoric acid can be selected as the electrolyte for tantalum metal powder.

[0050] It should be noted that the electrolytic cell containing the electrolyte can be made of glass. If the electrolyte contains hydrofluoric acid, the electrolytic cell can be replaced with tetrafluoroethylene.

[0051] 103. Connect the positive and negative electrodes of the power source to the metal powder and the electrolyte respectively, and apply power to cause the metal powder to oxidize.

[0052] In one embodiment, the power supply may be a DC regulated power supply, and the power supply voltage amplitude during the oxidation reaction may be 0.1V-50V. For example, the voltage may be specifically adjusted in units of 0.1V in the range of 0.1V-50V. The reaction time of power-on may be adaptively adjusted according to the amount of metal powder to be reacted, and may be 45s-6h. For example, the reaction time of power-on of tantalum metal powder may be 45s, and the reaction time of power-on of nickel metal powder may be 2h-6h.

[0053] In addition, when the mass and volume of the metal powder are relatively large, multiple positive electrode contact points can be connected to the metal powder that is approximately a block after being constrained, thereby reducing the resistance of the metal powder that is energized as a whole and accelerating the oxidation reaction.

[0054] Furthermore, the power supply can also be connected to a control device (computer, programmable logic controller, etc.) for automated control, and the automated control parameters can be data accumulated from multiple tests according to the method of the present application and used as preset data.

[0055] 104. Filter and rinse the reacted metal powder and dry it to obtain a metal / metal oxide composite material with an oxide film shell and a core-shell structure.

[0056] In one embodiment, the oxidized metal powder can be washed multiple times using a vacuum filtration device, and the drying temperature can be adjusted according to the oxidation temperature of different metals in the air, and the metal powder can be dried in a vacuum drying oven at 60°C-80°C, and the drying time can be 1h-3h. For example, the oxidized metal powder can be dried in a vacuum drying oven at 80°C for 1h, or in a vacuum drying oven at 60°C for 2h.

[0057] In a specific implementation, if the oxidation effect is not ideal, steps 102-103 can be repeated until the thickness and density of the metal oxide shell meet the requirements.

[0058] The method for preparing a metal / metal oxide composite material with a core-shell structure provided by the present application is to constrain metal powder into a block-like form and immerse it in an electrolyte for anodization, thereby preparing a metal oxide shell on the surface of the metal powder, breaking through existing technical prejudices and realizing the preparation of a metal / metal oxide composite material with a core-shell structure by anodization; in addition, the method for preparing a metal / metal oxide composite material with a core-shell structure provided by the present application is not only simple in preparation method and quick in steps, but also can adjust the uniformity of the metal oxide shell by controlling the magnitude of the current and the concentration of the electrolyte, and adjust the thickness of the metal oxide shell by controlling the power-on oxidation time, thereby achieving good control; in general, the method for preparing a metal / metal oxide composite material with a core-shell structure of the present application is simple in process and low in cost, and has the conditions for easy industrialization.

[0059] like Figure 2 As shown, the embodiment of the present application also provides a preparation device for a metal / metal oxide composite material having a core-shell structure (the electrolyte is not shown), comprising:

[0060] An electrolytic cell 1, a container 2, a pressurizing member 3 and a power source 4; the electrolytic cell 1 is used to contain an electrolyte; the top and the bottom of the container 2 are both open, and an isolation net 21 is arranged at the bottom of the container 2, and the isolation net 21 is used to prevent the metal powder 6 from leaking out; the pressurizing member 3 is in the shape of an elongated strip, and the first end of the pressurizing member 3 extends into the container 2 from the top opening, and the pressurizing member 3 is matched with the inner wall gap of the container 2, and the pressurizing member 3 is used to pressurize the metal powder 6 in the container 2 and is used as a positive electrode; the positive electrode of the power source 4 is connected to the pressurizing member 3, and the negative electrode 41 of the power source 4 extends into the electrolytic cell 1.

[0061] The material of the electrolytic cell 1 can be selected according to the reaction materials, but it should be noted that the position where the electrolytic cell 1 contacts the electrolyte is a non-conductive material, that is, the electrolytic cell 1 can be directly made of one material, such as glass, polytetrafluoroethylene, or the main part can be made of a material with a certain strength, and a polytetrafluoroethylene layer is coated on the surface of its accommodating cavity.

[0062] The container 2 can be a cylindrical structure, and there is no limitation on the cross-sectional shape of the cylinder. For example, it can be a regular polygon such as a circle, rectangle, triangle, or an irregular curved or irregular polygon. The isolation net 21 at the bottom of the container 2 can be integrally formed with the main body of the container 2, such as by 3D printing, injection molding, etc. The mesh size of the isolation net 21 needs to ensure that the metal powder does not leak out. The container 2 can be made of a resin material, such as polypropylene or polytetrafluoroethylene, or other corrosion-resistant materials. It should be noted that the container 2 can be vertically inserted into the electrolytic cell, with the top opening of the container 2 exposed above the electrolyte in the electrolytic cell.

[0063] The pressure piece 3 is in the shape of a long strip, and the cross-sectional shape of the pressure piece 3 needs to be compatible with the cross-sectional shape of the container 2 to ensure that the pressure piece 3 can extend into the container 2 and fit with the gap. The pressure piece 3 can be made of a conductive material, such as a carbon rod, which can be used as a part to apply pressure to the metal powder 6 and can also be used as a conductor to connect to the positive electrode of the power source 4; the pressure piece 3 can also be used as a part that applies pressure to the metal powder 6 instead of a conductor, and can be made of a corrosion-resistant insulator, such as a resin material. In this case, the power source 4 can energize the metal powder through an inert conductive metal wire or sheet. In this way, by adding the metal powder 6 into the container 2 and then applying pressure to the pressure piece 3, the loose metal powder 6 can be constrained into a state that approximates a block.

[0064] Power supply 4 needs to be a DC regulated power supply that can accurately adjust the output voltage within the range of 0.1v-50v.

[0065] In one embodiment, the preparation device provided in the present application further includes: a loading member 5, a second end of the pressure member 3 is provided with a slot, and the loading member 5 is detachably connected to the slot. The loading member 5 needs to have a certain weight, and there can be multiple loading members 5 with different weights, so that different gravity can be applied to the metal powder by replacing different loading members 5. The slot at the second end of the pressure member 3 can be an open slot, in which case the loading member 5 can be directly placed in the slot; the slot at the second end of the pressure member 3 can also be a slide groove with a dovetail-shaped or constricted cross-section, and the loading member 5 is adapted to be provided with a slide rail that matches the slide groove, so that the pressure member 3 can be slidably connected to the loading member 5; the above two methods are for demonstration and not as limitation.

[0066] Furthermore, the preparation device provided in the present application further includes: a support member (not shown in the figure), the support frame member being detachably connected to the electrolytic cell 1 and the container 2 respectively, and being used to fix the container 2 in the electrolytic cell 1.

[0067] Among them, the support member can be a support plate with a through-hole structure, the support plate can be covered on the electrolytic cell 1, and limited relative to the electrolytic cell 1, and the container 2 passes through the through-hole to achieve vertical limitation; the support member can also be a bracket structure, one end of the bracket is detachably connected to the electrolytic cell 1, such as bolt connection, snap connection, etc., and the other end of the bracket is detachably connected to the container 2, such as bolt connection, bayonet connection, etc.; technical personnel in this field can quickly produce the above-mentioned support member structure according to the above description, so the illustration of the support member is omitted. Through the setting of the support member, the container 2 and the electrolytic cell 1 can maintain a relative position relationship, so that the reaction proceeds smoothly.

[0068] It should be noted that the implementation of the subsequent specific embodiments is carried out using the preparation device of the metal / metal oxide composite material with a core-shell structure introduced in the above embodiment, so the various parts or tools in the preparation device will not be repeatedly introduced in the subsequent embodiments.

[0069] Example 1

[0070] Provided is a method for preparing a metal / metal oxide composite material having a core-shell structure of metal nickel:

[0071] (1) Take 5 g of spherical nickel metal powder, add 50 ml of 1 mol / L hydrochloric acid solution at 25° C., soak and pickle for 30 min, then rinse with deionized water until the pH of the soaking solution is 7, add 90% ethanol solution for ultrasonic cleaning for 10 min, and dry in a vacuum drying oven at 80° C. for 1 h;

[0072] (2) The cleaned nickel metal powder is placed in a container, a pressure piece made of graphite is used, and the pressure piece serves as the positive electrode. A loading piece is placed at the second end of the pressure piece to compact the nickel metal powder in the container. At the same time, a graphite negative electrode is also used as the negative electrode of the power supply.

[0073] (3) Add 100 ml of 2 mol / L potassium hydroxide solution as the electrolyte into the electrolytic cell.

[0074] (4) Use a DC regulated power supply to connect the two electrodes, set the voltage to 8V, and the current changes with the overall resistance of the nickel metal powder; the power-on time is 2h.

[0075] (5) Using a vacuum filter to filter and rinse the oxidized nickel metal powder until the pH of the soaking solution is 7, and drying it in a vacuum drying oven at 80° C. for 1 h to obtain a nickel metal / metal oxide composite material with a core-shell structure.

[0076] Example 2

[0077] Another method for preparing a metal / metal oxide composite material having a core-shell structure of nickel is provided:

[0078] (1) Take 5 g of spherical nickel metal powder, add 50 ml of 1 mol / L hydrochloric acid solution at 25° C., soak and pickle for 30 min, then rinse with deionized water until the pH of the soaking solution is 7, add 90% ethanol solution for ultrasonic cleaning for 10 min, and dry in a vacuum drying oven at 80° C. for 1 h;

[0079] (2) The cleaned nickel metal powder is placed in a container, a pressure piece made of graphite is used, and the pressure piece serves as the positive electrode. A loading piece is placed at the second end of the pressure piece to compact the nickel metal powder in the container. At the same time, a graphite negative electrode is also used as the negative electrode of the power supply.

[0080] (3) Add 100 ml of 3 mol / L potassium hydroxide solution as the electrolyte into the electrolytic cell.

[0081] (4) Use a DC regulated power supply to connect the two electrodes, set the voltage to 8V, and the current changes with the overall resistance of the nickel metal powder; the power-on time is 2h.

[0082] (5) Using a vacuum filter to filter and rinse the oxidized nickel metal powder until the pH of the soaking solution is 7, and drying it in a vacuum drying oven at 80° C. for 1 h to obtain a nickel metal / metal oxide composite material with a core-shell structure.

[0083] Example 3

[0084] Another method for preparing a metal / metal oxide composite material having a core-shell structure of nickel is provided:

[0085] (1) Take 5 g of spherical nickel metal powder, add 50 ml of 1 mol / L hydrochloric acid solution at 25° C., soak and pickle for 30 min, then rinse with deionized water until the pH of the soaking solution is 7, add 90% ethanol solution for ultrasonic cleaning for 10 min, and dry in a vacuum drying oven at 80° C. for 1 h;

[0086] (2) The cleaned nickel metal powder is placed in a container, a pressure piece made of graphite is used, and the pressure piece serves as the positive electrode. A loading piece is placed at the second end of the pressure piece to compact the nickel metal powder in the container. At the same time, a graphite negative electrode is also used as the negative electrode of the power supply.

[0087] (3) Add 100 ml of 3 mol / L potassium hydroxide solution as the electrolyte into the electrolytic cell.

[0088] (4) Use a DC regulated power supply to connect the two electrodes, set the voltage to 12V, and the current changes with the overall resistance of the nickel metal powder; the power-on time is 2h.

[0089] (5) Using a vacuum filter to filter and rinse the oxidized nickel metal powder until the pH of the soaking solution is 7, and drying it in a vacuum drying oven at 80° C. for 1 h to obtain a nickel metal / metal oxide composite material with a core-shell structure.

[0090] Example 4

[0091] A method for preparing a metal / metal oxide composite material having a core-shell structure of metal nickel is provided:

[0092] (1) Take 5 g of spherical nickel metal powder, add 50 ml of 1 mol / L hydrochloric acid solution at 25° C., soak and pickle for 30 min, then rinse with deionized water until the pH of the soaking solution is 7, add 90% ethanol solution for ultrasonic cleaning for 10 min, and dry in a vacuum drying oven at 80° C. for 1 h;

[0093] (2) The cleaned nickel metal powder is placed in a container, a pressure piece made of graphite is used, and the pressure piece serves as the positive electrode. A loading piece is placed at the second end of the pressure piece to compact the nickel metal powder in the container. At the same time, a graphite negative electrode is also used as the negative electrode of the power supply.

[0094] (3) Add 100 ml of 3 mol / L potassium hydroxide solution as the electrolyte into the electrolytic cell.

[0095] (4) Use a DC regulated power supply to connect the two electrodes, set the voltage to 12V, and the current changes with the overall resistance of the nickel metal powder; the power-on time is 6h.

[0096] (5) Using a vacuum filter to filter and rinse the oxidized nickel metal powder until the pH of the soaking solution is 7, and drying it in a vacuum drying oven at 80° C. for 1 h to obtain a nickel metal / metal oxide composite material with a core-shell structure.

[0097] Comparative Example 1

[0098] This is in contrast to the above-mentioned Embodiment 1, Embodiment 2, and Embodiment 3.

[0099] Take 5g of spherical nickel metal powder, add 50ml of 1mol / L hydrochloric acid solution at 25℃, soak and pickle for 30min, then rinse with deionized water until the pH of the soaking solution is 7, add 90% mass concentration ethanol solution for ultrasonic cleaning for 10min, and dry in a vacuum drying oven at 80℃ for 1h.

[0100] like Figure 3 As shown in the figure Figure 3 (a), (b), (c), and (d) are electron microscope scanning images of the composite materials prepared in Examples 1-4, respectively. Figure 3 (e) is an electron microscope scanning image of the material prepared in Comparative Example 1. By comparison, it can be seen that:

[0101] Figure 3 (e) The surface of the nickel metal particles in the comparative example is relatively smooth and has no shell layer. Figure 3 As shown in (a), (b), (c) and (d), a layer of nickel metal oxide shell is added to the surface of the nickel metal particles. It can be seen that the preparation method of the present application can successfully prepare a nickel metal / metal oxide composite material with a core-shell structure, which means that the preparation method of the present application can successfully prepare a metal / metal oxide composite material with a core-shell structure.

[0102] Comparative Example 1 and Example 2, as Figure 3 (a) shows the nickel metal oxide shell layer on the particle surface of the composite material prepared in Example 1, which has many irregular spots in the form of shadows ( Figure 3 (a) is circled in black), the shadow is the area where no oxide shell is formed; Figure 3 (b) shows the nickel metal oxide shell layer on the particle surface of the composite material prepared in Example 2, and its shadow morphology has few irregular spots and the shadow is light ( Figure 3 (b) is circled with a black coil), that is, a nickel metal oxide shell layer that relatively completely covers the nickel metal particles is formed. It can be seen that after increasing the electrolyte concentration, the nickel metal oxide shell layer is evenly covered, that is, the uniformity of the metal oxide shell layer generated by oxidation can be conveniently adjusted by appropriately increasing the electrolyte concentration under the preparation method shown in this application.

[0103] Further, compared to Example 2, Figure 3(c) shows that the nickel metal oxide shell layer on the particle surface of the composite material prepared in Example 3 has further reduced irregular spots in the shadow form ( Figure 3 (c) is almost invisible, that is, compared with Example 2, Example 3 forms a nickel metal oxide shell layer that more completely covers the nickel metal particles. Therefore, by appropriately increasing the electrolyte concentration and the voltage value (adjusted within the voltage value range shown in the present application) under the preparation method shown in the present application, the uniformity of the metal oxide shell layer generated by oxidation can be conveniently adjusted.

[0104] Compare Example 3 and Example 4 again, Figure 3 As shown in (d), the nickel metal oxide shell layer on the particle surface of the composite material prepared in Example 4 is more uniform and compact. Figure 3 (a), (b), and (c) show shadow spots, and are no longer Figure 3 The nickel metal oxide shell shown in (c) is as rough as before, the thickness increases, and even the surface begins to fall off in layers. This shows that extending the reaction time can increase the thickness and density of the nickel metal particle oxide shell, so that the nickel particle surface is completely coated, but when the thickness increases to a certain extent, the generated oxide shell begins to fall off. Therefore, the thickness and density of the metal oxide shell can be increased by adjusting the power-on oxidation time, but the power-on oxidation time cannot be increased indefinitely and should be controlled within 6 hours.

[0105] Example 5

[0106] Provided is a method for preparing a metal / metal oxide composite material having a core-shell structure of tantalum metal:

[0107] (1) Take 5 g of tantalum metal powder, add 25 ml of 98% mass concentration sulfuric acid at 50°C and 25 ml of 45% mass concentration hydrofluoric acid at 50°C, soak and pickle for 30 minutes, then rinse with deionized water until the pH of the soaking solution is 7, add 90% mass concentration ethanol solution for ultrasonic cleaning for 10 minutes, and dry in a vacuum drying oven at 80°C for 1 hour;

[0108] (2) The cleaned tantalum metal powder is placed in a container, a pressure piece made of graphite material is used, and the pressure piece is used as the positive electrode. A loading piece is placed at the second end of the pressure piece to compress the nickel metal powder in the container; at the same time, a graphite negative electrode is also used as the negative electrode of the power supply.

[0109] (3) A mixed acid of 98% by mass concentration sulfuric acid and 45% by mass concentration hydrofluoric acid in a volume ratio of 9 / 1 was added into the electrolytic cell as an electrolyte.

[0110] (4) Use a DC regulated power supply to connect the two electrodes, set the voltage to 20V, and the current changes with the overall resistance of the tantalum metal powder; the power-on time is 9 minutes.

[0111] (5) Use a vacuum filter to filter and rinse the oxidized metal powder until the pH of the soaking solution is 7, and dry it in a vacuum drying oven at 80°C for 5 hours.

[0112] (6) Repeat steps 2-5, leaving all other parameters unchanged and only adjusting the power-on time to 45 seconds.

[0113] (7) Using a vacuum filter to filter and rinse the oxidized metal powder until the pH of the soaking solution is 7, and drying in a vacuum drying oven at 80° C. for 1 h to obtain a tantalum metal / metal oxide composite material with a core-shell structure.

[0114] Comparative Example 2

[0115] Take 5g of tantalum metal powder, add 25ml of 98% mass concentration sulfuric acid at 50℃ and 25ml of 45% mass concentration hydrofluoric acid at 50℃, soak and pickle for 30min, then rinse with deionized water until the pH of the soaking solution is 7, add 90% mass concentration ethanol solution for ultrasonic cleaning for 10min, and dry in a vacuum drying oven at 80℃ for 1h to obtain the cleaned tantalum metal powder.

[0116] like Figure 4 As shown in the figure Figure 4 (a) is a scanning electron microscope image of the material prepared in Example 5, Figure 4 (b) is an electron microscope scanning image of the material prepared in Comparative Example 2. By comparison, it can be seen that:

[0117] Figure 4 (b) shows that the surface of the tantalum metal particles that have not undergone oxidation reaction is prismatically protruding. Figure 4 The surface of the tantalum metal particle after the oxidation reaction shown in (a) has a metal oxide shell layer, making the surface relatively round. It can be seen that the preparation method provided by the present application enables the surface of the tantalum metal particle to form a tightly coated oxide shell layer.

[0118] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for preparing a metal / metal oxide composite material having a core-shell structure, characterized in that: include: Clean and remove surface oxides, impurities and oil stains from metal powders, and dry them; constraining the metal powder into a near-block and immersing the block in an electrolyte; Connecting the positive electrode and the negative electrode of the power supply to the metal powder and the electrolyte respectively, and applying power to cause the metal powder to undergo an oxidation reaction; The metal powder after the reaction is filtered, rinsed and dried to obtain the metal / metal oxide composite material with a core-shell structure having an oxide film shell layer.

2. The method for preparing the metal / metal oxide composite material having a core-shell structure according to claim 1, characterized in that: The metal powder is one of nickel, tantalum, copper, iron, aluminum, aluminum alloy, magnesium alloy, titanium alloy, and nickel alloy; The particle size of the metal powder is 50 μm-1000 μm.

3. The method for preparing the metal / metal oxide composite material having a core-shell structure according to claim 1 or 2, characterized in that: The method for cleaning and removing surface oxides, impurities and oil stains of metal powder is as follows: Pickling to remove oxides and impurities, the pickling immersion temperature is 25-80°C, and the time is 5min-60min; The oil stains are removed by ultrasonic cleaning with alcohol solution or ultrasonic cleaning with organic solvent, and the time of ultrasonic cleaning with alcohol solution or ultrasonic cleaning with organic solvent is 5min-30min.

4. The method for preparing the metal / metal oxide composite material having a core-shell structure according to claim 1, characterized in that: The method of constraining the metal powder into a near-block and immersing the block in an electrolyte comprises: The metal powder is placed in a container with an isolation net at the bottom and immersed in an electrolyte, and pressure is applied to the metal powder in the container to make the metal powder approximate a block.

5. The method for preparing the metal / metal oxide composite material having a core-shell structure according to claim 1, characterized in that: The electrolyte used according to the different oxidation properties and activity levels of the metal powder is one or more of sulfuric acid, hydrofluoric acid, phosphoric acid, oxalic acid, and nitric acid, or the electrolyte is any one of potassium hydroxide and sodium hydroxide.

6. The method for preparing the metal / metal oxide composite material having a core-shell structure according to claim 1, characterized in that: The power supply is a DC regulated power supply, and the power supply voltage amplitude is 0.1V-50V during the oxidation reaction.

7. A preparation device for a metal / metal oxide composite material having a core-shell structure, characterized in that: include: An electrolytic cell, the electrolytic cell being used to contain an electrolyte; A container, wherein the top and the bottom of the container are both open, and an isolation net is arranged at the bottom of the container, and the isolation net is used to prevent the metal powder from leaking out; A pressure piece, the pressure piece is in the shape of an elongated strip, the first end of the pressure piece extends into the container from the top opening, the pressure piece is in gap fit with the inner wall of the container, the pressure piece is used to apply pressure to the metal powder in the container, and is used as a positive electrode; A power source, wherein the positive electrode of the power source is connected to the pressurizing member, and the negative electrode of the power source extends into the electrolytic cell.

8. The device for preparing the metal / metal oxide composite material with a core-shell structure according to claim 8, characterized in that: The container is cylindrical and made of resin material.

9. The device for preparing the metal / metal oxide composite material with a core-shell structure according to claim 7 or 8, characterized in that: Also includes: A loading piece, wherein a slot is provided at the second end of the pressurizing piece, and the loading piece is detachably connected to the slot.

10. The device for preparing the metal / metal oxide composite material with a core-shell structure according to claim 7 or 8, characterized in that: Also includes: A support member, wherein the support frame member is detachably connected to the electrolytic cell and the container, respectively, and is used to fix the container in the electrolytic cell.

Images