A high magnetic energy product hot pressed magnet and preparation method thereof

Abstract

The invention relates to the preparation field of hot pressed magnets, and specifically provides a high magnetic energy product hot pressed magnet and a preparation method. The hot pressed magnet is mainly prepared using neodymium iron boron magnetic powder and flaky metal soft magnetic powder as magnetic powder raw materials, wherein the flaky metal soft magnetic powder is at least one of carbonyl iron powder, iron nickel powder and iron cobalt powder; by targetedly adjusting the added weight of the flaky metal soft magnetic powder and the microscopic physical properties of the flaky metal soft magnetic powder, the remanence and maximum magnetic energy product of the prepared hot pressed magnet can be greatly improved, and the coercive force is still maintained at a high level, achieving unexpected technical effects; the preparation process is simple to operate, easy to control, low in cost, and easy to promote in industry.

Description

Technical Field

[0001] The invention relates to the field of preparation of hot pressed magnets, and in particular to a high magnetic energy product hot pressed magnet and a preparation method thereof. Background Art

[0002] At present, the maximum magnetic energy product of hot-deformed NdFeB magnets is still far from the theoretical value, which cannot meet the market demand for high-performance hot-deformed NdFeB magnets. The content and distribution of rare earth-rich phases in hot-deformed NdFeB magnets have an important influence on the magnetic properties and forming properties of the magnets. Too high a rare earth content will lead to an increase in the content of intergranular rare earth-rich phases in the magnet, causing abnormal growth of grains during hot pressing and hot deformation. At the same time, too much non-magnetic phase in the magnet has an adverse effect on the maximum magnetic energy product of the magnet; but if the rare earth content is too low, it will be unfavorable for the deformation orientation of the magnet grains, resulting in a low orientation degree of the magnet, and the maximum magnetic energy product of the magnet will also decrease.

[0003] At present, the commonly used preparation methods of hot-deformed NdFeB magnets are: (1) compounding soft magnetic materials and permanent magnetic materials, such as coating, electroplating or chemically plating soft magnetic materials on the surface of NdFeB magnetic powder; (2) adding high melting point materials such as BN, WC, etc. to the surface of magnetic powder or magnetic powder by physical and chemical methods. However, the methods of surface coating, electroplating or chemically plating soft magnetic materials, or adding some high melting point materials to the surface of magnetic powder or magnetic powder by physical and chemical methods have limited effect on improving the remanence and magnetic energy product of hot-deformed NdFeB magnets, and have the problems of complex process steps, low efficiency and high cost, which are not suitable for industrial mass production. Summary of the invention

[0004] The purpose of the present invention is to provide a high magnetic energy product hot-pressed magnet and a preparation method thereof, in view of the problems that the preparation of hot-deformed NdFeB magnets in the prior art has low magnetic energy product or complex process, low production efficiency and high cost. The magnet is mainly prepared using NdFeB magnetic powder and flaky metal soft magnetic powder as magnetic powder raw materials, wherein the flaky metal soft magnetic powder is at least one of carbonyl iron powder, iron-nickel powder and iron-cobalt powder; the maximum magnetic energy product of the prepared hot-pressed magnet is greatly improved by targeted adjustment of the added weight of the flaky metal soft magnetic powder and the microscopic physical properties of the flaky metal soft magnetic powder, and the present application mainly improves the magnetic properties by adding flaky metal soft magnetic powder, the preparation process is simple, the cost is low, and it is convenient for industrial promotion.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A high magnetic energy product hot-pressed magnet, comprising NdFeB magnetic powder and flaky metal soft magnetic powder.

[0007] Wherein, the flaky metal soft magnetic powder is at least one of carbonyl iron powder, iron-nickel powder and iron-cobalt powder;

[0008] The added weight of the flake metal soft magnetic powder accounts for 0.1% to 4% of the total weight of the mixed magnetic powder;

[0009] The flake thickness of the flaky metal soft magnetic powder is ≤800nm, and the flatness of at least 90% of the flaky metal soft magnetic powder is ≥3.5.

[0010] The present application provides a high magnetic energy product hot-pressed magnet, which is mainly prepared using neodymium iron boron magnetic powder and flaky metal soft magnetic powder as magnetic powder raw materials, wherein the flaky metal soft magnetic powder is at least one of carbonyl iron powder, iron nickel powder and iron cobalt powder; by targeted adjustment of the added weight of the flaky metal soft magnetic powder and the microscopic physical properties of the flaky metal soft magnetic powder, the maximum magnetic energy product of the prepared hot-pressed magnet is greatly improved, achieving unexpected technical effects.

[0011] Specifically, (1) the metal soft magnetic powder of the present application is in the form of flakes, and its shape characteristics are compared with conventional spherical carbonyl iron powder, aerosolized powder and other spherical powders. On the one hand, it is easier to adhere to the surface of the rapidly quenched magnetic powder during mixing, and on the other hand, due to its larger specific surface area, it is easier to participate in material exchange during the subsequent thermal deformation process; (2) The flake metal soft magnetic powder has the characteristics of high saturation magnetization, so that the magnet can use the coupling effect between strong magnetism and weak magnetism to improve the magnetic properties; (3) The high melting point characteristics of the flake metal soft magnetic powder can effectively inhibit the abnormal growth of grains in the magnet; (4) The flake metal soft magnetic powder can effectively regulate the distribution of the rare earth-rich phase in the magnet. Through the combined effect of the above points, the remanence and maximum magnetic energy product of the hot-deformed NdFeB magnet can be greatly improved, and the coercive force is still maintained at a high level. In addition, the process of mixing and adding flake metal soft magnetic powder is simple, the addition amount is easy to control, and it is easier to be widely used in industrial production.

[0012] Furthermore, the composition and content of NdFeB magnetic powder are expressed by the formula: RE x Fe 100-x-y-z M y B z , wherein RE is at least one of La, Ce, Pr, Nd, Gd, Tb, Dy and Ho, M is at least one of Co, Cu, Al, Ga and Zr, 20≤x≤40, 0≤y≤10, 0.7≤z≤1.5.

[0013] Preferably, RE is Nd, and M is Co and Ga.

[0014] Furthermore, the flaky metal soft magnetic powder contains ≥95 wt.%. Too low Fe content in the flaky metal soft magnetic powder will affect the magnetic properties of the prepared hot-pressed magnet. If the magnetic powder is oxidized, the iron content will decrease.

[0015] Preferably, the flaky metal soft magnetic powder is carbonyl iron powder.

[0016] Furthermore, the added weight of the flaky metal soft magnetic powder accounts for 0.2% to 2% of the total weight of the mixed magnetic powder. Through a large number of experimental studies, the inventors found that the addition amount of the flaky metal soft magnetic powder is a key factor affecting the magnetic properties of the hot-pressed magnet. If the addition amount is too large or too small, the maximum magnetic energy product of the prepared hot-pressed magnet cannot be significantly improved. Preferably, the added weight of the flaky metal soft magnetic powder accounts for 0.2% to 0.8% of the total weight of the mixed magnetic powder.

[0017] Furthermore, the thickness of the flaky metal soft magnetic powder is 400nm to 800nm, and at least 90% of the flaky metal soft magnetic powder has a flatness of 3.5 to 6. The inventors have found through research that the thickness and flatness control of the flaky metal soft magnetic powder are closely related to the expression of the magnetic properties of the hot-pressed magnet. If the ratio is large, the metal soft magnetic powder is prone to curling, which may increase the agglomeration of the flaky metal soft magnetic powder to a certain extent. If the ratio is too small, it will increase the distance that the metal soft magnetic powder diffuses into the interior of the grain, affecting the reaction and resulting in lower magnetic properties of the hot-pressed magnet.

[0018] Another object of the present invention is to provide a method for preparing the hot-pressed magnet.

[0019] A method for preparing the above-mentioned high magnetic energy product hot-pressed magnet comprises the following steps:

[0020] Step 1, mixing NdFeB magnetic powder and flaky metal soft magnetic powder evenly to obtain mixed magnetic powder;

[0021] Step 2, hot pressing the mixed magnetic powder to obtain an isotropic hot pressed magnetic blank;

[0022] Step 3: subjecting the isotropic hot-pressed magnetic blank to thermal deformation to obtain a high magnetic energy product hot-pressed magnet.

[0023] The method for preparing a high magnetic energy product hot-pressed magnet provided in the present application first mixes all magnetic powders, and then sequentially performs hot pressing and thermal deformation treatments to prepare a hot-pressed material. The method is simple to operate, easy to control, low in cost, high in preparation efficiency, and easy to promote in industry.

[0024] Furthermore, in step 2, the temperature of hot pressing is 550°C to 750°C, and the density of the magnetic blank reaches more than 98% of the theoretical density.

[0025] Furthermore, in step 3, the thermal deformation temperature is 650°C to 780°C, and the deformation rate is less than 4×10 -2 s -1 , deformation ≥70%.

[0026] Furthermore, in step 3, the deformation rate is 1×10 -2 s -1 ~3×10-2 s -1 The study found that if the deformation rate is too high, it may affect the quality of grain formation, fail to reach the expected state, and affect the magnetic properties of the hot-pressed magnet.

[0027] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0028] 1. The present application provides a high magnetic energy product hot-pressed magnet, which is mainly prepared by using NdFeB magnetic powder and flaky metal soft magnetic powder as magnetic powder raw materials, wherein the flaky metal soft magnetic powder is at least one of carbonyl iron powder, iron nickel powder and iron cobalt powder; by specifically adjusting the added weight of the flaky metal soft magnetic powder and the microscopic physical properties of the flaky metal soft magnetic powder, the remanence and maximum magnetic energy product of the prepared hot-pressed magnet can be greatly improved, (BH) max It can reach above 52 MGOe, and the coercivity is still maintained at a high level, achieving unexpected technical results.

[0029] 2. The method for preparing the high magnetic energy product hot-pressed magnet provided in the present application is to first mix all the magnetic powders, and then perform hot pressing molding and thermal deformation treatment in sequence to prepare the hot-pressed material. The method is simple to operate, easy to control, low in cost, high in preparation efficiency, and easy to promote in industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a scanning electron microscope image of the hot-pressed magnet of Example 1.

[0031] Figure 2 The X-ray diffraction patterns of Example 1 (a) and Comparative Example 1 (b) are shown.

[0032] Figure 3 This is the demagnetization curve of the magnet in Example 1. DETAILED DESCRIPTION

[0033] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0034] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0035] Example 1

[0036] Preparation of hot pressed magnets

[0037] Raw material preparation: 99.5 parts of NdFeB magnetic powder; 0.5 parts of flaky metal soft magnetic powder.

[0038] Among them, the formula of NdFeB magnetic powder according to its composition and mass content is: Nd 29.4Fe bal Co 3.9 Ga 0.46 B 0.92 .

[0039] The flaky metal soft magnetic powder is carbonyl iron powder, the thickness of the flaky metal soft magnetic powder is 400nm~800nm, and more than 90% of the flaky metal soft magnetic powder has a flatness of 4.5±0.2.

[0040] Step 1, mixing NdFeB magnetic powder and flaky metal soft magnetic powder evenly to obtain mixed magnetic powder;

[0041] Step 2, hot pressing the mixed magnetic powder, the hot pressing temperature is 650°C, the density of the magnetic blank reaches more than 98% of the theoretical density, and an isotropic hot pressed magnetic blank is obtained;

[0042] Step 3: The isotropic hot pressed magnetic blank is subjected to thermal deformation treatment, the thermal deformation temperature is 750°C, and the deformation rate is 3×10 -2 s -1 , the deformation amount is 70%, and a hot pressed magnet is obtained.

[0043] Example 2

[0044] Preparation of hot pressed magnets

[0045] Raw material preparation: 99.8 parts of NdFeB magnetic powder; 0.2 parts of flaky metal soft magnetic powder.

[0046] Among them, the formula of NdFeB magnetic powder according to its composition and mass content is: Nd 29.4 Fe bal Co 3.9 Ga 0.46 B 0.92

[0047] The flaky metal soft magnetic powder is carbonyl iron powder, the thickness of the flaky metal soft magnetic powder is 400nm~800nm, and more than 90% of the flaky metal soft magnetic powder has a flatness of 4.0±0.2.

[0048] Step 1, mixing NdFeB magnetic powder and flaky metal soft magnetic powder evenly to obtain mixed magnetic powder;

[0049] Step 2, hot pressing the mixed magnetic powder, the hot pressing temperature is 550°C, the density of the magnetic blank reaches more than 98% of the theoretical density, and an isotropic hot pressed magnetic blank is obtained;

[0050] Step 3: The isotropic hot pressed magnetic blank is subjected to thermal deformation treatment, the thermal deformation temperature is 650°C, and the deformation rate is 3×10 -2 s -1 , the deformation amount is 70%, and a hot pressed magnet is obtained.

[0051] Example 3

[0052] Preparation of hot pressed magnets

[0053] Raw material preparation: 98 parts of NdFeB magnetic powder; 2 parts of flaky metal soft magnetic powder.

[0054] Among them, the formula of NdFeB magnetic powder according to its composition and mass content is: Nd 29.4 Fe bal Co 3.9 Ga 0.46 B 0.92 .

[0055] The flaky metal soft magnetic powder is carbonyl iron powder, the thickness of the flaky metal soft magnetic powder is 400nm~800nm, and the flatness of more than 90% of the flaky metal soft magnetic powder is 4.5±0.2.

[0056] Step 1, mixing NdFeB magnetic powder and flaky metal soft magnetic powder evenly to obtain mixed magnetic powder;

[0057] Step 2, hot pressing the mixed magnetic powder, the hot pressing temperature is 750°C, the density of the magnetic blank reaches more than 98% of the theoretical density, and an isotropic hot pressed magnetic blank is obtained;

[0058] Step 3: The isotropic hot pressed magnetic blank is subjected to thermal deformation treatment, the thermal deformation temperature is 780°C, and the deformation rate is 1×10 -2 s -1 , the deformation amount is 70%, and a hot pressed magnet is obtained.

[0059] Example 4

[0060] Preparation of hot pressed magnets

[0061] Raw material preparation: 96 parts of NdFeB magnetic powder; 4 parts of flaky metal soft magnetic powder.

[0062] Among them, the formula of NdFeB magnetic powder according to its composition and mass content is: Nd 29.4 Fe bal Co 3.9 Ga 0.46 B 0.92 .

[0063] The flaky metal soft magnetic powder is carbonyl iron powder, the thickness of the flaky metal soft magnetic powder is 400nm~800nm, and more than 90% of the flaky metal soft magnetic powder has a flatness of 4.5±0.2.

[0064] Step 1, mixing NdFeB magnetic powder and flaky metal soft magnetic powder evenly to obtain mixed magnetic powder;

[0065] Step 2, hot pressing the mixed magnetic powder, the hot pressing temperature is 650°C, the density of the magnetic blank reaches more than 98% of the theoretical density, and an isotropic hot pressed magnetic blank is obtained;

[0066] Step 3: The isotropic hot pressed magnetic blank is subjected to thermal deformation treatment, the thermal deformation temperature is 750°C, and the deformation rate is 2×10 -2 s -1 , the deformation amount is 70%, and a hot pressed magnet is obtained.

[0067] Example 5

[0068] Preparation of hot pressed magnets

[0069] Raw material preparation: 99.5 parts of NdFeB magnetic powder; 0.5 parts of flaky metal soft magnetic powder.

[0070] Among them, the formula of NdFeB magnetic powder according to its composition and mass content is: Nd 29.4 Fe bal Co 3.9 Ga 0.46 B 0.92 .

[0071] The flaky metal soft magnetic powder is carbonyl iron powder, the thickness of the flaky metal soft magnetic powder is 400nm~800nm, and more than 90% of the flaky metal soft magnetic powder has a flatness of 5.5±0.2.

[0072] Step 1, mixing NdFeB magnetic powder and flaky metal soft magnetic powder evenly to obtain mixed magnetic powder;

[0073] Step 2, hot pressing the mixed magnetic powder, the hot pressing temperature is 650°C, the density of the magnetic blank reaches more than 98% of the theoretical density, and an isotropic hot pressed magnetic blank is obtained;

[0074] Step 3: The isotropic hot pressed magnetic blank is subjected to thermal deformation treatment, the thermal deformation temperature is 750°C, and the deformation rate is 3×10 -2 s -1 , the deformation amount is 70%, and a hot pressed magnet is obtained.

[0075] Example 6

[0076] Preparation of hot pressed magnets

[0077] Raw material preparation: 99.5 parts of NdFeB magnetic powder; 0.5 parts of flaky metal soft magnetic powder.

[0078] Among them, the formula of NdFeB magnetic powder according to its composition and mass content is: Nd 29.4 Fe bal Co 3.9 Ga 0.46 B 0.92 .

[0079] The flaky metal soft magnetic powder is iron-cobalt powder, the flake thickness of the flaky metal soft magnetic powder is 600±20 nm, and the flatness of 90%±0.5% of the flaky metal soft magnetic powder is 4.5±0.2.

[0080] Step 1, mixing NdFeB magnetic powder and flaky metal soft magnetic powder evenly to obtain mixed magnetic powder;

[0081] Step 2, hot pressing the mixed magnetic powder, the hot pressing temperature is 650°C, the density of the magnetic blank reaches more than 98% of the theoretical density, and an isotropic hot pressed magnetic blank is obtained;

[0082] Step 3: The isotropic hot pressed magnetic blank is subjected to thermal deformation treatment, the thermal deformation temperature is 750°C, and the deformation rate is 3×10 -2 s -1 , the deformation amount is 70%, and a hot pressed magnet is obtained.

[0083] Comparative Example 1

[0084] Comparative Example 1 Compared with Example 1, no flaky metal soft magnetic powder was added, and the specific preparation process was as follows:

[0085] Preparation of hot pressed magnets

[0086] Raw material preparation: NdFeB magnetic powder. The composition and mass content of NdFeB magnetic powder are expressed by the formula: Nd 29.4 Fe bal Co 3.9 Ga 0.46 B 0.92 .

[0087] Step 1, hot pressing the NdFeB magnetic powder, the hot pressing temperature is 650°C, the density of the magnetic blank reaches more than 98% of the theoretical density, and an isotropic hot pressed magnetic blank is obtained;

[0088] Step 2: subject the isotropic hot pressed magnetic blank to thermal deformation treatment, with the thermal deformation temperature being 750°C and the deformation rate being 3×10 -2 s -1 , the deformation amount is 70%, and a hot pressed magnet is obtained.

[0089] Comparative Example 2

[0090] Comparative Example 2 Compared with Example 1, the flaky metal soft magnetic powder is changed to spherical metal soft magnetic powder. The specific preparation process is as follows:

[0091] Preparation of hot pressed magnets

[0092] Raw material preparation: 99.5 parts of NdFeB magnetic powder; 0.5 parts of spherical metal soft magnetic powder.

[0093] Among them, the formula of NdFeB magnetic powder according to its composition and mass content is: Nd 29.4 Fe bal Co 3.9 Ga 0.46 B 0.92 .

[0094] Step 1, mixing NdFeB magnetic powder and spherical metal soft magnetic powder evenly to obtain mixed magnetic powder;

[0095] Step 2, hot pressing the mixed magnetic powder, the hot pressing temperature is 650°C, the density of the magnetic blank reaches more than 98% of the theoretical density, and an isotropic hot pressed magnetic blank is obtained;

[0096] Step 3: The isotropic hot pressed magnetic blank is subjected to thermal deformation treatment, the thermal deformation temperature is 750°C, and the deformation rate is 3×10 -2 s -1 , the deformation amount is 70%, and a hot pressed magnet is obtained.

[0097] Comparative Example 3

[0098] Comparative Example 3 Compared with Example 1, the addition ratio of the flaky metal soft magnetic powder is changed, and the specific preparation process is as follows:

[0099] Preparation of hot pressed magnets

[0100] Raw material preparation: 95 parts of NdFeB magnetic powder; 5 parts of flaky metal soft magnetic powder.

[0101] Among them, the formula of NdFeB magnetic powder according to its composition and mass content is: Nd 29.4 Fe bal Co 3.9 Ga 0.46 B 0.92 .

[0102] The flaky metal soft magnetic powder is carbonyl iron powder, the flake thickness of the flaky metal soft magnetic powder is 600±20nm, and the flatness of 90%±0.5% of the flaky metal soft magnetic powder is 4.5±0.2.

[0103] Step 1, mixing NdFeB magnetic powder and flaky metal soft magnetic powder evenly to obtain mixed magnetic powder;

[0104] Step 2, hot pressing the mixed magnetic powder, the hot pressing temperature is 650°C, the density of the magnetic blank reaches more than 98% of the theoretical density, and an isotropic hot pressed magnetic blank is obtained;

[0105] Step 3: The isotropic hot pressed magnetic blank is subjected to thermal deformation treatment, the thermal deformation temperature is 750°C, and the deformation rate is 3×10 -2 s -1 , the deformation amount is 70%, and a hot pressed magnet is obtained.

[0106] Comparative Example 4

[0107] Compared with Example 1, Comparative Example 4 changes the thickness of the flaky metal soft magnetic powder, and the specific preparation process is as follows:

[0108] Preparation of hot pressed magnets

[0109] Raw material preparation: 99.5 parts of NdFeB magnetic powder; 0.5 parts of flaky metal soft magnetic powder.

[0110] Among them, the formula of NdFeB magnetic powder according to its composition and mass content is: Nd 29.4 Fe bal Co 3.9 Ga 0.46 B 0.92 .

[0111] The flaky metal soft magnetic powder is carbonyl iron powder, the thickness of the flaky metal soft magnetic powder is 1200±50nm, and the flatness of 95%±0.5% of the flaky metal soft magnetic powder is 4.5±0.2.

[0112] Step 1, mixing NdFeB magnetic powder and flaky metal soft magnetic powder evenly to obtain mixed magnetic powder;

[0113] Step 2, hot pressing the mixed magnetic powder, the hot pressing temperature is 650°C, the density of the magnetic blank reaches more than 98% of the theoretical density, and an isotropic hot pressed magnetic blank is obtained;

[0114] Step 3: The isotropic hot pressed magnetic blank is subjected to thermal deformation treatment, the thermal deformation temperature is 750°C, and the deformation rate is 3×10 -2 s -1 , the deformation amount is 70%, and a hot pressed magnet is obtained.

[0115] Comparative Example 5

[0116] Compared with Example 1, Comparative Example 5 changes the deformation rate during the thermal deformation treatment, and the specific preparation process is as follows:

[0117] Preparation of hot pressed magnets

[0118] Raw material preparation: 99.5 parts of NdFeB magnetic powder; 0.5 parts of flaky metal soft magnetic powder.

[0119] Among them, the formula of NdFeB magnetic powder according to its composition and mass content is: Nd 29.4 Fe bal Co 3.9 Ga 0.46 B 0.92 .

[0120] The flaky metal soft magnetic powder is carbonyl iron powder, the flake thickness of the flaky metal soft magnetic powder is 600±20nm, and the flatness of 95%±0.5% of the flaky metal soft magnetic powder is 4.5±0.2.

[0121] Step 1, mixing NdFeB magnetic powder and flaky metal soft magnetic powder evenly to obtain mixed magnetic powder;

[0122] Step 2, hot pressing the mixed magnetic powder, the hot pressing temperature is 650°C, the density of the magnetic blank reaches more than 98% of the theoretical density, and an isotropic hot pressed magnetic blank is obtained;

[0123] Step 3: The isotropic hot pressed magnetic blank is subjected to thermal deformation treatment, the thermal deformation temperature is 750℃, and the deformation rate is 6×10 -2 s -1 , the deformation amount is 70%, and a hot pressed magnet is obtained.

[0124] The obtained hot pressed magnet samples were tested and the remanence (B r ), magnetic coercivity (H cb ), intrinsic coercivity (H cj ) and the maximum magnetic energy product ((BH) max )See Table 1.

[0125] Table 1 Remanence (B r ), magnetic coercivity (H cb ), intrinsic coercivity (H cj ) and the maximum magnetic energy product ((BH) max )Test Results

[0126]

[0127] It can be seen from Table 1 that the maximum magnetic energy product (BH) of the intrinsic coercive force of the high magnetic energy product hot-pressed magnet obtained in Example 1 is max ) is greater than 52MGOe, and the coercive force is maintained at a high level, i.e., greater than 12kOe. Compared with the rare earth permanent magnets prepared in the control examples 1-4 without adding flaky metal soft magnetic powder or metal soft magnetic powder of other shapes or sizes, the magnetic energy product of the embodiment 1 is significantly improved.

[0128] The present application provides a high magnetic energy product hot-pressed magnet, which is mainly prepared by using NdFeB magnetic powder and flaky metal soft magnetic powder as magnetic powder raw materials, wherein the flaky metal soft magnetic powder is at least one of carbonyl iron powder, iron nickel powder and iron cobalt powder; by specifically adjusting the added weight of the flaky metal soft magnetic powder and the microscopic physical properties of the flaky metal soft magnetic powder, the remanence and maximum magnetic energy product of the prepared hot-pressed magnet can be greatly improved, (BH) max It can reach above 52 MGOe, and the coercivity is still maintained at a high level, achieving unexpected technical results.

[0129] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high magnetic energy product hot pressed magnet, characterized in that: It is made of NdFeB magnetic powder and flaky metal soft magnetic powder. Wherein, the flaky metal soft magnetic powder is at least one of carbonyl iron powder, iron-nickel powder and iron-cobalt powder, and the flaky metal soft magnetic powder contains Fe ≥ 95 wt.%; The added weight of the flake metal soft magnetic powder accounts for 0.1% to 4% of the total weight of the mixed magnetic powder; The flake thickness of the flaky metal soft magnetic powder is 400nm to 800nm, and at least 90% of the flaky metal soft magnetic powder has a flatness ratio of 3.5 to 6; The hot pressed magnet can improve the remanence and the maximum magnetic energy product while maintaining the coercive force. The preparation method of the hot pressed magnet comprises the following steps: Step 1, mixing NdFeB magnetic powder and flaky metal soft magnetic powder evenly to obtain mixed magnetic powder; Step 2, hot pressing the mixed magnetic powder to obtain an isotropic hot pressed magnetic blank; Step 3: subjecting the isotropic hot-pressed magnetic blank to thermal deformation to obtain a high magnetic energy product hot-pressed magnet.

2. The high magnetic energy product hot-pressed magnet according to claim 1, characterized in that: The composition and content of NdFeB magnetic powder are expressed by the formula: RE x Fe 100-x-y-z M y B z , wherein RE is at least one of La, Ce, Pr, Nd, Gd, Tb, Dy and Ho, M is at least one of Co, Cu, Al, Ga and Zr, 20≤x≤40, 0≤y≤10, 0.7≤z≤1.

5.

3. The high magnetic energy product hot-pressed magnet according to claim 2, characterized in that: RE is Nd, and M is Co and Ga.

4. The high magnetic energy product hot-pressed magnet according to claim 1, characterized in that: The added weight of the flaky metal soft magnetic powder accounts for 0.2% to 2% of the total weight of the mixed magnetic powder.

5. The high magnetic energy product hot-pressed magnet according to claim 1, characterized in that: In the step 2, the temperature of hot pressing is 550°C to 750°C, and the density of the magnetic blank reaches more than 98% of the theoretical density.

6. The high magnetic energy product hot pressed magnet according to claim 1, characterized in that: In step 3, the thermal deformation temperature is 650°C to 780°C, and the deformation rate is less than 4×10 -2 s -1 , deformation ≥70%.

7. The high magnetic energy product hot-pressed magnet according to claim 6, characterized in that: In step 3, the deformation rate is 1×10 -2 s -1 ~3×10 -2 s -1 .

Images