A method for preparing a magnet based on electroplated copper composite diffusion source evaporation diffusion

Abstract

The invention discloses a preparation method of a magnet based on electroplated copper composite diffusion source evaporation diffusion, the preparation method is used to prepare a magnet based on electroplated copper composite diffusion source evaporation diffusion, comprising the following steps: S1: diffusion source preparation: the diffusion source is Dy or Tb, wherein the purity of Dy and Tb is 99.5%; S2: preparation of a pre-diffused magnet substrate; S3: electroplating copper treatment: electroplating copper treatment is performed on the surface of the pre-diffused magnet substrate, wherein the electroplating anode is pure copper with a purity of 99.9%, the electroplating solution is a copper sulfate solution with a concentration of 99.9%, and the thickness of the copper plating layer is 2.5-3 μm; S4: evaporation diffusion: the pre-diffused magnet substrate treated with electroplated copper is placed in an evaporation furnace together with the diffusion source for evaporation diffusion, and after the evaporation diffusion is completed, the magnet substrate that has completed evaporation diffusion is separated from the diffusion source. The invention ensures the consistency of performance of different batches of products and reduces the material cost of the diffusion source.

Description

Technical Field

[0001] The invention relates to the technical field of magnet processing, and in particular to a method for preparing a magnet based on electroplated copper composite diffusion source evaporation diffusion. Background Art

[0002] In the current magnet processing technology, the composite diffusion source evaporation diffusion process is widely used to improve the performance of magnets. It evaporates the diffusion source and deposits it on the surface of the magnet through high temperature heating, and then diffuses into the interior of the magnet, thereby changing the performance of the magnet.

[0003] Existing composite diffusion sources are usually made by melting heavy rare earth elements and low melting point metals into alloys. However, there is a significant difference in the saturated vapor pressure of heavy rare earth elements and low melting point metal elements. Therefore, during the evaporation process, different elements have different volatilization rates, which leads to changes in the composition of the diffusion source after repeated use, resulting in differences in the performance of different batches of products.

[0004] Although the prior art has already used heavy rare earth elements and low melting point metals with similar saturated vapor pressures to melt into alloys as composite diffusion sources, which can improve the problem of the difference in saturated vapor pressure between heavy rare earth elements and low melting point metal elements to a certain extent. However, since the diffusion source is in the form of an alloy, this causes the composition of the diffusion source to fluctuate after multiple evaporation diffusions, making it impossible to ensure the stability of the performance of the subsequent batches of products, and the performance cannot be maintained consistent with that of the previous batches of products. In addition, the diffusion source in the form of an alloy needs to be scrapped after being used several times, further increasing the material cost. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing a magnet based on electroplated copper composite diffusion source evaporation diffusion, which can ensure the stability and consistency of performance of multiple batches of products, and the diffusion source can be recycled.

[0006] To achieve the above object, the solution of the present invention is: a method for preparing a magnet based on electroplated copper composite diffusion source evaporation diffusion, the preparation method is used to prepare a magnet based on electroplated copper composite diffusion source evaporation diffusion, the magnet includes the following components by mass fraction:

[0007] A: 28-34wt.%, A includes A1 and A2, A1 is Dy or Tb, and the content of A1 is 0.8-5.0wt.% of the mass fraction of the magnet; the remainder of A2 is one or more of Nd, Pr, Ho, Ga, La, Ce and Er;

[0008] B1: 0.1-4.0wt.%, B1 is one or more of Cu, Al, Zn, Mn, W and V;

[0009] B2: 0.05-3.0wt.%, B2 is one or more of Zr, Nb and Ti;

[0010] C: 0.8~2.0wt.%, C is boron element;

[0011] The remainder of the magnet is D and other unavoidable impurities, where D is Fe;

[0012] The magnet has at least one surface E, the Cu content of the surface E is higher than the average Cu content of the magnet, and within a depth range of 150 μm from the surface E to the inside of the magnet, the Cu concentration gradually decreases with increasing depth;

[0013] The surface E is a diffusion surface of the magnet, which has a layer of heavy rare earth film prepared by evaporation diffusion, and the diffusion surface forms an arbitrary angle with the orientation direction of the magnet;

[0014] The method for preparing a magnet based on electroplated copper composite diffusion source evaporation diffusion comprises the following steps:

[0015] S1: Diffusion source preparation: The diffusion source is Dy or Tb, where the purity of Dy and Tb is 99.5%;

[0016] S2: Preparation of pre-diffused magnet matrix: After the magnet components are proportioned according to the mass fraction, the magnet matrix is ​​prepared by vacuum melting to throw out SC sheets, hydrogen crushing, air flow grinding, orientation molding, isostatic pressing, vacuum sintering, and aging treatment. The NdFeB magnet matrix is ​​cut into sheet matrices of the required shape and size by machining. After surface treatment, the magnet is cleaned and dried to obtain the pre-diffused magnet matrix;

[0017] S3: Electroplating copper treatment: Electroplating copper treatment is performed on the surface of the pre-diffused magnet substrate, wherein the electroplating anode is pure copper with a purity of 99.9%, the electroplating solution is a copper sulfate solution with a concentration of 99.9%, and the thickness of the copper plating layer is 2.5-3 μm;

[0018] S4: Evaporation diffusion: The pre-diffused magnet substrate that has been subjected to copper electroplating treatment is placed in an evaporation furnace together with a diffusion source for evaporation diffusion. After the evaporation diffusion is completed, the magnet substrate that has completed evaporation diffusion is separated from the diffusion source.

[0019] Preferably, the diffusion surface is perpendicular to the orientation direction of the magnet.

[0020] Preferably, in step S3, the pre-diffused magnet substrate is chamfered before being electroplated.

[0021] Preferably, in step S3, the pre-diffused magnet substrate and accompanying plated steel beads are subjected to copper electroplating.

[0022] Preferably, in step S4, the diffusion source is in the form of chips, and the amount of diffusion source added is 40-80 kg of diffusion source per 100 kg of pre-diffused magnet matrix.

[0023] Preferably, in step S4, the evaporation furnace is cylindrical.

[0024] Preferably, in step S4, the vacuum degree of the evaporation furnace is 10 -5 ~10 -2 Pa.

[0025] Preferably, in step S4, the diffusion temperature of the evaporation furnace is 800-950° C., and the diffusion time is 5-30 hours.

[0026] Preferably, in step S4, the aging temperature of the evaporation furnace is 400-650° C., and the aging time is 4-8 hours.

[0027] Preferably, in step S4, the magnet substrate after the evaporation diffusion is separated from the diffusion source by a vibration screening machine.

[0028] After adopting the above scheme, the beneficial effects of the present invention are:

[0029] 1. The present invention adjusts the order of adding the composite diffusion source, electroplates low-melting-point metal copper on the pre-diffused magnet substrate, and uses high-purity heavy rare earth elements, thereby avoiding the problem of component segregation caused by different element volatilization rates during the use of the traditional alloy-shaped composite diffusion source, and ensuring the consistency of performance of different batches of products.

[0030] 2. The composite diffusion source of the present invention adopts the method of adding low-melting-point metals and heavy rare earth elements separately. Compared with the composite diffusion source in the form of traditional alloys, the high-purity heavy rare earth elements can be directly recycled after the completion of evaporation diffusion, which reduces losses and reduces material costs. DETAILED DESCRIPTION

[0031] The present invention will now be further described in conjunction with specific implementation methods.

[0032] The present invention provides a method for preparing a magnet based on electroplated copper composite diffusion source evaporation diffusion. The method is used to prepare a magnet based on electroplated copper composite diffusion source evaporation diffusion. The magnet includes the following components in mass fractions:

[0033] A: 28-34wt.%, A includes A1 and A2, A1 is Dy or Tb, and the content of A1 is 0.8-5.0wt.% of the mass fraction of the magnet; the remainder of A2 is one or more of Nd, Pr, Ho, Ga, La, Ce and Er;

[0034] B1: 0.1-4.0wt.%, B1 is one or more of Cu, Al, Zn, Mn, W and V;

[0035] B2: 0.05-3.0wt.%, B2 is one or more of Zr, Nb and Ti;

[0036] C: 0.8~2.0wt.%, C is boron element;

[0037] The remainder of the magnet is D and other unavoidable impurities, where D is Fe;

[0038] The magnet has at least one surface E, the Cu content of the surface E is higher than the average Cu content of the magnet, and within a depth range of 150 μm from the surface E to the inside of the magnet, the Cu concentration gradually decreases with increasing depth;

[0039] The surface E is a diffusion surface of the magnet, which has a layer of heavy rare earth film prepared by evaporation diffusion, and the diffusion surface forms an arbitrary angle with the orientation direction of the magnet;

[0040] The method for preparing a magnet based on electroplated copper composite diffusion source evaporation diffusion comprises the following steps:

[0041] S1: Diffusion source preparation: The diffusion source is Dy or Tb, where the purity of Dy and Tb is 99.5%;

[0042] S2: Preparation of pre-diffused magnet matrix: After the magnet components are proportioned according to the mass fraction, the magnet matrix is ​​prepared by vacuum melting to throw out SC sheets, hydrogen crushing, air flow grinding, orientation molding, isostatic pressing, vacuum sintering, and aging treatment. The NdFeB magnet matrix is ​​cut into sheet matrices of the required shape and size by machining. After surface treatment, the magnet is cleaned and dried to obtain the pre-diffused magnet matrix;

[0043] S3: Electroplating copper treatment: Electroplating copper treatment is performed on the surface of the pre-diffused magnet substrate, wherein the electroplating anode is pure copper with a purity of 99.9%, the electroplating solution is a copper sulfate solution with a concentration of 99.9%, and the thickness of the copper plating layer is 2.5-3 μm;

[0044] S4: Evaporation diffusion: The pre-diffused magnet substrate that has been subjected to copper electroplating treatment is placed in an evaporation furnace together with a diffusion source for evaporation diffusion. After the evaporation diffusion is completed, the magnet substrate that has completed evaporation diffusion is separated from the diffusion source.

[0045] Furthermore, the diffusion surface is perpendicular to the orientation direction of the magnet, so that during the evaporation diffusion process, the heavy rare earth elements can diffuse more effectively along the grain boundaries perpendicular to the orientation direction of the magnet, which helps to maintain the orientation of the magnet and ensure that the magnet has stable magnetic properties in application.

[0046] Furthermore, in step S3, the pre-diffused magnet substrate is chamfered before electroplating, and sharp edges of the pre-diffused magnet substrate are polished to smooth angles to avoid corner chipping and edge knocking due to collision, thereby ensuring smooth electroplating.

[0047] Furthermore, in step S3, the pre-diffused magnet substrate and the accompanying plating steel beads are subjected to copper electroplating treatment, which can effectively prevent the pre-diffused magnet substrate from stacking and ensure the effect of evaporation diffusion.

[0048] Furthermore, in step S4, the diffusion source is in the form of chips, which has a large specific surface area, which is conducive to more complete contact between the diffusion source and the pre-diffused magnet substrate during the evaporation diffusion process, thereby improving the diffusion efficiency. The chip-shaped diffusion source can be more evenly distributed on the magnet surface during the evaporation process, thereby ensuring that the distribution of the diffusion elements inside the magnet is also more even. Specifically, the amount of diffusion source added is 40-80 kg of diffusion source per 100 kg of pre-diffused magnet substrate.

[0049] Furthermore, in step S4, the evaporation furnace is cylindrical, but not limited to this. A material lifting device is provided in the evaporation furnace. During evaporation diffusion, the furnace body rotates slowly, driving the diffusion source to flip in the furnace body, which can avoid adhesion between the pre-diffusion magnet matrix and the diffusion source, is conducive to uniform distribution of heat, and improves the evaporation diffusion efficiency.

[0050] Furthermore, in step S4, the vacuum degree of the evaporation furnace is 10 -5 ~10 -2 Pa.

[0051] Furthermore, in step S4, the diffusion temperature of the evaporation furnace is 800-950° C., and the diffusion time is 5-30 hours.

[0052] Furthermore, in step S4, the aging temperature of the evaporation furnace is 400-650° C., and the aging time is 4-8 hours.

[0053] Furthermore, in step S4, the magnet substrate after the evaporation diffusion is separated from the diffusion source by a vibration screening machine, and the single substance diffusion source at the separation point can be recycled, thereby reducing material costs.

[0054] In the present invention, the evaporation and diffusion steps in the evaporation furnace are carried out simultaneously, and the heavy rare earth vapor adheres to the surface of the pre-diffused magnet substrate to form a film while diffusing into the interior of the magnet. Before the evaporation diffusion, a layer of metal copper is electroplated on the surface of the pre-diffused magnet substrate, and the metal copper can promote the formation of a continuous thin layer of grain boundary phase between the main phase grains, and increase the demagnetization coupling effect between the main phase grains; and during the diffusion, the copper element enters the grain boundary phase first, widens the diffusion channel, is beneficial to the subsequent diffusion of the heavy rare earth element, improves the diffusion rate and diffusion depth, and increases the coercive force of the magnet after diffusion.

[0055] Embodiment 1

[0056] S1: Diffusion source preparation: The diffusion source is Dy, and the purity of Dy is 99.5%;

[0057] S2: Preparation of pre-diffused magnet matrix: After the magnet components are proportioned according to the mass fraction, the magnet matrix is ​​prepared by vacuum melting to throw out SC sheets, hydrogen crushing, air flow grinding, orientation molding, isostatic pressing, vacuum sintering, and aging treatment. The NdFeB magnet matrix is ​​cut into sheet matrices of the required shape and size by machining. After surface treatment, the magnet is cleaned and dried to obtain the pre-diffused magnet matrix;

[0058] S3: Electroplating copper treatment: Electroplating copper treatment is performed on the surface of the pre-diffused magnet substrate, wherein the electroplating anode is pure copper with a purity of 99.9%, the electroplating solution is a copper sulfate solution with a concentration of 99.9%, and the thickness of the copper plating layer is 2.5-3 μm;

[0059] S4: Evaporation diffusion: The pre-diffused magnet substrate that has been subjected to copper electroplating treatment is placed in an evaporation furnace together with a diffusion source for evaporation diffusion. After the evaporation diffusion is completed, the magnet substrate that has completed evaporation diffusion is separated from the diffusion source.

[0060] Among them, the vacuum degree of the evaporation furnace is 10 -5 ~10 -2 Pa; the diffusion temperature is 800~950℃, the diffusion time is 5~30h; the aging temperature is 400~650℃, and the aging time is 4~8h.

[0061] Table 1: Comparison of residual magnetic induction intensity and coercivity of single heavy rare earth element Dy after multiple batches of evaporation diffusion in alloy form and in combination with electroplated copper

[0062]

[0063] Among them, Br represents the residual magnetic induction intensity, kGs is the residual magnetic induction intensity unit kilogauss, Hcj represents the coercive force, and kOe is the coercive force unit kiloortes.

[0064] The single heavy rare earth element used in this embodiment is Dy element. One of the experimental groups is a method of smelting Dy element and metallic copper into an alloy, and the other is a method of combining Dy element with electroplated copper. Ten batches of products were evaporated and diffused, and the data of the first, fifth and tenth batches of products were tested and recorded.

[0065] It can be seen from Table 1 that when the Dy element is in alloy form, the residual magnetic induction intensity of different batches of products is 13.81 for the first batch, 13.97 for the fifth batch, and 13.79 for the tenth batch. Therefore, the diffusion source in alloy form has little effect on the residual magnetic induction intensity of different batches of products. As for the coercive force of different batches of products, the first batch is 19.73, the fifth batch is 19.28, and the tenth batch is 18.76, and there is a trend of gradually decreasing. Therefore, although the diffusion source in alloy form can improve the coercive force compared to the magnet matrix without evaporation diffusion, the coercive force of different batches of products has a large difference, and it is difficult to ensure the consistency of performance of different batches of products.

[0066] However, the present embodiment adopts a method of first electroplating metallic copper on the surface of the pre-diffused magnet substrate, and then using the heavy rare earth element Dy for evaporation diffusion. As shown in Table 1, the residual magnetic induction intensity of different batches of products is 13.83 for the first batch, 13.79 for the fifth batch, and 13.95 for the tenth batch, which is not much different from the alloy form. As for the coercive force of different batches of products, the first batch is 19.66, the fifth batch is 19.61, and the tenth batch is 19.71. Therefore, the coercive force of different batches of products in this embodiment is basically the same, and the difference in coercive force has little effect, which effectively ensures the consistency of performance of different batches of products, and has obvious performance improvement compared with the magnet substrate without evaporation diffusion. In addition, after the evaporation diffusion is completed, the Dy element can be recycled in this embodiment, saving material costs.

[0067] Embodiment 2

[0068] S1: Diffusion source preparation: The diffusion source is Tb, and the purity of Tb is 99.5%;

[0069] S2: Preparation of pre-diffused magnet matrix: After the magnet components are proportioned according to the mass fraction, the magnet matrix is ​​prepared by vacuum melting to throw out SC sheets, hydrogen crushing, air flow grinding, orientation molding, isostatic pressing, vacuum sintering, and aging treatment. The NdFeB magnet matrix is ​​cut into sheet matrices of the required shape and size by machining. After surface treatment, the magnet is cleaned and dried to obtain the pre-diffused magnet matrix;

[0070] S3: Electroplating copper treatment: Electroplating copper treatment is performed on the surface of the pre-diffused magnet substrate, wherein the electroplating anode is pure copper with a purity of 99.9%, the electroplating solution is a copper sulfate solution with a concentration of 99.9%, and the thickness of the copper plating layer is 2.5-3 μm;

[0071] S4: Evaporation diffusion: The pre-diffused magnet substrate that has been subjected to copper electroplating treatment is placed in an evaporation furnace together with a diffusion source for evaporation diffusion. After the evaporation diffusion is completed, the magnet substrate that has completed evaporation diffusion is separated from the diffusion source.

[0072] Among them, the vacuum degree of the evaporation furnace is 10 -5 ~10 -2 Pa; the diffusion temperature is 800~950℃, the diffusion time is 5~30h; the aging temperature is 400~650℃, and the aging time is 4~8h.

[0073] Table 2: Comparison of residual magnetic induction intensity and coercivity of single heavy rare earth element Tb after multiple batches of evaporation diffusion in alloy form and in combination with electroplated copper

[0074]

[0075] Among them, Br represents the residual magnetic induction intensity, kGs is the residual magnetic induction intensity unit kilogauss, Hcj represents the coercive force, and kOe is the coercive force unit kiloortes.

[0076] The single heavy rare earth element used in this embodiment is Tb element. One of the experimental groups is a method of smelting Tb element and metallic copper into an alloy, and the other is a method of combining Tb element with electroplated copper. Ten batches of products were evaporated and diffused, and the data of the first, fifth and tenth batches of products were tested and recorded.

[0077] It can be seen from Table 2 that when the Tb element is in alloy form, the residual magnetic induction intensity of different batches of products is 14.01 for the first batch, 14.21 for the fifth batch, and 14.08 for the tenth batch. Therefore, the diffusion source in alloy form has little effect on the residual magnetic induction intensity of different batches of products. As for the coercive force of different batches of products, the first batch is 19.91, the fifth batch is 19.34, and the tenth batch is 18.59, and there is a trend of gradually decreasing. Therefore, although the diffusion source in alloy form can improve the coercive force compared to the magnet matrix without evaporation diffusion, the coercive force of different batches of products has a large difference, and it is difficult to ensure the consistency of performance of different batches of products.

[0078] However, the present embodiment adopts a method of first electroplating metallic copper on the surface of the pre-diffused magnet substrate, and then using the heavy rare earth element Tb for evaporation diffusion. As shown in Table 2, the residual magnetic induction intensity of different batches of products is 14.11 for the first batch, 14.09 for the fifth batch, and 14.14 for the tenth batch, which is not much different from the alloy form. As for the coercive force of different batches of products, the first batch is 19.72, the fifth batch is 19.86, and the tenth batch is 18.79. Therefore, the coercive force of different batches of products in this embodiment is basically the same, and the difference in coercive force has little effect, which effectively ensures the consistency of performance of different batches of products, and has obvious performance improvement compared with the magnet substrate without evaporation diffusion. In addition, after the evaporation diffusion is completed, the Tb element can be recycled in this embodiment, saving material costs.

[0079] The above description is only a preferred embodiment of the present invention and is not a limitation on the design of this case. Any equivalent changes made based on the design key of this case shall fall within the protection scope of this case.

Claims

1. A method for preparing a magnet based on electroplated copper composite diffusion source evaporation diffusion, characterized in that: The preparation method is used to prepare a magnet based on electroplated copper composite diffusion source evaporation diffusion, and the magnet includes the following components in mass fractions: A: 28-34wt.%, A includes A1 and A2, A1 is Dy or Tb, and the content of A1 is 0.8-5.0wt.% of the mass fraction of the magnet; the remainder of A2 is one or more of Nd, Pr, Ho, Ga, La, Ce and Er; B1: 0.1-4.0wt.%, B1 is one or more of Cu, Al, Zn, Mn, W and V; B2: 0.05-3.0wt.%, B2 is one or more of Zr, Nb and Ti; C: 0.8~2.0wt.%, C is boron element; The remainder of the magnet is D and other unavoidable impurities, where D is Fe; The magnet has at least one surface E, the Cu content of the surface E is higher than the average Cu content of the magnet, and within a depth range of 150 μm from the surface E to the inside of the magnet, the Cu concentration gradually decreases with increasing depth; The surface E is a diffusion surface of the magnet, which has a layer of heavy rare earth film prepared by evaporation diffusion, and the diffusion surface forms an arbitrary angle with the orientation direction of the magnet; The method for preparing a magnet based on electroplated copper composite diffusion source evaporation diffusion comprises the following steps: S1: Diffusion source preparation: The diffusion source is Dy or Tb, where the purity of Dy and Tb is 99.5%; S2: Preparation of pre-diffused magnet matrix: After the magnet components are proportioned according to the mass fraction, the magnet matrix is ​​prepared by vacuum melting to throw out SC sheets, hydrogen crushing, air flow grinding, orientation molding, isostatic pressing, vacuum sintering, and aging treatment. The NdFeB magnet matrix is ​​cut into sheet matrices of the required shape and size by machining. After surface treatment, the magnet is cleaned and dried to obtain the pre-diffused magnet matrix; S3: Electroplating copper treatment: Electroplating copper treatment is performed on the surface of the pre-diffused magnet substrate, wherein the electroplating anode is pure copper with a purity of 99.9%, the electroplating solution is a copper sulfate solution with a concentration of 99.9%, and the thickness of the copper plating layer is 2.5-3 μm; S4: Evaporation diffusion: The pre-diffused magnet substrate that has been subjected to copper electroplating treatment is placed in an evaporation furnace together with a diffusion source for evaporation diffusion. After the evaporation diffusion is completed, the magnet substrate that has completed evaporation diffusion is separated from the diffusion source.

2. A method for preparing a magnet based on electroplated copper composite diffusion source evaporation diffusion as claimed in claim 1, characterized in that: The diffusion surface is perpendicular to the magnet orientation direction.

3. The method for preparing a magnet based on electroplated copper composite diffusion source evaporation diffusion as claimed in claim 1, characterized in that: In the step S3, the pre-diffused magnet substrate is chamfered before being electroplated.

4. The method for preparing a magnet based on electroplated copper composite diffusion source evaporation diffusion as claimed in claim 1, characterized in that: In the step S3, the pre-diffused magnet substrate and the accompanying plated steel beads are subjected to copper electroplating.

5. The method for preparing a magnet based on electroplated copper composite diffusion source evaporation diffusion as claimed in claim 1, characterized in that: In step S4, the diffusion source is in the form of chips, and the amount of the diffusion source added is 40-80 kg of the diffusion source per 100 kg of the pre-diffused magnet matrix.

6. The method for preparing a magnet based on electroplated copper composite diffusion source evaporation diffusion as claimed in claim 1, characterized in that: In the step S4, the evaporation furnace is cylindrical.

7. The method for preparing a magnet based on electroplated copper composite diffusion source evaporation diffusion as claimed in claim 1, characterized in that: In step S4, the vacuum degree of the evaporation furnace is 10 -5 ~10 -2 Pa.

8. The method for preparing a magnet based on electroplated copper composite diffusion source evaporation diffusion as claimed in claim 1, characterized in that: In the step S4, the diffusion temperature of the evaporation furnace is 800-950° C., and the diffusion time is 5-30 hours.

9. The method for preparing a magnet based on electroplated copper composite diffusion source evaporation diffusion as claimed in claim 1, characterized in that: In the step S4, the aging temperature of the evaporation furnace is 400-650° C., and the aging time is 4-8 hours.

10. The method for preparing a magnet based on electroplated copper composite diffusion source evaporation diffusion as claimed in claim 1, characterized in that: In the step S4, the magnet substrate after the evaporation diffusion is separated from the diffusion source by a vibration screening machine.

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