CN113403620A - Rare earth permanent magnet with anticorrosive coating and preparation method and application thereof - Google Patents
Rare earth permanent magnet with anticorrosive coating and preparation method and application thereof Download PDFInfo
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- CN113403620A CN113403620A CN202110702633.7A CN202110702633A CN113403620A CN 113403620 A CN113403620 A CN 113403620A CN 202110702633 A CN202110702633 A CN 202110702633A CN 113403620 A CN113403620 A CN 113403620A
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- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
- C23C28/02—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material
- C23C28/021—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material including at least one metal alloy layer
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- C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
- C23C10/18—Solid state diffusion of only metal elements or silicon into metallic material surfaces using liquids, e.g. salt baths, liquid suspensions
- C23C10/20—Solid state diffusion of only metal elements or silicon into metallic material surfaces using liquids, e.g. salt baths, liquid suspensions only one element being diffused
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- C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
- C23C10/60—After-treatment
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- C23C24/08—Coating starting from inorganic powder by application of heat or pressure and heat
- C23C24/10—Coating starting from inorganic powder by application of heat or pressure and heat with intermediate formation of a liquid phase in the layer
- C23C24/103—Coating with metallic material, i.e. metals or metal alloys, optionally comprising hard particles, e.g. oxides, carbides or nitrides
- C23C24/106—Coating with metal alloys or metal elements only
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- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
- C23C28/02—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material
- C23C28/023—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material only coatings of metal elements only
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F17/00—Multi-step processes for surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by subclass C21D or C22F or class C25
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
- H01F1/047—Alloys characterised by their composition
- H01F1/053—Alloys characterised by their composition containing rare earth metals
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
- H01F41/026—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets protecting methods against environmental influences, e.g. oxygen, by surface treatment
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F7/00—Magnets
- H01F7/02—Permanent magnets [PM]
- H01F7/0205—Magnetic circuits with PM in general
- H01F7/0221—Mounting means for PM, supporting, coating, encapsulating PM
Abstract
The invention discloses a rare earth permanent magnet with an anticorrosive coating, and a preparation method and application thereof. The rare earth permanent magnet comprises a rare earth permanent magnet matrix, and an alloying transition layer and a metal coating which are formed on the surface of the rare earth permanent magnet matrix, wherein the alloying transition layer is formed at the joint interface of the rare earth permanent magnet matrix and the metal coating by mutual diffusion of metals contained in the rare earth permanent magnet matrix and the metal coating through heat treatment. According to the invention, through carrying out two-stage heat treatment on the composite structure formed by the rare earth permanent magnet matrix and the metal coating, mutual diffusion occurs between the metal coating and the surface of the rare earth permanent magnet matrix, so that the binding force between the matrix and the metal coating is good, and the corrosion resistance of the rare earth permanent magnet is improved.
Description
Technical Field
The invention belongs to the technical field of surface protection of rare earth permanent magnets, and particularly relates to a rare earth permanent magnet with an anticorrosive coating, and a preparation method and application thereof.
Background
The rare earth permanent magnet has excellent comprehensive magnetic performance, is widely applied to various fields such as aerospace, national defense and military, instruments, communication, computers, medical appliances, household appliances, electronic information products and the like, becomes one of the basic important material bases in high and new technology and emerging industrial fields, and the yield and the dosage of the rare earth permanent magnet are increased year by year.
The rare earth permanent magnet consists of a main phase and a rare earth-rich phase, and the rare earth-rich phase is more active and is easy to generate oxidation corrosion. And the multiphase structure existing in the material and the chemical characteristic difference among the phases enable the rare earth permanent magnet material to show inherent insufficient corrosion resistance, once the grain boundary rare earth-rich phase is corroded and dissolved, the bonding medium among main phase grains in the magnet disappears, so that the main phase grains fall off, and in the serious case, the pulverization and aging of the magnet are caused. At present, the corrosion resistance of rare earth permanent magnet materials is improved mainly by adjusting the chemical components, surface treatment methods or alloy methods. Adjusting the chemical composition may degrade the magnetic properties of the magnet to some extent. The surface treatment method mostly adopts a chemical stable film layer formed on the surface of the magnet to isolate the corrosive environment, and the Physical Vapor Deposition (PVD) which is one of the surface treatment techniques is considered as a new direction for the development of rare earth permanent magnet protection, however, the technique has high cost. Although the corrosion resistance of the magnet can be improved to a certain extent by the existing alloy method, the production cost of the magnet is increased by the alloy method, and the magnetic property of the magnet is obviously reduced.
Disclosure of Invention
The invention mainly aims to provide a rare earth permanent magnet with an anticorrosive coating, and a preparation method and application thereof, so as to overcome the defects of the prior art.
In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:
the embodiment of the invention provides a rare earth permanent magnet with an anticorrosive coating, which comprises a rare earth permanent magnet matrix, and an alloying transition layer and a metal coating which are formed on the surface of the rare earth permanent magnet matrix, wherein the alloying transition layer is formed at the joint interface of the rare earth permanent magnet matrix and the metal coating by the mutual diffusion of metals contained in the rare earth permanent magnet matrix and the metal coating through heat treatment.
The embodiment of the invention also provides a preparation method of the rare earth permanent magnet with the anticorrosive coating, which comprises the following steps:
plating a metal coating on the rare earth permanent magnet substrate;
and performing primary heat treatment and secondary heat treatment on the obtained rare earth permanent magnet matrix-metal coating composite structure to diffuse metal elements contained in the rare earth permanent magnet matrix and the metal coating, and forming an alloying transition layer at the joint interface of the rare earth permanent magnet matrix and the metal coating, thereby obtaining the rare earth permanent magnet with the anticorrosive coating.
The embodiment of the invention also provides the rare earth permanent magnet with the anticorrosive coating prepared by the method.
The embodiment of the invention also provides application of the rare earth permanent magnet with the anticorrosive coating in the field of surface protection of the rare earth permanent magnet.
Compared with the prior art, the invention has the beneficial effects that:
(1) according to the invention, by carrying out two-stage heat treatment on the composite structure formed by the rare earth permanent magnet matrix and the metal coating, mutual diffusion is generated between the metal coating and the surface of the rare earth permanent magnet matrix to form an alloying transition layer, so that the binding force between the matrix and the metal coating is very good, and meanwhile, the corrosion-resistant coating is formed on the surface, thus the corrosion resistance of the rare earth permanent magnet is improved; because the rare earth permanent magnet material belongs to a brittle material and has lower mechanical strength, the invention simultaneously improves the hardness of the surface layer of the rare earth permanent magnet;
(2) the method provided by the invention has short heat treatment time, diffusion only occurs on the surface part of the rare earth permanent magnet, the corrosion resistance of the rare earth permanent magnet is greatly improved, the magnetic property of the rare earth permanent magnet is not influenced, meanwhile, the preparation method of the anticorrosive coating is simple and easy to operate, and the production cost is greatly reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a back-scattered picture of a rare earth permanent magnet with an anticorrosive coating prepared in example 1 of the present invention.
Detailed Description
In view of the defects of the prior art, the inventor of the present invention has long studied and largely practiced to propose the technical solution of the present invention, which will be clearly and completely described below, and it is obvious that the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
One aspect of the embodiment of the invention provides a rare earth permanent magnet with an anticorrosive coating, which comprises a rare earth permanent magnet substrate, and an alloying transition layer and a metal coating which are formed on the surface of the rare earth permanent magnet substrate, wherein the alloying transition layer is formed at the joint interface of the rare earth permanent magnet substrate and the metal coating by mutual diffusion of metals contained in the rare earth permanent magnet substrate and the metal coating through heat treatment.
In some more specific embodiments, the metal element contained in the metal plating layer includes any one or a combination of two or more of aluminum, copper, zinc and tin, and is not limited thereto.
Furthermore, the thickness of the metal coating is 1-50 μm.
Further, the thickness of the alloying transition layer is less than or equal to 15 μm.
Further, the rare earth permanent magnet matrix includes, but is not limited to, a neodymium iron boron permanent magnet.
Another aspect of an embodiment of the present invention also provides a method for preparing a rare earth permanent magnet having an anticorrosive coating layer, including:
plating a metal coating on the rare earth permanent magnet substrate;
and performing primary heat treatment and secondary heat treatment on the obtained rare earth permanent magnet matrix-metal coating composite structure to diffuse metal elements contained in the rare earth permanent magnet matrix and the metal coating, and forming an alloying transition layer at the joint interface of the rare earth permanent magnet matrix and the metal coating, thereby obtaining the rare earth permanent magnet with the anticorrosive coating.
In some more specific embodiments, the preparation method comprises: under the vacuum condition, the metal dispersion liquid is applied to the rare earth permanent magnet matrix in a dip coating or spraying mode, so that a metal coating is plated on the rare earth permanent magnet matrix.
Further, the metal dispersion liquid includes a metal material and a dispersion solvent including any one or a combination of two or more of ethanol, acetone, and a binder, and is not limited thereto.
Further, the metal material includes any one or a combination of two or more of aluminum, copper, zinc, and tin, and is not limited thereto.
Further, the particle size of the metal material is less than 10 μm.
Further, the binder includes a resin-based binder, and is not limited thereto.
In some more specific embodiments, the material of the metal plating layer includes any one or a combination of two or more of aluminum, copper, zinc, and tin, and is not limited thereto.
Furthermore, the thickness of the metal coating is 1-50 μm.
In some more specific embodiments, the preparation method comprises: and performing primary heat treatment on the obtained rare earth permanent magnet matrix-metal coating composite structure at 700-900 ℃ for 30-600 min in a vacuum environment, melting the coating metal and a matrix grain boundary phase, performing mutual diffusion, allowing part of the coating metal to diffuse into the grain boundary phase, reducing the proportion of a rare earth-rich phase in the grain boundary phase, improving the potential of the grain boundary phase, reducing the potential difference between the grain boundary phase and a main phase, improving the corrosion resistance of the magnet, allowing part of grain boundary phase elements to diffuse into the coating metal to form an alloying transition layer, and performing secondary heat treatment at 400-600 ℃ for 30-600 min to uniformly distribute the grain boundary phase, thereby obtaining the rare earth permanent magnet with the anticorrosive coating. Further, the temperature of the primary heat treatment is higher than the melting point of elements contained in the alloying transition layer.
In some more specific embodiments, the preparation method further comprises: the method comprises the following steps of pretreating a rare earth permanent magnet matrix before plating a metal coating on the rare earth permanent magnet matrix, wherein the pretreatment comprises oil removal, polishing and cleaning.
Further, the grinding treatment comprises: and sequentially polishing the surface of the rare earth permanent magnet matrix from coarse to fine by using abrasive paper with different particle sizes.
Further, the cleaning process includes: carrying out ultrasonic cleaning on the polished rare earth permanent magnet matrix by using a cleaning solution; preferably, the washing solution comprises a mixture of ethanol and acetone.
In some more specific embodiments, the method for preparing the rare earth permanent magnet with the anticorrosive coating specifically comprises the following steps:
s1, pretreating the rare earth permanent magnet matrix, including removing oil, polishing, and then sequentially performing ultrasonic cleaning in absolute ethyl alcohol and acetone solution;
s2, applying metal dispersion liquid on the surface of the rare earth permanent magnet matrix in a vacuum environment, and plating a metal coating on the rare earth permanent magnet matrix;
and S3, carrying out two-stage heat treatment on the obtained rare earth permanent magnet matrix-metal plating layer composite structure to obtain the rare earth permanent magnet with the anticorrosive plating layer.
Preferably, in step S1, the grinding includes grinding the rare earth permanent magnet matrix with different grit sandpaper in sequence from coarse to fine.
Preferably, in step S2, the metal dispersion is applied to the rare earth permanent magnet substrate by dip coating or spray coating, so that the metal plating layer is plated on the rare earth permanent magnet substrate.
Preferably, in step S2, the particle size of the metal in the metal dispersion is less than 10 microns
Preferably, in step S2, the metal in the metal dispersion may be one or more of aluminum, copper, zinc, and tin powder, and if there are more than one metal, the metal layer may be a single layer or multiple layers.
Preferably, in step S3, the temperature of the primary heat treatment is higher than the melting point of the elements contained in the alloyed transition layer, the temperature of the secondary heat treatment is 400 to 600 ℃, and the heat treatment time is 30 to 600 min. During the first-stage heat treatment, the metal coating is melted and interdiffused with the rare earth permanent magnet matrix to form an alloying transition layer, and the second-stage heat treatment further optimizes the matrix structure.
In the invention, before heat treatment, the metal in the metal coating is granular and can be single metal or multiple metals; during heat treatment, the metal coating is melted or has alloying reaction, and after the heat treatment, the metal in the metal coating is a single metal or an alloy formed by a plurality of metals.
The embodiment of the invention also provides the rare earth permanent magnet with the anti-corrosion coating prepared by the method
Another aspect of the embodiments of the present invention also provides the use of the rare earth permanent magnet with the anticorrosive coating in the field of surface protection of rare earth permanent magnets.
The technical solutions of the present invention are further described in detail below with reference to several preferred embodiments and the accompanying drawings, which are implemented on the premise of the technical solutions of the present invention, and a detailed implementation manner and a specific operation process are provided, but the scope of the present invention is not limited to the following embodiments.
The experimental materials used in the examples used below were all available from conventional biochemical reagents companies, unless otherwise specified.
Example 1
The method comprises the steps of degreasing a rare earth permanent magnet matrix (neodymium iron boron permanent magnet), sequentially polishing the rare earth permanent magnet matrix with #400, #600, #800, #1000, #1200, #1500 and #2000 abrasive paper, and sequentially performing ultrasonic cleaning on the polished matrix in absolute ethyl alcohol and acetone solution.
Adding aluminum powder into absolute ethyl alcohol in a vacuum environment, stirring to form an aluminum powder dispersion liquid, and coating the aluminum powder on the surface of the pretreated matrix in a dispersing way to form a metal coating;
the obtained rare earth permanent magnet matrix-metal coating composite structure is put into a vacuum furnace, and then is subjected to primary heat treatment at 900 ℃ for 120min and secondary heat treatment at 500 ℃ for 120min, so that the rare earth permanent magnet with the anticorrosive coating is obtained (the back scattering picture is shown in figure 1).
The obtained rare earth permanent magnet was tested for magnetic properties at room temperature, and the test results are shown in table 1, wherein Br represents remanence, unit is kGs; hcj represents coercivity, in kOe; (BH) m represents the magnetic energy product in MGOe.
The obtained rare earth permanent magnet is subjected to a high-pressure accelerated aging life test under the conditions of 130 ℃, steam pressure of 2.6atm and relative humidity of 100 percent, the oxidation weight increase delta W of the rare earth permanent magnet in unit area is measured after 168 hours of the test, and the test result is shown in Table 1 and is in mg/cm2。
The resulting rare earth permanent magnet was tested for surface vickers hardness at room temperature, the test results are shown in table 1, with the unit of Hv.
Example 2
The method comprises the steps of degreasing a rare earth permanent magnet (neodymium iron boron permanent magnet) matrix, sequentially polishing the matrix by #400, #600, #800, #1000, #1200, #1500 and #2000 abrasive paper, and sequentially performing ultrasonic cleaning on the polished matrix in absolute ethyl alcohol and acetone solution.
Adding aluminum powder into absolute ethyl alcohol in a vacuum environment, stirring to form an aluminum powder dispersion liquid, and coating the aluminum powder on the surface of the pretreated matrix in a dispersing way to form a metal coating;
and putting the obtained rare earth permanent magnet matrix-metal coating composite structure into a vacuum furnace, and then carrying out primary heat treatment for 30min at 900 ℃ and then carrying out secondary heat treatment for 120min at 500 ℃, thereby obtaining the rare earth permanent magnet with the anticorrosive coating.
The obtained rare earth permanent magnet was tested for magnetic properties at room temperature, and the test results are shown in table 1, wherein Br represents remanence, unit is kGs; hcj represents coercivity, in kOe; (BH) m represents the magnetic energy product in MGOe.
The obtained rare earth permanent magnet is subjected to a high-pressure accelerated aging life test under the conditions of 130 ℃, steam pressure of 2.6atm and relative humidity of 100 percent, the oxidation weight increase delta W of the rare earth permanent magnet in unit area is measured after 168 hours of the test, and the test result is shown in Table 1 and is in mg/cm2。
The resulting rare earth permanent magnet was tested for surface vickers hardness at room temperature, the test results are shown in table 1, with the unit of Hv.
Example 3
The method comprises the steps of degreasing a rare earth permanent magnet matrix (neodymium iron boron permanent magnet), sequentially polishing the rare earth permanent magnet matrix with #400, #600, #800, #1000, #1200, #1500 and #2000 abrasive paper, and sequentially performing ultrasonic cleaning on the polished matrix in absolute ethyl alcohol and acetone solution.
Adding aluminum powder into absolute ethyl alcohol in a vacuum environment, stirring to form an aluminum powder dispersion liquid, and coating the aluminum powder on the surface of the pretreated matrix in a dispersing way to form a metal coating;
and (3) putting the obtained rare earth permanent magnet matrix-metal coating composite structure into a vacuum furnace, and then carrying out primary heat treatment for 30min at 700 ℃ and then carrying out secondary heat treatment for 120min at 500 ℃, thereby obtaining the rare earth permanent magnet with the anticorrosive coating.
The obtained rare earth permanent magnet was tested for magnetic properties at room temperature, and the test results are shown in table 1, wherein Br represents remanence, unit is kGs; hcj represents coercivity, in kOe; (BH) m represents the magnetic energy product in MGOe.
The obtained rare earth permanent magnet is subjected to a high-pressure accelerated aging life test under the conditions of 130 ℃, steam pressure of 2.6atm and relative humidity of 100 percent, the oxidation weight increase delta W of the rare earth permanent magnet in unit area is measured after 168 hours of the test, and the test result is shown in Table 1 and is in mg/cm2。
The resulting rare earth permanent magnet was tested for surface vickers hardness at room temperature, the test results are shown in table 1, with the unit of Hv.
Example 4
The method comprises the steps of degreasing a rare earth permanent magnet matrix (neodymium iron boron permanent magnet), sequentially polishing the rare earth permanent magnet matrix with #400, #600, #800, #1000, #1200, #1500 and #2000 abrasive paper, and sequentially performing ultrasonic cleaning on the polished matrix in absolute ethyl alcohol and acetone solution.
Adding aluminum powder into absolute ethyl alcohol in a vacuum environment, stirring to form an aluminum powder dispersion liquid, and coating the aluminum powder on the surface of the pretreated matrix in a dispersing way to form a metal coating;
the obtained rare earth permanent magnet matrix-metal coating composite structure is put into a vacuum furnace, and then primary heat treatment is carried out for 60min at 700 ℃, and secondary heat treatment is carried out for 120min at 500 ℃, so that the rare earth permanent magnet with the anti-corrosion coating is obtained (a back scattering picture is shown in figure 1).
The obtained rare earth permanent magnet was tested for magnetic properties at room temperature, and the test results are shown in table 1, wherein Br represents remanence, unit is kGs; hcj represents coercivity, in kOe; (BH) m represents the magnetic energy product in MGOe.
The obtained rare earth permanent magnet is subjected to a high-pressure accelerated aging life test under the conditions of 130 ℃, steam pressure of 2.6atm and relative humidity of 100 percent, the oxidation weight increase delta W of the rare earth permanent magnet in unit area is measured after 168 hours of the test, and the test result is shown in table I, wherein the unit is mg/cm2。
The resulting rare earth permanent magnet was tested for surface vickers hardness at room temperature, the test results are shown in table I, with the unit of Hv.
Example 5
The method comprises the steps of degreasing a rare earth permanent magnet matrix (neodymium iron boron permanent magnet), sequentially polishing the rare earth permanent magnet matrix with #400, #600, #800, #1000, #1200, #1500 and #2000 abrasive paper, and sequentially performing ultrasonic cleaning on the polished matrix in absolute ethyl alcohol and acetone solution.
Adding the aluminum copper powder into absolute ethyl alcohol in a vacuum environment, stirring to form an aluminum copper powder dispersion liquid, and dispersing and coating the aluminum copper powder on the surface of the pretreated matrix to form a metal coating;
the obtained rare earth permanent magnet matrix-metal coating composite structure is put into a vacuum furnace, and then primary heat treatment is carried out for 120min at 800 ℃, and secondary heat treatment is carried out for 600min at 400 ℃, so that the rare earth permanent magnet with the anti-corrosion coating is obtained (back scattering pictures are shown in figure I).
The obtained rare earth permanent magnet is tested for magnetic property at room temperature, and the test result is shown in table I, wherein Br represents remanence, and the unit is kGs; hcj represents coercivity, in kOe; (BH) m represents the magnetic energy product in MGOe.
The obtained rare earth permanent magnet is subjected to a high-pressure accelerated aging life test under the conditions of 130 ℃, steam pressure of 2.6atm and relative humidity of 100 percent, the oxidation weight increase delta W of the rare earth permanent magnet in unit area is measured after 168 hours of the test, and the test result is shown in Table 1 and is in mg/cm2。
The resulting rare earth permanent magnet was tested for surface vickers hardness at room temperature, the test results are shown in table 1, with the unit of Hv.
Comparative example 1
The preparation method of this example is the same as example 1, except that the temperature of the primary heat treatment is 900 ℃ and the time is 120min, and the secondary heat treatment is not performed.
The obtained rare earth permanent magnet was subjected to a test of magnetic properties, a high-pressure accelerated aging life test and Vickers hardness at room temperature, and the test results are shown in Table 1.
TABLE 1 magnetic Properties of rare earth permanent magnet matrices, examples
Comparative example 2
The preparation method of the embodiment is the same as that of the embodiment 1, except that: the temperature of the primary heat treatment is lower than the melting point of the metal of the coating or the alloying reaction temperature, and the coating prepared by the embodiment cannot be well combined with the substrate and is easy to fall off.
Comparative example 3
The preparation method of the embodiment is the same as that of the embodiment 1, except that: the coating prepared by the embodiment cannot be combined with a matrix and is easy to fall off without primary and secondary heat treatment.
Comparative example 4
The preparation method of the embodiment is the same as that of the embodiment 1, except that: without primary heat treatment, the coating prepared in this example could not be combined with the substrate and was prone to peeling off.
In addition, the inventors of the present invention have also made experiments with other materials, process operations, and process conditions described in the present specification with reference to the above examples, and have obtained preferable results.
The aspects, embodiments, features and examples of the present invention should be considered as illustrative in all respects and not intended to be limiting of the invention, the scope of which is defined only by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.
The use of headings and chapters in this disclosure is not meant to limit the disclosure; each section may apply to any aspect, embodiment, or feature of the disclosure.
Throughout this specification, where a composition is described as having, containing, or comprising specific components or where a process is described as having, containing, or comprising specific process steps, it is contemplated that the composition of the present teachings also consist essentially of, or consist of, the recited components, and the process of the present teachings also consist essentially of, or consist of, the recited process steps.
It should be understood that the order of steps or the order in which particular actions are performed is not critical, so long as the teachings of the invention remain operable. Further, two or more steps or actions may be performed simultaneously.
While the invention has been described with reference to illustrative embodiments, it will be understood by those skilled in the art that various other changes, omissions and/or additions may be made and substantial equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated any use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another.
Claims (10)
1. The rare earth permanent magnet with the anti-corrosion coating is characterized by comprising a rare earth permanent magnet matrix, and an alloying transition layer and a metal coating which are formed on the surface of the rare earth permanent magnet matrix, wherein the alloying transition layer is formed at the joint interface of the rare earth permanent magnet matrix and the metal coating by mutual diffusion of metals contained in the rare earth permanent magnet matrix and the metal coating through heat treatment.
2. The rare earth permanent magnet with an anticorrosive coating according to claim 1, characterized in that: the metal element contained in the metal coating comprises any one or the combination of more than two of aluminum, copper, zinc and tin.
3. The rare earth permanent magnet with an anticorrosive coating according to claim 1, characterized in that: the thickness of the metal coating is 1-50 μm;
and/or the thickness of the alloying transition layer is less than or equal to 15 μm.
4. The rare earth permanent magnet with an anticorrosive coating according to claim 1, characterized in that: the rare earth permanent magnet matrix comprises a neodymium iron boron permanent magnet.
5. A preparation method of a rare earth permanent magnet with an anticorrosive coating is characterized by comprising the following steps:
plating a metal coating on the rare earth permanent magnet substrate;
and performing primary heat treatment and secondary heat treatment on the obtained rare earth permanent magnet matrix-metal coating composite structure to diffuse metal elements contained in the rare earth permanent magnet matrix and the metal coating, and forming an alloying transition layer at the joint interface of the rare earth permanent magnet matrix and the metal coating, thereby obtaining the rare earth permanent magnet with the anticorrosive coating.
6. The production method according to claim 5, characterized by comprising: under the vacuum condition, applying the metal dispersion liquid on the rare earth permanent magnet matrix in a dip-coating or spraying mode so as to plate a metal coating on the rare earth permanent magnet matrix; preferably, the metal dispersion liquid comprises a metal material and a dispersion solvent, wherein the dispersion solvent comprises any one or a combination of more than two of ethanol, acetone and a bonding agent; preferably, the metal material comprises any one or a combination of more than two of aluminum, copper, zinc and tin; preferably, the particle size of the metal material is less than 10 μm; preferably, the binder comprises a resinous binder;
and/or the material of the metal coating comprises any one or the combination of more than two of aluminum, copper, zinc and tin;
and/or the thickness of the metal coating is 1-50 μm.
7. The production method according to claim 5, characterized by comprising: performing primary heat treatment on the obtained rare earth permanent magnet matrix-metal coating composite structure at 700-900 ℃ for 30-600 min in a vacuum environment to form an alloying transition layer, and performing secondary heat treatment at 400-600 ℃ for 30-600 min to obtain the rare earth permanent magnet with the anticorrosive coating;
preferably, the temperature of the primary heat treatment is higher than the melting point of the elements contained in the alloying transition layer.
8. The method of claim 5, further comprising: the method comprises the following steps of pretreating a rare earth permanent magnet matrix before plating a metal coating on the rare earth permanent magnet matrix, wherein the pretreatment comprises oil removal, polishing and cleaning;
preferably, the grinding process comprises: sequentially polishing the surface of the rare earth permanent magnet matrix from coarse to fine by using abrasive paper with different particle sizes;
preferably, the cleaning process includes: carrying out ultrasonic cleaning on the polished rare earth permanent magnet matrix by using a cleaning solution; preferably, the washing solution comprises a mixture of ethanol and acetone.
9. A rare earth permanent magnet having an anticorrosive coating prepared by the method of any one of claims 5 to 8.
10. Use of a rare earth permanent magnet with an anticorrosive coating as claimed in any one of claims 1 to 4, 9 in the field of surface protection of rare earth permanent magnets; preferably, the rare earth permanent magnet comprises a neodymium iron boron permanent magnet.
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