CN112768169B - Preform, method for producing the same, method for producing corrosion-resistant magnet, and use of the same - Google Patents
Preform, method for producing the same, method for producing corrosion-resistant magnet, and use of the same Download PDFInfo
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- CN112768169B CN112768169B CN202011605936.9A CN202011605936A CN112768169B CN 112768169 B CN112768169 B CN 112768169B CN 202011605936 A CN202011605936 A CN 202011605936A CN 112768169 B CN112768169 B CN 112768169B
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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
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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
- H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
- H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
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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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Abstract
The invention discloses a neodymium iron boron magnet prefabricated product. The carbon content of the surface of the neodymium iron boron magnet prefabricated product is 2-35 wt%. The preform has good corrosion resistance after bluing. The invention also discloses a preparation method of the neodymium iron boron prefabricated product. The invention also discloses a production method of the corrosion-resistant magnet and application of the organic matter in improving the corrosion resistance of the neodymium iron boron magnet.
Description
Technical Field
The invention relates to a neodymium iron boron magnet prefabricated product and a preparation method thereof, and also relates to a production method of a corrosion-resistant magnet and application of an organic matter.
Background
The Nd-Fe-B magnet is a tetragonal crystal formed by Nd, fe and B, and its magnetic energy product (BH) max ) Is larger than samarium cobalt magnet, so it is widely used in hard disk, mobile phone, earphone and other electronic products. The neodymium iron boron magnet comprises a sintered neodymium iron boron magnet and a bonded neodymium iron boron magnet. The bonded neodymium iron boron magnet has better corrosion resistance. Sintered nd-fe-b magnets have poor corrosion resistance, and thus a protective film needs to be formed on the surface of the magnet.
CN104342614A discloses a surface treatment method of sintered neodymium iron boron magnet. Degreasing, deoiling and blow-drying the magnet by adopting sodium phosphate, sodium carbonate and sodium hydroxide; then, bluing treatment is carried out to form a ferroferric oxide protective film on the surface of the magnet. Specifically, the magnet is placed in a bluing furnace, preheated for 10 minutes at 300-350 ℃, introduced with water vapor, and bluing is carried out under the condition that the air pressure of the water vapor is 0.05-600 Pa. This method requires the introduction of steam to control the pressure of the steam, increases the difficulty of operation, and is not satisfactory in corrosion resistance.
CN100473759C discloses a surface treatment method for neodymium iron boron magnet. Polishing the magnet by adopting a mechanical vibration grinding and tumbling chamfering method; adding an alkaline degreasing agent for degreasing and deoiling; adding an acid solution for acid cleaning and rust removal; and placing the acid-washed magnet in blackening solution or bluing solution for chemical film plating. The blackening liquid comprises molybdate, aluminum salt and a complexing agent. Molybdate costs more. The bluing liquid comprises an alkali, a nitrite salt and an organic additive. Nitrite is not friendly to human health and the environment.
Disclosure of Invention
In one aspect, the present invention provides a neodymium iron boron magnet preform having good corrosion resistance after bluing.
On the other hand, the invention provides a preparation method of the neodymium iron boron magnet prefabricated product.
In still another aspect, the present invention provides a method for producing a corrosion-resistant magnet, which can provide a magnet having excellent corrosion resistance.
In another aspect, the invention provides an application of an organic substance in improving the corrosion resistance of a neodymium iron boron magnet.
The technical problem is solved by the following technical scheme.
On one hand, the invention provides a neodymium iron boron magnet prefabricated product, the carbon content of the surface of which is 2-35 wt%; the neodymium iron boron magnet prefabricated product is a prefabricated product of a sintered neodymium iron boron permanent magnet; the carbon content represents the weight percentage of the carbon elements on the surface of the neodymium-iron-boron magnet preform to all elements of the surface, as determined by X-ray energy spectroscopy.
On the other hand, the invention provides a preparation method of a neodymium iron boron magnet prefabricated product, which comprises the following steps: the method comprises the steps of pretreating the neodymium iron boron magnet by adopting pretreatment liquid to obtain a neodymium iron boron magnet prefabricated product, wherein the carbon content of the surface of the neodymium iron boron magnet prefabricated product is 2-35 wt%; wherein the pretreatment liquid is selected from one or more of alcohols containing 1 to 16 carbon atoms, ketones containing 3 to 16 carbon atoms, alkanes containing 1 to 16 carbon atoms, cycloalkanes containing 3 to 16 carbon atoms, rust preventive oil, gasoline, engine oil or diesel oil.
In still another aspect, the present invention provides a method for producing a corrosion-resistant magnet, comprising the steps of:
(1) Pretreating the neodymium iron boron magnet by adopting pretreatment liquid to obtain a neodymium iron boron magnet prefabricated product, wherein the carbon content on the surface of the neodymium iron boron magnet prefabricated product is 2-35 wt%; wherein the neodymium iron boron magnet is a sintered neodymium iron boron permanent magnet; the carbon content represents the weight percentage of the carbon elements on the surface of the neodymium-iron-boron magnet prefabricated product to all elements on the surface, and is measured by an X-ray energy spectrometer; the pretreatment liquid is one or more selected from alcohol containing 1-16 carbon atoms, ketone containing 3-16 carbon atoms, alkane containing 1-16 carbon atoms, cyclane containing 3-16 carbon atoms, anti-rust oil, gasoline, engine oil or diesel oil;
(2) And carrying out bluing treatment on the neodymium iron boron magnet prefabricated product to obtain the corrosion-resistant magnet.
According to the production method of the present invention, preferably, the pretreatment liquid is selected from one or more of an alkyl alcohol having 1 to 6 carbon atoms, an alkyl ketone having 3 to 6 carbon atoms, a cycloalkanone having 3 to 6 carbon atoms, gasoline, engine oil or diesel oil.
According to the production method of the invention, preferably, the bluing treatment is carried out in a tunnel bluing furnace, the bluing temperature is 200-480 ℃, and the bluing time is 5-60 min.
According to the production method of the present invention, preferably, the process for preparing the pre-treated ndfeb magnet comprises the steps of: and carrying out ultrasonic treatment on the magnet to be treated for 30-90 s in the presence of deoiling liquid to obtain the deoiling magnet.
According to the production method of the invention, preferably, the oil-removing liquid comprises sodium hydroxide and trisodium phosphate, and also comprises at least one compound selected from (a) to (c);
(a) Sodium carbonate;
(b) Sodium silicate;
(c) A surfactant;
the weight percentage of solute in the deoiling liquid is 0.3-5 wt%.
According to the production method of the present invention, preferably, the process for preparing the pre-treated ndfeb magnet further comprises the steps of: washing the deoiled magnet for 30-90 s under the action of ultrasonic waves, then drying the water on the surface of the washed magnet by blowing, and drying for 1-6 h at 90-150 ℃ to obtain the dried magnet.
According to the production method of the present invention, preferably, the process for preparing the pre-treated ndfeb magnet further comprises the steps of: carrying out sand blasting on the dry magnet on an automatic sand blasting machine; the swinging frequency of the spray gun is 2-15 Hz, the pressure of the spray gun is 0.01-0.5 MPa, and the sand blasting time is 2-20 min.
In another aspect, the invention also provides the application of the organic matter in improving the corrosion resistance of the neodymium iron boron magnet, wherein the neodymium iron boron magnet is a sintered neodymium iron boron permanent magnet; the organic matter is selected from one or more of alcohol containing 1-16 carbon atoms, ketone containing 3-16 carbon atoms, alkane containing 1-16 carbon atoms, cyclane containing 3-16 carbon atoms, antirust oil, gasoline, engine oil or diesel oil.
According to the invention, the carbon content of the surface of the sintered NdFeB magnet prefabricated product is controlled within a certain range, and the NdFeB magnet with good corrosion resistance can be obtained through simple bluing treatment.
Drawings
Fig. 1 is a schematic view of the structure of a corrosion resistant magnet according to the present invention.
The reference numerals are illustrated below:
1-protective film; 2-neodymium iron boron magnet.
Detailed Description
The present invention will be further described with reference to the following specific examples, but the scope of the present invention is not limited thereto.
< preform of NdFeB magnet >
The neodymium iron boron magnet preform of the present invention represents an intermediate product prior to forming the corrosion resistant magnet. The neodymium iron boron magnet is preferably a sintered neodymium iron boron permanent magnet. The carbon content of the surface of the neodymium iron boron magnet preform may be 2 to 35wt%. Generally, in the production process of sintered nd-fe-b magnets, it is necessary to ensure that the carbon content of the magnets is sufficiently low to ensure the magnetic properties thereof. Therefore, one generally has no motivation to increase the carbon content of the magnet preform surface. The present inventors have found that by controlling the carbon content on the surface of the magnet preform to a certain range, the corrosion resistance can be significantly improved. Although most of the carbon element is removed after the bluing treatment, it does improve the corrosion resistance of the magnet, for reasons that have not been clarified yet.
The carbon content represents the weight percentage of carbon element in all elements in the surface of the neodymium iron boron magnet prefabricated product. The carbon content was determined using an X-ray energy spectrometer (EDS). Typically, a scanning electron microscope is provided with EDS. The carbon content of the surface of the neodymium iron boron magnet preform is preferably 10 to 30wt%. The carbon content of the surface of the neodymium iron boron magnet preform is more preferably 15 to 25wt%. This contributes to further improvement of corrosion resistance.
In the prior art, the sintered neodymium-iron-boron magnet with better corrosion resistance can be obtained by controlling the atmospheric pressure of water vapor or controlling the atmosphere parameters of bluing treatment such as oxygen content and the like. The neodymium iron boron magnet prefabricated product can obtain excellent corrosion resistance through simple bluing treatment.
< preparation method of preform of NdFeB magnet >
And (3) pretreating the neodymium iron boron magnet by adopting pretreatment liquid to obtain a neodymium iron boron magnet prefabricated product. The neodymium iron boron magnet is preferably a sintered neodymium iron boron permanent magnet. The carbon content of the surface of the neodymium iron boron magnet prefabricated product is 2-35 wt%. Preferably, the surface of the neodymium iron boron magnet prefabricated product has the carbon content of 10-30 wt%; more preferably 15 to 25wt%. This can further improve the corrosion resistance.
The purpose of using the pretreatment liquid is to increase the carbon content on the surface of the neodymium iron boron magnet preform. Since it is necessary to minimize the carbon content of the magnet in the production process of the sintered nd-fe-b magnet to secure the magnetic properties thereof, it is impossible to conceive of increasing the carbon content of the surface of the magnet preform to improve the corrosion resistance. Although other methods exist for increasing the carbon content on the surface of the neodymium-iron-boron magnet preform, the pretreatment method using the pretreatment liquid is more convenient and reliable.
The pretreatment liquid may be one or more selected from the group consisting of alcohols having 1 to 16 carbon atoms, ketones having 3 to 16 carbon atoms, paraffins having 1 to 16 carbon atoms, naphthenes having 3 to 16 carbon atoms, rust preventive oils, gasoline, engine oils, and diesel oils. Preferably, the pretreatment liquid of the present invention is selected from one or more of alcohols having 1 to 16 carbon atoms, ketones having 3 to 16 carbon atoms, paraffins having 1 to 16 carbon atoms, rust preventive oil, gasoline, engine oil or diesel oil.
To avoid interference, the water content in the pretreatment solution was minimized. The pretreatment liquid preferably does not contain water. The prior art generally needs to introduce steam water to improve the bluing effect, and the invention does not need such operation and can be carried out under conventional conditions.
The pretreatment solution of the present invention may be an alcohol having 1 to 16 carbon atoms; preferably alcohols containing 1 to 10 carbon atoms; more preferably alcohols containing 1 to 6 carbon atoms. The alcohol may be an alkyl alcohol. Examples of alcohols include, but are not limited to, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, isopentanol, neopentanol, hexanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, 2-ethyl-1-butanol, 2, 3-dimethyl-2-butanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol.
The pretreatment solution of the present invention may be a ketone having 3 to 16 carbon atoms; preferably a ketone of 3 to 10 carbon atoms; more preferably a ketone having 3 to 6 carbon atoms. The ketone may be an alkyl ketone or a cyclic alkanone. Examples of ketones include, but are not limited to, acetone, butanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-octanone, 3-octanone, 4-octanone, 2-nonanone, 3-nonanone, 4-nonanone, 5-nonanone, cyclopentanone, cyclohexanone, cycloheptanone.
The pretreatment liquid of the present invention may be an alkane having 1 to 16 carbon atoms; preferably an alkane of 1 to 10 carbon atoms; more preferably an alkane having 1 to 6 carbon atoms. Examples of alkanes include, but are not limited to, methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, hexane, 2-methyl-pentane, 3-methyl-pentane, 2-ethyl-butane, heptane, 2-methylhexane, 3-methylhexane, 2-ethylpentane, 3-ethylpentane, octane, 2-methylheptane, 3-methylheptane, 4-methylheptane, 2-ethylhexane, 3-ethylhexane, nonane, 2-methyloctane, 3-methyloctane, 4-methyloctane, 2-ethylheptane, 3-ethylheptane, 4-ethylheptane, 2-propylhexane, 3-propylhexane, decane.
The pretreatment liquid of the present invention may be cycloalkane having 3 to 16 carbon atoms; preferably cycloalkanes having 3 to 12 carbon atoms; more preferably a cycloalkane having 3 to 9 carbon atoms. Examples of cycloalkanes include, but are not limited to, cyclopropane, cyclopentane, methylcyclopentane, ethylcyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane, isopropylcyclohexane.
The pretreatment liquid of the present invention may be one or more selected from the group consisting of rust preventive oil, gasoline, engine oil and diesel oil. According to one embodiment of the present invention, the pretreatment liquid is ethanol or engine oil. According to another embodiment of the present invention, the pretreatment liquid is engine oil. Thus, the method is more environment-friendly and has lower cost.
< method for producing Corrosion-resistant magnet >
The production method of the corrosion-resistant magnet comprises the following steps: (1) a pretreatment step; and (2) bluing. Optionally, before the pretreatment step, a degreasing, water washing, drying and sand blasting process may be further included to perform a surface treatment on the magnet to be treated, so as to facilitate the binding of the pretreatment liquid to the magnet.
Oil removal
And (4) carrying out oil removal treatment on the magnet to be treated. The magnet to be treated is a sintered neodymium iron boron permanent magnet. The magnet to be treated can be a neodymium iron boron magnet subjected to chamfering treatment. Therefore, the surface of the neodymium iron boron magnet can be smoother, and formation of a protective film is facilitated.
In the invention, the deoiling liquid can be adopted to carry out deoiling treatment on the magnet to be treated, so as to obtain the deoiled magnet. In certain embodiments, the neodymium iron boron magnet is sonicated in the presence of a degreasing fluid. Before pretreatment, the magnet to be treated is subjected to ultrasonic treatment for 30-90 s in the presence of deoiling liquid, so that the deoiling magnet is obtained. The time of ultrasonic treatment can be 30-90 s; preferably 30 to 60s; more preferably 30 to 50 seconds. This facilitates the removal of grease from the magnet surface.
The deoiling liquid of the invention can comprise sodium hydroxide, trisodium phosphate and at least one compound selected from (a) to (c); sodium carbonate, (b) sodium silicate, and (c) a surfactant. The degreasing fluid may be an aqueous solution comprising the solute. The surfactant can be one or more selected from sodium dodecyl sulfate, tween 40, tween 60, monolauryl phosphate MAP, coconut oil fatty diethanol amide, NP-8, NP-9, NP-10, OP-8, OP-10, OP-13 and OP-15; preferably, the surfactant is selected from one or more of Tween 60, monolauryl phosphate MAP, coconut oil fatty diethanol amide, NP-8, NP-9, OP-8, OP-10; more preferably, the surfactant is selected from one or more of the group consisting of monolauryl phosphate MAP, coconut oil fatty acyl diethanol amine, OP-10. The weight percentage of solute in the deoiling liquid can be 0.3-5 wt%; preferably 0.3 to 3wt%; more preferably 0.5 to 2wt%. This contributes to achieving a better oil removal effect, thereby improving the degree of binding of the magnet to the pretreatment liquid.
In certain embodiments, the deoiling liquid comprises sodium hydroxide, trisodium phosphate and sodium silicate. Preferably, the degreasing fluid consists of sodium hydroxide, trisodium phosphate, sodium silicate and water. The amount of sodium hydroxide may be 10 to 40 parts by weight; preferably 20 to 40 parts by weight; more preferably 20 to 30 parts by weight. The trisodium phosphate can be used in an amount of 15-40 parts by weight; preferably 25 to 40 parts by weight; more preferably 25 to 30 parts by weight. The amount of sodium silicate may be 1-15 parts by weight; preferably 3 to 10 parts by weight; more preferably 5 to 8 parts by weight.
In other embodiments, the deoiling liquid comprises sodium hydroxide, sodium carbonate, trisodium phosphate and a surfactant. Preferably, the deoiling liquid consists of sodium oxide, sodium carbonate, trisodium phosphate, surfactant and water. The amount of sodium hydroxide may be 10 to 40 parts by weight; preferably 20 to 40 parts by weight; more preferably 20 to 30 parts by weight. The amount of sodium carbonate may be 10 to 50 parts by weight; preferably 20 to 40 parts by weight; more preferably 30 to 40 parts by weight. The trisodium phosphate can be used in an amount of 10 to 50 parts by weight; preferably 20 to 40 parts by weight; more preferably 30 to 40 parts by weight. The amount of the surfactant may be 1 to 7 parts by weight; preferably 1 to 5 parts by weight; more preferably 2 to 4 parts by weight.
In still other embodiments, the deoiling liquid comprises sodium hydroxide, sodium carbonate, trisodium phosphate and sodium silicate. Preferably, the degreasing liquid consists of sodium hydroxide, sodium carbonate, trisodium phosphate, sodium silicate and water. The amount of sodium hydroxide may be 5 to 25 parts by weight; preferably 10 to 25 parts by weight; more preferably 10 to 15 parts by weight. The amount of sodium carbonate may be 10 to 40 parts by weight; preferably 20 to 40 parts by weight; more preferably 20 to 30 parts by weight. The trisodium phosphate can be used in an amount of 40-80 parts by weight; preferably 50 to 80 parts by weight; more preferably 50 to 70 parts by weight. The amount of sodium silicate may be 1-8 parts by weight; preferably 1 to 5 parts by weight; more preferably 2 to 4 parts by weight.
Washing with water and drying
The deoiled magnet can be washed with water and dried to obtain a dried magnet. The purpose of water washing is to clean the deoiling liquid remained on the surface of the magnet. According to one embodiment of the invention, ultrasonic water washing is used. Washing the deoiled magnet under the action of ultrasonic wave. The time of water washing can be 30-90 s; preferably 30 to 60s; more preferably 40 to 60 seconds.
The purpose of drying is to remove moisture from the magnet surface. According to one embodiment of the invention, the washed magnet surface is now moisture dried and then oven dried in an oven. The drying temperature can be 90-150 ℃; preferably 90 to 130 ℃; more preferably from 90 to 110 ℃. The drying time can be 1-6 h; preferably 1-4 h; more preferably 1 to 3 hours. This is advantageous in improving the degree of binding of the magnet to the pretreatment liquid.
Sand blasting
And carrying out sand blasting treatment on the dried magnet to obtain the neodymium iron boron magnet. Preferably, the blasting treatment may be performed in an automatic blasting machine. The swinging frequency of the spray gun can be 2-15 Hz; preferably 5 to 12Hz; more preferably 8 to 10Hz. The pressure of the spray gun can be 0.01-0.5 MPa; preferably 0.02 to 0.3MPa; more preferably 0.02 to 0.25MPa. The sand blasting time can be 2-20 min; preferably 2-10 min; more preferably 5 to 7min. Such treatment conditions are advantageous for improving the degree of binding of the magnet to the pretreatment liquid.
Step of pretreatment
And (3) pretreating the neodymium iron boron magnet (the magnet subjected to sand blasting) by using pretreatment liquid to obtain a neodymium iron boron magnet prefabricated product. The pretreatment solution was as described above. And will not be described in detail herein.
The carbon content on the surface of the neodymium iron boron magnet prefabricated product is 2-35 wt%; preferably 10 to 30wt%; more preferably 15 to 25wt%. The carbon content represents the weight percentage of carbon elements on the surface of the neodymium iron boron magnet preform to all elements of the surface, as determined by X-ray energy spectroscopy (EDS).
The invention finds that the carbon content of the surface of the magnet preform has a great influence on the corrosion resistance of the treated neodymium-iron-boron magnet. The processed neodymium iron boron magnet has ideal corrosion resistance due to the fact that the carbon content is too high or too low. Although the mechanism is not clear, the applicant speculates that the pretreatment liquid may penetrate into the pores of the magnet surface, and improve the corrosion resistance of these portions after bluing treatment, thereby improving the corrosion resistance of the magnet as a whole. Thus, the preform of the present invention does not require a particularly complex bluing process to improve corrosion resistance.
Bluing treatment step
And (4) carrying out bluing treatment on the neodymium iron boron magnet treated by the pretreatment liquid to obtain the corrosion-resistant magnet. In the prior art, the sintered neodymium-iron-boron magnet with better corrosion resistance can be obtained by controlling the atmospheric pressure of water vapor or controlling the atmosphere parameters of bluing treatment such as oxygen content and the like. The neodymium iron boron magnet prefabricated product can improve the corrosion resistance of the magnet through a simple bluing treatment process.
The bluing treatment may be carried out under ordinary conditions without additionally controlling the water vapor partial pressure and the oxygen partial pressure. The bluing temperature and bluing time are still important for the improvement of corrosion resistance, but it is relatively easy to control these parameters. The bluing temperature of the invention can be 200-480 ℃; preferably 300 to 450 ℃; more preferably 350 to 400 ℃. The bluing time can be 5-60 min; preferably 8-20 min; more preferably 10 to 15min. This is advantageous in improving the corrosion resistance of the magnet. The bluing treatment may be performed in a bluing oven. The bluing furnace is preferably a tunnel bluing furnace. This is advantageous for mass production and improves the consistency of magnet performance.
< use of organic Material >
The invention also provides the application of the organic matter in improving the corrosion resistance of the neodymium iron boron magnet, and the neodymium iron boron magnet prefabricated product is a prefabricated product of a sintered neodymium iron boron permanent magnet. The organic matter is selected from one or more of alcohol containing 1-16 carbon atoms, ketone containing 3-16 carbon atoms, alkane containing 1-16 carbon atoms, cyclane containing 3-16 carbon atoms, antirust oil, gasoline, engine oil or diesel oil; preferably one or more of alcohols containing 1 to 16 carbon atoms, ketones containing 3 to 16 carbon atoms, paraffins containing 1 to 16 carbon atoms, gasoline, motor oil or diesel oil; more preferably one or more of alcohols containing 1 to 16 carbon atoms, motor oils or diesel fuels. The organic matter can increase the carbon content on the surface of the neodymium iron boron magnet prefabricated product. In the production of sintered nd-fe-b magnets, it is desirable to minimize the carbon content of the magnet to ensure its magnetic properties, and it is not easily conceivable to increase the carbon content of the magnet preform surface by some organics to improve corrosion resistance. To avoid interference, the water content of the organic matter is minimized. According to one embodiment of the invention, the organic substance does not contain moisture.
The organic matter of the present invention may be an alcohol having 1 to 16 carbon atoms; preferably alcohols containing 1 to 10 carbon atoms; more preferably alcohols containing 1 to 6 carbon atoms. The alcohol may be an alkyl alcohol. Examples of alcohols include, but are not limited to, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, isopentanol, neopentanol, hexanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, 2-ethyl-1-butanol, 2, 3-dimethyl-2-butanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol.
The organic matter of the present invention may be a ketone having 3 to 16 carbon atoms; preferably a ketone of 3 to 10 carbon atoms; more preferably a ketone having 3 to 6 carbon atoms. The ketone may be an alkyl ketone or a cyclic alkanone. Examples of ketones include, but are not limited to, acetone, butanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-octanone, 3-octanone, 4-octanone, 2-nonanone, 3-nonanone, 4-nonanone, 5-nonanone, cyclopentanone, cyclohexanone, cycloheptanone.
The organic material of the present invention may be an alkane having 1 to 16 carbon atoms; preferably an alkane of 1 to 10 carbon atoms; more preferably an alkane having 1 to 6 carbon atoms. Examples of alkanes include, but are not limited to, methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, hexane, 2-methyl-pentane, 3-methyl-pentane, 2-ethyl-butane, heptane, 2-methylhexane, 3-methylhexane, 2-ethylpentane, 3-ethylpentane, octane, 2-methylheptane, 3-methylheptane, 4-methylheptane, 2-ethylhexane, 3-ethylhexane, nonane, 2-methyloctane, 3-methyloctane, 4-methyloctane, 2-ethylheptane, 3-ethylheptane, 4-ethylheptane, 2-propylhexane, 3-propylhexane, decane.
The organic matter of the present invention may be cycloalkane containing 3 to 16 carbon atoms; preferably cycloalkanes having 3 to 12 carbon atoms; more preferably a cycloalkane having 3 to 9 carbon atoms. Examples of cycloalkanes include, but are not limited to, cyclopropane, cyclopentane, methylcyclopentane, ethylcyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane, isopropylcyclohexane.
The organic matter of the invention can be selected from one or more of antirust oil, gasoline, engine oil or diesel oil. According to one embodiment of the invention, the organic substance is ethanol or engine oil. According to another embodiment of the invention, the organic substance is engine oil. Thus, the method is more environment-friendly and has lower cost.
The use may comprise the steps of: the neodymium iron boron magnet is pretreated by adopting pretreatment liquid, and a neodymium iron boron magnet prefabricated product with the surface carbon content of 2-35 wt% is obtained. The neodymium iron boron magnet prefabricated product is a prefabricated product of a sintered neodymium iron boron permanent magnet. Preferably, the surface carbon content is 10 to 30wt%. More preferably, the surface carbon content is 15 to 25wt%. Specifically, the above-mentioned use may include the steps of: (1) deoiling, washing and drying; (2) a step of sand blasting; (3) a pretreatment step; and (4) bluing. The organic matter corresponds to the pretreatment liquid described above; the specific procedures and parameters are as described above.
The test methods of examples and comparative examples are described below:
(1) Surface carbon content:
the experimental procedure was carried out according to the method of GB/T-17359-2012.
(2) And (3) corrosion resistance testing:
the experimental process is carried out according to the method of GB/T-6807-2001, and the specific method is as follows: cooling the corrosion-resistant magnet to room temperature, immediately soaking the corrosion-resistant magnet in 3wt% sodium chloride aqueous solution, taking out samples at 15-25 ℃ every 1h, cleaning, blow-drying, visually checking whether the corrosion-resistant magnet surface is rusted, and recording the longest time that the corrosion-resistant magnet surface is not rusted.
Examples 1 to 3 and comparative examples 1 to 2
In an oil removing tank, in the presence of oil removing liquid (the weight percentage of solute is 1wt%, the composition of solute is shown in table 1, and the solvent is water), conducting ultrasonic treatment on the sintered neodymium iron boron magnet (the volume is 57.9 × 10.94 × 1.8 mm) subjected to chamfering treatment for 40s, and obtaining an oil removing magnet; and (3) ultrasonically washing the deoiled magnet for 50s, drying the moisture on the surface of the magnet, then placing the magnet in an oven, and drying for 2h at 100 ℃ to obtain a dried magnet.
And (3) placing the dried magnet into an automatic sand blasting machine for sand blasting treatment to obtain the sand-blasted magnet serving as the neodymium-iron-boron magnet. The gun rocking frequency, gun pressure and blasting time are shown in table 2.
And completely immersing the neodymium iron boron magnet into the pretreatment liquid for pretreatment to obtain a neodymium iron boron magnet prefabricated product. The carbon contents of the pretreatment liquid and the surface of the ndfeb magnet preform are shown in table 2.
Placing the neodymium iron boron magnet prefabricated product in a tunnel type bluing furnace for bluing to obtain a corrosion-resistant magnet; the bluing temperatures and bluing times are shown in Table 2. Fig. 1 is a schematic view of the structure of a corrosion resistant magnet according to the present invention. The corrosion-resistant magnet includes a neodymium iron boron magnet 2 and a protective film 1 attached thereto.
Comparative example 3
In an oil removing tank, in the presence of oil removing liquid (the weight percentage of solute is 1wt%, the composition of solute is shown in table 1, and the solvent is water), carrying out ultrasonic treatment on the chamfered sintered neodymium iron boron magnet (the volume is 57.9 × 10.94 × 1.8 mm) for 40s to obtain an oil removing magnet; and (3) carrying out ultrasonic water washing on the deoiled magnet for 50s, drying the moisture on the surface of the magnet, then placing the magnet in an oven, and drying for 2h at 100 ℃ to obtain a dried magnet.
And (3) placing the dried magnet into an automatic sand blasting machine for sand blasting treatment to obtain the sand-blasted magnet serving as the neodymium-iron-boron magnet. The swinging frequency of the spray gun is 5.0Hz, the pressure of the spray gun is 0.05MPa, and the sand blasting time is 10min.
And (4) placing the neodymium iron boron magnet in a tunnel type bluing furnace for bluing to obtain the corrosion-resistant magnet. The bluing temperature was 300 ℃ and the bluing time was 18min.
TABLE 1
TABLE 2
Examples of the experiments
The treated magnets of the above examples and comparative examples were subjected to a corrosion resistance test, and the results are shown in table 3.
TABLE 3
| Serial number | Saline assay (3wt% NaCl)/h |
| Example 1 | 6 |
| Example 2 | 8 |
| Example 3 | 7 |
| Comparative example 1 | 2 |
| Comparative example 2 | 3 |
| Comparative example 3 | 1 |
It is clear from example 1, comparative example 1 and comparative example 2 that the carbon content of the preform surface has an important influence on the corrosion resistance. The carbon content of comparative example 1 was too low, resulting in a decrease in corrosion resistance. The carbon content of comparative example 2 was too high, resulting in a decrease in corrosion resistance. As can be seen from examples 1 to 3 and comparative example 3, the corrosion resistance of the magnet subjected to the pretreatment is significantly better than that of the magnet not subjected to the pretreatment.
The present invention is not limited to the above-described embodiments, and any variations, modifications, and substitutions which may occur to those skilled in the art may be made without departing from the spirit of the invention.
Claims (10)
1. A neodymium iron boron magnet prefabricated product is characterized in that the carbon content of the surface of the neodymium iron boron magnet prefabricated product is 2-35 wt%; the neodymium iron boron magnet prefabricated product is a prefabricated product of a sintered neodymium iron boron permanent magnet; the carbon content represents the weight percentage of the carbon elements on the surface of the neodymium-iron-boron magnet prefabricated product to all elements on the surface, and is measured by an X-ray energy spectrometer;
the neodymium iron boron magnet prefabricated product is prepared by the following method: pretreating the neodymium iron boron magnet by adopting pretreatment liquid to obtain a neodymium iron boron magnet prefabricated product; wherein the pretreatment liquid is one or more selected from the group consisting of alcohols having 1 to 16 carbon atoms, ketones having 3 to 16 carbon atoms, paraffins having 1 to 16 carbon atoms, naphthenes having 3 to 16 carbon atoms, rust preventive oil, gasoline, engine oil and diesel oil.
2. The method of manufacturing a neodymium-iron-boron magnet preform according to claim 1, characterized by comprising the steps of: pretreating the neodymium iron boron magnet by adopting pretreatment liquid to obtain a neodymium iron boron magnet prefabricated product, wherein the carbon content on the surface of the neodymium iron boron magnet prefabricated product is 2-35 wt%; wherein the pretreatment liquid is selected from one or more of alcohols containing 1 to 16 carbon atoms, ketones containing 3 to 16 carbon atoms, alkanes containing 1 to 16 carbon atoms, cycloalkanes containing 3 to 16 carbon atoms, rust preventive oil, gasoline, engine oil or diesel oil.
3. A method for producing a corrosion-resistant magnet, comprising the steps of:
(1) Pretreating the neodymium iron boron magnet by adopting pretreatment liquid to obtain a neodymium iron boron magnet prefabricated product, wherein the carbon content on the surface of the neodymium iron boron magnet prefabricated product is 2-35 wt%; wherein the neodymium iron boron magnet is a sintered neodymium iron boron permanent magnet; the carbon content represents the weight percentage of the carbon elements on the surface of the neodymium-iron-boron magnet prefabricated product to all elements on the surface, and is measured by an X-ray energy spectrometer; the pretreatment liquid is one or more selected from alcohol containing 1-16 carbon atoms, ketone containing 3-16 carbon atoms, alkane containing 1-16 carbon atoms, cyclane containing 3-16 carbon atoms, anti-rust oil, gasoline, engine oil or diesel oil;
(2) And carrying out bluing treatment on the neodymium iron boron magnet prefabricated product to obtain the corrosion-resistant magnet.
4. The production method according to claim 3, wherein the pretreatment liquid is one or more selected from the group consisting of an alkyl alcohol having 1 to 6 carbon atoms, an alkyl ketone having 3 to 6 carbon atoms, a cycloalkanone having 3 to 6 carbon atoms, gasoline, engine oil, and diesel oil.
5. The production method according to claim 3, wherein the bluing is carried out in a tunnel bluing furnace at a bluing temperature of 200 to 480 ℃ for a bluing time of 5 to 60min.
6. The production method according to claim 3, wherein the preparation process of the neodymium-iron-boron magnet for pretreatment comprises the following steps: and carrying out ultrasonic treatment on the magnet to be treated for 30-90 s in the presence of deoiling liquid to obtain the deoiling magnet.
7. The production method according to claim 6, wherein the deoiling liquid comprises sodium hydroxide and trisodium phosphate, and further comprises at least one compound selected from (a) to (c);
(a) Sodium carbonate;
(b) Sodium silicate;
(c) A surfactant;
the weight percentage of solute in the deoiling liquid is 0.3-5 wt%.
8. The production method according to claim 6, wherein the preparation process of the neodymium-iron-boron magnet for pretreatment further comprises the following steps: washing the deoiled magnet for 30-90 s under the action of ultrasonic waves, drying the water on the surface of the washed magnet by blowing, and drying for 1-6 h at 90-150 ℃ to obtain the dried magnet.
9. The production method according to claim 8, wherein the preparation process of the neodymium-iron-boron magnet for pretreatment comprises the following steps: carrying out sand blasting on the dry magnet on an automatic sand blasting machine; the swinging frequency of the spray gun is 2-15 Hz, the pressure of the spray gun is 0.01-0.5 MPa, and the sand blasting time is 2-20 min.
10. The application of the organic matter in improving the corrosion resistance of the neodymium iron boron magnet is characterized by comprising the following steps of: pretreating a neodymium iron boron magnet by adopting an organic matter to obtain a neodymium iron boron magnet prefabricated product, wherein the carbon content on the surface of the neodymium iron boron magnet prefabricated product is 2-35 wt%; the organic matter is selected from one or more of alcohol containing 1-16 carbon atoms, ketone containing 3-16 carbon atoms, alkane containing 1-16 carbon atoms, cyclane containing 3-16 carbon atoms, antirust oil, gasoline, engine oil or diesel oil.
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