JP2022104854A - Preform and method of manufacturing the same, and production method and use of anticorrosive magnet - Google Patents

Abstract

To provide a neodymium iron boron magnet preform which has good corrosion resistance after a blueing treatment, and a manufacturing method.SOLUTION: A neodymium iron boron magnet preform contains 2-35 wt% of carbon on a preform surface, and has good corrosion resistance after a blueing treatment. In order to improve corrosion resistance of a neodymium iron boron magnet, an organic material is used which is one kind or a plurality of kinds selected out of alcohol including 1-16 carbon atoms, ketone including 3-16 carbon atoms, alkane including 1-16 carbon atoms, cycloalkane including 3-16 carbon atoms, rust preventive oil, gasoline, engine oil, and Diesel oil, and improves corrosion resistance of the neodymium iron boron magnet.SELECTED DRAWING: None

Description

The present invention relates to a neodymium iron boron magnet preform, a method for producing the same, a method for producing a corrosion resistant magnet, and the use of an organic substance.

Neodymium iron-boron magnets are square crystal crystals consisting of neodymium, iron, and boron, and because their magnetic energy product (BHmax) is larger than that of samarium-cobalt magnets, they are widely used in electronic products such as hard disks, mobile phones, and earphones. There is. Neodymium iron-boron magnets include sintered neodymium iron-boron magnets and bonded neodymium iron-boron magnets. Bond neodymium iron boron magnets have excellent corrosion resistance. Sintered neodymium iron boron magnets have relatively poor corrosion resistance, so it is necessary to form a protective film on the magnet surface.

CN104342614A is baked with sodium phosphate, sodium carbonate and sodium hydroxide to degrease the magnet to remove oil, blow dry, and then perform brewing treatment to form an iron oxide protective film on the magnet surface. A method for surface treatment of a neodymium iron boron magnet is disclosed. Specifically, the magnet is placed in a brewing furnace, preheated at 300 to 350 ° C for 10 minutes, steam is introduced, and the brewing treatment is performed under the condition of steam pressure of 0.05 to 600 Pa. In this method, it is necessary to introduce water vapor in order to control the water vapor pressure, which increases the difficulty of operation and the corrosion resistance is not ideal.

CN100473759C has a process of polishing magnets using mechanical vibration polishing and chamfering by barrel polishing, a process of adding an alkaline degreasing agent to degrease to remove oil, and a process of adding an acidic solution to remove rust by pickling. A method for surface-treating a neodymium iron boron magnet, which comprises a step of removing the magnet and putting the pickled magnet in a blackening solution or a brewing solution to perform electropolishing plating, is disclosed. The blackening solution contains molybdate, an aluminum salt, and a complexing agent. Molybdate is expensive. The brewing solution contains alkalis, nitrites and organic additives. Nitrite is not human health and environmentally friendly.

The present invention provides a neodymium iron boron magnet preform having good corrosion resistance after being blued.

The present invention also provides a method for producing a neodymium iron boron magnet preform.

On the other hand, the present invention provides a method for producing a corrosion-resistant magnet, and the magnet obtained by the method has good corrosion resistance.

The present invention also provides the use of organic substances to improve the corrosion resistance of neodymium iron boron magnets.

The present invention has solved the above technical problems with the following configuration.
The present invention is a neodymium iron boron magnet preform having a carbon content of 2 to 35 wt% on the surface, wherein the neodymium iron boron magnet preform is a preform of a sintered neodymium iron boron permanent magnet and has a carbon content. Provides a neodymium iron boron magnet preform which represents the weight percentage of carbon elements in all surface elements as measured by an X-ray energy spectroscope.

Further, the present invention is a step of pretreating a neodymium iron boron magnet with a pretreatment liquid to obtain a neodymium iron boron magnet preform, wherein the carbon content on the surface of the neodymium iron boron magnet preform is 2 to 35 wt%. The pretreatment liquid is an alcohol containing 1 to 16 carbon atoms, a ketone containing 3 to 16 carbon atoms, an alkane containing 1 to 16 carbon atoms, and a cycloalkane containing 3 to 16 carbon atoms. Provided is a method for producing a neodymium iron boron magnet preform, which comprises a step of obtaining a neodymium iron boron magnet preform, which is one or more selected from rust preventive oil, gasoline, engine oil or diesel oil.

In addition, the present invention
This is a step of pretreating a neodymium iron boron magnet using a pretreatment liquid to obtain a neodymium iron boron magnet preform, wherein the carbon content on the surface of the neodymium iron boron magnet preform is 2 to 35 wt%, and the neodymium iron The boron magnet is a sintered neodymium iron boron permanent magnet, and the carbon content represents the weight percentage of the carbon element in all the elements on the surface of the neodymium iron boron magnet preform as measured by an X-ray energy spectroscope. Liquid contains alcohol containing 1 to 16 carbon atoms, ketone containing 3 to 16 carbon atoms, alcan containing 1 to 16 carbon atoms, cycloalkane containing 3 to 16 carbon atoms, rust preventive oil, gasoline, The process of obtaining neodymium iron boron magnet preform, which is one or more selected from engine oil or diesel oil (1), and
Neodymium Iron Boron Magnet Preform is blued to obtain corrosion resistant magnet (2),
Provided are methods for producing corrosion-resistant magnets, including.

According to the production method according to the present invention, the pretreatment liquid is an alkyl alcohol containing 1 to 16 carbon atoms, an alkyl ketone containing 3 to 6 carbon atoms, and a cycloalkanone containing 3 to 6 carbon atoms. It is preferably one or more selected from gasoline, engine oil or diesel oil.

According to the production method according to the present invention, the brewing treatment is preferably carried out in a tunnel type brewing furnace at a brewing temperature of 200 to 480 ° C. and a brewing time of 5 to 60 min.

According to the production method according to the present invention, the manufacturing process of the neodymium iron boron magnet used for the pretreatment may include a step of ultrasonically treating the magnet to be treated in the presence of a degreasing liquid for 30 to 90 s to obtain a degreased magnet. preferable.

According to the production method according to the present invention, the degreasing solution contains sodium hydroxide, trisodium phosphate, and at least one compound selected from (a) to (c).
(A) Sodium carbonate (b) Sodium silicate (c) Surfactant The weight percentage of the solute in the degreasing solution is preferably 0.3 to 5 wt%.

According to the production method according to the present invention, in the manufacturing process of the neodymium iron boron magnet used for the pretreatment, the degreased magnet is further washed with water for 30 to 90 s by the action of ultrasonic waves, and the water on the surface is blown off to the washed magnet. It is preferable to include a step of drying the magnet and drying it at 90 to 150 ° C. for 1 to 6 hours to obtain a dried magnet.

According to the production method according to the present invention, the manufacturing process of the neodymium iron boron magnet used for the pretreatment further uses a dry magnet, a spray gun swing frequency of 2 to 15 Hz, a spray gun pressure of 0.01 to 0.5 MPa, and a sandblast time of 2 to. It is preferable to include a step of sandblasting with an automatic sandblasting machine in 20 minutes.

Further, the present invention is the use of an organic substance for improving the corrosion resistance of the neodymium iron boron magnet, wherein the neodymium iron boron magnet is a sintered neodymium iron boron permanent magnet, and the organic substance has 1 to 16 carbon atoms. Selected from alcohols containing 3 to 16 carbon atoms, ketones containing 3 to 16 carbon atoms, alcans containing 1 to 16 carbon atoms, cycloalkanes containing 3 to 16 carbon atoms, rust preventive oils, gasoline, engine oils or diesel oils. Provided is the use of an organic substance for improving the corrosion resistance of a neodymium iron boron magnet, which is one or more kinds.

According to the present invention, by controlling the carbon content on the surface of the sintered neodymium iron boron magnet preform within a certain range, a neodymium iron boron magnet having good corrosion resistance can be obtained by a simple brewing treatment.

It is a schematic diagram which shows the structure of the corrosion-resistant magnet which concerns on this invention.

1, protective film, 2, neodymium iron boron magnet

Hereinafter, the present invention will be further described with reference to specific examples, but the scope of the present invention is not limited thereto.

Neodymium Iron Boron Magnet Preform The neodymium iron boron magnet preform according to the present invention represents an intermediate product before forming a corrosion resistant magnet. The neodymium iron-boron magnet is preferably a sintered neodymium iron-boron permanent magnet. The carbon content on the surface of the neodymium iron boron magnet preform may be 2 to 35 wt%. Normally, in the manufacturing process of a sintered neodymium iron boron magnet, it is necessary to keep the carbon content in the magnet sufficiently low in order to secure the magnetic properties of the magnet. Therefore, there is no suggestion from the prior art to increase the amount of carbon on the surface of the magnet preform. In the present invention, it has been found that the corrosion resistance is remarkably improved by controlling the amount of carbon on the surface of the magnet material within a certain range. Although the reason is not clear, it is certainly possible to improve the corrosion resistance of the magnet, although most of the carbon is removed by the brewing treatment.

The carbon content represents the weight percentage of the carbon element in all the elements on the surface of the neodymium iron boron magnet preform. The carbon content is measured with an X-ray energy spectrometer (EDS). Scanning electron microscopes are usually equipped with an EDS. The carbon content on the surface of the neodymium iron boron magnet preform is preferably 10 to 30 wt%. The carbon content on the surface of the neodymium iron boron magnet preform is more preferably 15 to 25 wt%. This is advantageous for further improvement of corrosion resistance.

In the prior art, it is generally necessary to control the bluing treatment atmosphere parameters such as water vapor pressure or oxygen content in order to obtain sintered neodymium iron boron magnets with good corrosion resistance. The neodymium iron boron magnet preform according to the present invention can obtain excellent corrosion resistance by a simple bluing treatment.

Manufacturing Method of Neodymium Iron Boron Magnet Preform A neodymium iron boron magnet pretreatment is performed using a pretreatment liquid to obtain a neodymium iron boron magnet preform. The neodymium iron-boron magnet is preferably a sintered neodymium iron-boron permanent magnet. The carbon content on the surface of neodymium iron boron magnet preform is 2-35 wt%. The carbon content on the surface of the neodymium iron-boron magnet preform according to the present invention is preferably 10 to 30 wt%, more preferably 15 to 25 wt%. This further improves the corrosion resistance.

The use of the pretreatment solution aims to increase the carbon content on the surface of the neodymium iron-boron magnet preform. However, in order to ensure magnetic properties, it is necessary to minimize the carbon content in the magnet in the production process of sintered neodymium iron boron magnets. Therefore, corrosion resistance is increased by increasing the carbon content on the surface of the magnet preform. It is not easy to think of improving. There are other ways to increase the carbon content on the neodymium iron boron magnet preform surface, but using a pretreatment solution for pretreatment is more convenient and reliable.

Pretreatment liquids include alcohols containing 1 to 16 carbon atoms, ketones containing 3 to 16 carbon atoms, alkanes containing 1 to 16 carbon atoms, and cycloalkanes containing 3 to 16 carbon atoms. It may be one or more selected from rust preventive oil, gasoline, engine oil and diesel. Preferably, the pretreatment liquid in the present invention is an alcohol containing 1 to 16 carbon atoms, a ketone containing 3 to 16 carbon atoms, an alkane containing 1 to 16 carbon atoms, a rust preventive oil, a gasoline, and an engine. One or more selected from oils and diesel oils.

The water content in the pretreatment solution should be reduced as much as possible to avoid interference. The pretreatment liquid preferably does not contain water. In the prior art, it is usually necessary to introduce steam water in order to improve the effect of the brewing treatment, but in the present invention, such an operation is not necessary and can be carried out under normal conditions. ..

The pretreatment liquid in the present invention may be an alcohol containing 1 to 16 carbon atoms, preferably an alcohol containing 1 to 10 carbon atoms, and more preferably containing 1 to 6 carbon atoms. Alcohol. The alcohol may be an alkyl alcohol. Examples of alcohols are methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, isoamyl alcohol, neopentyl alcohol, 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, undecyl alcohol, dodecanol, tridecyl alcohol, myristyl alcohol, pentadecanol, Including, but not limited to, cetyl alcohol.

The pretreatment liquid in the present invention may be a ketone containing 3 to 16 carbon atoms, preferably a ketone having 3 to 10 carbon atoms, and more preferably having 3 to 6 carbon atoms. It is a ketone. The ketone may be an alkyl ketone or a cycloalkanone. Examples of ketones are acetone, butanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-octanone, 3-octanone, 4-octanone, 2 -Includes, but is not limited to, nonanonone, 3-nonanonone, 4-nonanonone, 5-nonanonone, cyclopentanone, cyclohexanone, cycloheptanone.

The pretreatment liquid in the present invention may be an alkane containing 1 to 16 carbon atoms, preferably an alkane having 1 to 10 carbon atoms, and more preferably an alkane having 1 to 6 carbon atoms. Is. Examples of alkanes are methane, ethane, propane, n-butane, isobutane, n-pentane, isopentan, neopentane, hexane, 2-methylpentane, 3-methylpentane, 2-ethylbutane, heptane, 2-methylhexane, 3- Methylhexane, 2-ethylpentane, 3-ethylpentane, octane, 2-methylheptane, 3-methylheptane, 4-methylheptane, 2-ethylhexane, 3-ethylhexane, nonane, 2-methyloctane, 3-methyl It includes, but is not limited to, octane, 4-methyloctane, 2-ethylheptane, 3-ethylheptane, 4-ethylheptane, 2-propylhexane, 3-propylhexane, and decane.

The pretreatment liquid in the present invention may be a cycloalkane containing 3 to 16 carbon atoms, preferably a cycloalkane containing 3 to 12 carbon atoms, and more preferably 3 to 9 carbon atoms. It is a cycloalkane containing a carbon atom. Examples of cycloalkanes include, but are not limited to, cyclopropane, cyclopentane, methylcyclopentane, ethylcyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane, isopropylcyclohexane.

The pretreatment liquid in the present invention may be one or more selected from rust preventive oil, gasoline, engine oil and diesel. According to one aspect of the invention, the pretreatment liquid is alcohol or engine oil. According to another aspect of the invention, the pretreatment liquid is engine oil. This is more environmentally friendly and less costly.

Method for Producing Corrosion-Resistant Magnet The method for producing a corrosion-resistant magnet in the present invention includes (1) a pretreatment step; (2) a brewing treatment step. Prior to the pretreatment step, degreasing, washing with water, drying, and sandblasting processes may optionally be included. As a result, the magnet to be treated is surface-treated, which is advantageous for the adhesion between the pretreatment liquid and the magnet.

The magnet to be degreased is degreased. The magnet to be processed is a sintered neodymium iron boron permanent magnet. The magnet treated in the present invention may be a chamfered neodymium iron boron magnet. As a result, the surface of the neodymium iron-boron magnet becomes smoother, which is advantageous for forming a protective film.

In the present invention, a magnet treated with a degreasing solution may be degreased to obtain a degreasing magnet. In certain embodiments, neodymium iron boron magnets are sonicated in the presence of a degreasing solution. Before pretreatment, the magnet to be treated is sonicated for 30-90s in the presence of a degreasing solution to obtain a degreasing magnet. The ultrasonic processing time may be 30 to 90 s, preferably 30 to 60 s, and more preferably 30 to 50 s. This is advantageous for removing oils and fats on the magnet surface.
The degreasing solution in the present invention may contain sodium hydroxide, trisodium phosphate and at least one compound selected from (a) to (c).
(A) Sodium carbonate, (b) Sodium silicate, (c) Surfactant The degreasing solution may be an aqueous solution containing the solute. Surfactants are sodium dodecylsulfonate, tween 40, tween 60, monolauryl phosphate MAP, coconut oil fatty acid diethanolamine, NP-8, NP-9, NP-10, OP-8, OP-10, OP-13, It may be one or more selected from OP-15, preferably the surfactant is Tween 60, monolauryl phosphate MAP, coconut oil fatty acid diethanolamine, NP-8, NP-9, OP-8, One or more selected from OP-10, more preferably the surfactant is monolauryl phosphate MAP, coconut oil fatty acid diethanolamine, one or more selected from OP-10. The weight percentage of the solute in the degreasing liquid may be 0.3 to 5 wt%, preferably 0.3 to 3 wt%, and more preferably 0.5 to 2 wt%. This is advantageous in enhancing the degreasing effect and enhancing the adhesion between the magnet and the pretreatment liquid.

In certain embodiments, the degreasing solution comprises sodium hydroxide, trisodium phosphate and sodium silicate. Preferably, the degreasing solution consists of sodium hydroxide, trisodium phosphate, sodium silicate and water. The amount of sodium hydroxide used may be 10 to 40 parts by weight, preferably 20 to 40 parts by weight, and more preferably 20 to 30 parts by weight. The amount of trisodium phosphate used may be 15 to 40 parts by weight, preferably 25 to 40 parts by weight, and more preferably 25 to 30 parts by weight. The amount of sodium silicate used may be 1 to 15 parts by weight, preferably 3 to 10 parts by weight, and more preferably 5 to 8 parts by weight.

In another embodiment, the degreasing solution contains sodium hydroxide, sodium carbonate, trisodium phosphate and a surfactant. Preferably, the degreasing solution consists of sodium hydroxide, sodium carbonate, trisodium phosphate, surfactant and water. The amount of sodium hydroxide used may be 10 to 40 parts by weight, preferably 20 to 40 parts by weight, and more preferably 20 to 30 parts by weight. The amount of sodium carbonate used may be 10 to 50 parts by weight, preferably 20 to 40 parts by weight, and more preferably 30 to 40 parts by weight. The amount of trisodium phosphate used may be 10 to 50 parts by weight, preferably 20 to 40 parts by weight, and more preferably 30 to 40 parts by weight. The amount of the surfactant used may be 1 to 7 parts by weight, preferably 1 to 5 parts by weight, and more preferably 2 to 4 parts by weight.

In another embodiment, the degreasing solution comprises sodium hydroxide, sodium carbonate, trisodium phosphate and sodium silicate. Preferably, the degreasing solution consists of sodium hydroxide, sodium carbonate, trisodium phosphate, sodium silicate and water. The amount of sodium hydroxide used may be 5 to 25 parts by weight, preferably 10 to 25 parts by weight, and more preferably 10 to 15 parts by weight. The amount of sodium carbonate used may be 10 to 40 parts by weight, preferably 20 to 40 parts by weight, and more preferably 20 to 30 parts by weight. The amount of trisodium phosphate used may be 40 to 80 parts by weight, preferably 50 to 80 parts by weight, and more preferably 50 to 70 parts by weight. The amount of sodium silicate used may be 1 to 8 parts by weight, preferably 1 to 5 parts by weight, and more preferably 2 to 4 parts by weight.

Washing with water and drying The degreasing magnet may be washed with water and dried to become a dry magnet. The purpose of washing with water is to clean the degreasing liquid remaining on the magnet surface. According to one embodiment of the present invention, ultrasonic water washing is used. Wash the degreasing magnet with water under the action of ultrasonic waves. The washing time may be 30 to 90 s, preferably 30 to 60 s, and more preferably 40 to 60 s.

The purpose of drying is to remove moisture on the magnet surface. According to one embodiment of the present invention, the water on the surface of the magnet washed with water is blown off to dry it, and then it is dried in an oven. The drying temperature may be 90 to 150 ° C, preferably 90 to 130 ° C, and more preferably 90 to 110 ° C. The drying time may be 1 to 6 hours, preferably 1 to 4 hours, and more preferably 1 to 3 hours. This contributes to increasing the degree of adhesion between the magnet and the pretreatment liquid.

Sandblast Dry magnets are sandblasted to obtain neodymium iron boron magnets. Further, it is preferable that the sandblasting process is performed in an automatic sandblasting machine. The swing frequency of the spray gun may be 2 to 15 Hz, preferably 5 to 12 Hz, more preferably 8 to 10 Hz. The spray gun pressure may be 0.01 to 0.5 MPa, preferably 0.02 to 0.3 MPa, and more preferably 0.02 to 0.25 MPa. The sandblasting time is 2 to 20 min, preferably 2 to 10 min, and more preferably 5 to 7 min. Such treatment conditions are advantageous for improving the adhesion between the magnet and the pretreatment liquid.

Pretreatment Step A neodymium iron boron magnet (magnet after sandblasting) is pretreated with a pretreatment liquid to obtain a neodymium iron boron magnet preform. The pretreatment liquid is as described above. The description thereof is omitted here.

The carbon content on the surface of the neodymium iron boron magnet preform is 2 to 35 wt%, preferably 10 to 30 wt%, and more preferably 15 to 25 wt%. Carbon content means the weight percentage of carbon in all elements of the neodymium iron boron magnet preform surface as measured by an X-ray energy analyzer (EDS).

The present invention has found that the carbon content on the surface of the magnet preform has a great effect on the corrosion resistance of the neodymium iron boron magnet after treatment. If the carbon content is too high or too low, the treated neodymium iron-boron magnet cannot be imparted with sufficient corrosion resistance. Although the mechanism is not clear, it is presumed that the pretreatment liquid permeates the pores on the magnet surface and improves the corrosion resistance of these parts after the brewing treatment, thereby improving the corrosion resistance of the entire magnet. .. Therefore, the preform according to the present invention can improve corrosion resistance without subjecting a particularly complicated brewing process.

Bluning treatment step The neodymium iron boron magnet after being treated with the pretreatment liquid is blued to obtain a corrosion resistant magnet. In the prior art, in order to obtain a sintered neodymium iron boron magnet with excellent corrosion resistance, it is necessary to control the atmosphere parameters of the bluing treatment such as the pressure of water vapor and the oxygen content. The neodymium iron boron magnet preform according to the present invention can improve the corrosion resistance of the magnet by a simple bluing treatment process.

The brewing treatment may be performed under normal conditions, and it is not necessary to separately control the partial pressure of steam and the partial pressure of oxygen. Also, the brewing temperature and brewing time are important for improving corrosion resistance, but these parameters are relatively easy to control. The brewing temperature in the present invention may be 200 to 480 ° C, preferably 300 to 450 ° C, and more preferably 350 to 400 ° C. The brewing time may be 5 to 60 min, preferably 8 to 20 min, more preferably 10 to 15 min. This contributes to the improvement of the corrosion resistance of the magnet. The brewing process may be performed in the brewing furnace. The brewing furnace is preferably a tunnel type brewing furnace. As a result, mass productivity is excellent and the uniformity of magnet characteristics can be improved.

Use of Organics The present invention further provides the use of organics to further improve the corrosion resistance of neodymium iron-boron magnets. The preform of the neodymium iron boron magnet is a preform of a sintered neodymium iron boron permanent magnet. The organic substances are alcohol containing 1 to 16 carbon atoms, ketone containing 3 to 16 carbon atoms, alkane containing 1 to 16 carbon atoms, cycloalkane containing 3 to 16 carbon atoms, and rust prevention. One or more selected from oils, gasolines, engine oils and diesels, preferably alcohols containing 1 to 16 carbon atoms, ketones containing 3 to 16 carbon atoms, 1 to 16 carbon atoms. One or more selected from alcan, gasoline, engine oil or diesel oil containing, more preferably one selected from alcohol containing 1 to 16 carbon atoms, engine oil or diesel oil. There are multiple species. The organic matter can increase the carbon content on the surface of the neodymium iron boron magnet preform. However, in order to ensure magnetic properties, it is necessary to minimize the carbon content in the magnet in the production process of sintered neodymium iron boron magnets, so carbon on the surface of the magnet preform using a specific organic substance. It is not easy to think of improving corrosion resistance by increasing the content. Water content in organic matter should be reduced as much as possible to avoid interference. According to one embodiment of the invention, the organic matter does not contain water.

The organic substance in the present invention may be an alcohol containing 1 to 16 carbon atoms, preferably an alcohol containing 1 to 10 carbon atoms, and more preferably an alcohol containing 1 to 6 carbon atoms. be. The alcohol may be an alkyl alcohol. Examples of alcohols are methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, isoamyl alcohol, neopentyl alcohol, 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, undecyl alcohol, dodecanol, tridecyl alcohol, myristyl alcohol, pentadecanol, cetyl Contains, but is not limited to, alcohol.

The organic substance in the present invention may be a ketone containing 3 to 16 carbon atoms, preferably a ketone having 3 to 10 carbon atoms, and more preferably a ketone having 3 to 6 carbon atoms. The ketone may be an alkyl ketone or a cycloalkanone. Examples of ketones are acetone, butanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-octanone, 3-octanone, 4-octanone, 2 -Includes, but is not limited to, nonanones, 3-nonanones, 4-nonanones, 5-nonanones, cyclopentanones, cyclohexanones, cycloheptanones.

The organic substance in the present invention may be an alkane containing 1 to 16 carbon atoms, preferably an alkane having 1 to 10 carbon atoms, and more preferably an alkane having 1 to 6 carbon atoms. Examples of alkanes are methane, ethane, propane, n-butane, isobutane, n-pentane, isopentan, neopentane, hexane, 2-methylpentane, 3-methylpentane, 2-ethylbutane, heptane, 2-methylhexane, 3-. Methylhexane, 2-ethylpentane, 3-ethylpentane, octane, 2-methylheptane, 3-methylheptane, 4-methylheptane, 2-ethylhexane, 3-ethylhexane, nonane, 2-methyloctane, 3-methyl It includes, but is not limited to, octane, 4-methyloctane, 2-ethaneheptane, 3-ethylheptane, 4-ethylheptane, 2-propylhexane, 3-propylhexane, and decane.

The organic substance in the present invention may be a cycloalkane containing 3 to 16 carbon atoms, preferably a cycloalkane containing 3 to 12 carbon atoms, and more preferably containing 3 to 9 carbon atoms. It is a cycloalkane. Examples of cycloalkanes include, but are not limited to, cyclopropane, cyclopentane, methylcyclopentane, ethylcyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane, isopropylcyclohexane.

The organic substance according to the present invention may be one or more selected from rust preventive oil, gasoline, engine oil and diesel oil. According to one embodiment of the invention, the organic matter is ethanol or engine oil. According to another embodiment of the invention, the organic matter is engine oil. This is more environmentally friendly and less costly.

The use described above comprises the step of pretreating a neodymium iron boron magnet with a pretreatment solution to obtain a neodymium iron boron magnet preform having a surface carbon content of 2 to 35 wt%. Neodymium iron boron magnet preform is a preform of sintered neodymium iron boron permanent magnet. Preferably, the carbon content on the surface is 10-30 wt%. More preferably, the carbon content on the surface is 15-25 wt%. Specifically, the above-mentioned use may include (1) degreasing, washing with water, drying step, (2) sandblasting step, (3) pretreatment step, and (4) brewing treatment step. The organic matter corresponds to the pretreatment liquid described in the preamble, and the detailed process and parameters are as described in the preamble.

The test methods of Examples and Comparative Examples will be described below.
(1) Carbon content on the surface:
The experimental process is carried out according to the method of GB / T-17359-2012.
(2) Corrosion resistance test:
The experimental process was carried out according to the method of GB / T-6807-2001. Specifically, when the corrosion-resistant magnet was lowered to room temperature, it was immediately immersed in a 3 wt% sodium chloride aqueous solution, and the sample was taken out every hour at 15 to 25 ° C. , Washed, blow-dried, visually checked for rust on the surface of the corrosion-resistant magnet, and recorded the longest time without rust on the surface of the corrosion-resistant magnet.

Examples 1-3 and Comparative Examples 1-2
Sintered neodymium iron boron magnet (volume) chamfered in the presence of a degreasing solution (the weight percentage of the solute is 1 wt%, the composition of the solute is as shown in Table 1, and the solvent is water) in the degreasing tank. 57.9 x 10.94 x 1.8 mm) is ultrasonically treated for 40 s to manufacture a defatted magnet, the defatted magnet is washed with ultrasonic water for 50 S, the water on the magnet surface is blow-dried, then placed in an oven and dried at 100 ° C for 2 hours. And obtained a dry magnet.

The dry magnet was placed in an automatic sandblasting machine and sandblasted, and the magnet after the sandblasting was obtained as a neodymium iron boron magnet. The spray gun swing frequency, spray gun pressure and sandblast time are shown in Table 2.

The neodymium iron-boron magnet was completely immersed in the pretreatment liquid for pretreatment to obtain a neodymium iron-boron magnet preform. Table 2 shows the carbon content on the surface of the pretreatment liquid and neodymium iron boron magnet preform.

The neodymium iron boron magnet preform was placed in a tunnel-type brewing furnace and subjected to brewing treatment to obtain a corrosion-resistant magnet. The brewing temperature and brewing time were as shown in Table 2. FIG. 1 is a schematic view showing 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 to the neodymium iron-boron magnet 2.

Comparative example 3
Sintered neodymium iron boron magnets chamfered in the presence of a degreasing solution (the weight percentage of the solute is 1 wt%, the composition of the solute is as shown in Table 1, and the solvent is water) in the degreasing tank ( (Volume 57.9 x 10.94 x 1.8 mm) is ultrasonically treated for 40 s to manufacture a defatted magnet. The defatted magnet is washed with ultrasonic water for 50 S, the water on the magnet surface is blown off and dried, and then the magnet is placed in an oven at 100 ° C. It was dried for 2 hours to obtain a dried magnet.

The dry magnet was placed in an automatic sandblasting machine and sandblasted, and the magnet after the sandblasting was obtained as a neodymium iron boron magnet. The spray gun swing frequency was 5.0 Hz, the spray gun pressure was 0.05 MPa, and the sandblast time was 10 min.

A neodymium iron-boron magnet was placed in a tunnel-type brewing furnace and treated to obtain a corrosion-resistant magnet. The brewing temperature was 300 ° C. and the brewing time was 18 min.

Test Examples Table 3 shows the results obtained by conducting corrosion resistance tests on the treated magnets of the above-mentioned Examples and Comparative Examples.

From Example 1, Comparative Example 1 and Comparative Example 2, it was found that the carbon content on the surface of the preform had an important effect on the corrosion resistance. In Comparative Example 1, the carbon content was too low, so that the corrosion resistance was lowered. In Comparative Example 2, the carbon content was too high, so that the corrosion resistance was also lowered. As can be seen from Examples 1-3 and Comparative Example 3, the pretreated magnet has significantly better corrosion resistance than the untreated magnet.
The present invention is not limited to the above-described embodiment, and any modifications, improvements, substitutions, etc. that can be conceived by those skilled in the art are included in the scope of the present invention without departing from the spirit of the present invention.

Claims (10)

A neodymium iron boron magnet preform having a carbon content of 2 to 35 wt% on the surface, wherein the neodymium iron boron magnet preform is a preform of a sintered neodymium iron boron permanent magnet, and the carbon content is X-ray. Neodim iron boron magnet preform A neodymium iron boron magnet preform, which is characterized by representing the weight percentage of carbon elements in all elements on the surface of the neodymium iron boron magnet preform measured by an energy spectroscope. A step of pretreating a neodymium iron boron magnet using a pretreatment liquid to obtain a neodymium iron boron magnet preform, wherein the carbon content on the surface of the neodymium iron boron magnet preform is 2 to 35 wt%, and the pretreatment is described above. Liquid contains alcohol containing 1 to 16 carbon atoms, ketone containing 3 to 16 carbon atoms, alkane containing 1 to 16 carbon atoms, cycloalkane containing 3 to 16 carbon atoms, rust preventive oil, gasoline, The method for producing a neodymium iron boron magnet preform according to claim 1, further comprising a step of obtaining a neodymium iron boron magnet preform, which is one or more selected from engine oil or diesel oil. This is a step of pretreating a neodymium iron boron magnet using a pretreatment liquid to obtain a neodymium iron boron magnet preform, wherein the carbon content on the surface of the neodymium iron boron magnet preform is 2 to 35 wt%, and the neodymium iron The boron magnet is a sintered neodymium iron boron permanent magnet, and the carbon content represents the weight percentage of the carbon element in all the elements on the surface of the neodymium iron boron magnet preform as measured by an X-ray energy spectroscope. Liquid contains alcohol containing 1 to 16 carbon atoms, ketone containing 3 to 16 carbon atoms, alcan containing 1 to 16 carbon atoms, cycloalkane containing 3 to 16 carbon atoms, rust preventive oil, gasoline, The process of obtaining neodymium iron boron magnet preform, which is one or more selected from engine oil or diesel oil (1), and
(2) Neodymium iron boron magnet The process of bluing the preform to obtain a corrosion-resistant magnet,
A method for producing a corrosion-resistant magnet, which comprises. The pretreatment liquid contains an alkyl alcohol containing 1 to 16 carbon atoms, an alkyl ketone containing 3 to 6 carbon atoms, a cycloalkanone containing 3 to 6 carbon atoms, a rust preventive oil, gasoline, engine oil or diesel. The production method according to claim 3, wherein the oil is one or more selected from oils. The production method according to claim 3, wherein the brewing treatment is performed in a tunnel type brewing furnace at a brewing temperature of 200 to 480 ° C. and a brewing time of 5 to 60 min. The third aspect of claim 3, wherein the process for manufacturing a neodymium iron boron magnet used for pretreatment includes a step of ultrasonically treating a magnet treated in the presence of a degreasing liquid for 30 to 90s to obtain a degreasing magnet. Production method. The degreasing solution contains sodium hydroxide, trisodium phosphate, and at least one compound selected from (a) to (c).
(A) Sodium carbonate (b) Sodium silicate (c) Surfactant The production method according to claim 6, wherein the weight percentage of the solute in the degreasing solution is 0.3 to 5 wt%. The manufacturing process of neodymium iron boron magnets used for pretreatment is to wash the degreased magnets with water for 30 to 90s by the action of ultrasonic waves, blow off the water on the surface of the washed magnets and dry them, and then dry them at 90 to 150 ° C. The production method according to claim 6, further comprising a step of drying for 6 hours to obtain a dried magnet. The manufacturing process of neodymium iron boron magnets used for pretreatment is the process of sandblasting dry magnets into an automatic sandblasting machine with a spray gun swing frequency of 2 to 15 Hz, a spray gun pressure of 0.01 to 0.5 MPa, and a sandblasting time of 2 to 20 minutes. The production method according to claim 8, wherein the production method comprises. The use of an organic substance to improve the corrosion resistance of a neodymium iron boron magnet, wherein the neodymium iron boron magnet is a sintered neodymium iron boron permanent magnet, and the organic substance is an alcohol containing 1 to 16 carbon atoms, 3 to One or more selected from ketones containing 16 carbon atoms, alkanes containing 1 to 16 carbon atoms, cycloalkanes containing 3 to 16 carbon atoms, rust preventive oils, gasoline, engine oils or diesel oils. The use of organic matter to improve the corrosion resistance of neodymium iron-boron atoms, characterized by being present.

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