A hydrogenated erbium-resistant neodymium iron boron magnet, its preparation method, and a cylindrical magnet block made of the magnet

Abstract

This application relates to the technical field of neodymium iron boron magnets, and specifically discloses a hydrogenated erbium corrosion-resistant neodymium iron boron magnet, a preparation method thereof, and a cylindrical magnet block made of the magnet. A hydrogenated erbium corrosion-resistant neodymium iron boron magnet includes a magnetic matrix and a corrosion-resistant layer coated on the surface of the magnetic matrix. The magnetic matrix includes the following components in weight percentage: praseodymium-neodymium alloy 15-29%; boron 5.2-6%; erbium 1-10%; copper 0-2%; zirconium 0-2%; cobalt 0-2%; niobium 0-2%; aluminum 0-2%; gallium 0-2%; the balance is iron. The hydrogenated erbium corrosion-resistant neodymium iron boron magnet of this application has the advantage of good corrosion resistance in a high-temperature environment.

Description

Technical Field

[0001] The present application relates to the technical field of neodymium iron boron magnets. More specifically, it relates to a hydrogenated erbium corrosion-resistant neodymium iron boron magnet, a preparation method thereof, and a cylindrical magnet block made of the magnet. Background Art

[0002] In recent years, the neodymium iron boron magnet industry, as a sunrise industry for energy conservation and environmental protection, has been widely used in fields such as information technology, automobiles, nuclear magnetic resonance, wind power generation, and motors. It is expected that the compound growth rate in the next 3 - 5 years will be about 20%. Due to China's obvious resource, cost, and market advantages, the world's neodymium iron boron industry is shifting to China. Currently, China's neodymium iron boron production has accounted for more than 70% of the global production.

[0003] Neodymium iron boron magnets are divided into two types: sintered neodymium iron boron and bonded neodymium iron boron. Among them, sintered neodymium iron boron uses powder metallurgy technology. The melted alloy is first made into powder, and then pressed into a green body in a magnetic field. The green body is sintered in an inert gas or vacuum to achieve densification. After machining, products of different shapes can be made. It has a good coercivity value, extremely high magnetic properties, and very excellent mechanical properties. The maximum working temperature can reach 200°C.

[0004] Due to the high activity of the materials of sintered neodymium iron boron magnets and their poor corrosion resistance, they are extremely easy to oxidize. Especially under the conditions of higher temperature and humidity, the electrochemical potentials of the various constituent phases of the magnet are different. When they come into contact with each other in a humid and hot corrosion environment, corrosion microcells will be formed, accelerating intergranular corrosion and resulting in very serious oxidation of the magnet.

[0005] To address the problem of easy oxidation of neodymium iron boron magnets, technicians add trace metal elements to neodymium iron boron magnets to improve the corrosion resistance of the magnets. However, the addition of these trace elements will have an adverse impact on the magnetic properties of the magnets. In addition, a metal coating or polymer coating is formed on the surface of the neodymium iron boron magnet to improve the corrosion resistance of the magnet.

[0006] For the above polymer coating, the corrosion resistance is prone to decline in a working environment at a higher temperature. Summary of the Invention

[0007] In order to improve the problem of the decline in the performance of the anti-corrosion layer of neodymium iron boron magnets at a higher working temperature, the present application provides a hydrogenated erbium corrosion-resistant neodymium iron boron magnet, a preparation method thereof, and a cylindrical magnet block made of the magnet.

[0008] In a first aspect, the present application provides a hydrogenated erbium corrosion-resistant neodymium iron boron magnet, adopting the following technical solution: A hydrogenated erbium corrosion-resistant neodymium iron boron magnet includes a magnetic matrix and an anti-corrosion layer coated on the surface of the magnetic matrix. The magnetic matrix includes the following components in weight percentages:

[0009] Praseodymium-neodymium alloy: 15 - 29%;

[0010] Boron: 5.2 - 6%;

[0011] Erbium: 1 - 10%;

[0012] Copper: 0 - 2%;

[0013] Zirconium: 0 - 2%;

[0014] Cobalt: 0 - 2%;

[0015] Niobium: 0 - 2%;

[0016] Aluminum: 0 - 2%;

[0017] Gallium: 0 - 2%;

[0018] The balance is iron.

[0019] By adopting the above technical solution, using hydrogenated erbium to replace dysprosium and a part of neodymium can reduce the cost while ensuring the magnetic properties of the magnet, improving the comprehensive economic benefits. Moreover, after adding erbium element and compounding it with other element components, the corrosion potential difference between different component crystal phases can be reduced, weakening intergranular corrosion. In addition, a corrosion prevention layer is coated on the surface of the magnetic matrix to form a dense coating on the surface of the magnetic matrix, which has good corrosion resistance and wear resistance, enabling it to work normally in a relatively harsh environment, with a wider application range and better stability.

[0020] In the second aspect, the present application provides a preparation method of a hydrogenated erbium corrosion-resistant neodymium-iron-boron magnet, adopting the following technical solution:

[0021] A preparation method of a hydrogenated erbium corrosion-resistant neodymium-iron-boron magnet, comprising the following steps:

[0022] S1: Melting: Mix the formula amounts of praseodymium-neodymium alloy, copper, zirconium, cobalt, niobium, aluminum, gallium, boron and iron evenly and melt them to obtain a melted alloy ingot;

[0023] S2: Powder making: Hydrogenate the melted alloy ingot to make powder, add hydrogenated erbium after powder making and mix evenly to obtain a hydrogenated material; then further crush the hydrogenated material by air jet milling process to obtain powder;

[0024] S3: Molding: Load and press the powder in a mold to obtain a green body;

[0025] S4: Sintering: Sinter the green body to obtain a blank;

[0026] S5: Centerless grinding: Grind the blank to obtain a magnetic matrix;

[0027] S6: Anti-corrosion processing: It is obtained by spraying an anti-corrosion composition on the surface of the magnetic substrate and forming an anti-corrosion layer after curing and drying; the anti-corrosion composition is mainly made of the following raw materials in parts by weight: 100-150 parts of solvent, 25-35 parts of epoxy resin, 10-15 parts of ethylenediamine, 5-10 parts of nickel powder, 20-30 parts of zinc powder, 2-5 parts of methyl oleate, and 5-10 parts of anti-corrosion agent; the anti-corrosion agent is composed of aluminum organic acid, sodium metasilicate, and pyridine-2,5-dicarboxylic acid in a molar ratio of (20-30):(5-7.5):(1-3).

[0028] By adopting the above technical solution, first, the formula amounts of praseodymium-neodymium alloy, copper, zirconium, cobalt, niobium, aluminum, and gallium are mixed evenly and then melted to form an alloy material. Then, the hydrogen breaking process is adopted for pulverization, and hydrogen broken erbium powder is added at the same time, so that the components of the magnet are fully mixed evenly, the pores of the magnet are smaller, the state of the crystal phases of each component is improved, and the function of refining the crystal grains is achieved, thereby weakening the intergranular corrosion between the main phase and the other phases. And, after coating the anti-corrosion layer on the surface of the magnetic substrate, elements such as zinc and nickel in the anti-corrosion layer components can penetrate into the magnetic substrate during use, forming a dense passivation film on the surface of the magnetic substrate, inhibiting the progress of corrosion and reducing the corrosion rate. In addition, aluminum organic acid in the anti-corrosion agent can carry out cross-linking grafting between molecular chains with the assistance of sodium metasilicate and pyridine-2,5-dicarboxylic acid, and form a dense cross-linked protection structure in the epoxy resin system after curing. At the same time, zinc powder and nickel powder can be embedded and attached in the cross-linked protection structure to form a dense protection layer. In a working environment at a higher temperature, the organic acid radicals in the cross-linked structure can form strong complexation with aluminum, zinc, nickel, etc., improving the high-temperature stability of the cross-linked protection structure, so that the magnet can work at a higher temperature environment for a longer time.

[0029] Further preferably, in the step S4, the size of the mold during sintering can be adjusted according to actual needs, thereby adjusting the size of the product. The finished product specifications of this application include, but are not limited to, small-sized neodymium-iron-boron magnets with a diameter between 4 mm and 10 mm, and their shapes include, but are not limited to, cylinders, cuboids, etc.

[0030] By adopting the above technical solution, the protective agent of this application can play a very good anti-oxidation and lubrication role, making the distribution uniformity of the neodymium-iron-boron powder raw materials better. Moreover, when producing small cylindrical magnet products, due to the finer and more uniform crystal grains of the magnet in this application, the isotropy and consistency of the product are better, and the magnetism is stable and uniform, which is very suitable for application in the processing of precision equipment.

[0031] Preferably, the aluminum organic acid is at least one of aluminum citrate, aluminum oxalate, and aluminum tartrate.

[0032] By adopting the above technical solution, the types of aluminum organic acids are optimized and adjusted, the reaction activity and steric hindrance of aluminum organic acids are balanced, the bonding force and stability of the crosslinked protective structure are improved, and further the corrosion resistance of the anti-corrosion layer is enhanced.

[0033] Preferably, the aluminum organic acid is composed of aluminum citrate and aluminum tartrate in a molar ratio of (2 - 5):(0.6 - 1).

[0034] By adopting the above technical solution, the composition ratio of the aluminum organic acid is further tested and adjusted, the complexing ability of the organic acid root to elements such as aluminum, zinc, and nickel is balanced, and the penetration amount of the corresponding elements into the magnetic matrix is controlled, which will neither have too great an impact on the magnetic properties of the magnet nor affect the corrosion resistance under high temperature conditions.

[0035] Preferably, the thickness of the anti-corrosion layer is 300 - 500 μm.

[0036] By adopting the above technical solution, the thickness of the anti-corrosion layer is optimized and adjusted, the corrosion resistance of the magnetic matrix is improved without affecting the magnetic properties, and the comprehensive practicality and production cost are considered.

[0037] Preferably, the mass ratio of the anti-corrosion agent to the epoxy resin is (0.05 - 0.065):1.

[0038] By adopting the above technical solution, the mass ratio of the anti-corrosion agent to the epoxy resin is adjusted and tested, the crosslinked structure state formed by the aluminum organic acid in the resin system is improved, and the bonding property and anti-corrosion property of the anti-corrosion layer are enhanced.

[0039] Preferably, the raw materials of the anti-corrosion composition further include 0.5 - 0.75 parts by weight of chitosan hydrochloride.

[0040] By adopting the above technical solution, after adding chitosan hydrochloride, molecular chain entanglement and bridging can be formed in the crosslinked structure, further improving the density of the anti-corrosion layer, reducing the penetration of external corrosive substances into the anti-corrosion layer, and enhancing the corrosion resistance of the anti-corrosion layer.

[0041] Preferably, the solvent is composed of dimethyl sulfoxide, ethylene glycol, and water in a mass ratio of (2 - 3.5):(7 - 12):(30 - 35).

[0042] By adopting the above technical solution, the composition ratio of the solvent is optimized and adjusted. The compound use of dimethyl sulfoxide, ethylene glycol, and water can greatly promote the dispersion and migration of various substances in the anti-corrosion layer, improve the isotropy of the anti-corrosion layer, and make the corrosion resistance more stable.

[0043] Preferably, the surface of the magnetic matrix is electroplated before spraying the anti-corrosion composition.

[0044] By adopting the above technical solution, a passivation film can be formed on the surface of the magnetic substrate after electroplating treatment, which, in cooperation with the anti-corrosion layer, can achieve a very good double protection effect. Moreover, the bonding state between the surface of the electroplated magnetic substrate and the anti-corrosion layer is better, the bonding force is stronger, and phenomena such as peeling are not likely to occur, and it is more stable during long-term use.

[0045] In a third aspect, the present application provides a cylindrical magnetic block, which is made of the above-mentioned hydrogen-cracked erbium neodymium iron boron magnet.

[0046] In summary, the present application has the following beneficial effects:

[0047] 1. Since the present application uses hydrogen-cracked erbium to replace dysprosium and a part of neodymium to prepare a neodymium iron boron magnet with excellent magnetic properties, and an anti-corrosion layer is coated on the surface of the magnetic substrate, the corrosion resistance and stability of the magnet at higher temperatures are greatly improved.

[0048] 2. In the present application, aluminum organic acid forms a cross-linked protection structure in the epoxy resin system to control the infiltration amount of elements such as aluminum, zinc, and nickel, and further improves the high-temperature stability of the anti-corrosion layer under the action of high-temperature complexation.

[0049] 3. The hydrogen-cracked erbium corrosion-resistant neodymium iron boron magnet prepared by the preparation method of the present application has the advantage of working in a relatively harsh environment and is suitable for working in humid and high-temperature environments. Specific embodiments

[0050] The following further describes the present application in detail with reference to embodiments.

[0051] The raw materials in the embodiments and comparative examples of the present application are all ordinary commercially available products unless otherwise specified.

[0052] Embodiments

[0053] Example 1

[0054] The hydrogen-cracked erbium corrosion-resistant neodymium iron boron magnet of this embodiment includes a magnetic substrate and an anti-corrosion layer coated on the surface of the magnetic substrate. The magnetic substrate includes the following components in weight percentage: praseodymium-neodymium alloy 15%, boron 5.2%, erbium 1%, and the balance is iron.

[0055] The preparation method of the hydrogen-cracked erbium corrosion-resistant neodymium iron boron magnet of this embodiment includes the following steps:

[0056] S1: Melting:

[0057] 1). Sampling inspection and recheck of the raw materials, and at the same time checking whether the raw materials are oxidized or contaminated with oil;

[0058] 2). Conduct pre-use inspections on equipment such as melting furnaces and crucibles to ensure normal operation of the equipment;

[0059] 3), Load the formula amount of praseodymium-neodymium alloy and iron into the crucible from the bottom up in order of melting point. The materials should be packed firmly and steadily to prevent falling. Then polish the copper roller until the surface of the copper roller is smooth and flat without accumulated materials. Next, dock the tundish with the copper roller, press the mullite tightly, start the copper roller, and finally close the furnace lid;

[0060] 4), Start the vacuum pump to evacuate, and at the same time turn on the intermediate frequency power supply to heat. Adjust the power to about 90KW. When the materials in the furnace turn slightly red and the vacuum degree is less than 1Pa, fill argon into the furnace and keep the argon pressure in the furnace at 0.05MPa;

[0061] 5), Slowly adjust the potentiometer power to 360KW and continue to heat the materials in the crucible. After the iron completely falls into the bottom liquid, melt for another 8 - 10 minutes. When the color of the molten steel changes from dark red to white, reduce the potentiometer power setting to 200KW and continue to melt for 3 - 5 minutes;

[0062] 6), Adjust the power to 130KW, then pour it into the tray to form a package sheet. During the pouring process, gradually reduce the power as the tilting angle of the crucible increases continuously. After the pouring is completed, let the package sheet cool naturally for 10 - 15 minutes, and then air-cool for 150 minutes to obtain the melted alloy ingot. Inspect the melted alloy ingot and reserve it after passing the inspection;

[0063] S2: Powder making:

[0064] 1), Hydrogenate and break the melted alloy ingot to make coarse powder, and then stir the coarse powder. During the stirring process of the coarse powder, add hydrogenated erbium powder materials. After mixing evenly, obtain the hydrogenated and broken materials;

[0065] 2), Process the hydrogenated and broken materials by the jet mill process. First, prepare for startup. After checking that the equipment is running normally, set the parameters: the nitrogen supply pressure is 0.2KPa, the filter pressure is 0.015MPa, the grinding chamber pressure is 0.024MPa, the cleaning gas pressure is 0.2MPa, the compressed air pressure is 0.5MPa. Further grind the hydrogenated and broken materials to obtain powder materials;

[0066] S3: Molding:

[0067] 1), First, prepare for work. Evacuate the glove box, select a suitable mold (design the size and shape of the mold according to customer needs), adjust the gap between the punch and the mold, control the temperature below 25°C, the humidity less than 70%, check the airtightness of the sealed box, confirm no air leakage, and then adjust the orientation current to 65A;

[0068] 2), Check the filling amount of the filler in the mold, evacuate the glove box after closing it. When the value displayed by the oxygen control instrument is below 0.05, load the prepared powder material into the mold, and control the weighing error within ±1g. During the operation process, always keep the value of the oxygen control instrument less than 0.05;

[0069] 3), Adjust the demagnetization electrical materials according to the specifications so that there are no residual powder burrs on the two end faces and edges of the product blank in the magnetization direction. Then adjust the press pressure to meet the specifications of the pressed product. Generally, the pressure is 5-6 MPa. After pressing, a green compact is obtained, which is packaged and reserved for use;

[0070] S4: Sintering:

[0071] 1), Preparation before starting the machine: Check whether the water pressure of the cooling circulation (0.1-0.2 MPa), the air power gas source pressure (0.4-0.8 MPa), and the argon gas source pressure of the system protection gas (0.6-0.8 MPa) are normal;

[0072] 2), Check whether the heating molybdenum sheet and the molybdenum sheet electrical connector in the furnace body are normal, ensure that there is no residual miscellaneous material slag on the surface of the molybdenum sheet and the molybdenum sheet electrical connector is intact;

[0073] 3), Check whether there are any missing products in the furnace and clean the slag and scraps in the furnace in time; Check whether the furnace door sealing ring is intact, wipe the sealing part of the furnace door to ensure there is no sundry;

[0074] 4), Place the green compact on the rack in the isostatic pressing workshop and store it in a nitrogen bag. After the quantity meets the furnace entry conditions, connect the furnace truck to discharge oxygen below 800 ppm, place the sintering tray (pay attention to the accurate position), and at the same time move the product tray out and stack it neatly on the sintering tray according to the specified requirements. Note that this process must be fast, orderly, and handled gently. The topmost product tray must be covered. After stacking, quickly load it into the furnace chamber and place it on the bracket (pay attention to avoiding touching the heating molybdenum sheet and thermocouple in the furnace), withdraw the loading truck, and quickly close the furnace door;

[0075] 5), Sinter according to the following sintering process: First, heat up to 900 °C and hold for 30 min, then heat up to 1250 °C at a heating rate of 5 °C / min and sinter for 90 min, then cool down to 950 °C and hold for 4 h, and then cool and temper to obtain. After sintering, a blank is obtained, which is stored in the warehouse for use after passing the inspection;

[0076] S5: Centerless grinding:

[0077] 1), Preparation before starting the machine: Clean the key parts of the machine tool (grinding wheel, guide wheel dressing system, guide rail, etc.);

[0078] 2), Grind the blank to obtain a magnetic matrix. During the processing, the feed amount of the guide wheel should not be too large, the feed speed should be slow, and the gap between the grinding wheel and the support plate generally remains between 1 mm and 1.5 mm;

[0079] S6: Anti-corrosion processing: Use a spraying machine to evenly spray the anti-corrosion composition on the surface of the magnetic substrate, and form an anti-corrosion layer after curing and drying at a temperature of 120 °C. The thickness of the anti-corrosion layer is 300 μm.

[0080] The anti-corrosion composition of this embodiment is made by uniformly mixing the following raw materials by weight: 100 kg of solvent, 25 kg of epoxy resin, 10 kg of ethylenediamine, 10 kg of nickel powder, 20 kg of zinc powder, 2 kg of methyl oleate, and 5 kg of anti-corrosion agent.

[0081] Among them, the epoxy resin is epoxy resin E-44. The anti-corrosion agent is composed of aluminum benzoate, sodium metasilicate, and pyridine-2,5-dicarboxylic acid in a molar ratio of 20:7.5:1.

[0082] The cylindrical magnetic block of this embodiment is made of the above-mentioned hydrogenated erbium neodymium iron boron magnet, with a diameter of 10 mm and a height of 20 mm.

[0083] Example 2

[0084] The hydrogenated erbium corrosion-resistant neodymium iron boron magnet of this embodiment includes a magnetic substrate and an anti-corrosion layer coated on the surface of the magnetic substrate. The magnetic substrate includes the following components by weight percentage: 29% of praseodymium-neodymium alloy, 6% of boron, 10% of erbium, 2% of copper, 2% of zirconium, 2% of cobalt, 2% of niobium, 2% of aluminum, 2% of gallium, and the balance is iron.

[0085] The preparation method of the hydrogenated erbium corrosion-resistant neodymium iron boron magnet of this embodiment is different from that of Example 1 in that:

[0086] Step S6: Anti-corrosion processing: Use a spraying machine to evenly spray the anti-corrosion composition on the surface of the magnetic substrate, and form an anti-corrosion layer after curing and drying at a temperature of 150 °C. The thickness of the anti-corrosion layer is 300 μm.

[0087] The anti-corrosion composition of this embodiment is made by uniformly mixing the following raw materials by weight: 100 kg of solvent, 25 kg of epoxy resin, 10 kg of ethylenediamine, 10 kg of nickel powder, 20 kg of zinc powder, 2 kg of methyl oleate, and 5 kg of anti-corrosion agent.

[0088] Among them, the epoxy resin is epoxy resin 6101. The anti-corrosion agent is composed of aluminum benzoate, sodium metasilicate, and pyridine-2,5-dicarboxylic acid in a molar ratio of 20:7.5:1.

[0089] Example 3

[0090] The hydrogenated erbium corrosion-resistant neodymium iron boron magnet of this embodiment includes a magnetic substrate and an anti-corrosion layer coated on the surface of the magnetic substrate. The magnetic substrate includes the following components by weight percentage: 25% of praseodymium-neodymium alloy, 5.6% of boron, 7.5% of erbium, 1.2% of copper, 1.5% of zirconium, 1.8% of cobalt, 1.5% of niobium, 1.5% of aluminum, 1.85% of gallium, and the balance is iron.

[0091] The preparation method of the hydrogen-cracked erbium-corrosion-resistant neodymium iron boron magnet in this embodiment is different from that in Embodiment 1 in that:

[0092] Step S6: Anti-corrosion processing: Use a spraying machine to evenly spray the anti-corrosion composition on the surface of the magnetic substrate, and cure and dry it at a temperature of 135 °C to form an anti-corrosion layer with a thickness of 300 μm.

[0093] The anti-corrosion composition in this embodiment is made by uniformly mixing the following raw materials by weight: 100 kg of solvent, 25 kg of epoxy resin, 10 kg of ethylenediamine, 10 kg of nickel powder, 20 kg of zinc powder, 2 kg of methyl oleate, and 5 kg of anti-corrosion agent.

[0094] Among them, the solvent is ethylene glycol. The epoxy resin is epoxy resin E-51. The anti-corrosion agent is composed of aluminum benzoate, sodium metasilicate, and pyridine-2,5-dicarboxylic acid in a molar ratio of 20:7.5:1.

[0095] Embodiment 4

[0096] The hydrogen-cracked erbium-corrosion-resistant neodymium iron boron magnet in this embodiment includes a magnetic substrate and an anti-corrosion layer coated on the surface of the magnetic substrate. The magnetic substrate includes the following components by weight percentage: 25% of praseodymium-neodymium alloy, 5.6% of boron, 7.5% of erbium, 1.2% of copper, 1.5% of zirconium, 1.8% of cobalt, 1.5% of niobium, 1.5% of aluminum, 1.85% of gallium, and the balance is iron.

[0097] The preparation method of the hydrogen-cracked erbium-corrosion-resistant neodymium iron boron magnet in this embodiment is the same as that in Embodiment 3.

[0098] The anti-corrosion composition in this embodiment is made by uniformly mixing the following raw materials by weight: 150 kg of solvent, 35 kg of epoxy resin, 15 kg of ethylenediamine, 5 kg of nickel powder, 30 kg of zinc powder, 5 kg of methyl oleate, and 10 kg of anti-corrosion agent.

[0099] Among them, the solvent is ethylene glycol. The epoxy resin is epoxy resin E-51. The anti-corrosion agent is composed of aluminum benzoate, sodium metasilicate, and pyridine-2,5-dicarboxylic acid in a molar ratio of 20:7.5:1.

[0100] Embodiment 5

[0101] The hydrogen-cracked erbium-corrosion-resistant neodymium iron boron magnet in this embodiment includes a magnetic substrate and an anti-corrosion layer coated on the surface of the magnetic substrate. The magnetic substrate includes the following components by weight percentage: 25% of praseodymium-neodymium alloy, 5.6% of boron, 7.5% of erbium, 1.2% of copper, 1.5% of zirconium, 1.8% of cobalt, 1.5% of niobium, 1.5% of aluminum, 1.85% of gallium, and the balance is iron.

[0102] The preparation method of the hydrogen-cracked erbium-corrosion-resistant neodymium iron boron magnet in this embodiment is the same as that in Embodiment 3.

[0103] The anti-corrosion composition of this embodiment is made by uniformly mixing raw materials with the following weights: 130 kg of solvent, 30 kg of epoxy resin, 12 kg of ethylenediamine, 8 kg of nickel powder, 25 kg of zinc powder, 3.5 kg of methyl oleate, and 8.5 kg of anti-corrosion agent.

[0104] Among them, the solvent is ethylene glycol. The epoxy resin is polyacrylate. The anti-corrosion agent is composed of aluminum benzoate, sodium metasilicate, and pyridine-2,5-dicarboxylic acid in a molar ratio of 20:7.5:1.

[0105] Example 6

[0106] The hydrogenated erbium-corrosion-resistant NdFeB magnet of this embodiment includes a magnetic matrix and an anti-corrosion layer coated on the surface of the magnetic matrix. The magnetic matrix includes the following components by weight percentage: 25% of praseodymium-neodymium alloy, 5.6% of boron, 7.5% of erbium, 1.2% of copper, 1.5% of zirconium, 1.8% of cobalt, 1.5% of niobium, 1.5% of aluminum, 1.85% of gallium, and the balance is iron.

[0107] The preparation method of the hydrogenated erbium-corrosion-resistant NdFeB magnet of this embodiment is the same as that of Example 3.

[0108] The anti-corrosion composition of this embodiment is made by uniformly mixing raw materials with the following weights: 130 kg of solvent, 30 kg of epoxy resin, 12 kg of ethylenediamine, 8 kg of nickel powder, 25 kg of zinc powder, 3.5 kg of methyl oleate, and 8.5 kg of anti-corrosion agent.

[0109] Among them, the solvent is ethylene glycol. The epoxy resin is epoxy resin E-51. The anti-corrosion agent is composed of aluminum benzoate, sodium metasilicate, and pyridine-2,5-dicarboxylic acid in a molar ratio of 30:5:3.

[0110] Example 7

[0111] The components of the hydrogenated erbium-corrosion-resistant NdFeB magnet of this embodiment are the same as those of Example 6.

[0112] The preparation method of the hydrogenated erbium-corrosion-resistant NdFeB magnet of this embodiment is the same as that of Example 6.

[0113] The difference between the anti-corrosion composition of this embodiment and that of Example 6 is that the organic acid aluminum in the raw materials is aluminum citrate, and the rest is the same as that of Example 6.

[0114] Example 8

[0115] The components of the hydrogenated erbium-corrosion-resistant NdFeB magnet of this embodiment are the same as those of Example 6.

[0116] The preparation method of the hydrogenated erbium-corrosion-resistant NdFeB magnet of this embodiment is the same as that of Example 6.

[0117] The anti-corrosion composition of this example is different from that of Example 6 in that: in the raw materials, aluminum organic acid is composed of aluminum oxalate and aluminum tartrate at a molar ratio of 2:1, and the rest is the same as that of Example 6.

[0118] Example 9

[0119] The components of the hydrogen-disrupted erbium corrosion-resistant NdFeB magnet in this example are the same as those of Example 6.

[0120] The preparation method of the hydrogen-disrupted erbium corrosion-resistant NdFeB magnet in this example is the same as that of Example 6.

[0121] The anti-corrosion composition of this example is different from that of Example 6 in that: in the raw materials, aluminum organic acid is composed of aluminum citrate and aluminum tartrate at a molar ratio of 2:1, and the rest is the same as that of Example 6.

[0122] Example 10

[0123] The components of the hydrogen-disrupted erbium corrosion-resistant NdFeB magnet in this example are the same as those of Example 6.

[0124] The preparation method of the hydrogen-disrupted erbium corrosion-resistant NdFeB magnet in this example is the same as that of Example 6.

[0125] The anti-corrosion composition of this example is different from that of Example 6 in that: in the raw materials, aluminum organic acid is composed of aluminum citrate and aluminum tartrate at a molar ratio of 5:0.6, and the rest is the same as that of Example 6.

[0126] Example 11

[0127] The components of the hydrogen-disrupted erbium corrosion-resistant NdFeB magnet in this example are the same as those of Example 10.

[0128] The preparation method of the hydrogen-disrupted erbium corrosion-resistant NdFeB magnet in this example is different from that of Example 10 in that: in step S6, the thickness of the anti-corrosion layer is 500 μm.

[0129] The anti-corrosion composition of this example is the same as that of Example 10.

[0130] Example 12

[0131] The components of the hydrogen-disrupted erbium corrosion-resistant NdFeB magnet in this example are the same as those of Example 11.

[0132] The preparation method of the hydrogen-disrupted erbium corrosion-resistant NdFeB magnet in this example is the same as that of Example 11.

[0133] The anti-corrosion composition of this example is different from that of Example 11 in that: the raw materials further include 0.5 kg of chitosan hydrochloride, and the rest is the same as that of Example 11.

[0134] Example 13

[0135] The components of the hydrogen-cracked erbium-corrosion-resistant NdFeB magnet in this example are the same as those in Example 11.

[0136] The preparation method of the hydrogen-cracked erbium-corrosion-resistant NdFeB magnet in this example is the same as that in Example 11.

[0137] The difference between the anti-corrosion composition of this example and that of Example 11 is that: the raw materials further include 0.75 kg of chitosan hydrochloride, and the rest are the same as those in Example 11.

[0138] Example 14

[0139] The components of the hydrogen-cracked erbium-corrosion-resistant NdFeB magnet in this example are the same as those in Example 12.

[0140] The preparation method of the hydrogen-cracked erbium-corrosion-resistant NdFeB magnet in this example is the same as that in Example 12.

[0141] The difference between the anti-corrosion composition of this example and that of Example 12 is that: the solvent in the raw materials is composed of dimethyl sulfoxide, ethylene glycol, and water in a mass ratio of 3.5:7:30, and the rest are the same as those in Example 12.

[0142] Example 15

[0143] The components of the hydrogen-cracked erbium-corrosion-resistant NdFeB magnet in this example are the same as those in Example 12.

[0144] The preparation method of the hydrogen-cracked erbium-corrosion-resistant NdFeB magnet in this example is the same as that in Example 12.

[0145] The difference between the anti-corrosion composition of this example and that of Example 12 is that: the solvent in the raw materials is composed of dimethyl sulfoxide, ethylene glycol, and water in a mass ratio of 2:12:35, and the rest are the same as those in Example 12.

[0146] Example 16

[0147] The components of the hydrogen-cracked erbium-corrosion-resistant NdFeB magnet in this example are the same as those in Example 15.

[0148] The difference between the preparation method of the hydrogen-cracked erbium-corrosion-resistant NdFeB magnet in this example and that of Example 15 is that: in step S6, the surface of the magnetic matrix is electroplated before spraying the anti-corrosion composition, and the electroplating solution includes the following components: nickel sulfamate 2.5%, zinc sulfate 5%, potassium hydroxide 2%, and the balance is deionized water; the electroplating process is: current density 2 A / dm 2 , and the coating thickness is 5 μm.

[0149] The anti-corrosion composition of this example is the same as that of Example 15.

[0150] Comparative Example

[0151] Comparative Example 1

[0152] The hydrogen-breaking erbium-corrosion-resistant NdFeB magnet of this comparative example includes a magnetic matrix and an anti-corrosion layer coated on the surface of the magnetic matrix. The magnetic matrix includes the following components by weight percentage: praseodymium-neodymium alloy 25%, boron 5.6%, erbium 7.5%, copper 1.2%, zirconium 1.5%, cobalt 1.8%, niobium 1.5%, aluminum 1.5%, gallium 1.85%, and the balance is iron.

[0153] The preparation method of the hydrogen-breaking erbium-corrosion-resistant NdFeB magnet of this comparative example is different from that of Example 1 in that:

[0154] Step S6: Anti-corrosion processing: Use a spraying machine to evenly spray the anti-corrosion composition on the surface of the magnetic matrix, and form an anti-corrosion layer after curing and drying at a temperature of 135°C. The thickness of the anti-corrosion layer is 300 μm.

[0155] The anti-corrosion composition of this comparative example is made by uniformly mixing the following raw materials by weight: 105 kg of solvent, 25 kg of epoxy resin, 10 kg of ethylenediamine, 10 kg of nickel powder, 20 kg of zinc powder, and 2 kg of methyl oleate.

[0156] Among them, the solvent is ethylene glycol. The epoxy resin is epoxy resin E-51.

[0157] Comparative Example 2

[0158] The hydrogen-breaking erbium-corrosion-resistant NdFeB magnet of this comparative example includes a magnetic matrix and an anti-corrosion layer coated on the surface of the magnetic matrix. The magnetic matrix includes the following components by weight percentage: praseodymium-neodymium alloy 25%, boron 5.6%, erbium 7.5%, copper 1.2%, zirconium 1.5%, cobalt 1.8%, niobium 1.5%, aluminum 1.5%, gallium 1.85%, and the balance is iron.

[0159] The preparation method of the hydrogen-breaking erbium-corrosion-resistant NdFeB magnet of this comparative example is different from that of Example 1 in that:

[0160] Step S6: Anti-corrosion processing: Use a spraying machine to evenly spray the anti-corrosion composition on the surface of the magnetic matrix, and form an anti-corrosion layer after curing and drying at a temperature of 135°C. The thickness of the anti-corrosion layer is 300 μm.

[0161] The anti-corrosion composition of this comparative example is made by uniformly mixing the following raw materials by weight: 100 kg of solvent, 25 kg of epoxy resin, 10 kg of ethylenediamine, 10 kg of nickel powder, 20 kg of zinc powder, 2 kg of methyl oleate, and 5 kg of anti-corrosion agent.

[0162] Among them, the solvent is ethylene glycol. The epoxy resin is epoxy resin E-51. The anti-corrosion agent is composed of sodium metasilicate and pyridine-2,5-dicarboxylic acid in a molar ratio of 7.5:1.

[0163] Comparative Example 3

[0164] The hydrogen-disrupted erbium corrosion-resistant Nd-Fe-B magnet of this comparative example includes a magnetic matrix and an anti-corrosion layer coated on the surface of the magnetic matrix. The magnetic matrix includes the following components by weight percentage: praseodymium-neodymium alloy 25%, boron 5.6%, erbium 7.5%, copper 1.2%, zirconium 1.5%, cobalt 1.8%, niobium 1.5%, aluminum 1.5%, gallium 1.85%, and the balance is iron.

[0165] The preparation method of the hydrogen-disrupted erbium corrosion-resistant Nd-Fe-B magnet of this comparative example is different from that of Example 1 in that:

[0166] Step S6: Anti-corrosion processing: Use a spraying machine to evenly spray the anti-corrosion composition on the surface of the magnetic matrix, and form an anti-corrosion layer after curing and drying at a temperature of 135 °C. The thickness of the anti-corrosion layer is 300 μm.

[0167] The anti-corrosion composition of this comparative example is made by uniformly mixing the following raw materials by weight: 100 kg of solvent, 25 kg of epoxy resin, 10 kg of ethylenediamine, 10 kg of nickel powder, 20 kg of zinc powder, 2 kg of methyl oleate, and 5 kg of anti-corrosion agent.

[0168] Among them, the solvent is ethylene glycol. The epoxy resin is epoxy resin E-51. The anti-corrosion agent is aluminum benzoate.

[0169] Comparative Example 4

[0170] The hydrogen-disrupted erbium corrosion-resistant Nd-Fe-B magnet of this comparative example includes a magnetic matrix and an anti-corrosion layer coated on the surface of the magnetic matrix. The magnetic matrix includes the following components by weight percentage: praseodymium-neodymium alloy 25%, boron 5.6%, erbium 7.5%, copper 1.2%, zirconium 1.5%, cobalt 1.8%, niobium 1.5%, aluminum 1.5%, gallium 1.85%, and the balance is iron.

[0171] The preparation method of the hydrogen-disrupted erbium corrosion-resistant Nd-Fe-B magnet of this comparative example is different from that of Example 1 in that:

[0172] Step S6: Anti-corrosion processing: Use a spraying machine to evenly spray the anti-corrosion composition on the surface of the magnetic matrix, and form an anti-corrosion layer after curing and drying at a temperature of 135 °C. The thickness of the anti-corrosion layer is 300 μm.

[0173] The anti-corrosion composition of this comparative example is made by uniformly mixing the following raw materials by weight: 100 kg of solvent, 25 kg of epoxy resin, 10 kg of ethylenediamine, 10 kg of nickel powder, 20 kg of zinc powder, 2 kg of methyl oleate, and 5 kg of anti-corrosion agent.

[0174] Among them, the solvent is ethylene glycol. The epoxy resin is epoxy resin E-51. The anti-corrosion agent is zinc phosphate.

[0175] Comparative Example 5

[0176] The hydrogen-breaking erbium-corrosion-resistant NdFeB magnet of this comparative example includes a magnetic matrix and an anti-corrosion layer coated on the surface of the magnetic matrix. The magnetic matrix includes the following components by weight percentage: praseodymium-neodymium alloy 25%, boron 5.6%, erbium 7.5%, copper 1.2%, zirconium 1.5%, cobalt 1.8%, niobium 1.5%, aluminum 1.5%, gallium 1.85%, and the balance is iron.

[0177] The difference between the preparation method of the hydrogen-breaking erbium-corrosion-resistant NdFeB magnet of this comparative example and that of Example 1 lies in:

[0178] Step S6: Anti-corrosion processing: Use a spraying machine to evenly spray the anti-corrosion composition on the surface of the magnetic matrix, and cure and dry it at a temperature of 135 °C to form an anti-corrosion layer with a thickness of 300 μm.

[0179] The anti-corrosion composition of this comparative example is made by uniformly mixing the following raw materials by weight: 100 kg of solvent, 25 kg of epoxy resin, 10 kg of ethylenediamine, 10 kg of nickel powder, 20 kg of zinc powder, 2 kg of methyl oleate, and 5 kg of anti-corrosion agent.

[0180] Among them, the solvent is ethylene glycol. The epoxy resin is epoxy resin E-51. The anti-corrosion agent is composed of aluminum organic acid, sodium metasilicate, and pyridine-2,5-dicarboxylic acid in a molar ratio of 10:8:5.

[0181] Performance detection test

[0182] Detection method

[0183] Take the hydrogen-breaking erbium-corrosion-resistant NdFeB magnets of Examples 1-16 and Comparative Examples 1-5 and test their corrosion resistance under high-temperature conditions according to the national standard GB / T2423. Using the surface rusting time as the test end point, the test results are shown in Table 1.

[0184] Table 1 Performance test data of the hydrogen-breaking erbium-corrosion-resistant NdFeB magnets of Examples 1-16 and Comparative Examples 1-5

[0185] Serial number 200℃(h) Example 1 206.3 Example 2 235.7 Example 3 252.1 Example 4 262.3 Example 5 278.6 Example 6 389.5 Example 7 412.3 Example 8 405.6 Example 9 433.9 Example 10 446 Example 11 461.1 Example 12 493.2 Example 13 486.3 Example 14 501.2 Example 15 505.8 Example 16 526.2 Comparative example 1 103.6 Comparative example 2 155.3 Comparative example 3 167.2 Comparative example 4 138.6 Comparative example 5 241.6

[0186] Analysis of Examples 1-3 and Comparative Example 1 and in combination with Table 1 shows that after adding an anti-corrosion agent to the anti-corrosion composition of this application, the corrosion resistance of the anti-corrosion layer under high-temperature working conditions is greatly improved. Moreover, by optimizing and adjusting the component ratio of the magnetic matrix, the corrosion potential difference between the main phase and the other phases can be improved, and under the protection of the anti-corrosion layer, the neutral salt spray test can reach 252 h, which is about twice that of Comparative Example 1 without adding an anti-corrosion agent.

[0187] Analysis of Examples 4-5, Comparative Examples 2-4 and in combination with Table 1 shows that by further optimizing and testing the composition ratio of the corrosion inhibitor and giving play to the synergistic effect among aluminum organic acid, sodium metasilicate and pyridine-2,5-dicarboxylic acid, it can be seen that the neutral salt spray resistance time of Example 5 is increased by about 79% compared with that of Comparative Example 2 without adding aluminum organic acid. Moreover, when only aluminum organic acid is added in Comparative Example 3, the corrosion resistance performance also drops significantly compared with that of Example 5, which may be due to the decrease in the stability of aluminum organic acid in high-temperature environment. In addition, compared with the conventional phosphorus-based corrosion inhibitor, the neutral salt spray resistance time of Example 5 is increased by about 2.1 times.

[0188] Analysis of Examples 6-10, Comparative Example 5 and in combination with Table 1 shows that by testing and adjusting the composition ratio of aluminum organic acid and selecting aluminum organic acid with appropriate reaction activity, the corrosion resistance of the anti-corrosion layer is further improved. It can be seen that the neutral salt spray resistance time of Example 10 is increased by about 14.5% compared with that of Example 6.

[0189] Analysis of Example 11, Examples 12-13, Examples 14-15, Example 16 and in combination with Table 1 shows that by further optimizing the process of the anti-corrosion layer, selecting appropriate thickness and suitable solvent, it helps to improve the dispersion uniformity of each component of the anti-corrosion layer and the isotropy of the anti-corrosion layer. And adding chitosan hydrochloride and electroplating on the surface of the magnetic matrix, the double protection of the electroplating layer and the anti-corrosion layer further improves the corrosion resistance of the anti-corrosion layer.

[0190] This specific embodiment is only an explanation of the present application, and it does not limit the present application. Those skilled in the art can make modifications without creative contributions to this embodiment according to needs after reading this specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A hydrogen-disrupted erbium corrosion-resistant NdFeB magnet, characterized in that, It includes a magnetic matrix and an anti-corrosion layer coated on the surface of the magnetic matrix. The magnetic matrix comprises components in the following weight percentages: Praseodymium-neodymium alloy 15 - 29%; Boron 5.2 - 6%; Erbium 1 - 10%; Copper 0 - 2%; Zirconium 0 - 2%; Cobalt 0 - 2%; Niobium 0 - 2%; Aluminum 0 - 2%; Gallium 0 - 2%; The balance is iron; A method for preparing a hydrogenated erbium corrosion-resistant neodymium iron boron magnet, comprising the following steps: S1: Melting: Mix the formula amounts of praseodymium-neodymium alloy, copper, zirconium, cobalt, niobium, aluminum, gallium, boron and iron evenly and carry out melting to obtain a melted alloy ingot; S2: Powder making: Carry out hydrogenation and powder making on the melted alloy ingot. After powder making, add hydrogenated erbium and mix evenly to obtain a hydrogenated material; then further pulverize the hydrogenated material by a jet mill process to obtain a powder; S3: Forming: Fill and press the powder in a mold to obtain a green body; S4: Sintering: Sinter the green body to obtain a blank; S5: Centerless grinding: Grind the blank to obtain a magnetic matrix; S6: Anti-corrosion processing: Spray an anti-corrosion composition on the surface of the magnetic matrix, and after curing and drying, form an anti-corrosion layer to obtain it; The anti-corrosion composition is mainly made of the following raw materials in parts by weight: 100 - 150 parts of solvent, 25 - 35 parts of epoxy resin, 10 - 15 parts of ethylenediamine, 5 - 10 parts of nickel powder, 20 - 30 parts of zinc powder, 2 - 5 parts of methyl oleate, 5 - 10 parts of anti-corrosion agent; The anti-corrosion agent is composed of aluminum organic acid, sodium metasilicate, pyridine-2,5-dicarboxylic acid in a molar ratio of (20 - 30):(5 - 7.5):(1 - 3); The thickness of the anti-corrosion layer is 300 - 500 μm; The solvent is composed of dimethyl sulfoxide, ethylene glycol, water in a mass ratio of (2 - 3.5):(7 - 12):(30 - 35).

2. The hydrogen-disrupted erbium corrosion-resistant neodymium iron boron magnet according to claim 1, wherein The aluminum organic acid is at least one of aluminum citrate, aluminum oxalate, aluminum tartrate.

3. The hydrogen-disrupted erbium-corrosion-resistant neodymium-iron-boron magnet according to claim 2, wherein The aluminum organic acid is composed of aluminum citrate and aluminum tartrate in a molar ratio of (2 - 5):(0.6 - 1).

4. The hydrogenated erbium-resistant neodymium iron boron magnet according to claim 1, characterized in that, The mass ratio of the anti-corrosion agent to the epoxy resin is (0.05 - 0.065):

1.

5. A hydrogen-disrupted erbium-corrosion-resistant neodymium iron boron magnet according to claim 1, wherein The raw materials of the anti-corrosion composition further include 0.5 - 0.75 parts by weight of chitosan hydrochloride.

6. The hydrogenated erbium-corrosion-resistant neodymium iron boron magnet according to claim 1, wherein, The surface of the magnetic matrix is electroplated before spraying the anti-corrosion composition.

7. A cylindrical magnetic block, characterized in that, Obtained from the hydrogenated erbium corrosion-resistant neodymium iron boron magnet as described in claim 1.