CN114267532A - Processing method of high-magnetism sintered neodymium-iron-boron magnet - Google Patents
Processing method of high-magnetism sintered neodymium-iron-boron magnet Download PDFInfo
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- CN114267532A CN114267532A CN202111619757.5A CN202111619757A CN114267532A CN 114267532 A CN114267532 A CN 114267532A CN 202111619757 A CN202111619757 A CN 202111619757A CN 114267532 A CN114267532 A CN 114267532A
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- 238000010438 heat treatment Methods 0.000 claims abstract description 22
- 239000000843 powder Substances 0.000 claims abstract description 18
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- Hard Magnetic Materials (AREA)
- Manufacturing Cores, Coils, And Magnets (AREA)
Abstract
The invention relates to the technical field of magnets, in particular to a processing method of a high-magnetism sintered neodymium-iron-boron magnet, which comprises the following steps: (1) taking neodymium iron boron magnet powder, carrying out orientation molding in a magnetic field, and then carrying out isostatic pressing treatment and compression molding to prepare a magnet green body; (2) placing the magnet green body in a sintering furnace for sintering, and then carrying out tempering heat treatment to obtain a magnet substrate; (3) and cleaning the surface of the prepared magnet substrate, and coating a corrosion-resistant protective coating on the outer surface of the magnet substrate to prepare the high-magnetism sintered neodymium-iron-boron magnet. The processing method of the high-magnetism sintered neodymium iron boron magnet is simple and easy to control in operation, high in production efficiency and product yield, stable in product quality and beneficial to industrial production, and the prepared sintered neodymium iron boron magnet has excellent magnetic performance and corrosion resistance and excellent comprehensive performance.
Description
Technical Field
The invention relates to the technical field of magnets, in particular to a processing method of a high-magnetism sintered neodymium iron boron magnet.
Background
The neodymium-iron-boron magnet is a tetragonal crystal formed of neodymium, iron, and boron. The neodymium iron boron is divided into sintered neodymium iron boron and bonded neodymium iron boron. The sintered Nd-Fe-B permanent magnet material has excellent magnetic performance, is widely applied to the fields of electronics, electric machinery, medical instruments, toys, packaging, hardware machinery, aerospace and the like, and is more commonly provided with a permanent magnet motor, a loudspeaker, a magnetic separator, a computer disk driver, a magnetic resonance imaging equipment instrument and the like. With the development of science and technology and the progress of society, the performance requirements of people on the neodymium iron boron magnet are higher and higher. However, the existing neodymium iron boron magnet sintering process is easy to cause various defects of the magnet, the product yield is not high, and the magnetic performance and the corrosion resistance of the neodymium iron boron magnet are required to be further improved so as to improve the service performance and prolong the service life of the neodymium iron boron magnet.
Disclosure of Invention
In order to overcome the defects and shortcomings in the prior art, the invention aims to provide the processing method of the high-magnetism sintered neodymium-iron-boron magnet and the high-magnetism sintered neodymium-iron-boron magnet.
The purpose of the invention is realized by the following technical scheme: a processing method of a high-magnetism sintered NdFeB magnet comprises the following steps:
(1) taking neodymium iron boron magnet powder, carrying out orientation molding in a magnetic field, and then carrying out isostatic pressing treatment and compression molding to prepare a magnet green body;
(2) placing the magnet green body in a sintering furnace for sintering, and then carrying out tempering heat treatment to obtain a magnet substrate;
(3) and cleaning the surface of the prepared magnet substrate, and coating a corrosion-resistant protective coating on the outer surface of the magnet substrate to prepare the high-magnetism sintered neodymium-iron-boron magnet.
The processing method of the high-magnetism sintered neodymium iron boron magnet is simple and easy to control in operation, high in production efficiency and product yield, stable in product quality and beneficial to industrial production, the prepared sintered neodymium iron boron magnet has excellent magnetic performance and mechanical performance, and the corrosion resistance of the sintered neodymium iron boron magnet is remarkably improved by tightly coating the corrosion-resistant protective coating on the outer surface of the magnet substrate.
Further, in the step (1), the neodymium iron boron magnet powder comprises the following raw materials in percentage by mass: 21-24% of neodymium, 6.7-7.4% of praseodymium, 0.98-1.18% of boron, 1.3-1.7% of lanthanum, 0.6-0.9% of aluminum, 0.3-0.5% of cobalt, 0.2-0.24% of copper, 0.15-0.19% of zirconium, 0.14-0.22% of gallium, 1.0-1.5% of silicon, 3-4.5% of graphene and the balance of iron. According to the invention, the graphene is matched with silicon, lanthanum, cobalt, praseodymium, gallium and other components, so that the prepared neodymium iron boron magnet has excellent magnetic property and mechanical property.
Further, in the step (1), the neodymium iron boron magnet powder is oriented in a magnetic field with the magnetic field intensity of 2.5-3.0T.
Further, in the step (1), the pressure of the isostatic pressing treatment is 300-400MPa, and the treatment time is 2-3 min.
Further, in the step (2), the green magnet is placed in a sintering furnace for sintering under the protection of argon, the temperature is raised to 640-. According to the invention, the neodymium iron boron magnet green body is sintered in an argon atmosphere, the sintering step, the sintering temperature and the sintering time are controlled, the green body is protected from being oxidized easily, and the inner crack of the green body is prevented, so that the magnet has good magnetic property uniformity, good mechanical property and magnetic property, stable product quality and high product yield, and is beneficial to industrial production.
Further, in the step (2), the sintered magnet green body is subjected to a tertiary tempering treatment. The temperature of the first-stage tempering heat treatment is 900-950 ℃, and the heat preservation time is 120-180 min; the temperature of the second-stage tempering heat treatment is 620-680 ℃, and the heat preservation time is 120-180 min; the temperature of the third-stage tempering heat treatment is 550-. According to the invention, the sintered neodymium-iron-boron magnet green body is subjected to three tempering treatments by adopting the steps and the process parameters, so that the neodymium-iron-boron magnet has uniform and stable crystal grains, and the magnetic property and the mechanical property of the sintered neodymium-iron-boron magnet are improved.
Further, in the step (3), the step of coating the surface of the neodymium iron boron magnet substrate with the corrosion-resistant protective coating comprises the following specific steps:
s1, placing the magnet substrate in the corrosion-resistant protective coating for dipping, then pulling the magnet substrate upwards, separating the magnet substrate from the corrosion-resistant protective coating and suspending the magnet substrate above the corrosion-resistant protective coating; repeating the steps of dipping and pulling to obtain a magnet matrix coated with a primary coating;
and S2, curing the primary coating film of the magnet substrate to obtain the high-magnetism sintered NdFeB magnet coated with the corrosion-resistant protective coating.
According to the neodymium iron boron magnet, the corrosion resistance of the magnet base body can be obviously improved, the service life of the magnet base body is prolonged, and the application range of the magnet base body is widened by coating the corrosion-resistant protective coating on the outer surface of the magnet base body; the preparation method of the sintered neodymium-iron-boron magnet is simple in process, convenient to operate and control, high in production efficiency, beneficial to industrial production, stable in quality of the prepared product and excellent in comprehensive performance.
Further, in the step S1, the corrosion-resistant protective coating includes a component a and a component B, where the component a includes the following raw materials in parts by weight: 90-100 parts of bisphenol A epoxy resin, 12-20 parts of phenolic resin, 10-16 parts of acrylic resin, 5-9 parts of polytetrafluoroethylene, 14-20 parts of inorganic filler, 14-20 parts of functional assistant, 5-10 parts of hydroxyethyl cellulose, 4-8 parts of styrene-acrylic emulsion, 14-20 parts of zinc powder, 1-4 parts of silane coupling agent and 45-60 parts of solvent. The component B comprises the following raw materials in parts by weight: 2-5 parts of curing agent and 5-8 parts of diluent.
The corrosion-resistant protective coating is coated on the outer surface of the magnet substrate, so that the corrosion resistance of the magnet is improved, and the service life of the magnet is prolonged. The corrosion-resistant protective coating adopted by the corrosion-resistant protective coating comprises a component A and a component B, wherein the component A and the component B can be separately placed and stored before use, and the component A and the component B are mixed when in use; the component A is prepared by compounding bisphenol A type epoxy resin, phenolic resin and acrylic resin, and is matched with polytetrafluoroethylene, a functional auxiliary agent, hydroxyethyl cellulose, styrene-acrylic emulsion, zinc powder, a silane coupling agent and other raw materials, and inorganic filler is added into a coating system, so that the raw materials can be mutually benefited, good matching is realized, the prepared corrosion-resistant protective coating can be tightly coated on the surface of a magnet substrate to form a uniform and smooth coating, the coating has strong adhesive force with the magnet substrate and is not easy to fall off, the prepared neodymium iron boron magnet has excellent corrosion resistance and long service life, and the appearance of the magnet is favorably improved. The bisphenol A type epoxy resin is preferably, but not limited to, a bisphenol A type epoxy resin (E-03 type). The phenolic resin may be p-tert-octylphenol formaldehyde resin, but is not limited to phenolic resin SP-1068. The acrylic resin is preferably, but not limited to, acrylic resin Mitsubishi BR 113. The polytetrafluoroethylene is Komu Teflon 650 XTX. The styrene-acrylic emulsion is styrene-acrylic emulsion Badfei RS-5969.
Further, the silane coupling agent is at least one of a silane coupling agent KH-550, a silane coupling agent KH-560 and a silane coupling agent KH-792. The silane coupling agent is adopted, so that the mechanical property of the coating and the bonding strength of the coating and the magnet substrate are improved.
Further, the inorganic filler is at least one of nano calcium carbonate, nano silicon dioxide and nano talcum powder. The particle size of the inorganic filler is 30-70 nm. Preferably, the inorganic filler is prepared from nano calcium carbonate, nano silicon dioxide and nano talcum powder according to the weight ratio of 1-2: 1-2: 1. By adopting the inorganic filler, the corrosion resistance and the mechanical property of the corrosion-resistant protective coating can be improved, the proportion of bisphenol A epoxy resin, phenolic resin and the like can be reduced, the cost is reduced, and the dimensional stability is improved.
Further, the preparation method of the functional auxiliary agent comprises the following steps: mixing 8-12 parts of graphene, 5-10 parts of isobutylene-maleic anhydride copolymer, 5-10 parts of vinyl bis stearamide, 4-8 parts of isobutyl triethoxysilane and 10-15 parts of polyethylene glycol in parts by weight, uniformly stirring at 85-95 ℃, and keeping the temperature for 45-90 min; obtaining the functional additive. According to the invention, graphene, isobutylene-maleic anhydride copolymer, vinyl bis-stearamide, isobutyl triethoxysilane and other raw materials are compounded and added into a coating system, so that the graphene, the isobutylene-maleic anhydride copolymer, the vinyl bis-stearamide, the isobutyl triethoxysilane and other raw materials are well matched with bisphenol A epoxy resin, phenolic resin, acrylic resin and the like, and the corrosion resistance and the mechanical property of the coating and the bonding strength of the coating and a magnet substrate are improved. The isobutylene-maleic anhydride copolymer is preferably, but not necessarily, isobutylene-maleic anhydride copolymer ISOBAM-600.
Further, the curing agent is at least one of ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine and diethylaminopropylamine. The curing agent can be used for crosslinking and curing the epoxy resin with the ring to form a reticular three-dimensional polymer, so that the corrosion resistance and the mechanical property of the coating are improved, the coating is not easy to fall off from the magnet matrix, and the combination is tight.
Further, the diluent is at least one of ethanol, ethyl acetate and acetone. The solvent is at least one of acetone, xylene and n-butanol.
Further, the preparation method of the corrosion-resistant protective coating comprises the following steps:
the preparation method of the component A comprises the following steps:
a1, uniformly mixing the functional additive, the silane coupling agent and the solvent according to the parts by weight, then adding the bisphenol A type epoxy resin, the phenolic resin, the acrylic resin, the hydroxyethyl cellulose and the polytetrafluoroethylene, and stirring for 20-30min at the temperature of 70-80 ℃ to obtain a mixture A1;
a2, adding inorganic filler, styrene-acrylic emulsion and zinc powder into the mixture A, and stirring at 70-80 ℃ for 20-30min to obtain a mixture A2; grinding and filtering the mixture B to obtain filtrate, namely the component A.
The preparation method of the component B comprises the following steps: and mixing the curing agent and the diluent, and uniformly stirring to obtain the component B.
The preparation method of the corrosion-resistant protective coating respectively prepares the component A and the component B, the component A and the component B can be separately placed and stored before use, and the component A and the component B are mixed when in use; the corrosion-resistant protective coating prepared by the preparation method can be uniformly coated on the outer surface of the magnet substrate, a uniform and stable coating with smooth appearance is formed on the surface of the magnet, and the binding force between the coating and the magnet substrate is strong.
Further, in the step S1, the dipping time is 30 to 40 seconds each time, the time for separating the magnet base body from the corrosion-resistant protective coating and suspending the magnet base body after each pulling is 60 to 90 seconds, and the repetition times are 20 to 30 times.
Further, in the step S2, the curing temperature of the primary coating film is 80 to 90 ℃, and the curing time is 25 to 35 min.
According to the invention, by adopting the steps and controlling the technological parameters of the steps, the corrosion-resistant protective coating is tightly coated on the outer surface of the high-magnetism sintered neodymium-iron-boron magnet to form a uniform, stable, flat and smooth coating, the adhesion force between the coating and the magnet substrate is strong, the coating is not easy to fall off, so that the prepared neodymium-iron-boron magnet has excellent corrosion resistance and long service life, and the appearance of the magnet is favorably improved.
The invention also provides a high-magnetism sintered neodymium iron boron magnet, which comprises the following raw materials in percentage by mass: 21-24% of neodymium, 6.7-7.4% of praseodymium, 0.98-1.18% of boron, 1.3-1.7% of lanthanum, 0.6-0.9% of aluminum, 0.3-0.5% of cobalt, 0.2-0.24% of copper, 0.15-0.19% of zirconium, 0.14-0.22% of gallium, 1.0-1.5% of silicon, 3-4.5% of graphene and the balance of iron. According to the invention, the high-magnetism sintered neodymium iron boron magnet is prepared by matching the graphene with silicon, lanthanum, cobalt, praseodymium, gallium and other components, and has excellent magnetic property and mechanical property and strong practicability.
The invention has the beneficial effects that: the processing method of the high-magnetism sintered neodymium iron boron magnet is simple and easy to control in operation, high in production efficiency and product yield, stable in product quality and beneficial to industrial production, and the prepared sintered neodymium iron boron magnet has excellent magnetic performance and corrosion resistance and excellent comprehensive performance.
Detailed Description
The present invention will be further described with reference to the following examples for facilitating understanding of those skilled in the art, and the description of the embodiments is not intended to limit the present invention.
Example 1
In this embodiment, a processing method of a high-magnetism sintered neodymium iron boron magnet includes the following steps:
(1) taking neodymium iron boron magnet powder, carrying out orientation molding in a magnetic field, and then carrying out isostatic pressing treatment and compression molding to prepare a magnet green body;
(2) placing the magnet green body in a sintering furnace for sintering, and then carrying out tempering heat treatment to obtain a magnet substrate;
(3) and cleaning the surface of the prepared magnet substrate, and coating a corrosion-resistant protective coating on the outer surface of the magnet substrate to prepare the high-magnetism sintered neodymium-iron-boron magnet.
Further, in the step (1), the neodymium iron boron magnet powder comprises the following raw materials in percentage by mass: 22.5% of neodymium, 6.9% of praseodymium, 1.1% of boron, 1.5% of lanthanum, 0.75% of aluminum, 0.4% of cobalt, 0.22% of copper, 0.17% of zirconium, 0.17% of gallium, 1.3% of silicon, 3.8% of graphene and the balance of iron.
Further, in the step (1), the neodymium iron boron magnet powder is oriented in a magnetic field with the magnetic field intensity of 2.8T.
Further, in the step (1), the pressure of the isostatic pressing treatment is 350MPa, and the treatment time is 2.5 min.
Further, in the step (2), the magnet green body is placed in a sintering furnace under the protection of argon gas for sintering, the temperature is increased to 660 ℃ at 8 ℃/min, the temperature is kept for 210min, then the temperature is increased to 1050 ℃ at 10 ℃/min, and the magnet green body is sintered at the temperature for 240 min.
Further, in the step (2), the sintered magnet green body is subjected to a tertiary tempering treatment. The temperature of the first-stage tempering heat treatment is 920 ℃, and the heat preservation time is 150 min; the temperature of the second-stage tempering heat treatment is 650 ℃, and the heat preservation time is 150 min; the temperature of the third-stage tempering heat treatment is 580 ℃, and the heat preservation time is 75 min.
Further, in the step (3), the step of coating the surface of the neodymium iron boron magnet substrate with the corrosion-resistant protective coating comprises the following specific steps:
s1, placing the magnet substrate in the corrosion-resistant protective coating for dipping, then pulling the magnet substrate upwards, separating the magnet substrate from the corrosion-resistant protective coating and suspending the magnet substrate above the corrosion-resistant protective coating; repeating the steps of dipping and pulling to obtain a magnet matrix coated with a primary coating;
and S2, curing the primary coating film of the magnet substrate to obtain the high-magnetism sintered NdFeB magnet coated with the corrosion-resistant protective coating.
In the embodiment, the corrosion-resistant protective coating comprises a component A and a component B, wherein the component A comprises the following raw materials in parts by weight: 95 parts of bisphenol A epoxy resin, 16 parts of phenolic resin, 13 parts of acrylic resin, 7 parts of polytetrafluoroethylene, 16 parts of inorganic filler, 17 parts of functional assistant, 8 parts of hydroxyethyl cellulose, 6 parts of styrene-acrylic emulsion, 16 parts of zinc powder, 2 parts of silane coupling agent and 50 parts of solvent; the component B comprises the following raw materials in parts by weight: 3 parts of curing agent and 7 parts of diluent. The bisphenol A type epoxy resin is bisphenol A type epoxy resin (E-03 type). The phenolic resin is phenolic resin SP-1068. The acrylic resin is acrylic resin Mitsubishi BR 113. The polytetrafluoroethylene is Komu Teflon 650 XTX. The styrene-acrylic emulsion is styrene-acrylic emulsion Badfei RS-5969.
Further, the silane coupling agent consists of a silane coupling agent KH-550 and a silane coupling agent KH-792 according to a weight ratio of 2: 1. The particle size of the inorganic filler is 30-70 nm. The inorganic filler is prepared from nano calcium carbonate, nano silicon dioxide and nano talcum powder according to the weight ratio of 2: 1: 1.
Further, the preparation method of the functional auxiliary agent comprises the following steps: mixing 10 parts of graphene, 7 parts of isobutylene-maleic anhydride copolymer, 7 parts of vinyl bis stearamide, 6 parts of isobutyl triethoxysilane and 12 parts of polyethylene glycol in parts by weight, uniformly stirring at 90 ℃, and keeping the temperature for 60 min; obtaining the functional additive. The isobutylene-maleic anhydride copolymer is isobutylene-maleic anhydride copolymer ISOBAM-600.
Further, the curing agent is diethylenetriamine. The diluent consists of ethanol, ethyl acetate and acetone according to the weight ratio of 1:1: 2. The solvent is composed of acetone and n-butanol according to the weight ratio of 1: 2.
Further, the preparation method of the corrosion-resistant protective coating comprises the following steps:
the preparation method of the component A comprises the following steps:
a1, uniformly mixing the functional additive, the silane coupling agent and the solvent according to the parts by weight, then adding the bisphenol A type epoxy resin, the phenolic resin, the acrylic resin, the hydroxyethyl cellulose and the polytetrafluoroethylene, and stirring for 25min at the temperature of 75 ℃ to obtain a mixture A1;
a2, adding an inorganic filler, a styrene-acrylic emulsion and zinc powder into the mixture A, and stirring at 75 ℃ for 25min to obtain a mixture A2; grinding and filtering the mixture B to obtain a filtrate, namely a component A;
the preparation method of the component B comprises the following steps: and mixing the curing agent and the diluent, and uniformly stirring to obtain the component B.
The preparation method of the sintered neodymium-iron-boron magnet comprises the following steps:
s1, placing the magnet substrate in the corrosion-resistant protective coating for dipping, then pulling the magnet substrate upwards, separating the magnet substrate from the corrosion-resistant protective coating and suspending the magnet substrate above the corrosion-resistant protective coating; repeating the steps of dipping and pulling to obtain a magnet matrix coated with a primary coating;
and S2, curing the primary coating film of the magnet substrate to obtain the sintered neodymium iron boron magnet coated with the corrosion-resistant protective coating.
Further, in the step S1, the dipping time is 5S each time, the time for detaching the magnet base from the corrosion-resistant protective coating and suspending the magnet base after each pulling is 80S, and the number of times of repetition is 25. In the step S2, the curing temperature of the primary coating film was 85 ℃ and the curing time was 30 min.
Example 2
In this embodiment, a processing method of a high-magnetism sintered neodymium iron boron magnet includes the following steps:
(1) taking neodymium iron boron magnet powder, carrying out orientation molding in a magnetic field, and then carrying out isostatic pressing treatment and compression molding to prepare a magnet green body;
(2) placing the magnet green body in a sintering furnace for sintering, and then carrying out tempering heat treatment to obtain a magnet substrate;
(3) and cleaning the surface of the prepared magnet substrate, and coating a corrosion-resistant protective coating on the outer surface of the magnet substrate to prepare the high-magnetism sintered neodymium-iron-boron magnet.
Further, in the step (1), the neodymium iron boron magnet powder comprises the following raw materials in percentage by mass: 21% of neodymium, 7.4% of praseodymium, 0.98% of boron, 1.7% of lanthanum, 0.69% of aluminum, 0.5% of cobalt, 0.2% of copper, 0.19% of zirconium, 0.14% of gallium, 1.5% of silicon, 3% of graphene and the balance of iron.
Further, in the step (1), the neodymium iron boron magnet powder is oriented in a magnetic field with the magnetic field intensity of 2.5T.
Further, in the step (1), the pressure of the isostatic pressing treatment is 300MPa, and the treatment time is 3 min.
Further, in the step (2), the magnet green body is placed in a sintering furnace under the protection of argon gas for sintering, the temperature is raised to 640 ℃ at the speed of 7 ℃/min, the temperature is kept for 240min, then the temperature is raised to 1000 ℃ at the speed of 8 ℃/min, and the magnet green body is sintered for 270min at the temperature.
Further, in the step (2), the sintered magnet green body is subjected to a tertiary tempering treatment. The temperature of the first-stage tempering heat treatment is 900 ℃, and the heat preservation time is 180 min; the temperature of the second-stage tempering heat treatment is 620 ℃, and the heat preservation time is 180 min; the temperature of the third-stage tempering heat treatment is 550 ℃, and the heat preservation time is 60 min.
Further, in the step (3), the step of coating the surface of the neodymium iron boron magnet substrate with the corrosion-resistant protective coating comprises the following specific steps:
s1, placing the magnet substrate in the corrosion-resistant protective coating for dipping, then pulling the magnet substrate upwards, separating the magnet substrate from the corrosion-resistant protective coating and suspending the magnet substrate above the corrosion-resistant protective coating; repeating the steps of dipping and pulling to obtain a magnet matrix coated with a primary coating;
and S2, curing the primary coating film of the magnet substrate to obtain the high-magnetism sintered NdFeB magnet coated with the corrosion-resistant protective coating.
In the embodiment, the corrosion-resistant protective coating comprises a component A and a component B, wherein the component A comprises the following raw materials in parts by weight: 90 parts of bisphenol A type epoxy resin, 12 parts of phenolic resin, 10 parts of acrylic resin, 5 parts of polytetrafluoroethylene, 14 parts of inorganic filler, 14 parts of functional assistant, 5 parts of hydroxyethyl cellulose, 4 parts of styrene-acrylic emulsion, 14 parts of zinc powder, 1 part of silane coupling agent and 45 parts of solvent; the component B comprises the following raw materials in parts by weight: 2 parts of curing agent and 5 parts of diluent.
Further, the silane coupling agent consists of a silane coupling agent KH-550 and a silane coupling agent KH-560 according to a weight ratio of 2: 1. The inorganic filler is prepared from nano calcium carbonate, nano silicon dioxide and nano talcum powder according to the weight ratio of 1: 2: 1.
Further, the preparation method of the functional auxiliary agent comprises the following steps: mixing 8 parts of graphene, 5 parts of isobutylene-maleic anhydride copolymer, 5 parts of vinyl bis stearamide, 4 parts of isobutyl triethoxysilane and 10 parts of polyethylene glycol in parts by weight, uniformly stirring at 85 ℃, and keeping the temperature for 90 min; obtaining the functional additive.
Further, the curing agent is ethylene diamine and triethylene tetramine according to the weight ratio of 1: 1. The diluent is ethanol, ethyl acetate and acetone according to a weight ratio of 1:1: 3, and (3). The solvent is composed of acetone and xylene according to the weight ratio of 2: 1.
Further, the preparation method of the corrosion-resistant protective coating comprises the following steps:
the preparation method of the component A comprises the following steps:
a1, uniformly mixing the functional additive, the silane coupling agent and the solvent according to the parts by weight, then adding the bisphenol A type epoxy resin, the phenolic resin, the acrylic resin, the hydroxyethyl cellulose and the polytetrafluoroethylene, and stirring for 30min at the temperature of 70 ℃ to obtain a mixture A1;
a2, adding an inorganic filler, a styrene-acrylic emulsion and zinc powder into the mixture A, and stirring at 70 ℃ for 30min to obtain a mixture A2; grinding and filtering the mixture B to obtain a filtrate, namely a component A;
the preparation method of the component B comprises the following steps: and mixing the curing agent and the diluent, and uniformly stirring to obtain the component B.
The invention also provides a preparation method of the sintered neodymium-iron-boron magnet, which comprises the following steps:
s1, placing the magnet substrate in the corrosion-resistant protective coating for dipping, then pulling the magnet substrate upwards, separating the magnet substrate from the corrosion-resistant protective coating and suspending the magnet substrate above the corrosion-resistant protective coating; repeating the steps of dipping and pulling to obtain a magnet matrix coated with a primary coating;
and S2, curing the primary coating film of the magnet substrate to obtain the sintered neodymium iron boron magnet coated with the corrosion-resistant protective coating.
Further, in step S1, the dipping time is 30S each time, the time for which the magnet substrate is separated from the corrosion-resistant protective coating and suspended after each pulling is 90S, and the number of times of the above-mentioned steps is 30. In the step S2, the curing temperature of the primary coating film is 80 ℃ and the curing time is 35 min.
The rest of this embodiment is similar to embodiment 1, and is not described herein again.
Example 3
In this embodiment, a processing method of a high-magnetism sintered neodymium iron boron magnet includes the following steps:
(1) taking neodymium iron boron magnet powder, carrying out orientation molding in a magnetic field, and then carrying out isostatic pressing treatment and compression molding to prepare a magnet green body;
(2) placing the magnet green body in a sintering furnace for sintering, and then carrying out tempering heat treatment to obtain a magnet substrate;
(3) and cleaning the surface of the prepared magnet substrate, and coating a corrosion-resistant protective coating on the outer surface of the magnet substrate to prepare the high-magnetism sintered neodymium-iron-boron magnet.
Further, in the step (1), the neodymium iron boron magnet powder comprises the following raw materials in percentage by mass: 24% of neodymium, 6.7% of praseodymium, 1.18% of boron, 1.37% of lanthanum, 0.9% of aluminum, 0.3% of cobalt, 0.24% of copper, 0.15% of zirconium, 0.22% of gallium, 1.0% of silicon, 4.5% of graphene and the balance of iron.
Further, in the step (1), the neodymium iron boron magnet powder is oriented in a magnetic field with the magnetic field intensity of 3.0T.
Further, in the step (1), the pressure of the isostatic pressing treatment is 400MPa, and the treatment time is 2 min.
Further, in the step (2), the magnet green body is placed in a sintering furnace under the protection of argon gas for sintering, the temperature is increased to 680 ℃ at 9 ℃/min, the temperature is kept for 180min, then the temperature is increased to 1100 ℃ at 12 ℃/min, and the magnet green body is sintered for 210min at the temperature.
Further, in the step (2), the sintered magnet green body is subjected to a tertiary tempering treatment. The temperature of the first-stage tempering heat treatment is 950 ℃, and the heat preservation time is 120 min; the temperature of the second-stage tempering heat treatment is 680 ℃, and the heat preservation time is 120 min; the temperature of the third-stage tempering heat treatment is 600 ℃, and the heat preservation time is 90 min.
Further, in the step (3), the step of coating the surface of the neodymium iron boron magnet substrate with the corrosion-resistant protective coating comprises the following specific steps:
s1, placing the magnet substrate in the corrosion-resistant protective coating for dipping, then pulling the magnet substrate upwards, separating the magnet substrate from the corrosion-resistant protective coating and suspending the magnet substrate above the corrosion-resistant protective coating; repeating the steps of dipping and pulling to obtain a magnet matrix coated with a primary coating;
and S2, curing the primary coating film of the magnet substrate to obtain the high-magnetism sintered NdFeB magnet coated with the corrosion-resistant protective coating.
In the embodiment, the corrosion-resistant protective coating comprises a component A and a component B, wherein the component A comprises the following raw materials in parts by weight: 100 parts of bisphenol A epoxy resin, 20 parts of phenolic resin, 16 parts of acrylic resin, 9 parts of polytetrafluoroethylene, 20 parts of inorganic filler, 20 parts of functional assistant, 10 parts of hydroxyethyl cellulose, 8 parts of styrene-acrylic emulsion, 20 parts of zinc powder, 4 parts of silane coupling agent and 60 parts of solvent; the component B comprises the following raw materials in parts by weight: 5 parts of curing agent and 8 parts of diluent.
Further, the preparation method of the functional auxiliary agent comprises the following steps: mixing 12 parts of graphene, 10 parts of isobutylene-maleic anhydride copolymer, 10 parts of vinyl bis-stearamide, 8 parts of isobutyl triethoxysilane and 15 parts of polyethylene glycol in parts by weight, uniformly stirring at 95 ℃, and keeping the temperature for 45 min; obtaining the functional additive.
Further, the preparation method of the corrosion-resistant protective coating comprises the following steps:
the preparation method of the component A comprises the following steps:
a1, uniformly mixing the functional additive, the silane coupling agent and the solvent according to the parts by weight, then adding the bisphenol A type epoxy resin, the phenolic resin, the acrylic resin, the hydroxyethyl cellulose and the polytetrafluoroethylene, and stirring for 20min at the temperature of 80 ℃ to obtain a mixture A1;
a2, adding an inorganic filler, a styrene-acrylic emulsion and zinc powder into the mixture A, and stirring at 80 ℃ for 20min to obtain a mixture A2; grinding and filtering the mixture B to obtain a filtrate, namely a component A;
the preparation method of the component B comprises the following steps: and mixing the curing agent and the diluent, and uniformly stirring to obtain the component B.
The invention also provides a preparation method of the sintered neodymium-iron-boron magnet, which comprises the following steps:
s1, placing the magnet substrate in the corrosion-resistant protective coating for dipping, then pulling the magnet substrate upwards, separating the magnet substrate from the corrosion-resistant protective coating and suspending the magnet substrate above the corrosion-resistant protective coating; repeating the steps of dipping and pulling to obtain a magnet matrix coated with a primary coating;
and S2, curing the primary coating film of the magnet substrate to obtain the sintered neodymium iron boron magnet coated with the corrosion-resistant protective coating.
Further, in step S1, the dipping time is 40S each time, the time for which the magnet base is separated from the corrosion-resistant protective coating and suspended after each pulling is 60S, and the number of repetitions is 30. In the step S2, the curing temperature of the primary coating film is 90 ℃ and the curing time is 25 min.
The rest of this embodiment is similar to embodiment 1, and is not described herein again.
Example 4
In this embodiment, a processing method of a high-magnetism sintered neodymium iron boron magnet includes the following steps:
(1) taking neodymium iron boron magnet powder, carrying out orientation molding in a magnetic field, and then carrying out isostatic pressing treatment and compression molding to prepare a magnet green body;
(2) placing the magnet green body in a sintering furnace for sintering, and then carrying out tempering heat treatment to obtain a magnet substrate;
(3) and cleaning the surface of the prepared magnet substrate, and coating a corrosion-resistant protective coating on the outer surface of the magnet substrate to prepare the high-magnetism sintered neodymium-iron-boron magnet.
Further, in the step (1), the neodymium iron boron magnet powder comprises the following raw materials in percentage by mass: 23.2% of neodymium, 7.2% of praseodymium, 1.15% of boron, 1.6% of lanthanum, 0.7% of aluminum, 0.35% of cobalt, 0.22% of copper, 0.17% of zirconium, 0.19% of gallium, 1.2% of silicon, 3.8% of graphene and the balance of iron.
In the embodiment, the corrosion-resistant protective coating comprises a component A and a component B, wherein the component A comprises the following raw materials in parts by weight: 95 parts of bisphenol A epoxy resin, 15 parts of phenolic resin, 12 parts of acrylic resin, 6 parts of polytetrafluoroethylene, 16 parts of inorganic filler, 15 parts of functional assistant, 6 parts of hydroxyethyl cellulose, 5 parts of styrene-acrylic emulsion, 16 parts of zinc powder, 3 parts of silane coupling agent and 55 parts of solvent; the component B comprises the following raw materials in parts by weight: 4 parts of curing agent and 7 parts of diluent.
Further, the preparation method of the functional auxiliary agent comprises the following steps: mixing 10 parts of graphene, 6 parts of isobutylene-maleic anhydride copolymer, 7 parts of vinyl bis stearamide, 5 parts of isobutyl triethoxysilane and 12 parts of polyethylene glycol in parts by weight, uniformly stirring at 90 ℃, and keeping the temperature for 60 min; obtaining the functional additive.
The rest of this embodiment is similar to embodiment 1, and is not described herein again.
Comparative example 1
The comparative example differs from example 1 in that: the corrosion-resistant protective paint of the comparative example does not contain a functional additive, the functional additive is replaced by a mixture of epoxy resin, acrylic resin and phenolic resin with the same amount, and the weight ratio of the epoxy resin, the acrylic resin and the phenolic resin in the comparative example is the same as that in example 1. The rest of this embodiment is similar to embodiment 1, and is not described herein again.
Comparative example 2
The comparative example differs from example 1 in that: the corrosion-resistant protective coating of the comparative example does not contain styrene-acrylic emulsion, hydroxyethyl cellulose and polytetrafluoroethylene, the styrene-acrylic emulsion, the hydroxyethyl cellulose and the polytetrafluoroethylene are replaced by the mixture of epoxy resin, acrylic resin and phenolic resin with the same amount, and the weight ratio of the epoxy resin, the acrylic resin and the phenolic resin in the comparative example is the same as that in example 1. The rest of this embodiment is similar to embodiment 1, and is not described herein again.
The sintered nd-fe-b magnets prepared in examples 1 to 4 and comparative examples 1 to 2 were formed into a coating layer having a thickness of 30 ± 3 μm, and a performance test was performed. Wherein the salt spray resistance is GB/T1771-2007; water resistance according to GB/T1771-1993; acid and alkali resistance according to GB/T9274-1988; the moisture and heat resistance is in accordance with GB/T1740-2007; flash rust inhibition test the test performance was determined according to HG/T4759-2014, with the following results:
flash rust inhibition test: examples 1 to 4 and comparative examples 1 to 2 were normal. Water resistance test (500 h): examples 1-4 and comparative examples 1-2 did not blister, flake, rust, or crack. Salt spray resistance test (500 h): examples 1-4 and comparative example 2 did not blister, flake, rust, crack; comparative example 1 was slightly peeled off and rusted. Acid resistance test (48H, 50g/L, H)2SO4): examples 1-4 were all free of abnormalities; comparative examples 1-2 were slightly peeled off and slightly rusted. Alkali resistance test (240h,50g/L, NaOH): examples 1-4 were all free of abnormalities; comparative examples 1-2 all foamed. Test for Wet Heat resistance (240 h): examples 1 to 4 did not blister, did not peel off, did not rust, did not crack, the bubble density of comparative example 1 was very low, several bubbles, and the bubble density of comparative example 2 was low with a few bubbles, slightly peeled off.
The impact resistance, the grid test and the comprehensive aging performance test of the protective coating were carried out on examples 1 to 4 and comparative examples 1 to 2, and the test results are as follows:
wherein the impact resistance is in accordance with GB/T1732-1993, and the impact resistance test takes 5cm as an interval. The lattice test is according to GB/T9286-1998; the rating method for coating ageing is according to GB/T1766-2008.
The Nd-Fe-B magnets of examples 1-4 were prepared into cylinder magnets with height of phi 250mm × 25mm, and the observation and performance measurement of examples 1-4 were carried out according to GB/T13560-:
| item | Maximum magnetic energy product | Intrinsic coercive force | Compressive strength |
| Unit of | MGoe | KA/m | N/mm2 |
| Example 1 | 58 | 1256 | 1178 |
| Example 2 | 55 | 1189 | 1152 |
| Example 3 | 53 | 1205 | 1196 |
| Example 4 | 56 | 1228 | 1132 |
The processing method of the high-magnetism sintered neodymium iron boron magnet is simple and easy to control in operation, high in production efficiency and product yield, stable in product quality and beneficial to industrial production, and the prepared sintered neodymium iron boron magnet has excellent magnetic performance and corrosion resistance and excellent comprehensive performance.
The above-described embodiments are preferred implementations of the present invention, and the present invention may be implemented in other ways without departing from the spirit of the present invention.
Claims (10)
1. A processing method of a high-magnetism sintered neodymium iron boron magnet is characterized by comprising the following steps: the method comprises the following steps:
(1) taking neodymium iron boron magnet powder, carrying out orientation molding in a magnetic field, and then carrying out isostatic pressing treatment and compression molding to prepare a magnet green body;
(2) placing the magnet green body in a sintering furnace for sintering, and then carrying out tempering heat treatment to obtain a magnet substrate;
(3) and cleaning the surface of the prepared magnet substrate, and coating a corrosion-resistant protective coating on the outer surface of the magnet substrate to prepare the high-magnetism sintered neodymium-iron-boron magnet.
2. The processing method of the high-magnetism sintered neodymium-iron-boron magnet according to claim 1, characterized in that: in the step (1), the neodymium iron boron magnet powder is oriented in a magnetic field with the magnetic field intensity of 2.5-3.0T.
3. The processing method of the high-magnetism sintered neodymium-iron-boron magnet according to claim 1, characterized in that: in the step (1), the pressure of the isostatic pressing treatment is 300-400MPa, and the treatment time is 2-3 min.
4. The processing method of the high-magnetism sintered neodymium-iron-boron magnet according to claim 1, characterized in that: in the step (2), the green magnet is placed in a sintering furnace for sintering under the protection of argon, the temperature is raised to 640-.
5. The processing method of the high-magnetism sintered neodymium-iron-boron magnet according to claim 1, characterized in that: and (3) in the step (2), carrying out three-stage tempering treatment on the sintered magnet green body.
6. The processing method of the high-magnetism sintered neodymium-iron-boron magnet according to claim 5, characterized in that: in the step (2), the temperature of the first-stage tempering heat treatment is 950 ℃ and the heat preservation time is 180 min; the temperature of the second-stage tempering heat treatment is 620-680 ℃, and the heat preservation time is 120-180 min; the temperature of the third-stage tempering heat treatment is 550-.
7. The processing method of the high-magnetism sintered neodymium-iron-boron magnet according to claim 1, characterized in that: in the step (1), the neodymium iron boron magnet powder comprises the following raw materials in percentage by mass: 21-24% of neodymium, 6.7-7.4% of praseodymium, 0.98-1.18% of boron, 1.3-1.7% of lanthanum, 0.6-0.9% of aluminum, 0.3-0.5% of cobalt, 0.2-0.24% of copper, 0.15-0.19% of zirconium, 0.14-0.22% of gallium, 1.0-1.5% of silicon, 3-4.5% of graphene and the balance of iron.
8. The processing method of the high-magnetism sintered neodymium-iron-boron magnet according to claim 1, characterized in that: in the step (3), the specific steps of coating the surface of the neodymium iron boron magnet substrate with the corrosion-resistant protective coating are as follows:
s1, placing the magnet substrate in the corrosion-resistant protective coating for dipping, then pulling the magnet substrate upwards, separating the magnet substrate from the corrosion-resistant protective coating and suspending the magnet substrate above the corrosion-resistant protective coating; repeating the steps of dipping and pulling to obtain a magnet matrix coated with a primary coating;
and S2, curing the primary coating film of the magnet substrate to obtain the high-magnetism sintered NdFeB magnet coated with the corrosion-resistant protective coating.
9. The method for processing a high-magnetism sintered neodymium-iron-boron magnet according to claim 8, characterized in that: in the step S1, the corrosion-resistant protective coating comprises a component A and a component B, wherein the component A comprises the following raw materials in parts by weight: 90-100 parts of bisphenol A epoxy resin, 12-20 parts of phenolic resin, 10-16 parts of acrylic resin, 5-9 parts of polytetrafluoroethylene, 14-20 parts of inorganic filler, 14-20 parts of functional assistant, 5-10 parts of hydroxyethyl cellulose, 4-8 parts of styrene-acrylic emulsion, 14-20 parts of zinc powder, 1-4 parts of silane coupling agent and 45-60 parts of solvent.
10. The utility model provides a high magnetism sintering neodymium iron boron magnet which characterized in that: the neodymium iron boron magnet comprises the following raw materials in percentage by mass: 21-24% of neodymium, 6.7-7.4% of praseodymium, 0.98-1.18% of boron, 1.3-1.7% of lanthanum, 0.6-0.9% of aluminum, 0.3-0.5% of cobalt, 0.2-0.24% of copper, 0.15-0.19% of zirconium, 0.14-0.22% of gallium, 1.0-1.5% of silicon, 3-4.5% of graphene and the balance of iron.
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