Anisotropic bonding magnetic material and preparation method thereof

Abstract

The invention provides an anisotropic bonded magnetic material and a preparation method thereof. The anisotropic bonded magnetic material includes a component represented by formula (I): Re1x1Re2y1Tm1Fe100-x1-y1-z1-m1Bz1 (I) wherein Re1 is selected from Nd, or Pr and Nd, Re2 is selected from one or more of La, Ce, Dy and Tb, T is selected from one or more of transition metal elements, 27.5 < = x1 < = 40, 0 < = y1 < = 12, 0.95 < = z1 < = 1.05, 0 < = m1 < = 12, and y1 and m1 are not 0 at the same time; the average roundness of the bonded magnetic material is greater than or equal to 0.8. The average roundness of the anisotropic bonded magnetic material is larger than or equal to 0.8, the shape of the anisotropic bonded magnetic material is closer to a sphere, and the surface defects are fewer, so that the magnetic material has better grain orientation consistency and more excellent magnetic properties such as residual magnetism, coercive force and magnetic energy product.

Description

Technical Field

[0001] The invention relates to the technical field of rare earth permanent magnetic materials, and in particular to an anisotropic bonded magnetic material and a preparation method thereof. Background Art

[0002] Rare earth permanent magnet materials are a type of alloy material composed of rare earth metals (such as neodymium, praseodymium, samarium, etc.) and transition metals (such as iron, cobalt, etc.). They have high magnetic energy product, coercive force and remanence, and are widely used in motors, wind turbines, hybrid vehicles and high-end electronic products. As the third generation of permanent magnet materials, neodymium iron boron (Nd-Fe-B) has been widely used for its excellent magnetic properties. NdFeB magnets can be divided into three categories according to different production methods: bonded NdFeB, sintered NdFeB and hot pressed-hot deformed NdFeB. Among them, bonded NdFeB is made by mixing magnetic powder and bonding material, and has the advantages of low cost, high dimensional accuracy, large shape freedom, good mechanical strength and light weight.

[0003] The preparation of magnetic powder is the most important step in the production of bonded NdFeB magnets. The magnetic powder used to prepare bonded magnets is mainly divided into isotropic magnetic powder and anisotropic magnetic powder (i.e., anisotropic magnetic powder). Among them, anisotropic magnetic powder is usually prepared by hydrogen absorption-disproportionation-dehydrogenation-recombination process (HDDR process). The essence of the HDDR process is that rare earth metal compounds absorb hydrogen in a high-temperature hydrogen atmosphere and decompose into disproportionated products. Subsequently, the disproportionated products are recombined into the original compound phase with fine grains during the dehydrogenation process, thereby achieving the refinement of the original rare earth metal compound grains. The fine grains generated by the recombination retain the crystal orientation of the original rare earth metal compound, so that its texture is anisotropic.

[0004] The existing document (publication number CN1701396A) discloses a method for manufacturing anisotropic magnet powder, which comprises the following steps: a high-temperature hydrogenation step in which a RFeB alloy containing rare earth elements Y, B, and Fe as main components is maintained in a treatment environment at a first treatment pressure (P1) of 10 to 100 kPa and a first treatment temperature (T1) in the range of 953 to 1133 K; the RFeB alloy after the high-temperature hydrogenation step is placed in a second treatment pressure (P2) of 10 kPa or more and a second treatment temperature (T3) of 953 to 1133 K. A structural stabilization process in which the RFeB alloy treated in a treatment environment at a second treatment temperature (T2) in the range of 1033 to 1213 K and under the condition of T2>T1 or P2>P1; a controlled exhaust process in which the RFeB alloy treated in the structural stabilization process is maintained in a treatment environment at a third treatment pressure (P2) in the range of 0.1 to 10 kPa of hydrogen partial pressure and a third treatment temperature (T3) in the range of 1033 to 1213 K; a forced exhaust process in which the residual hydrogen (H) is removed from the RFeB alloy treated in the controlled exhaust process. The manufacturing method of the present invention can improve the magnetic properties of anisotropic magnet powder.

[0005] An existing document (publication number CN112424888A) discloses a method for manufacturing rare earth magnet powder, which method comprises a disproportionation step, in which a magnet raw material absorbs hydrogen to undergo a disproportionation reaction, wherein the magnet raw material is obtained by exposing a cast alloy containing a rare earth element (referred to as "R"), boron (B) and a transition element (referred to as "TM") to a hydrogen atmosphere at 350°C to 550°C; and a recombination step, in which hydrogen is desorbed from the magnet raw material after the disproportionation step to undergo a recombination reaction; there is no restriction on the hydrogen partial pressure of the hydrogen atmosphere to which the cast alloy is exposed, for example, it can be 1 kPa to 250 kPa; the cast alloy preferably comprises an ingot that has been solution treated before being exposed to the hydrogen atmosphere; by keeping the temperature of the hydrogen atmosphere (hydrogen crushing temperature) within a predetermined range, cracks are mainly generated in the grain boundary phase, and cracks in the main phase are suppressed; this is also reflected after HDDR, and it is believed that a magnet powder with high magnetic properties is obtained.

[0006] However, although the above-mentioned HDDR process can improve the magnetic properties and grain refinement of magnetic materials, it still fails to effectively eliminate the surface defects of the magnetic material particles, resulting in the obtained magnetic materials having low roundness and sphericity, poor fluidity and poor consistency of grain orientation, thereby limiting its performance and processing convenience in higher-end application fields.

[0007] On this basis, a kind of anisotropic bonded magnetic material with high roundness, good fluidity and good grain orientation consistency and its preparation method have been studied and developed, which is of great significance to improving the processing performance and magnetic properties such as remanence, coercive force and magnetic energy product of anisotropic bonded magnetic materials. Summary of the invention

[0008] The main purpose of the present invention is to provide an anisotropic bonded magnetic material and a preparation method thereof, so as to solve the problems of low roundness, poor fluidity and poor grain orientation consistency of anisotropic bonded magnetic powder in the prior art, as well as the resulting poor processing performance and magnetic properties such as remanence, coercive force and magnetic energy product of the anisotropic bonded magnetic material.

[0009] In order to achieve the above object, the present invention provides an anisotropic bonded magnetic material, which comprises a component shown in formula (I), Re 1 x1 Re 2 y1 T m1 Fe 100-x1-y1-z1-m1 B z1 (I), where Re 1 Selected from Nd, or Pr and Nd, Re 2 One or more selected from the group consisting of La, Ce, Dy and Tb, T selected from one or more transition metal elements, 27.5≤x 1 ≤40,0≤y 1 ≤12, 0.95≤z 1 ≤1.05,0≤m 1 ≤12, and y 1 and m 1 Different from 0 at the same time; the average roundness of anisotropic bonded magnetic material is ≥0.8.

[0010] Furthermore, in formula (I), x 1 27.5~30.5,y 1 0.1~2.5, z 1 0.98~1.05, m 1 3 to 6.

[0011] Furthermore, the anisotropic bonded magnetic material is in a granular form, and its average sphericity is ≥ 0.5, preferably 0.65 to 0.80.

[0012] Furthermore, the D of the anisotropic bonded magnetic material 50 It is 80~120μm.

[0013] Furthermore, the average aspect ratio of the anisotropic bonded magnetic material is ≥0.75.

[0014] Furthermore, the average surface ratio of the anisotropic bonded magnetic material is ≤1.35, preferably 1 to 1.35.

[0015] Furthermore, the anisotropic bonded magnetic material includes orderly arranged grains, and the ratio of the average grain sizes of the grains is (0.85-1.25):1.

[0016] Furthermore, in the anisotropic bonded magnetic material, the angle between the easy magnetization axes of each grain is ≤10°.

[0017] Furthermore, T is selected from one or more of the group consisting of Co, Zr, Cu, Y, Nb and Zn.

[0018] Furthermore, the anisotropic bonded magnetic material comprises, from the inside to the outside, a core and a coating layer arranged on the surface of the core, the core having a composition represented by formula (I), and the material of the coating layer is a phosphorus-containing compound; preferably, the thickness of the coating layer is 10 to 150 nm; preferably, the volume ratio of the core to the coating layer is (1 to 150):(1 to 2); preferably, the phosphorus-containing compound is selected from phosphoric acid and / or phosphates, and more preferably, the phosphates are selected from manganese phosphates and / or zinc phosphates.

[0019] In order to achieve the above-mentioned object, another aspect of the present invention further provides a method for preparing the above-mentioned anisotropic bonded magnetic material provided by the present application, the preparation method comprising: step S1, performing a first hydrogen crushing treatment on the alloy casting in an oxygen-free environment to obtain a first hydrogen crushing product, the above-mentioned alloy casting having a composition shown in formula (II), Re 1 x2 T m2 Fe 100-x2-z2-m2 B z2 (II), where 27.5≤x 2 ≤30.5,0.95≤z 2 ≤1.05,0≤m 2 ≤15; Step S2, performing a second hydrogen crushing treatment on the alloy ingot in an oxygen-free environment to obtain a second hydrogen crushing product, wherein the alloy ingot has a composition shown in formula (III), Re 1 x3 Re 2 y2 T 100-x3-y2 (III), where 70≤x 3 ≤95,0≤y 2 ≤20;y 2 and m 2are not 0 at the same time; step S3, performing a first grinding treatment on the second hydrogen crushing product to obtain a first grinding treatment product; step S4, performing HDDR treatment on the first hydrogen crushing product in an oxygen-free environment to obtain an HDDR magnetic material; step S5, mixing the HDDR magnetic material and the first grinding treatment product, and performing heat treatment and cooling treatment in sequence to obtain a pre-product; the weight ratio of the HDDR magnetic material to the first grinding treatment product is (85-100):(0.1-15); step S6, performing a second grinding treatment on the pre-product to obtain anisotropic bonded magnetic material.

[0020] Furthermore, in formula (II), x 2 27.5~29.5, z 2 0.98~1.05, m 2 It is 0 to 9.

[0021] Furthermore, in formula (III), x 3 50~80,y 2 It is 0.5 to 20.

[0022] Furthermore, between step S1 and step S2, the first hydrogen-crushed product is subjected to a third grinding process to obtain a hydrogen-crushed magnetic material; preferably, the D of the hydrogen-crushed magnetic material 50 It is 60~100μm.

[0023] Furthermore, the first grinding process, the second grinding process and the third grinding process are performed by grinding, airflow milling, stirring or extrusion; preferably, the first grinding process, the second grinding process and the third grinding process are each independently selected from ball milling or airflow milling.

[0024] Furthermore, air flow milling is used for the first grinding treatment, the second grinding treatment and the third grinding treatment. In the first grinding treatment, the grinding gas is selected from nitrogen and / or argon, the gas pressure is 400-500 kPa, the gas flow rate is 300-500 m / s, and the grinding time is 30-180 min. In the second grinding treatment and the third grinding treatment, the grinding gas is independently selected from nitrogen and / or argon, the gas pressure is independently 100-200 kPa, the gas flow rate is independently 10-200 m / s, and the grinding time is independently 0.5-30 min.

[0025] Furthermore, in step S1, the first hydrogen crushing treatment includes a first hydrogen absorption crushing stage and a first hydrogen discharge stage, wherein the temperature of the first hydrogen absorption crushing stage is 20-500°C, the hydrogen pressure is 90-100 kPa, and the time is 30-400 min, and the temperature of the first hydrogen discharge stage is 20-500°C, and the time is 10-200 min.

[0026] Furthermore, in step S2, the second hydrogen crushing treatment includes a second hydrogen absorption crushing stage and a second hydrogen discharge stage, wherein the temperature of the second hydrogen absorption crushing stage is 20-650°C, the hydrogen pressure is 90-100 kPa, and the time is 20-720 min, and the temperature of the second hydrogen discharge stage is 20-650°C, and the time is 10-200 min.

[0027] Further, the first hydrogen fragmentation treatment and the second hydrogen fragmentation treatment are each independently performed in an oxygen-free environment.

[0028] Further, in step S3, the D of the first polishing product 90 ≤10μm, preferably 3-5μm.

[0029] Further, in step S4, the HDDR treatment includes a hydrogen absorption and disproportionation stage and a dehydrogenation and recombination stage, wherein the temperature of the hydrogen absorption and disproportionation stage is 790-845°C, the hydrogen pressure is 29-50kPa, and the time is 90-205min; the dehydrogenation and recombination stage includes a first dehydrogenation stage and a second dehydrogenation stage, the temperature of the first dehydrogenation stage is 810-875°C, the hydrogen pressure is 500-5000Pa, and the time is 5-60min, and the temperature of the second dehydrogenation stage is 810-875°C, the hydrogen pressure is 0.1-5Pa, and the time is 60-90min; preferably, the HDDR treatment is carried out in an oxygen-free environment.

[0030] Furthermore, in step S5, the heat treatment temperature is 780-820° C. and the time is 30-120 min.

[0031] Furthermore, in step S5, the cooling rate of the cooling treatment is 5-15°C / s.

[0032] Furthermore, step S6 includes: performing a second grinding treatment on the pre-product to obtain a second grinding treatment product, performing a surface coating treatment on the second grinding treatment product to obtain an anisotropic bonded magnetic material, wherein the anisotropic bonded magnetic material includes, from the inside to the outside, an inner core and a coating layer arranged on the surface of the inner core, the inner core has a composition shown in formula (I), and the material of the coating layer is a phosphorus-containing compound; preferably, the surface coating treatment includes: mixing a phosphorus-containing precursor with a solvent to obtain a mixed liquid; immersing the second grinding treatment product in the mixed liquid, and obtaining the anisotropic bonded magnetic material after drying.

[0033] Furthermore, the weight ratio of the second polishing treatment product to the phosphorus-containing precursor is (900-1000):(1-9).

[0034] Furthermore, in the mixed solution, the weight percentage of the phosphorus-containing precursor is 10-20wt%.

[0035] Furthermore, the drying temperature is 30-45° C. and the drying time is 30-90 min.

[0036] Furthermore, the phosphorus-containing precursor is selected from phosphoric acid and / or phosphates, and more preferably the phosphates are selected from manganese phosphates and / or zinc phosphates.

[0037] Further, the solvent is selected from acetone and / or ethanol.

[0038] By applying the technical solution of the present invention, compared with the anisotropic bonded magnetic powder with lower roundness in the prior art, the average roundness of the anisotropic bonded magnetic material provided by the present application is ≥0.8, indicating that the shape of the anisotropic bonded magnetic material in the present application is closer to a sphere, its surface is relatively smooth, and it has better fluidity during processing, thereby improving the bulk density of the anisotropic bonded magnetic material; at the same time, the anisotropic bonded magnetic material with higher roundness has fewer surface defects, better consistency of grain orientation, and is not easy to adhere to each other, and can also reduce the orientation deviation caused by adhesion between magnetic materials, further improve the consistency of grain orientation, thereby significantly improving the intrinsic coercivity of the anisotropic magnetic material, and can also improve its magnetic properties such as remanence and magnetic energy product. Compared with anisotropic bonded magnetic materials with other components, the use of anisotropic bonded magnetic materials with the components shown in formula (I) of the present application, and limiting the types and contents of each element component within the above-mentioned specific range can improve the stability of the anisotropic bonded magnetic material and the magnetic properties such as remanence, coercivity and magnetic energy product. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0040] Figure 1 An optical microscope photograph of the anisotropic bonded magnetic material prepared in Example 1 is shown (magnification is 100 times);

[0041] Figure 2 The scanning electron microscope image (SEM image) of the anisotropic bonded magnetic material prepared in Example 1 is shown;

[0042] Figure 3 An optical microscope photograph of the anisotropic bonded magnetic material prepared in Comparative Example 1 is shown (the magnification is 100 times);

[0043] Figure 4 A scanning electron microscope image (SEM image) of the anisotropic bonded magnetic material prepared in Comparative Example 1 is shown. DETAILED DESCRIPTION

[0044] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0045] As described in the background technology, the existing anisotropic bonded magnetic powder has low roundness, poor fluidity and poor grain orientation consistency, and the resulting processing performance and magnetic properties such as remanence, coercive force and magnetic energy product of the anisotropic bonded magnetic material are poor. In order to solve the above technical problems, the first aspect of the present application provides an anisotropic bonded magnetic material, the anisotropic bonded magnetic material includes the components shown in formula (I), Re 1 x1 Re 2 y1 T m1 Fe 100-x1-y1-z1-m1 B z1 (I), where Re 1 Selected from Nd, or Pr and Nd, Re 2 One or more selected from the group consisting of La, Ce, Dy and Tb, T selected from one or more transition metal elements, 27.5≤x 1 ≤40,0≤y 1 ≤12, 0.95≤z 1 ≤1.05,0≤m 1 ≤12, and y 1 and m 1 Different from 0 at the same time; the average roundness of anisotropic bonded magnetic material is ≥0.8.

[0046] It should be noted that the calculation formula for the roundness of the anisotropic bonded magnetic material in this application is shown in formula (IV): (IV), where d 1 is the diameter of a circle with the same cross-sectional area as the anisotropic bonded magnetic material, d 2 is the diameter of a circle having the same circumference as the cross section of the anisotropic bonded magnetic material. Based on the above calculation formula, it can be obtained that the roundness of a sphere is 1, and the closer the roundness of the anisotropic bonded magnetic material is to 1, the closer its shape is to a sphere.

[0047] Compared with the anisotropic bonded magnetic powder with lower roundness in the prior art, the average roundness of the anisotropic bonded magnetic material provided in the present application is ≥0.8, indicating that the shape of the anisotropic bonded magnetic material in the present application is closer to a sphere, its surface is relatively smooth, and it has better fluidity during processing, thereby improving the loose density of the anisotropic bonded magnetic material; at the same time, the anisotropic bonded magnetic material with higher roundness has fewer surface defects, better consistency of grain orientation, and is not easy to adhere to each other between the anisotropic bonded magnetic materials, and can also reduce the orientation deviation caused by adhesion between magnetic materials, further improve the consistency of grain orientation, thereby significantly improving the intrinsic coercivity of the anisotropic magnetic material, and can also improve its magnetic properties such as remanence and magnetic energy product. Compared with anisotropic bonded magnetic materials with other components, the use of anisotropic bonded magnetic materials with the components shown in formula (I) of the present application, and limiting the type and content of each element component within the above-mentioned specific range can improve the stability of the anisotropic bonded magnetic material and the magnetic properties such as remanence, coercivity and magnetic energy product.

[0048] In order to obtain anisotropic bonded magnetic materials with better stability and better magnetic properties such as remanence, coercivity and magnetic energy product, in a preferred embodiment, in formula (I), x 1 27.5~30.5,y 1 0.1~2.5, z 1 0.98~1.05, m 1 3 to 6.

[0049] In order to obtain anisotropic bonded magnetic materials with better magnetic properties such as remanence, coercive force and magnetic energy product, in a preferred embodiment, T includes but is not limited to one or more of the group consisting of Co, Zr, Cu, Y, Nb and Zn.

[0050] In the present application, the sphericity of anisotropic bonded magnetic materials refers to the ratio of the surface area of ​​a sphere with the same volume as the anisotropic bonded magnetic material to the surface area of ​​the anisotropic bonded magnetic material. The closer the sphericity of the anisotropic bonded magnetic material is to 1, the closer its shape is to a sphere. In a preferred embodiment, the anisotropic bonded magnetic material is granular, and its average sphericity is ≥ 0.5. Compared with other ranges, limiting the average sphericity of the anisotropic bonded magnetic material to the above range indicates that its particle morphology is closer to a sphere, which is beneficial to improving the fluidity of the anisotropic bonded magnetic material during processing, and is beneficial to improving its loose density. At the same time, it is also beneficial to improve the consistency of grain orientation in the anisotropic bonded magnetic material, and then it is beneficial to improve the magnetic properties of the anisotropic magnetic material such as remanence, coercive force and magnetic energy product. Preferably, the average sphericity of the anisotropic bonded magnetic material is 0.65 to 0.8. Specifically, the average sphericity of the anisotropic bonded magnetic material may be 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, or 0.8.

[0051] In a preferred embodiment, D of the anisotropic bonded magnetic material 50 The D of anisotropic bonded magnetic materials is 80 to 120 μm. 50 Including but not limited to the above range, limiting it within the above range is beneficial to improving the fluidity of the anisotropic bonded magnetic material.

[0052] In the present application, the aspect ratio of the anisotropic bonded magnetic material refers to the ratio of the distance between the two farthest points on the outer surface of the anisotropic bonded magnetic material (the longest spatial diagonal) to the distance perpendicular to the spatial diagonal of the line segment. The closer the aspect ratio of the anisotropic bonded magnetic material is to 1, the closer its shape is to a sphere. In a preferred embodiment, the average aspect ratio of the anisotropic bonded magnetic material is ≥ 0.75. Compared with other ranges, limiting the average aspect ratio of the anisotropic bonded magnetic material to the above range indicates that its particle morphology is closer to a sphere, which is beneficial to improving the fluidity of the anisotropic bonded magnetic material during processing, and is beneficial to improving its loose density. At the same time, it is also beneficial to improve the consistency of grain orientation in the anisotropic bonded magnetic material, and thus is beneficial to improve the magnetic properties of the anisotropic magnetic material such as remanence, coercive force and magnetic energy product.

[0053] The calculation formula of the surface ratio R of the anisotropic bonded magnetic material in this application is shown in formula (V), Wherein, L is the circumference of the cross section of the anisotropic bonded magnetic material, and S is the area of ​​the cross section of the anisotropic bonded magnetic material. The closer the surface ratio of the anisotropic bonded magnetic material is to 1, the closer its shape is to a sphere. In a preferred embodiment, the average surface ratio of the anisotropic bonded magnetic material is ≤1.35, preferably 1 to 1.35. Compared with other ranges, limiting the average surface ratio of the anisotropic bonded magnetic material to the above range indicates that its particle morphology is closer to a sphere, which is beneficial to improve the fluidity of the anisotropic bonded magnetic material during processing, and is beneficial to improve its loose density. At the same time, it is also beneficial to improve the consistency of grain orientation in the anisotropic bonded magnetic material, and thus it is beneficial to improve the magnetic properties of the anisotropic magnetic material such as remanence, coercive force and magnetic energy product.

[0054] In a preferred embodiment, the anisotropic bonded magnetic material includes orderly arranged grains, and the ratio of the average grain size of each grain is (0.85-1.25):1. Compared with other ranges, limiting the ratio of the average grain size of each grain to the above range is conducive to improving the consistency of the grain size and the uniformity of the microstructure in the anisotropic bonded magnetic material, thereby facilitating the improvement of the magnetic properties such as the remanence, coercive force and magnetic energy product of the anisotropic bonded magnetic material. Preferably, the ratio of the average grain size of each grain of the anisotropic bonded magnetic material is (0.85-1):1. Specifically, the ratio between the longest spatial diagonals in each grain of the anisotropic bonded magnetic material can be 0.85:1, 0.9:1, 0.95:1, 1:1, 1.05:1, 1.1:1, 1.15:1, 1.2:1 or 1.25:1.

[0055] In a preferred embodiment, in the anisotropic bonded magnetic material, the angle between the easy magnetization axes of each crystal grain is ≤10°. Compared with other ranges, limiting the angle between the easy magnetization axes of each crystal grain in the anisotropic bonded magnetic material to the above range is conducive to improving the consistency of grain orientation, thereby facilitating the improvement of magnetic properties such as remanence, coercive force and magnetic energy product of the anisotropic bonded magnetic material.

[0056] In order to improve the high temperature resistance and corrosion resistance of the anisotropic bonded magnetic material and improve its service performance in extreme application environments, in a preferred embodiment, the anisotropic bonded magnetic material includes a core and a coating layer arranged on the surface of the core from the inside to the outside, the core has the composition shown in the above formula (I) of the present application, and the material of the coating layer is a phosphorus-containing compound. Compared with other materials, the phosphorus-containing compound can form a strong chemical bond with the metal element on the surface of the core to generate a dense phosphide coating layer, which is conducive to the protective effect of the coating layer on the core, and is conducive to inhibiting the erosion of the corrosive medium and high temperature environment, thereby helping to improve the high temperature resistance and corrosion resistance of the anisotropic bonded magnetic material.

[0057] In a preferred embodiment, the coating layer has a thickness of 10 to 150 nm. The coating layer thickness includes but is not limited to the above range. Limiting it within the above range is beneficial to inhibiting the erosion of the core by the corrosive medium and the high temperature environment, thereby improving the high temperature resistance and corrosion resistance of the anisotropic bonded magnetic material, and also helps to inhibit the decrease in the magnetic properties of the anisotropic bonded magnetic material caused by the coating layer being too thick. Preferably, the coating layer has a thickness of 10 to 50 nm; more preferably, the coating layer has a thickness of 20 to 30 nm.

[0058] In a preferred embodiment, the volume ratio of the core to the coating is (1-150):(1-2). The volume ratio of the core to the coating includes but is not limited to the above range. Limiting it within the above range is conducive to the protective effect of the coating on the core, and is conducive to inhibiting the erosion of the core by corrosive media and high temperature environments, thereby helping to improve the high temperature resistance and corrosion resistance of the anisotropic bonded magnetic material, and is also conducive to inhibiting the decrease in magnetic properties caused by excessive thickness of the coating and excessive volume share. Preferably, the volume ratio of the core to the coating is (10-120):(1-2), or (20-100):(1-2), or (40-60):(1-2). Specifically, the volume ratio of the core to the coating can be 150:1, 120:1, 100:1, 60:1, 40:1, 20:1, 10:1 or 1:2.

[0059] In order to form a denser phosphide coating layer, further inhibit the erosion of the inner core by corrosive media and high temperature environment, and further improve the high temperature resistance and corrosion resistance of the anisotropic bonded magnetic material, preferably, the phosphorus-containing compound includes but is not limited to phosphoric acid and / or phosphates; more preferably, the phosphates include but are not limited to manganese phosphates and / or zinc phosphates; further preferably, the phosphates include but are not limited to manganese phosphates and / or zinc phosphates.

[0060] The second aspect of the present application also provides a method for preparing the above-mentioned anisotropic bonded magnetic material provided by the present application, the preparation method comprising: step S1, performing a first hydrogen crushing treatment on the alloy casting in an oxygen-free environment to obtain a first hydrogen crushing product, the alloy casting having a composition shown in formula (II), Re 1 x2 T m2 Fe 100-x2-z2-m2 B z2 (II), where 27.5≤x 2 ≤30.5,0.95≤z 2 ≤1.05,0≤m 2 ≤15,Re 1and T have the same definition as the above formula (I) of the present application; step S2, performing a second hydrogen crushing treatment on the alloy ingot in an oxygen-free environment to obtain a second hydrogen crushing product, the alloy ingot having a composition shown in formula (III), Re 1 x3 Re 2 y2 T 100-x3-y2 (III), where 70≤x 3 ≤95,0≤y 2 ≤20,y 2 and m 2 Not at the same time 0, Re 1 、Re 2 and T have the same definition as the above-mentioned formula (I) of the present application; step S3, performing a first grinding treatment on the second hydrogen crushing product to obtain a first grinding treatment product; step S4, performing HDDR treatment on the first hydrogen crushing product in an oxygen-free environment to obtain an HDDR magnetic material; step S5, mixing the HDDR magnetic material with the first grinding treatment product, and sequentially performing heat treatment and cooling treatment to obtain a pre-product; the weight ratio of the HDDR magnetic material to the first grinding treatment product is (85-100):(0.1-15); step S6, performing a second grinding treatment on the pre-product to obtain anisotropic bonded magnetic material.

[0061] In the above-mentioned preparation method provided by the present application, the first hydrogen crushing treatment in step S1 and the second hydrogen crushing treatment in step S2 can refine the grains of the alloy flakes and the alloy ingots; step S3 performs a grinding treatment on the second hydrogen crushing product to remove the sharp edges and corners on its surface and eliminate its surface defects, thereby refining the grain size of the second hydrogen crushing product and improving the consistency of the grain orientation to obtain a first grinding treatment product; step S4 performs an HDDR treatment on the first hydrogen crushing product in an oxygen-free environment to improve the grain structure of the first hydrogen crushing product, improve the consistency of its grain orientation, and inhibit the formation of oxides; step S4 performs an HDDR treatment on the first hydrogen crushing product in an oxygen-free environment to improve the grain structure of the first hydrogen crushing product and improve the consistency of its grain orientation, while inhibiting the formation of oxides; Step S5 mixes the HDDR magnetic material with the first grinding treatment product according to a specific weight ratio to obtain a pre-product having the composition shown in formula (I); Step S6 performs a second grinding treatment on the pre-product to remove the sharp edges on its surface, making its morphology closer to a sphere, and at the same time eliminate its surface defects and improve the consistency of its grain orientation, thereby improving the magnetic properties such as the remanence, coercive force and magnetic energy product of the anisotropic magnetic material. In addition, it can reduce the adhesion between the pre-products and improve the fluidity of the anisotropic bonded magnetic material, thereby improving the bulk density and molding quality of the anisotropic bonded magnetic material in the subsequent processing process.

[0062] Compared with other methods, the above-mentioned preparation method provided by the present application can obtain anisotropic bonded magnetic materials having the composition shown in formula (I), an average roundness ≥ 0.8 and a shape closer to a sphere, thereby improving the fluidity of the anisotropic bonded magnetic materials; at the same time, the anisotropic bonded magnetic materials with higher roundness have fewer surface defects, better consistency of grain orientation, and are not easy to adhere to each other. It can also reduce the orientation deviation caused by adhesion between magnetic materials, further improve the consistency of grain orientation, thereby improving the magnetic properties such as remanence, coercive force and magnetic energy product of the anisotropic magnetic materials. Compared with anisotropic bonded magnetic materials with other compositions, the anisotropic bonded magnetic materials with the composition shown in formula (I) of the present application have better stability and magnetic properties such as remanence, coercive force and magnetic energy product.

[0063] In order to obtain anisotropic bonded magnetic materials with better stability and better magnetic properties such as remanence, coercivity and magnetic energy product, preferably, in formula (II), x 2 27.5~29.5, z 2 0.98~1.05, m 2 is 0 to 9; preferably, in formula (III), x 3 50~80,y 2 It is 0.5 to 20.

[0064] In order to improve the microstructure of the alloy casting, thereby further improving the magnetic properties of the anisotropic bonded magnetic material, in a preferred embodiment, in step S1, the preparation method of the alloy casting is: melting the mother alloy having the composition shown in formula (II) into a rapid-solidification casting sheet, and performing a heat preservation treatment on the rapid-solidification casting sheet to obtain the alloy casting sheet; the temperature of the heat preservation treatment is 1080-1170°C, and the time is 5-30 hours; preferably, the heat preservation treatment time is 10-20 hours.

[0065] In order to remove the sharp edges and corners on the surface of the first hydrogen crushing product and eliminate its surface defects, thereby refining the grain size of the first hydrogen crushing product and improving the consistency of grain orientation, in a preferred embodiment, between step S1 and step S2, a third grinding treatment is also included for the first hydrogen crushing product to obtain a hydrogen crushing magnetic material.

[0066] In order to improve the consistency of the anisotropic bonded magnetic material, in a preferred embodiment, the hydrogen-crushed magnetic material D 50 It is 60~100μm.

[0067] In a preferred embodiment, the first grinding process, the second grinding process and the third grinding process are performed by grinding, air flow grinding, stirring or extrusion. Compared with other methods, the first grinding process, the second grinding process and the third grinding process by the above method are beneficial to remove the sharp edges and corners on the surface of the first hydrogen crushing product, the second hydrogen crushing product and the pre-product, and are beneficial to eliminate their surface defects, thereby being beneficial to refining their grains and improving the consistency of their grain orientation, thereby being beneficial to improving the roundness, fluidity and magnetic properties of the anisotropic bonded magnetic material.

[0068] In order to further improve the effect of the grinding treatment, further remove the sharp edges and corners on the surface of the first hydrogen crushing product, the second hydrogen crushing product and the pre-product, eliminate their surface defects, and further improve the roundness, fluidity and magnetic properties of the anisotropic bonded magnetic material, preferably, the first grinding treatment, the second grinding treatment and the third grinding treatment independently include but are not limited to ball milling or air flow milling.

[0069] In order to further improve the effect of the grinding treatment, further remove the sharp edges and corners on the surfaces of the first hydrogen crushing product, the second hydrogen crushing product and the pre-product, eliminate their surface defects, and further improve the roundness, fluidity and magnetic properties of the anisotropic bonded magnetic material, air flow grinding is used for the first grinding treatment, the second grinding treatment and the third grinding treatment. In the first grinding treatment, the grinding gas includes but is not limited to nitrogen and / or argon, the gas pressure is 400-500kPa, the gas flow rate is 300-500m / s, and the grinding time is 30-180min; in the second grinding treatment and the third grinding treatment, the grinding gas independently includes but is not limited to nitrogen and / or argon, the gas pressure is independently 100-200kPa, the gas flow rate is independently 10-200m / s, and the grinding time is independently 0.5-30min.

[0070] In a preferred embodiment, in step S1, the first hydrogen crushing treatment includes a first hydrogen absorption crushing stage and a first hydrogen discharge stage, wherein the temperature of the first hydrogen absorption crushing stage is 20-500°C, the hydrogen pressure is 90-100 kPa, and the time is 30-400 min, and the temperature of the first hydrogen discharge stage is 20-500°C, and the time is 10-200 min. The various process parameters in the first hydrogen crushing treatment include but are not limited to the above ranges, and limiting them within the above ranges is conducive to refining the size of the first hydrogen crushing product, facilitating subsequent processing, thereby facilitating improving the roundness, fluidity and magnetic properties of the anisotropic bonded magnetic material.

[0071] In a preferred embodiment, in step S2, the second hydrogen crushing treatment includes a second hydrogen absorption crushing stage and a second hydrogen discharge stage, wherein the temperature of the second hydrogen absorption crushing stage is 20-650°C, the hydrogen pressure is 90-100 kPa, and the time is 20-720 min, and the temperature of the second hydrogen discharge stage is 20-650°C, and the time is 10-200 min. The various process parameters in the second hydrogen crushing treatment include but are not limited to the above ranges, and limiting them within the above ranges is conducive to refining the grain size of the second hydrogen crushing product, facilitating subsequent processing, thereby facilitating improving the roundness, fluidity and magnetic properties of the anisotropic bonded magnetic material.

[0072] In order to improve the consistency of the first polishing product, thereby further improving the consistency of the anisotropic bonded magnetic material, in a preferred embodiment, in step S3, the D of the first polishing product is 90 ≤10μm.

[0073] In order to further improve the consistency of the first polishing product, and thus further improve the consistency of the anisotropic bonded magnetic material, preferably, the D of the first polishing product is 90 3~5μm.

[0074] In a preferred embodiment, in step S4, the HDDR treatment includes a hydrogen absorption disproportionation stage and a dehydrogenation and recombination stage, wherein the temperature of the hydrogen absorption disproportionation stage is 790-845°C, the hydrogen pressure is 29-50 kPa, and the time is 90-205 min; the dehydrogenation and recombination stage includes a first dehydrogenation stage and a second dehydrogenation stage, wherein the temperature of the first dehydrogenation stage is 810-875°C, the hydrogen pressure is 500-5000 Pa, and the time is 5-60 min, and the temperature of the second dehydrogenation stage is 810-875°C, the hydrogen pressure is 0.1-5 Pa, and the time is 60-90 min. The process parameters of each stage in the HDDR treatment include but are not limited to the above ranges, and limiting them within the above ranges is conducive to improving the treatment effect of HDDR, improving the grain structure of the first hydrogen crushing product, and improving the consistency of its grain orientation, thereby facilitating the acquisition of anisotropic bonded magnetic materials with better magnetic properties.

[0075] In a preferred embodiment, in step S5, the temperature of the heat treatment is 780-820°C and the time is 30-120 minutes. The temperature and time of the heat treatment include but are not limited to the above ranges. Limiting them within the above ranges is beneficial to promoting the fusion between the HDDR magnetic material and the first polishing product, to obtaining a pre-product having the composition shown in formula (I), to inhibiting the excessive growth of grains, and to improving their uniformity, thereby facilitating the improvement of the stability of the anisotropic bonded magnetic material and the magnetic properties such as remanence, coercive force and magnetic energy product.

[0076] In a preferred embodiment, in step S5, the cooling rate of the cooling treatment is 5 to 15°C / s. The cooling rate of the cooling treatment includes but is not limited to the above range. Limiting it to the above range is beneficial to suppressing abnormal growth of the pre-product grains during the cooling treatment, and is beneficial to improving the uniformity of its grains, thereby facilitating the improvement of the stability of the anisotropic bonded magnetic material and the magnetic properties such as remanence, coercive force and magnetic energy product.

[0077] In order to improve the high temperature resistance and corrosion resistance of the anisotropic bonded magnetic material and improve its serviceability in extreme application environments, in a preferred embodiment, step S6 includes: performing a second grinding treatment on the pre-product to obtain a second grinding treatment product, and performing a surface coating treatment on the second grinding treatment product to obtain an anisotropic bonded magnetic material, wherein the anisotropic bonded magnetic material includes a core and a coating layer arranged on the surface of the core, the core has the composition shown in the above formula (I), and the material of the coating layer is a phosphorus-containing compound.

[0078] In a preferred embodiment, the surface coating treatment includes: mixing a phosphorus-containing precursor with a solvent to obtain a mixed solution; immersing the second polishing treatment product in the mixed solution, and obtaining anisotropic bonded magnetic material after drying. Compared with other methods, the above method is simple and easy to operate, and the source of reagents is abundant. The above method is conducive to improving the effect of surface coating treatment, obtaining a denser coating layer, and exerting the protective effect of the coating layer, inhibiting the erosion of the core by corrosive media and high temperature environment, thereby improving the high temperature resistance and corrosion resistance of the anisotropic bonded magnetic material.

[0079] In a preferred embodiment, the weight ratio of the second polishing product to the phosphorus-containing precursor is (900-1000):(1-9). The weight ratio of the second polishing product to the phosphorus-containing precursor includes but is not limited to the above range. Limiting it within the above range is conducive to obtaining a coating layer with a more suitable thickness, which is conducive to inhibiting the erosion of the core by corrosive media and high-temperature environments, thereby helping to improve the high temperature resistance and corrosion resistance of the anisotropic bonded magnetic material. Preferably, the weight ratio of the second polishing product to the phosphorus-containing precursor is 1000:(1-3).

[0080] In a preferred embodiment, the weight percentage of the phosphorus-containing precursor in the mixed solution is 10-20wt%. The weight percentage of the phosphorus-containing precursor includes but is not limited to the above range, and limiting it within the above range is conducive to improving the binding efficiency of the phosphorus-containing precursor with the metal element on the surface of the anisotropic bonded magnetic material, improving the density and uniformity of the phosphide coating layer, thereby helping to reduce the erosion of the core by the corrosive medium and the high temperature environment, and further helping to improve the high temperature resistance and corrosion resistance of the anisotropic bonded magnetic material.

[0081] In order to further improve the effect of the surface coating treatment, further promote the formation of the coating layer, and further improve the density and stability of the coating layer, in a preferred embodiment, the drying temperature is 30 to 45° C. and the time is 30 to 90 minutes.

[0082] In a preferred embodiment, the phosphorus-containing precursor includes but is not limited to phosphoric acid and / or phosphates, preferably, the phosphates include but are not limited to manganese phosphates and / or zinc phosphates; more preferably, the phosphates include but are not limited to manganese phosphates and / or zinc phosphates. Compared with other materials, the phosphorus-containing precursor can form a strong chemical bond with the metal elements on the surface of the inner core to generate a dense phosphide coating layer, which is beneficial to reduce the erosion of the inner core by corrosive media and high temperature environments, and further helps to improve the high temperature resistance and corrosion resistance of the anisotropic bonded magnetic material.

[0083] In order to improve the dispersibility of the phosphorus-containing precursor and further enhance the effect of the surface coating treatment, in a preferred embodiment, the solvent includes but is not limited to acetone and / or ethanol.

[0084] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0085] Example 1

[0086] A method for preparing anisotropic bonded magnetic material, specifically comprising the following steps:

[0087] (1) PrNd alloy, NbFe alloy, Co element, ferroboron alloy and Fe element were smelted at 1450°C for 4 hours to obtain a composition (PrNd) 29 Nb 0.25 Co 2.5 Fe 67.25 A quick-solidified cast sheet of B, the quick-solidified cast sheet having a thickness of 1 mm, then kept in an oxygen-free environment at 1150° C. for 18 hours, and after cooling, an alloy cast sheet having a thickness ranging from 35 to 50 mm is obtained;

[0088] (2) subjecting the alloy casting obtained in step (1) to hydrogen crushing treatment in an oxygen-free environment, firstly heating the alloy casting to 400° C., charging hydrogen to a hydrogen pressure of 95 kPa, maintaining the temperature under this condition for 180 min, and then dehydrogenating the alloy casting at 350° C. for 45 min to obtain a hydrogen crushing product;

[0089] (3) grinding the hydrogen crushing product obtained in step (2) for 30 minutes in an oxygen-free argon environment using a jet mill to obtain D 50 The hydrogen crushed magnetic powder is 87.5 μm, wherein the pressure of argon gas is 100 kPa and the gas flow rate is 10 m / s;

[0090] (4) PrNd alloy, La, Ce, Cu and Zr were smelted at 1450°C for 4 hours to obtain a composition (PrNd) 80 La 5 Ce 5 Cu 5 Zr 5 The master alloy is smelted at 1450°C for 4 hours to obtain an alloy ingot with the same composition, and then subjected to hydrogen crushing treatment in an oxygen-free environment. First, the temperature is raised to 500°C, hydrogen is charged to a hydrogen pressure of 100 kPa, and after maintaining the condition for 100 minutes, dehydrogenation is performed at 500°C for 90 minutes to obtain a hydrogen crushing product;

[0091] (5) grinding the hydrogen crushing product obtained in step (2) for 180 min in an oxygen-free argon environment using a jet mill to obtain D 90 The first polishing product is 9 μm, wherein the pressure of argon gas is 300 kPa and the gas flow rate is 400 m / s;

[0092] (6) placing the hydrogen-crushed magnetic powder obtained in step (3) in a hydrogen treatment furnace and performing HDDR treatment in an oxygen-free environment, first heating to 790° C., charging with hydrogen until the hydrogen pressure reaches 34 kPa, and maintaining under this condition for 120 min; then continuing to heat to 825° C., and increasing the hydrogen pressure to 50 kPa, and maintaining under this condition for 20 min; then cooling to 820° C., slowly evacuating for 1 h until the hydrogen pressure reaches 3 kPa, and then quickly evacuating to a hydrogen pressure of <1 Pa, and maintaining under this condition for 1.5 h before cooling to room temperature to obtain HDDR magnetic powder;

[0093] (7) mixing the HDDR magnetic powder obtained in step (6) and the first polishing product obtained in step (5) at a weight ratio of 100:3, and then sequentially performing heat treatment and cooling treatment to obtain a pre-product, wherein the heat treatment temperature is 810° C., the time is 120 min, and the cooling rate of the cooling treatment is 15° C. / s;

[0094] (8) The pre-product obtained in step (7) was polished for 30 min in an oxygen-free argon environment (argon pressure of 100 kPa, gas flow rate of 10 m / s) using a jet mill to obtain a second polished product, the composition of which is (PrNd) 28.7 La 0.12 Ce 0.11 Nb 0.21 Co 2.2 Cu 0.12 Zr 0.11 Fe 67.47 B 0.96 ;

[0095] (9) immersing the second polishing product obtained in step (8) in a phosphoric acid acetone solution (the phosphoric acid content is 20 wt%) for surface coating treatment, wherein the weight ratio of the second polishing product to the phosphoric acid is 1000:3; drying treatment is performed at 45° C. for 35 min until the acetone is completely volatilized to obtain D 50 The anisotropic bonded magnetic material is 91 μm, and the anisotropic bonded magnetic material includes a core and a coating layer arranged on the surface of the core from the inside to the outside, wherein the D 50 The surface roughness is 91 μm, and the thickness of the coating layer is 30 nm.

[0096] The optical microscope photograph of the anisotropic bonded magnetic material prepared in Example 1 is as follows: Figure 1 As shown in the scanning electron microscope image Figure 2 As shown. Figure 1 and Figure 2 It can be seen that the morphology of the anisotropic bonded magnetic material obtained in Example 1 is close to a sphere, and the roundness and sphericity are relatively high.

[0097] Example 2

[0098] The difference from Example 1 is:

[0099] In step (1), the PrNd alloy, the ferroboron alloy and the Fe element are smelted at 1450° C. for 4 h to obtain a PrNd alloy having a composition of 29 Fe 70 B. A quick-solidified casting sheet with a thickness of 1.5 mm, followed by keeping the temperature at 1170°C in an oxygen-free environment for 10 hours, and after cooling, obtaining an alloy casting sheet with a thickness ranging from 50 to 70 mm;

[0100] The process of HDDR treatment in step (6) is as follows: HDDR treatment is performed in an oxygen-free environment, firstly the temperature is raised to 820°C, hydrogen is charged until the hydrogen pressure is 36 kPa, and the condition is maintained for 120 min; then the temperature is further raised to 845°C, and the hydrogen pressure is increased to 50 kPa, and the condition is maintained for 20 min; then the temperature is lowered to 830°C, vacuum is slowly evacuated for 1 h until the hydrogen pressure is 3 kPa, and then vacuum is quickly evacuated until the hydrogen pressure is less than 1 Pa, and the condition is maintained for 1.5 h before cooling to room temperature to obtain HDDR magnetic powder;

[0101] In step (9), the content of phosphoric acid in the acetone solution of phosphoric acid is 15 wt %, and the weight ratio of phosphoric acid to the second polishing product is 2.8:1000;

[0102] The remaining steps are the same as those in Example 1.

[0103] The anisotropic bonded magnetic material prepared in this embodiment includes a core and a coating layer arranged on the surface of the core from the inside to the outside, wherein the composition of the core is (PrNd)28.85 La 0.06 Ce 0.07 Cu 0.02 Zr 0.13 Fe 69.92 B 0.95 , the kernel D 50 The surface roughness is 88 μm, and the thickness of the coating layer is 28 nm.

[0104] Example 3

[0105] The difference from Example 1 is:

[0106] In step (1), PrNd alloy, Co element, ferroboron alloy and Fe element are smelted at 1450°C for 4 hours to obtain a composition (PrNd) 29 Co 3 Fe 67 B. A quick-solidified casting sheet with a thickness of 1 mm is then kept in an oxygen-free environment at 1150°C for 18 hours, and after cooling, an alloy casting sheet with uneven thickness is obtained, and its thickness ranges from 35 to 50 mm;

[0107] In step (4), PrNd alloy, Dy single substance, Ce single substance, Cu single substance and Zr single substance are smelted at 1420° C. for 2 h to obtain a composition (PrNd) 80 Dy 10 Ce 5 Cu 2 Zr 3 Master alloy;

[0108] The specific process of HDDR treatment in step (6) is as follows: perform HDDR treatment in an oxygen-free environment, first heat to 800°C, fill with hydrogen until the hydrogen pressure is 36 kPa, and maintain under this condition for 120 minutes; then continue to heat to 825°C, and increase the hydrogen pressure to 50 kPa, and maintain under this condition for 20 minutes; then cool to 810°C, slowly evacuate for 1 hour until the hydrogen pressure is 3 kPa, then quickly evacuate to a hydrogen pressure of <1 Pa, and maintain under this condition for 1.5 hours before cooling to room temperature to obtain HDDR magnetic powder;

[0109] In step (7), the weight ratio of the HDDR magnetic powder obtained in step (6) to the first polishing product obtained in step (5) is 100:2;

[0110] In step (9), the content of phosphoric acid in the acetone solution of phosphoric acid is 10 wt %, and the weight ratio of phosphoric acid to the second polishing product is 2.5:1000;

[0111] The remaining steps are the same as those in Example 1.

[0112] The anisotropic bonded magnetic material prepared in this embodiment includes a core and a coating layer arranged on the surface of the core from the inside to the outside, wherein the composition of the core is Nd 29.8 Dy 0.019 Ce 0.00097 Cu 0.039 Zr 0.058 Co 2.903 Fe 66.20003 B 0.98 , the kernel D 50 The surface roughness is 92 μm, and the thickness of the coating layer is 26 nm.

[0113] Example 4

[0114] The difference from Example 1 is that in the hydrogen crushing treatment in step (2), the temperature of the hydrogen absorption crushing stage is 20°C, the hydrogen pressure is 90 kPa, and the time is 400 min; the temperature of the dehydrogenation stage is 20°C, and the time is 200 min; and the gas flow rate in the air flow mill treatment in step (3) is 100 m / s, and the remaining steps are the same as in Example 1.

[0115] The D of the hydrogen-crushed magnetic powder obtained in step (3) of this embodiment 50 is 90μm.

[0116] Example 5

[0117] The difference from Example 1 is that in the hydrogen crushing treatment in step (2), the temperature of the hydrogen absorption crushing stage is 500°C, the hydrogen pressure is 100 kPa, and the time is 30 min; the temperature of the dehydrogenation stage is 500°C, and the time is 10 min; and the gas flow rate in the air flow mill treatment in step (3) is 100 m / s, and the remaining steps are the same as in Example 1.

[0118] The D of the hydrogen-crushed magnetic powder obtained in step (3) of this embodiment 50 It is 92μm.

[0119] Example 6

[0120] The difference from Example 1 is that in the hydrogen crushing treatment in step (2), the temperature of the hydrogen absorption crushing stage is 650°C, the hydrogen pressure is 85 kPa, and the time is 720 min; the temperature of the dehydrogenation stage is 650°C, and the time is 300 min; and the gas flow rate in the air flow mill treatment in step (3) is 300 m / s, and the remaining steps are the same as in Example 1.

[0121] The D of the hydrogen-crushed magnetic powder obtained in step (3) of this embodiment 50 It is 98μm.

[0122] Example 7

[0123] The difference from Example 1 is that in the hydrogen crushing treatment in step (4), the temperature of the hydrogen absorption crushing stage is 20°C, the hydrogen pressure is 100 kPa, and the time is 720 min; the temperature of the dehydrogenation stage is 20°C, and the time is 200 min. The remaining steps are the same as in Example 1.

[0124] Example 8

[0125] The difference from Example 1 is that in the hydrogen crushing treatment in step (4), the temperature of the hydrogen absorption crushing stage is 700°C, the hydrogen pressure is 110 kPa, and the time is 300 min; the temperature of the dehydrogenation stage is 700°C, and the time is 300 min. The remaining steps are the same as in Example 1.

[0126] Example 9

[0127] The difference from Example 1 is that in step (5), the gas flow rate in the air flow mill treatment is 500 m / s, the air flow mill time is 180 min, and the remaining steps are the same as in Example 1.

[0128] The D of the first polishing product obtained in step (5) of this embodiment is 90 is 2μm.

[0129] Example 10

[0130] The difference from Example 1 is that the gas flow rate in the air flow mill treatment in step (5) is 250 m / s, the air flow mill time is 180 min, and the remaining steps are the same as Example 1.

[0131] The D of the first polishing product obtained in step (5) of this embodiment is 90 is 10μm.

[0132] Embodiment 11

[0133] The difference from Example 1 is that the specific process of HDDR treatment in step (6) is as follows: HDDR treatment is carried out in an oxygen-free environment, firstly the temperature is raised to 790°C, hydrogen is introduced until the hydrogen pressure reaches 29 kPa, and this condition is maintained for 90 min; then the temperature is continued to be raised to 820°C, and the hydrogen pressure is increased to 45 kPa, and this condition is maintained for 30 min; then the temperature is lowered to 810°C, and vacuum is slowly evacuated for 0.5 h until the hydrogen pressure reaches 1 kPa, and then vacuum is quickly evacuated until the hydrogen pressure is less than 1 Pa, and this condition is maintained for 1 h before cooling to room temperature to obtain HDDR magnetic powder; the remaining steps are the same as Example 1.

[0134] Example 12

[0135] The difference from Example 1 is that the specific process of HDDR treatment in step (6) is as follows: HDDR treatment is carried out in an oxygen-free environment, firstly the temperature is raised to 840°C, hydrogen is introduced until the hydrogen pressure reaches 45 kPa, and this condition is maintained for 205 min; then the temperature is continued to be raised to 845°C, and the hydrogen pressure is increased to 50 kPa, and this condition is maintained for 30 min; then the temperature is lowered to 875°C, and vacuum is slowly evacuated for 0.5 h until the hydrogen pressure reaches 5 kPa, and then vacuum is quickly evacuated until the hydrogen pressure reaches <1 Pa, and this condition is maintained for 1.5 h before cooling to room temperature to obtain HDDR magnetic powder; the remaining steps are the same as Example 1.

[0136] Example 13

[0137] The difference from Example 1 is that the specific process of HDDR treatment in step (6) is as follows: HDDR treatment is carried out in an oxygen-free environment, firstly the temperature is raised to 860°C, hydrogen is charged until the hydrogen pressure reaches 50 kPa, and this condition is maintained for 205 min; then the temperature is continued to be raised to 915°C, and the hydrogen pressure is increased to 55 kPa, and this condition is maintained for 30 min; then the temperature is lowered to 900°C, and vacuum is slowly evacuated for 0.5 h until the hydrogen pressure reaches 3 kPa, and then vacuum is quickly evacuated until the hydrogen pressure is less than 1 Pa, and this condition is maintained for 0.5 h before cooling to room temperature to obtain HDDR magnetic powder; the remaining steps are the same as Example 1.

[0138] Embodiment 14

[0139] The difference from Example 1 is that in step (7), the heat treatment temperature is 780° C. and the time is 30 min. The remaining steps are the same as Example 1.

[0140] Embodiment 15

[0141] The difference from Example 1 is that in step (7), the heat treatment temperature is 820° C. and the time is 120 min. The remaining steps are the same as in Example 1.

[0142] Example 16

[0143] The difference from Example 1 is that in step (7), the heat treatment temperature is 750° C. and the time is 20 min. The remaining steps are the same as Example 1.

[0144] Embodiment 17

[0145] The difference from Example 1 is that the gas flow rate of the air flow mill treatment in step (8) is 10 m / s, the air flow mill time is 30 min, and the remaining steps are the same as Example 1.

[0146] Embodiment 18

[0147] The difference from Example 1 is that the gas flow rate of the air flow mill treatment in step (8) is 200 m / s, the air flow mill time is 0.5 min, and the remaining steps are the same as Example 1.

[0148] Embodiment 19

[0149] The difference from Example 1 is that the gas flow rate of the air flow mill treatment in step (8) is 350 m / s, the air flow mill time is 60 min, and the remaining steps are the same as Example 1.

[0150] Embodiment 20

[0151] The difference from Example 1 is that step (9) is omitted, and the remaining steps are the same as those of Example 1. The anisotropic magnetic material prepared in this example does not contain a coating layer.

[0152] Comparative Example 1

[0153] A method for preparing anisotropic bonded magnetic material, specifically comprising the following steps:

[0154] (1) PrNd alloy, Co element, ferroboron alloy and Fe element were smelted at 1450°C for 4 hours to obtain a composition (PrNd) 29 Co 3 Fe 67 The master alloy of B is smelted at 1450°C for 4 hours to obtain an alloy ingot with the same composition, then kept in an oxygen-free environment at 1150°C for 18 hours, and cooled to obtain a heat-treated alloy ingot;

[0155] (2) performing hydrogen crushing treatment on the heat-treated alloy ingot obtained in step (1) in an oxygen-free environment, firstly heating the alloy ingot to 300° C., charging the alloy with hydrogen until the hydrogen pressure reaches 100 kPa, maintaining the ingot under this condition for 200 min, and then dehydrogenating the ingot at 350° C. for 120 min to obtain a hydrogen crushing product;

[0156] (3) The hydrogen bankrupt obtained in step (2) is placed in a hydrogen treatment furnace (the same model as in embodiment 1) and subjected to HDDR treatment in an oxygen-free environment. First, the temperature is raised to 790° C., hydrogen is charged to a hydrogen pressure of 29 kPa, and the condition is maintained for 150 min; then the temperature is further raised to 825° C., and the hydrogen pressure is increased to 60 kPa, and the condition is maintained for 20 min; then the temperature is lowered to 815° C., and vacuum is slowly evacuated for 30 min until the hydrogen pressure is 3 kPa, and then vacuum is quickly evacuated to a vacuum degree of <1 Pa, and the condition is maintained for 1 h before cooling to room temperature to obtain D 50 The HDDR magnetic powder is 97μm, and the composition of the HDDR magnetic powder is Nd 29 Co 3 Fe 67 B.

[0157] (4) immersing the HDDR magnetic powder obtained in step (3) in a phosphoric acid acetone solution (the content of phosphoric acid is 20wt%) for surface coating treatment, wherein the weight ratio of the HDDR magnetic powder to the phosphoric acid is 1000:3; drying treatment is performed at 45°C for 90 minutes until the acetone is completely volatilized to obtain anisotropic bonded magnetic material, wherein the anisotropic bonded magnetic material includes a core and a coating layer arranged on the surface of the core from the inside to the outside, wherein the composition of the core is (PrNd) 29 Co 3 Fe 67 B, kernel D 50 The surface roughness is 98 μm, and the thickness of the coating layer is 10 nm.

[0158] The optical microscope photograph of the anisotropic bonded magnetic material prepared in Comparative Example 1 is as follows: Figure 3 As shown in the scanning electron microscope image Figure 4 As shown. Figure 3 and Figure 4 It can be seen that the anisotropic bonded magnetic material obtained in Comparative Example 1 has an irregular morphology, poor roundness and sphericity; Figure 1 and Figure 3 It can be seen that compared with Comparative Example 1, the roundness and sphericity of the anisotropic bonded magnetic material prepared in Example 1 are significantly improved.

[0159] Comparative Example 2

[0160] The difference from Example 1 is that step (8) is omitted, and the pre-product obtained in step (7) is directly subjected to surface coating treatment, and the remaining steps are the same as those in Example 1.

[0161] Comparative Example 3

[0162] The difference from Example 1 is that step (5) is omitted, the hydrogen crushing product obtained in step (4) is not polished, and the remaining steps are the same as those in Example 1.

[0163] The anisotropic bonded magnetic materials prepared in all the examples and comparative examples of the present application were characterized, including the D 50 , average roundness, average sphericity, average aspect ratio, average surface rate and fluidity. The specific characterization methods are as follows:

[0164] (1) The D of anisotropic bonded magnetic materials was measured using a laser particle size analyzer (HELOS / BF, Quantum Design, USA). 50 ;

[0165] (2) The average roundness, average sphericity, average aspect ratio and average surface ratio of the anisotropic bonded magnetic material were measured using a dry dynamic image particle size analyzer (Jinan Micro-Nano Particle Instrument Co., Ltd., Winner300D);

[0166] (3) The fluidity of anisotropic bonded magnetic materials was measured using a powder comprehensive properties tester (Dandong Better Instrument Co., Ltd., model BT-1000).

[0167] The test results are shown in Table 1.

[0168] Table 1

[0169]

[0170]

[0171] The magnetic properties of the anisotropic bonded magnetic materials prepared in all the embodiments and comparative examples of the present application were tested using a vibrating sample magnetometer (VSM, Quantum Design, USA, MVL111), including remanence Br, intrinsic coercivity Hcj and maximum magnetic energy product (BH). m The test results are shown in Table 2.

[0172] Table 2

[0173] Br(kGs) Hcj(kOe) <![CDATA[(BH) m (MGOe)]]> Example 1 13.9 13.1 41.6 Example 2 13.8 13.1 41.2 Example 3 13.9 13.5 41.8 Example 4 13.7 13.4 41.7 Example 5 13.9 13.5 41.5 Example 6 13.4 12.9 39.8 Example 7 13.7 13.7 41.3 Example 8 13.6 13.0 41.1 Example 9 13.7 13.8 41.5 Example 10 13.5 12.7 40.9 Embodiment 11 13.6 13.4 40.1 Example 12 13.5 13.8 39.9 Example 13 13.4 13.9 39.5 Embodiment 14 13.7 13.7 39.8 Embodiment 15 13.6 13.4 40.5 Example 16 13.5 12.8 39.5 Embodiment 17 13.9 13.2 41.6 Embodiment 18 13.6 12.9 40.2 Embodiment 19 13.5 12.8 39.8 Embodiment 20 13.8 13.5 41.7 Comparative Example 1 13.2 12.6 39.2 Comparative Example 2 13.1 12.0 38.5 Comparative Example 3 13.2 12.2 38.9

[0174] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0175] By comparing Examples 1 to 3 and Comparative Example 1, it can be seen that compared with other methods, the preparation method of the anisotropic bonded magnetic material provided by the present application can obtain an anisotropic bonded magnetic material having a composition shown in formula (I), an average roundness ≥0.8, and a shape closer to a sphere, thereby improving the fluidity of the anisotropic bonded magnetic material; at the same time, the anisotropic bonded magnetic material with higher roundness has fewer surface defects, better consistency of grain orientation, and is not easy to stick together. It can also reduce the orientation deviation caused by adhesion between magnetic materials, further improve the consistency of grain orientation, thereby improving the magnetic properties of the anisotropic magnetic material such as remanence, coercive force and magnetic energy product.

[0176] By comparing Examples 1 to 3 and Comparative Example 2, it can be seen that the grinding treatment of the pre-product in step (8) can obtain an anisotropic bonded magnetic material with a shape closer to a sphere, thereby improving the fluidity of the anisotropic bonded magnetic material, reducing its surface defects, and improving the consistency of grain orientation, thereby significantly improving the intrinsic coercive force of the anisotropic magnetic material, and improving its magnetic properties such as remanence and magnetic energy product.

[0177] Comparison of Examples 1 to 3 and Comparative Example 3 shows that the second hydrogen crushing product is polished in step (5) to obtain D 90The first grinding treatment product is smaller, thereby improving the efficiency of subsequent heat treatment and cooling treatment, obtaining anisotropic bonded magnetic materials with higher roundness, improving the fluidity of anisotropic bonded magnetic materials, reducing their surface defects, and improving the consistency of grain orientation, thereby significantly improving the intrinsic coercive force of the anisotropic magnetic materials, and improving their magnetic properties such as remanence and magnetic energy product.

[0178] By comparing Examples 1, 4 to 6, it can be seen that, compared with other ranges, limiting the process parameters in the first hydrogen crushing treatment and the gas flow rate and grinding time of the grinding gas in the third grinding within the above-mentioned range of the present application is beneficial to refining the size of the first hydrogen crushing product, facilitating subsequent processing, thereby helping to improve the roundness and fluidity of the anisotropic bonded magnetic material, and further helping to improve the magnetic properties of the anisotropic bonded magnetic material, such as the remanence, coercive force and magnetic energy product.

[0179] By comparing Examples 1, 7 and 8, it can be seen that, compared with other ranges, limiting the process parameters in the second hydrogen crushing treatment within the above-mentioned range of the present application is beneficial to refining the grain size of the second hydrogen crushing product, facilitating subsequent processing, thereby helping to improve the roundness and fluidity of the anisotropic bonded magnetic material, and further helping to improve the magnetic properties of the anisotropic bonded magnetic material, such as remanence, coercive force and magnetic energy product.

[0180] By comparing Examples 1, 9 and 10, it can be seen that, compared with other ranges, limiting the gas flow rate of the grinding gas and the grinding time in the first grinding to the above-mentioned range of the present application is beneficial to improving the effect of the first grinding treatment, removing the sharp edges and corners on the surface of the second hydrogen crushing product, eliminating its surface defects, and at the same time improving the efficiency of subsequent heat treatment and cooling treatment, thereby improving the roundness and fluidity of the anisotropic bonded magnetic material, and further improving the magnetic properties of the anisotropic bonded magnetic material, such as the remanence, coercive force and magnetic energy product.

[0181] By comparing Examples 1 and 11 to 13, it can be seen that, compared with other ranges, limiting the process parameters of each stage in the HDDR treatment within the above-mentioned range of the present application is beneficial to improving the treatment effect of HDDR, improving the grain structure of the first hydrogen crushing product, and improving the consistency of its grain orientation, thereby helping to improve the remanence and magnetic energy product of the anisotropic bonded magnetic material.

[0182] By comparing Examples 1 and 14 to 16, it can be seen that, compared with other ranges, limiting the temperature and time of the heat treatment within the above-mentioned range of the present application is beneficial to promoting the fusion between the HDDR magnetic material and the first polishing treatment product, is beneficial to obtaining a pre-product having the composition shown in formula (I), is beneficial to inhibiting the excessive growth of grains, and improving their uniformity, thereby helping to improve the stability of the anisotropic bonded magnetic material and its magnetic properties such as remanence, coercive force and magnetic energy product.

[0183] By comparing Examples 1 and 17 to 19, it can be seen that, compared with other ranges, limiting the gas flow rate of the grinding gas and the grinding time in the second grinding within the above-mentioned range of the present application is beneficial to improving the effect of the second grinding treatment, removing sharp edges and corners on the surface of the pre-product, and eliminating its surface defects, thereby helping to improve the roundness and fluidity of the anisotropic bonded magnetic material, and further helping to improve the magnetic properties of the anisotropic bonded magnetic material, such as remanence, coercive force and magnetic energy product.

[0184] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those described herein, for example.

[0185] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An anisotropic bonded magnetic material, characterized in that: The anisotropic bonded magnetic material comprises the components shown in formula (I), Re 1 x1 Re 2 y1 T m1 Fe 100-x1-y1-z1-m1 B z1 (I), where Re 1 Selected from Nd, or Pr and Nd, Re 2 One or more selected from the group consisting of La, Ce, Dy and Tb, T selected from one or more transition metal elements, 27.5≤x1≤40, 0≤y1≤12, 0.95≤z1≤1.05, 0≤m1≤12, and the y1 and the m1 are not 0 at the same time; the average roundness of the anisotropic bonded magnetic material is ≥0.

8.

2. The anisotropic bonded magnetic material according to claim 1, characterized in that: The anisotropic bonded magnetic material is in granular form, and its average sphericity is ≥ 0.5, preferably 0.65 to 0.80; Preferably, the D of the anisotropic bonded magnetic material 50 80~120μm; Preferably, the average aspect ratio of the anisotropic bonded magnetic material is ≥0.75; Preferably, the average surface ratio of the anisotropic bonded magnetic material is ≤1.35, preferably 1 to 1.

35.

3. The anisotropic bonded magnetic material according to claim 1 or 2, characterized in that: The T is selected from one or more of the group consisting of Co, Zr, Cu, Y, Nb and Zn; Preferably, in the formula (I), x1 is 27.5 to 30.5, y1 is 0.1 to 2.5, z1 is 0.98 to 1.05, and m1 is 3 to 6; Preferably, the anisotropic bonded magnetic material comprises orderly arranged grains, and the ratio of the average grain size of each grain is (0.85-1.25):1; More preferably, in the anisotropic bonded magnetic material, the angle between the easy magnetization axes of the grains is ≤10°.

4. The anisotropic bonded magnetic material according to any one of claims 1 to 3, characterized in that: The anisotropic bonded magnetic material comprises, from the inside to the outside, a core and a coating layer arranged on the surface of the core, the core has a composition represented by formula (I), and the material of the coating layer is a phosphorus-containing compound; Preferably, the coating layer has a thickness of 10 to 150 nm; Preferably, the volume ratio of the core to the coating layer is (1-150):(1-2); Preferably, the phosphorus-containing compound is selected from phosphoric acid and / or phosphates, and more preferably, the phosphates are selected from manganese phosphates and / or zinc phosphates.

5. A method for preparing the anisotropic bonded magnetic material according to any one of claims 1 to 4, characterized in that: The preparation method comprises: Step S1, performing a first hydrogen crushing treatment on the alloy casting in an oxygen-free environment to obtain a first hydrogen crushing product, wherein the alloy casting has a composition shown in formula (II), Re 1 x2 T m2 Fe 100-x2-z2-m2 B z2 (II), where 27.5≤x2≤30.5, 0.95≤z2≤1.05, 0≤m2≤15; Step S2, performing a second hydrogen crushing treatment on the alloy ingot in an oxygen-free environment to obtain a second hydrogen crushing product, wherein the alloy ingot has a composition shown in formula (III), Re 1 x3 Re 2 y2 T 100-x3-y2 (III), where 70≤x3≤95, 0≤ y2≤20; y2 and m2 are not 0 at the same time; Step S3, performing a first polishing treatment on the second hydrogen crushing product to obtain a first polishing treatment product; Step S4, performing HDDR treatment on the first hydrogen fragmentation product in an oxygen-free environment to obtain an HDDR magnetic material; Step S5, mixing the HDDR magnetic material with the first polishing product, and sequentially performing heat treatment and cooling treatment to obtain a pre-product; the weight ratio of the HDDR magnetic material to the first polishing product is (85-100):(0.1-15); Step S6, performing a second grinding process on the pre-product to obtain the anisotropic bonded magnetic material.

6. The method for preparing anisotropic bonded magnetic material according to claim 5, characterized in that: In the formula (II), x2 is 27.5 to 29.5, z2 is 0.98 to 1.05, and m2 is 0 to 9; Preferably, in the formula (III), x3 is 50 to 80, and y2 is 0.5 to 20; Preferably, between step S1 and step S2, the first hydrogen-crushed product is further subjected to a third grinding treatment to obtain a hydrogen-crushed magnetic material; Preferably, the hydrogen crushing magnetic material D 50 60~100μm; Preferably, the first grinding process, the second grinding process and the third grinding process are performed by grinding, air flow grinding, stirring or extrusion; More preferably, the first grinding process, the second grinding process and the third grinding process are each independently selected from ball milling or jet milling; More preferably, air flow milling is used for the first grinding treatment, the second grinding treatment and the third grinding treatment. In the first grinding treatment, the grinding gas is selected from nitrogen and / or argon, the gas pressure is 300-500 kPa, the gas flow rate is 400-500 m / s, and the grinding time is 30-180 min. In the second grinding treatment and the third grinding treatment, the grinding gas is independently selected from nitrogen and / or argon, the gas pressure is independently 100-200 kPa, the gas flow rate is independently 10-200 m / s, and the grinding time is independently 0.5-30 min.

7. The method for preparing anisotropic bonded magnetic material according to claim 5 or 6, characterized in that: In step S1, the first hydrogen crushing treatment includes a first hydrogen absorption crushing stage and a first hydrogen discharge stage, wherein the temperature of the first hydrogen absorption crushing stage is 20-500°C, the hydrogen pressure is 90-100 kPa, and the time is 30-400 min, and the temperature of the first hydrogen discharge stage is 20-500°C, and the time is 10-200 min; Preferably, in step S2, the second hydrogen crushing treatment includes a second hydrogen absorption crushing stage and a second hydrogen discharge stage, wherein the temperature of the second hydrogen absorption crushing stage is 20-650°C, the hydrogen pressure is 90-100 kPa, and the time is 20-720 min, and the temperature of the second hydrogen discharge stage is 20-650°C, and the time is 10-200 min.

8. The method for preparing anisotropic bonded magnetic material according to any one of claims 5 to 7, characterized in that: In step S3, the D 90 ≤10μm, preferably 3-5μm.

9. The method for preparing anisotropic bonded magnetic material according to claim 8, characterized in that: In step S4, the HDDR treatment includes a hydrogen absorption disproportionation stage and a dehydrogenation and recombination stage, wherein the temperature of the hydrogen absorption disproportionation stage is 790-845°C, the hydrogen pressure is 29-50 kPa, and the time is 90-205 min; the dehydrogenation and recombination stage includes a first dehydrogenation stage and a second dehydrogenation stage, wherein the temperature of the first dehydrogenation stage is 810-875°C, the hydrogen pressure is 500-5000 Pa, and the time is 5-60 min, and the temperature of the second dehydrogenation stage is 810-875°C, the hydrogen pressure is 0.1-5 Pa, and the time is 60-90 min; Preferably, in step S5, the heat treatment temperature is 780-820°C and the time is 30-120 min; Preferably, in step S5, the cooling rate of the cooling treatment is 5-15°C / s.

10. The method for preparing anisotropic bonded magnetic material according to claim 5, characterized in that: The step S6 comprises: performing the second grinding treatment on the pre-product to obtain a second grinding treatment product, performing a surface coating treatment on the second grinding treatment product to obtain the anisotropic bonded magnetic material, wherein the anisotropic bonded magnetic material comprises, from the inside to the outside, a core and a coating layer arranged on the surface of the core, the core has a composition shown in formula (I), and the material of the coating layer is a phosphorus-containing compound; Preferably, the surface coating treatment comprises: mixing a phosphorus-containing precursor with a solvent to obtain a mixed solution; immersing the second polishing treatment product in the mixed solution, and obtaining the anisotropic bonded magnetic material after drying; Preferably, the weight ratio of the second polishing product to the phosphorus-containing precursor is (900-1000):(1-9); Preferably, in the mixed solution, the weight percentage of the phosphorus-containing precursor is 10-20wt%; Preferably, the drying process is carried out at a temperature of 30 to 45°C and for a time of 30 to 90 minutes; Preferably, the phosphorus-containing precursor is selected from phosphoric acid and / or phosphates, and more preferably, the phosphate is selected from manganese phosphates and / or zinc phosphates; Preferably, the solvent is selected from acetone and / or ethanol.

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