Magnetic magnesium block body, magnetic magnesium-based composite material and preparation method of magnetic magnesium block body and magnetic magnesium-based composite material

Abstract

The invention relates to a magnetic magnesium block, a magnetic magnesium-based composite material and a preparation method of the magnetic magnesium block and the magnetic magnesium-based composite material, and relates to the technical field of magnetic magnesium-based composite materials. According to the main technical scheme, the preparation method of the magnetic magnesium block comprises the following steps that matrix powder, a dispersing agent and a volatile solvent are mixed and then subjected to first dispersion treatment, and a mixture subjected to first dispersion treatment is obtained; wherein the matrix powder is magnesium powder or magnesium alloy powder; mixing the magnetic particle powder, a dispersing agent and a volatile solvent, and carrying out second dispersion treatment to obtain a mixture subjected to the second dispersion treatment; sequentially carrying out mixing, ball milling treatment and drying treatment on the mixture subjected to the first dispersion treatment and the mixture subjected to the second dispersion treatment to obtain magnetic magnesium powder subjected to dispersion treatment; and carrying out cold isostatic pressing treatment on the dispersed magnetic magnesium powder to obtain the magnetic magnesium block. The method is mainly used for improving the distribution uniformity of the magnetic reinforced particles in the magnetic magnesium-based composite material.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic magnesium-based composite materials, and in particular to a magnetic magnesium block, a magnetic magnesium-based composite material and a preparation method thereof. Background Art

[0002] Magnesium is a light metal with great potential. It has low density and has broad application prospects in aerospace, automobile manufacturing and other fields with strong demand for lightweight. Magnesium has good electromagnetic shielding performance and recyclability. Although magnesium has mutual constraints in electromagnetic shielding and mechanical properties, magnesium-based composite materials have opened up new directions for solving these problems. Magnesium is widely distributed in nature and its reserves are relatively abundant, which provides a basis for its widespread application. Its lightweight characteristics enable products to reduce weight while improving energy efficiency, playing an increasingly important role in modern industry.

[0003] Magnetic magnesium-based composites are a new type of material with special properties. In terms of material properties, magnesium alloys themselves have the advantages of low density and high specific strength, while magnetic magnesium-based composites introduce magnetic functions while retaining these properties. From a magnetic point of view, the magnetic properties of magnetic magnesium-based composites provide new possibilities for their application in electronics, electrical and other fields. For example, they have potential application value in electromagnetic shielding, electromagnetic induction, magnetic storage, etc. At the same time, their magnetism can be regulated by specific preparation processes and alloy compositions to meet the needs of different application scenarios. However, the development of magnetic magnesium-based composites also faces some challenges. In the preparation process, how to accurately control the introduction of magnetism and ensure the performance stability of the material is a key issue.

[0004] Here, the relevant technologies of magnesium-based composite materials with magnetic particles as reinforcement phase are mainly as follows:

[0005] (1) The first technology discloses a method for preparing a nano-silica / ferroferric oxide magnetic contrast particle reinforced bio-magnesium-based composite material. The main technical scheme recorded therein is: silica and ferroferric oxide particles are mixed by high-temperature ball milling, and then hot pressed into a combination, and then the combination is added to magnesium slurry and heated to obtain a liquid magnesium-based composite material melt, and finally, magnesium blocks are added to the above-mentioned liquid magnesium-based composite material melt under the premise of ultrasonic and mechanical stirring, and finally hot pressed to obtain a silica / ferroferric oxide magnetic contrast particle reinforced bio-magnesium-based composite material.

[0006] (2) The second technology discloses a method for preparing an iron particle reinforced magnesium-based composite material. The main technical scheme recorded therein is: a certain proportion of iron particles and magnesium chips are placed in a graphite crucible and melted at high temperature under a protective atmosphere, and stirred with a low-carbon steel impeller to ensure uniform dispersion. Then, the iron particles are discharged into a steel mold through a hole at the bottom of the crucible and cooled to form an iron particle reinforced magnesium-based composite material.

[0007] The above two technologies for preparing magnetic magnesium-based composite materials are mainly ball milling and high-temperature melting processes. Specifically, the raw material powders are mixed by ball milling to obtain a uniformly mixed powder, and then dispersed by mechanical stirring in the high-temperature melting stage. Finally, the magnetic magnesium-based composite material is prepared by cold pressing or hot pressing.

[0008] In summary, the above-mentioned prior art for preparing magnetic magnesium-based composite materials has at least the following technical problems:

[0009] It uses simple ball milling to mix powders. Especially when the reinforcing particles are nanometer-sized, the powder mixing will be uneven, leading to agglomeration. Dispersion strengthening is the main strengthening mechanism of magnetic magnesium-based composite materials. Uneven mixing of powders will lead to a serious decrease in plasticity and reduce the overall magnetization strength of the material. It may also change the magnetocrystalline anisotropy of the material, resulting in the deflection of the easiest magnetization direction. Summary of the invention

[0010] In view of this, the present invention provides a magnetic magnesium block, a magnetic magnesium-based composite material and a preparation method thereof, the main purpose of which is to improve the uniformity of the distribution of magnetically enhanced particles in the magnetic magnesium-based composite material.

[0011] In order to achieve the above object, the present invention mainly provides the following technical solutions:

[0012] On the one hand, an embodiment of the present invention provides a method for preparing a magnetic magnesium block, wherein the method for preparing the magnetic magnesium block comprises the following steps:

[0013] A first dispersion treatment step: mixing a base powder, a dispersant, and a volatile solvent, and performing a first dispersion treatment to obtain a mixture after the first dispersion treatment; wherein the base powder is magnesium powder or magnesium alloy powder;

[0014] A second dispersion treatment step: mixing the magnetic particle powder, the dispersant and the volatile solvent, and then performing a second dispersion treatment to obtain a mixture after the second dispersion treatment;

[0015] The step of preparing magnetic magnesium powder is: mixing, ball-milling and drying the mixture after the first dispersion treatment and the mixture after the second dispersion treatment in sequence to obtain the magnetic magnesium powder after the dispersion treatment;

[0016] Cold isostatic pressing step: cold isostatic pressing the dispersed magnetic magnesium powder to obtain a magnetic magnesium block.

[0017] Preferably, the first dispersion treatment includes ultrasonic treatment and ball milling treatment performed sequentially; preferably, in the first dispersion treatment: the time of the ultrasonic treatment is not less than 1 hour, preferably 1-4 hours; preferably, in the first dispersion treatment: the ultrasonic treatment is performed in an ultrasonic cell crusher; preferably, in the first dispersion treatment: the rotation speed of the ball milling treatment is not less than 100 rpm / min, preferably 100-180 rpm / min; the time of the ball milling treatment is not less than 18 hours, preferably 18-40 hours.

[0018] Preferably, the second dispersion treatment comprises ultrasonic treatment and ball milling treatment performed sequentially; preferably, in the second dispersion treatment: the time of the ultrasonic treatment is not less than 1 hour, preferably 1-4 hours; preferably, in the second dispersion treatment: the ultrasonic treatment is performed in an ultrasonic cell crusher; preferably, in the second dispersion treatment: the rotation speed of the ball milling treatment is not less than 100 rpm / min, preferably 100-180 rpm / min; the time of the ball milling treatment is not less than 18 hours, preferably 18-40 hours.

[0019] Preferably, the magnetic particle powder is selected from iron, carbonyl iron, ferrite, barium ferrite BaFe 12 O 19 , one or more of nickel.

[0020] Preferably, the dispersant is selected from one or more of sorbitan stearate Span-60, polyvinyl pyrrolidone PVP, tert-octylphenoxy polyethylene ethoxyethanol Triton X-100, and polyoxyethylene polyoxypropylene ether block copolymer Pluronic.

[0021] Preferably, the volatile solvent is selected from one of anhydrous ethanol, acetone and methanol.

[0022] Preferably, the average particle size of the matrix powder is 30 to 150 microns.

[0023] Preferably, the magnetic particle powder is nanometer-sized or micrometer-sized; preferably, the average particle size of the nanometer-sized magnetic particle powder is 15 to 100 nanometers.

[0024] Preferably, in the first dispersing treatment step: the mass ratio of the base powder to the volatile solvent is 1:2 to 1:25; and the dispersant is 1 to 5 wt % of the mass of the volatile solvent.

[0025] Preferably, in the second dispersion treatment step: the mass ratio of the magnetic particle powder to the volatile solvent is 1:2 to 1:25; and the dispersant is 1 to 5 wt % of the mass of the volatile solvent.

[0026] Preferably, in the step of preparing the magnetic magnesium powder: the mixture of the second dispersion treatment is gradually added to the mixture of the first dispersion treatment for mixing; wherein, during the mixing process, continuous stirring is required; and / or the rotation speed of the ball milling treatment is not less than 100 rpm / min; the time of the ball milling treatment is not less than 18 hours; and / or the drying treatment is used to volatilize the volatile solvent in the mixture; and / or in the magnetic magnesium powder after the dispersion treatment: the mass ratio of the magnetic particle powder to the matrix powder is 1:1.5 to 1:10.

[0027] Preferably, in the cold isostatic pressing step: the cold isostatic pressing pressure is not less than 180 MPa, preferably 180-300 MPa. The holding time is not less than 4 min, preferably 4-20 min. And / or the magnetic magnesium powder after the dispersion treatment is put into a balloon and cold isostatic pressing is performed at a set pressure to obtain a compacted magnetic magnesium block.

[0028] On the other hand, an embodiment of the present invention provides a magnetic magnesium block, wherein the magnetic magnesium block is prepared by the preparation method of the magnetic magnesium block described in any one of the above items; preferably, the magnetic magnesium block is spherical; preferably, the mass of each of the magnetic magnesium blocks is greater than 5g, preferably 5g to 60g.

[0029] In another aspect, an embodiment of the present invention provides a method for preparing a magnetic magnesium-based composite material, wherein the method for preparing the magnetic magnesium-based composite material comprises the following steps:

[0030] Melting and casting steps: placing the magnetic magnesium block into molten magnesium liquid or magnesium alloy liquid under a protective atmosphere for smelting treatment; after the smelting is completed, casting treatment is performed to obtain a magnetic magnesium-based composite material ingot; wherein the magnetic magnesium block is the above-mentioned magnetic magnesium block;

[0031] Preferably, in the smelting and casting steps: the temperature of the smelting treatment is not lower than 770°C and not higher than 820°C; the temperature of the casting treatment is not lower than 730°C and not higher than 755°C;

[0032] Preferably, during the smelting process: high shear stirring is required, and the stirring speed is not less than 2000 rpm / min and not more than 4000 rpm / min, and the smelting time is not less than 10 min and not more than 30 min;

[0033] Preferably, after the smelting and casting steps, the method further comprises:

[0034] Hot extrusion step: hot extruding the magnetic magnesium-based composite material ingot to obtain a magnetic magnesium-based composite material rod;

[0035] Further preferably, in the hot extrusion step: the hot extrusion temperature is 250-400° C., and the extrusion ratio is 7:1 to 30:1.

[0036] On the other hand, an embodiment of the present invention provides a magnetic magnesium-based composite material, wherein the magnetic magnesium-based composite material includes a matrix material and a reinforcement phase; wherein the reinforcement phase is magnetic particles; the matrix material is magnesium or a magnesium alloy; wherein, in the magnetic magnesium-based composite material, the mass fraction of the reinforcement phase is 1-10wt%, preferably, the reinforcement phase is uniformly distributed in the matrix of the magnetic magnesium-based composite material; preferably, the reinforcement phase is nanometer-scale or micrometer-scale; preferably, the matrix is ​​micrometer-scale; preferably, the magnetic magnesium-based composite material is prepared by the above-mentioned preparation method of the magnetic magnesium-based composite material.

[0037] Compared with the prior art, the magnetic magnesium block, magnetic magnesium-based composite material and preparation method thereof of the present invention have at least the following beneficial effects:

[0038] On the one hand, an embodiment of the present invention provides a magnetic magnesium block and a preparation method thereof, the main steps of which are as follows: after mixing a matrix powder, a dispersant, and a volatile solvent, a first dispersion treatment is performed to obtain a mixture after the first dispersion treatment; wherein the matrix powder is magnesium powder or magnesium alloy powder; after mixing a magnetic particle powder, a dispersant, and a volatile solvent, a second dispersion treatment is performed to obtain a mixture after the second dispersion treatment; the mixture after the first dispersion treatment and the mixture after the second dispersion treatment are sequentially mixed, ball milled, and dried to obtain a magnetic magnesium powder after the dispersion treatment; the magnetic magnesium powder after the dispersion treatment is cold isostatically pressed to obtain a magnetic magnesium block. It should be noted that in the first dispersion treatment step, the dispersant is coated on the surface of the matrix powder particles to prevent the matrix powder from agglomerating; in the second dispersion treatment step, the dispersant is coated on the surface of the magnetic particles to prevent the matrix powder from agglomerating. On the basis of the first dispersion treatment step and the second dispersion treatment step, ultrasound and ball milling are further performed to improve the uniformity of the mixing of the matrix powder and the magnetic powder, and due to the presence of the dispersant on the particle surface, agglomeration can be fully avoided. Then, a drying process is performed to evaporate the volatile solvent to obtain uniformly dispersed magnetic magnesium powder (i.e., to ensure that the magnetic particles are uniformly dispersed in the magnesium matrix). If the magnetic magnesium powder is directly used as a raw material to prepare a magnetic magnesium-based composite material, the magnetic magnesium powder is put into a molten magnesium liquid or a magnesium alloy liquid, but the powder is prone to explosion. Here, in order to avoid explosion (to ensure the effective addition of magnetic materials), the inventors cold isostatically press the magnetic magnesium powder to prepare a magnetic magnesium block as a raw material for preparing a magnetic magnesium-based composite material. Therefore, the magnetic particles in the magnetic magnesium block prepared by the embodiment of the present invention are uniformly dispersed, and the magnetic magnesium-based composite material is prepared using the magnetic magnesium-based composite material as a raw material, which can improve the uniformity of the distribution of magnetically enhanced particles in the magnetic magnesium-based composite material.

[0039] On the other hand, an embodiment of the present invention provides a magnetic magnesium-based composite material and a preparation method thereof, which comprises the following steps: placing a magnetic magnesium block into a molten magnesium liquid or magnesium alloy liquid under a protective atmosphere for smelting treatment, and performing high shear stirring during the smelting process; after the smelting is completed, performing a casting process to obtain an ingot; and performing a hot extrusion process on the ingot to obtain a magnetic magnesium-based composite material. Here, the magnetic magnesium block is the magnetic magnesium block mentioned above. Since the magnetic material in the magnetic magnesium block is evenly distributed, the dispersion strengthening mechanism can be ensured. At the same time, the high shear stirring after adding the block further ensures dispersion, thereby ensuring the mechanical properties and magnetic properties of the magnetic magnesium-based composite material.

[0040] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a TEM image of magnetic particle distribution of a magnetic magnesium-based composite material prepared in Example 1 of the present invention;

[0042] Figure 2 is a tensile stress-strain curve diagram of a magnetic magnesium-based composite material prepared in Example 1 of the present invention;

[0043] Figure 3 is a room temperature hysteresis loop diagram of a magnetic magnesium-based composite material prepared in Example 1 of the present invention;

[0044] Figure 4 is a TEM image of magnetic particle distribution of a magnetic magnesium-based composite material prepared in Example 2 of the present invention;

[0045] Figure 5 is a tensile stress-strain curve diagram of the magnetic magnesium-based composite material prepared in Example 2 of the present invention;

[0046] Figure 6 It is the room temperature hysteresis loop diagram of the magnetic magnesium-based composite material prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0047] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention application are described in detail below in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures, or characteristics in one or more embodiments may be combined in any suitable form.

[0048] On the one hand, the embodiments of the present invention provide a magnetic magnesium block, a magnetic magnesium-based composite material and a preparation method thereof, so as to realize the preparation of a magnetic magnesium-based composite material with uniform dispersion of magnetic particles. The scheme of the present invention is mainly as follows:

[0049] On the one hand, an embodiment of the present invention provides a method for preparing a magnetic magnesium block, wherein the method for preparing the magnetic magnesium block comprises the following steps:

[0050] The first dispersion treatment step: after mixing the base powder, the dispersant and the volatile solvent, performing the first dispersion treatment to obtain a mixture after the first dispersion treatment; wherein the base powder is magnesium powder or magnesium alloy powder.

[0051] Wherein, the first dispersion treatment includes ultrasonic treatment and ball milling treatment performed in sequence; preferably, the ultrasonic treatment time is not less than 1 hour; preferably, the ultrasonic treatment is performed in an ultrasonic cell crusher; the rotation speed of the ball milling treatment is not less than 100 rpm / min; and the ball milling treatment time is not less than 18 hours.

[0052] Preferably, the dispersant is selected from one of the dispersants such as sorbitan stearate Span-60, polyvinyl pyrrolidone PVP, tert-octylphenoxy polyethylene ethoxyethanol Triton X-100, polyoxyethylene polyoxypropylene ether block copolymer Pluronic.

[0053] Preferably, the volatile solvent is selected from one of anhydrous ethanol, acetone, methanol and other volatile solvents;

[0054] Preferably, the magnesium alloy is AZ31B magnesium alloy or the like.

[0055] Second dispersion treatment step: After mixing the magnetic particle powder, the dispersant and the volatile solvent, a second dispersion treatment is performed to obtain a mixture after the second dispersion treatment.

[0056] Preferably, the second dispersion treatment includes ultrasonic treatment and ball milling treatment performed sequentially; the time of ultrasonic treatment is not less than 1 hour; preferably, the ultrasonic treatment is performed in an ultrasonic cell crusher; preferably, the rotation speed of ball milling treatment is not less than 100 rpm / min, and the time of ball milling treatment is not less than 18 hours.

[0057] Preferably, the magnetic particle powder is iron, carbonyl iron, ferrite, barium ferrite BaFe 12 O 19 , nickel, etc.

[0058] The step of preparing magnetic magnesium powder is as follows: the mixture after the first dispersion treatment and the mixture after the second dispersion treatment are sequentially mixed, ball-milled and dried to obtain the magnetic magnesium powder after the dispersion treatment.

[0059] The mixing method is mainly: slowly pouring the mixture obtained by the second dispersion treatment into the mixture obtained by the first dispersion treatment, and stirring is required during the mixing process.

[0060] The rotation speed of the ball milling treatment is not less than 100 rpm / min; and the time of the ball milling treatment is not less than 18 hours.

[0061] The drying process is used to volatilize the volatile solvent in the mixture.

[0062] Cold isostatic pressing step: cold isostatic pressing the dispersed magnetic magnesium powder to obtain a magnetic magnesium block.

[0063] The cold isostatic pressing pressure is not less than 180 MPa and the holding time is not less than 4 min; and / or

[0064] The dispersed magnetic magnesium powder is placed in a balloon (the number of layers of the balloon is greater than 5 layers, preferably greater than 8 layers, and more preferably 10 layers to avoid water leakage), and cold isostatic pressing is performed under a set pressure to obtain a compacted magnetic magnesium block. A large amount of magnetic magnesium powder can be cold isostatically pressed to prepare a large amount of compacted magnetic magnesium blocks, which can be used as raw materials for preparing magnetic magnesium-based composite materials.

[0065] It should be noted here that:

[0066] (1) In the first dispersion treatment step, the dispersant is coated on the surface of the matrix powder particles to prevent the matrix powder from agglomerating; in the second dispersion treatment step, the dispersant is coated on the surface of the magnetic particles to prevent the matrix powder from agglomerating. On the basis of the first dispersion treatment step and the second dispersion treatment step, ultrasound and ball milling are further performed to improve the uniformity of the mixing of the matrix powder and the magnetic powder, and since the dispersant exists on the surface of the particles, agglomeration can be fully avoided. Then, a drying treatment is performed to evaporate the volatile solvent to obtain a uniformly dispersed magnetic magnesium powder.

[0067] (2) If magnetic magnesium powder is directly used as a raw material to prepare a magnetic magnesium-based composite material, the magnetic magnesium powder is put into a molten magnesium liquid or a magnesium alloy liquid, but the powder is easy to explode. Here, in order to avoid the occurrence of explosion, the inventors cold isostatically press the magnetic magnesium powder to prepare a magnetic magnesium block as a raw material for preparing a magnetic magnesium-based composite material. It should also be noted that the dispersant in the magnetic magnesium block will be volatilized when it is added to the molten magnesium liquid or the magnesium alloy liquid at a later stage.

[0068] On the other hand, an embodiment of the present invention provides a method for preparing a magnetic magnesium-based composite material, wherein the method for preparing the magnetic magnesium-based composite material comprises the following steps:

[0069] Melting and casting steps: Under a protective atmosphere, the magnetic magnesium block is placed in molten magnesium liquid or magnesium alloy liquid for smelting treatment; after the smelting is completed, a casting treatment is performed to obtain a magnetic magnesium-based composite material ingot; wherein the magnetic magnesium block is the above-mentioned magnetic magnesium block.

[0070] Preferably, the temperature of the smelting treatment is not less than 770°C and not more than 820°C, and the temperature of the casting treatment is not less than 730°C and not more than 755°C; preferably, during the smelting treatment, the stirring speed is not less than 2000rpm / min, and the stirring time is not less than 10min. Preferably, the stirring is a high-speed stirring with stainless steel high shear to further ensure the dispersibility.

[0071] The number of magnetic magnesium blocks added to the molten magnesium is determined according to the mass fraction of magnetic particles in the desired magnetic magnesium-based composite material, the mass of magnesium liquid or magnesium alloy liquid, and the mass of each component in each magnetic magnesium block.

[0072] Hot extrusion step: hot extruding the ingot to obtain a magnetic magnesium-based composite material rod. Preferably, the hot extrusion temperature is 250-400°C and the extrusion ratio is 7:1-30:1.

[0073] The present invention is further described below by specific experimental examples:

[0074] The following embodiments all use the same melting furnace and extruder to perform melting, casting and hot extrusion on the materials.

[0075] Example 1

[0076] This embodiment prepares a magnetic magnesium-based composite material, wherein the raw materials used are: iron powder with an average particle size of 20nm and a purity of 99.9%, magnesium powder with an average particle size of 75μm and a purity of 99%, magnesium blocks with a purity of 99.995%, anhydrous ethanol (volatile solvent) and sorbitan stearate (Span-60, dispersant). The specific preparation steps include:

[0077] The first dispersion treatment step and the second dispersion treatment step: first weigh 11.83g of dispersant Span-60 (according to the ratio of 1.5wt% ethanol), pour it into 1L of anhydrous ethanol, slightly heat and stir with a magnetic stirrer to prepare the dispersant solution, and then pour it into two containers in equal amounts. Weigh 20g of iron powder and 60g of magnesium powder, add magnesium powder to the first container containing the dispersant solution, and add iron powder to the second container containing the dispersant solution. Ultrasound and ball mill the mixture in the first container to obtain a mixture after the first dispersion treatment; ultrasonic and ball mill the mixture in the second container to obtain a mixture after the second dispersion treatment. Among them, an ultrasonic cell crusher is used for ultrasound, the power is 1620W, and the time is 2h; the speed of the ball mill is 120rpm / min, and the time is 24h.

[0078] Preparation of magnetic magnesium powder: slowly pour the iron powder solution (mixture after the second dispersion treatment) into the magnesium powder solution (mixture after the first dispersion treatment), and then perform ball milling at a speed of 120 rpm / min for 24 hours to obtain a uniformly mixed iron-magnesium solution, and finally wait for the ethanol to evaporate to obtain magnetic magnesium powder.

[0079] Cold isostatic pressing treatment steps: the dried magnetic magnesium powder is placed in a ten-layer balloon and maintained at a pressure of 240 MPa for 5 minutes to obtain a compacted magnetic magnesium block (wherein the mass of the magnetic magnesium block is 10 to 40 g).

[0080] Melting and casting: Under a protective atmosphere, first put 1152g of magnesium block into a graphite crucible and heat it to 750℃ to form molten magnesium liquid, weigh 50g of magnetic magnesium block, put it into the molten magnesium liquid, and then use stainless steel high shear stirring to mix it evenly, the speed is 3030rpm / min, the time is 15min, turn off the heating and drop the temperature to 735℃ before casting to obtain an ingot.

[0081] Hot extrusion: the ingot is extruded at a temperature of 350° C., wherein the extrusion ratio is 25:1, a rod with a diameter of 8.7 mm is extruded, and finally a magnetic magnesium-based composite material (iron-magnesium composite material rod) with an iron mass fraction of 1% is obtained.

[0082] Figure 1 This is a TEM image of the magnetic particle distribution of the magnetic magnesium-based composite material in Example 1. It can be seen that the iron particles are evenly distributed in the magnesium matrix.

[0083] Figure 2 It is a tensile stress-strain curve diagram of a magnetic magnesium-based composite material prepared in Example 1, and its tensile strength is 184 MPa.

[0084] Figure 3 This is a room temperature hysteresis loop diagram of a magnetic magnesium-based composite material prepared in Example 1. It can be seen that the material has an obvious response to an external magnetic field, and the saturation magnetization intensity is 1.5emu / g.

[0085] Example 2

[0086] This embodiment prepares a magnetic magnesium-based composite material, wherein the raw materials used are: barium ferrite (BaFe 12 O 19 ) powder, AZ31B powder with an average particle size of 75 μm, AZ31B block, acetone and polyvinyl pyrrolidone (PVP, dispersant). The specific preparation steps are as follows:

[0087] First dispersion treatment step, second dispersion treatment step: first weigh 11.83g of dispersant PVP (according to 1.5wt.% acetone ratio), pour it into 1L of acetone, slightly heat and stir with a magnetic stirrer to prepare the dispersant solution, and then pour equal amounts into two containers. Weigh 70g of barium ferrite (BaFe 12 O 19 ) powder and 130g AZ31B powder, add AZ31B powder to the first container containing the dispersant solution, add barium ferrite (BaFe 12 O 19) powder. The mixture in the first container is subjected to ultrasound and ball milling to obtain a mixture after the first dispersion treatment; the mixture in the second container is subjected to ultrasound and ball milling to obtain a mixture after the second dispersion treatment. The ultrasound is performed using an ultrasonic cell crusher with a power of 1620 W and a time of 2 hours; the speed of the ball milling is 120 rpm / min and the time is 24 hours.

[0088] Preparation of magnetic magnesium powder: barium ferrite (BaFe 12 O 19 ) powder solution (mixture after the second dispersion treatment) was slowly poured into the AZ31B powder solution (mixture after the first dispersion treatment), and then ball milled at a speed of 120 rpm / min for 24 hours to obtain a uniformly mixed AZ31B-BaFe 12 O 19 solution, and finally wait for the acetone to evaporate to obtain magnetic magnesium powder.

[0089] Cold isostatic pressing: The dried magnetic magnesium powder is placed in a ten-layer balloon and maintained at a pressure of 240 MPa for 5 minutes to obtain a compacted magnetic magnesium block (wherein the mass of the magnetic magnesium block is 10 to 40 g).

[0090] Melting and casting: Under protective atmosphere, first put 1080g of AZ31B block into a graphite crucible and heat it to 750℃ to form molten AZ31 melt. Weigh 125g of magnetic magnesium block into the molten AZ31 melt, then use stainless steel high shear stirring to mix it evenly, the speed is 3030rpm / min, the time is 15min, turn off the heating to reduce the temperature to 735℃, and cast to obtain an ingot.

[0091] Hot extrusion: The ingot was extruded at 350°C, with an extrusion ratio of 25:1 and an extrusion diameter of 8.7 mm. Finally, barium ferrite (BaFe 12 O 19 ) AZ31B-BaFe with a mass fraction of 3.6% 12 O 19 Composite rods (magnetic magnesium-based composite materials).

[0092] Figure 4 This is a TEM image of the magnetic particle distribution of a magnetic magnesium-based composite material prepared in Example 2. It can be seen that the barium ferrite particles are relatively evenly distributed in the matrix.

[0093] Figure 5 It is a tensile stress-strain curve diagram of the magnetic magnesium-based composite material prepared in Example 2, and its tensile strength is 217 MPa.

[0094] Figure 6This is the room temperature hysteresis loop diagram of the magnetic magnesium-based composite material prepared in Example 2. The material has an obvious response to an external magnetic field, and its saturation magnetization intensity is 3.3emu / g.

[0095] Comparative Example 1

[0096] Comparative Example 1 is to prepare a magnetic block by directly cold isostatically pressing magnetic particles, then add the magnetic block into molten magnesium liquid, cast it after high shear stirring, and finally extrude it into a rod-shaped magnetic magnesium-based composite material.

[0097] Compared with the above embodiments, the main problem of comparative example 1 is that the magnetic particles themselves already have mutual forces, and then cold isostatic pressing is performed to completely agglomerate them into a cold-pressed block. The binding force between the particles is very strong. Even after the high-temperature melting process, the particles will still agglomerate in large quantities, seriously affecting the mechanical properties, and also reducing the overall magnetization intensity of the magnetic composite material. Secondly, at the moment when the cold-pressed block of pure magnetic particles is directly put into the molten magnesium liquid, the loss of magnetic particles due to oxidation and burning is relatively serious, resulting in a large amount of slag before casting, and the amount of magnetic particles added cannot be guaranteed.

[0098] Comparative Example 2

[0099] In Comparative Example 2, magnesium powder and magnetic particles are directly added to a volatile solvent with a dispersant, and then a mixed powder is obtained by ball milling and drying. A cold-pressed block of the mixed powder is obtained by cold isostatic pressing, which is then added to molten magnesium liquid, cast after high-shear stirring, and finally extruded into a rod-shaped magnetic magnesium-based composite material.

[0100] It should be noted that the first dispersion treatment and the second dispersion treatment of the above-mentioned embodiment of the present invention can form a certain proportion of suspension by means of ultrasound and ball milling, and at the same time produce a separation effect between the powders. Comparative Example 2 omits the above steps. Since the same kind of powders are composed of the same substance and have the same physical and chemical properties, the interaction force between them is relatively consistent and can be combined more effectively, which makes the interaction force between the same kind of powders greater than the interaction force between different kinds of powders. Therefore, only the subsequent blending and ball milling methods are not enough to disperse the magnetic particles well, and the agglomeration phenomenon is more serious, which affects the mechanical properties and magnetization intensity.

[0101] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a magnetic magnesium block, characterized in that: The method for preparing the magnetic magnesium block comprises the following steps: A first dispersion treatment step: mixing a base powder, a dispersant, and a volatile solvent, and performing a first dispersion treatment to obtain a mixture after the first dispersion treatment; wherein the base powder is magnesium powder or magnesium alloy powder; A second dispersion treatment step: mixing the magnetic particle powder, the dispersant and the volatile solvent, and then performing a second dispersion treatment to obtain a mixture after the second dispersion treatment; The step of preparing magnetic magnesium powder is: mixing, ball-milling and drying the mixture after the first dispersion treatment and the mixture after the second dispersion treatment in sequence to obtain the magnetic magnesium powder after the dispersion treatment; Cold isostatic pressing step: cold isostatic pressing the dispersed magnetic magnesium powder to obtain a magnetic magnesium block.

2. The method for preparing a magnetic magnesium block according to claim 1, characterized in that: The first dispersion treatment includes ultrasonic treatment and ball milling treatment performed sequentially; Preferably, in the first dispersion treatment: the ultrasonic treatment time is not less than 1 hour, preferably 1-4 hours; Preferably, in the first dispersion treatment: ultrasonic treatment is performed in an ultrasonic cell pulverizer; Preferably, in the first dispersion treatment: the rotation speed of the ball milling treatment is not less than 100 rpm / min, preferably 100-180 rpm / min; the time of the ball milling treatment is not less than 18 h, preferably 18-40 h.

3. The method for preparing a magnetic magnesium block according to claim 1, characterized in that: The second dispersion treatment includes ultrasonic treatment and ball milling treatment performed sequentially; Preferably, in the second dispersion treatment: the ultrasonic treatment time is not less than 1 hour, preferably 1-4 hours; Preferably, in the second dispersion process: ultrasonic treatment is performed in an ultrasonic cell pulverizer; Preferably, in the second dispersion treatment: the rotation speed of the ball milling treatment is not less than 100 rpm / min, preferably 100-180 rpm / min; the time of the ball milling treatment is not less than 18 h, preferably 18-40 h.

4. The method for preparing a magnetic magnesium block according to claim 1, characterized in that: The magnetic particle powder is selected from iron, carbonyl iron, ferrite, barium ferrite BaFe 12 O 19 , nickel; and / or The dispersant is selected from one or more of sorbitan stearate Span-60, polyvinyl pyrrolidone PVP, tert-octylphenoxy polyethylene ethoxyethanol Triton X-100, and polyoxyethylene polyoxypropylene ether block copolymer Pluronic; and / or The volatile solvent is selected from one of anhydrous ethanol, acetone and methanol; and / or The average particle size of the matrix powder is 30 to 150 microns; and / or The magnetic particle powder is nanometer-sized or micrometer-sized; preferably, the average particle size of the nanometer-sized magnetic particle powder is 15 to 100 nanometers.

5. The method for preparing a magnetic magnesium block according to claim 1, characterized in that: In the first dispersing treatment step: the mass ratio of the base powder to the volatile solvent is 1:2 to 1:25; the dispersant is 1 to 5 wt % of the mass of the volatile solvent; and / or In the second dispersion treatment step: the mass ratio of the magnetic particle powder to the volatile solvent is 1:2 to 1:25; the dispersant is 1 to 5 wt % of the mass of the volatile solvent.

6. The method for preparing a magnetic magnesium block according to claim 1, characterized in that: In the step of preparing magnetic magnesium powder: The mixture obtained by the second dispersion treatment is gradually added to the mixture obtained by the first dispersion treatment for mixing; wherein, during the mixing process, stirring is required continuously; and / or The ball milling speed is not less than 100 rpm / min; the ball milling time is not less than 18 h; and / or The drying process is used to volatilize the volatile solvent in the mixture; and / or In the magnetic magnesium powder after the dispersion treatment, the mass ratio of the magnetic particle powder to the matrix powder is 1:1.5 to 1:

10.

7. The method for preparing a magnetic magnesium block according to claim 1, characterized in that: In the cold isostatic pressing step: The cold isostatic pressing pressure is not less than 180 MPa, preferably 180-300 MPa. The holding time is not less than 4 min, preferably 4-20 min. And / or The dispersed magnetic magnesium powder is filled into a balloon and subjected to cold isostatic pressing at a set pressure to obtain a compacted magnetic magnesium block.

8. A magnetic magnesium block, characterized in that: The magnetic magnesium block is prepared by the method for preparing a magnetic magnesium block according to any one of claims 1 to 7; Preferably, the magnetic magnesium block is spherical; Preferably, the mass of each magnetic magnesium block is greater than 5g, preferably 5g to 60g.

9. A method for preparing a magnetic magnesium-based composite material, characterized in that: The preparation method of the magnetic magnesium-based composite material comprises the following steps: Melting and casting step: in a protective atmosphere, placing the magnetic magnesium block into molten magnesium liquid or magnesium alloy liquid for smelting treatment; after the smelting is completed, casting treatment is performed to obtain a magnetic magnesium-based composite material ingot; wherein the magnetic magnesium block is the magnetic magnesium block according to claim 8; Preferably, in the smelting and casting steps: the temperature of the smelting treatment is not lower than 770°C and not higher than 820°C; the temperature of the casting treatment is not lower than 730°C and not higher than 755°C; Preferably, during the smelting process: high shear stirring is required, and the stirring speed is not less than 2000 rpm / min and not more than 4000 rpm / min, and the smelting time is not less than 10 min and not more than 30 min; Preferably, after the smelting and casting steps, the method further comprises: Hot extrusion step: hot extruding the magnetic magnesium-based composite material ingot to obtain a magnetic magnesium-based composite material rod; Further preferably, in the hot extrusion step: the hot extrusion temperature is 250-400° C., and the extrusion ratio is 7:1 to 30:

1.

10. A magnetic magnesium-based composite material, characterized in that: The magnetic magnesium-based composite material comprises a matrix material and a reinforcement phase; wherein the reinforcement phase is magnetic particles; the matrix material is magnesium or a magnesium alloy; wherein, in the magnetic magnesium-based composite material, the mass fraction of the reinforcement phase is 1-10wt%; Preferably, the reinforcing phase is uniformly distributed in the matrix of the magnetic magnesium-based composite material; preferably, the reinforcing phase is nanometer-scale or micrometer-scale; preferably, the matrix is ​​micrometer-scale; Preferably, the magnetic magnesium-based composite material is prepared by the preparation method of the magnetic magnesium-based composite material according to claim 9.

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