A method for preparing a neodymium iron boron magnet

Abstract

The present invention belongs to the technical field of NdFeB, and in particular, is a method for preparing NdFeB magnets, including the following selected materials, such as rare earth metal neodymium, metal element iron, non-metallic element boron, and added samarium, niobium, aluminum, copper, nickel and chromium. The melt-quenched NdFeB microcrystalline flakes and preparation method thereof, by adding samarium, nickel and chromium to replace praseodymium, dysprosium and terbium, so that the NdFeB remanence in the present invention can reach 1.35T and low temperature coefficient; the temperature coefficient is -0.02% / ℃, and the use temperature can reach 680℃; it has a high magnetic energy product, at a working temperature of 180℃, its magnetic energy product and temperature stability and chemical stability will be greater than that of NdFeB magnetic materials; it has excellent plasticity and ductility, and can also be made into semi-hard magnetic alloys, and has better characteristics than other magnetic materials, is more resistant to high temperatures, and can maintain magnetic properties without decay when used at a temperature of 400℃.

Description

Technical Field

[0001] The invention relates to the technical field of neodymium iron boron, and in particular to a method for preparing a neodymium iron boron magnet. Background Art

[0002] Neodymium magnets, also known as NdFeB magnets, are tetragonal crystals formed by neodymium, iron, and boron (Nd2Fe14B). In 1982, Sagawa Masato of Sumitomo Special Metals discovered neodymium magnets. The magnetic energy product of this magnet is greater than that of samarium cobalt magnets, and it was the material with the largest magnetic energy product in the world at that time. Later, Sumitomo Special Metals successfully developed powder metallurgy and General Motors successfully developed the rotary spray melting method, which can produce neodymium iron boron magnets. This magnet is a permanent magnet with magnetic properties second only to absolute zero holmium magnets, and is also the most commonly used rare earth magnet. Neodymium iron boron magnets are widely used in electronic products such as hard drives, mobile phones, headphones, and battery-powered tools.

[0003] Most of the raw materials used in the production of existing NdFeB are rare metals such as praseodymium, dysprosium and terbium. The NdFeB produced from these rare metals has a high temperature coefficient and poor plasticity, is not resistant to high temperatures, is brittle and easy to crack, making subsequent processing difficult and easy to wear and scrap. Therefore, a method for preparing NdFeB magnets is needed. Summary of the invention

[0004] Based on the existing technical problems, the present invention proposes a method for preparing a neodymium iron boron magnet.

[0005] The invention provides a method for preparing a neodymium iron boron magnet, which comprises the following selected materials, such as rare earth metal neodymium, metal element iron, non-metallic element boron, and added samarium, niobium, aluminum, copper, nickel and chromium.

[0006] Preferably, the mass percentage content of each component is 28%-31% of rare earth metal neodymium, 62%-66% of metal element iron, 1.1%-1.2% of non-metallic element boron, and added elements of 0.5%-1.1% of samarium, 0.4%-0.6% of niobium, 0.3%-0.5% of aluminum, 0.05%-0.15% of copper, 0.2%-0.3% of nickel and 0.2%-0.3% of chromium.

[0007] Preferably, step 1, preparing ingredients;

[0008] Step 2: smelting;

[0009] Step 3: Hydrogen crushing;

[0010] Step 4: Jet milling;

[0011] Step 5: Forming;

[0012] Step 6: static pressure, gradually release the pressure to the object to gradually reduce the density of the product to meet the predetermined requirements;

[0013] Step 7, oil stripping, is to remove the static pressed product packaging and prepare for sintering;

[0014] Step 8: Put the product into a specific sintering furnace for a series of sintering. The small steps can be divided into: entering the furnace, sintering, taking out of the furnace, demagnetizing, and reverse firing to obtain the rough product;

[0015] Step nine: Put the sintered blank materials on the grinding machine, wire cutting, slicing, punching, electroplating, and finally magnetizing, packaging and shipping as required.

[0016] Preferably, in the step 2, the pretreated raw materials are mixed according to proportion, added into a vacuum melting furnace, and spun after high-temperature melting under argon protection; so that the product has uniform composition, high crystal orientation, good organizational consistency, and avoids the formation of a-Fe.

[0017] Preferably, in step three, the hydrogen absorption property of rare earth intermetallic compounds is utilized to place the NdFeB alloy in a hydrogen environment, and the hydrogen enters the alloy along the Nd-rich phase thin layer, causing it to expand, burst and break.

[0018] Preferably, in step 4, the material is crushed by high-speed collision in the airflow chamber, which causes no wear on the inner wall of the grinding chamber and allows rapid preparation of powder.

[0019] Preferably, in step five, the magnetic powder is mixed with an adhesive, heated and mixed, granulated, dried, and then sent to a heating chamber by a spiral guide rod for heating, injected into a mold cavity for molding, and the finished product is obtained after cooling; generally, nylon 6, polyamide, polyester and PVC are added in an amount of 20% to 30% (volume fraction), combined with a rigid adhesive permanent magnet with a complex shape.

[0020] Preferably, the sintering process in step eight is divided into two stages of sintering and aging. The sintering temperature is about 1040°C to 1070°C for hydrogen-stripped crushed material, about 1080°C to 1200°C for ingot hydrogen crushed material, and about 1090°C to 1140°C for ingot material. The aging is divided into two stages of aging at 880°C to 910°C and 510°C to 620°C. The entire process from sintering and aging to unloading takes 22 to 40 hours.

[0021] Preferably, in step nine, a slicer is used for cutting, and a double-sided grinder is required for processing for higher precision or CPK requirements.

[0022] The beneficial effects of the present invention are:

[0023] By adding samarium, nickel and chromium to replace praseodymium, dysprosium and terbium, the remanence of the NdFeB in the present invention can reach 1.35T and the temperature coefficient is low; the temperature coefficient is -0.02% / ℃, and the use temperature can reach 680℃; it has a high magnetic energy product, and at a working temperature of 180℃, its magnetic energy product, temperature stability and chemical stability are greater than those of NdFeB magnetic materials; it has excellent plasticity and ductility, and can also be made into semi-hard magnetic alloys, and has better characteristics than other magnetic materials, is more resistant to high temperatures, and can maintain magnetic properties without decay when used at a temperature of 400°C. It has good mechanical processing performance, whether it is drilling, cutting, planing, stamping, etc. or making some thinner heterosexual magnets, it can meet the effect of avoiding the brittleness, fragility and cracking of other magnetic magnetic materials. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0025] A method for preparing a neodymium iron boron magnet, step 1, ingredients; including the following selected materials, such as rare earth metal neodymium, metallic element iron, non-metallic element boron, and added samarium, niobium, aluminum, copper, nickel and chromium; the mass percentage content of each component is respectively 28%-31% of rare earth metal neodymium, 62%-66% of metallic element iron, 1.1%-1.2% of non-metallic element boron, and added elements of 0.5%-1.1%, 0.4%-0.6% of niobium, 0.3%-0.5% of aluminum, 0.05%-0.15% of copper, 0.2%-0.3% of nickel and 0.2%-0.3% of chromium;

[0026] Step 2, smelting; in step 2, the pre-treated raw materials are mixed according to the proportion, added into a vacuum melting furnace, and smelted at high temperature under the protection of argon gas, and then spun; so that the product composition is uniform, the crystal orientation is high, the organization consistency is good, and the formation of a-Fe is avoided;

[0027] Step 3, hydrogen crushing; In step 3, the hydrogen absorption property of rare earth intermetallic compounds is used to place the NdFeB alloy in a hydrogen environment, and the hydrogen enters the alloy along the Nd-rich phase thin layer, causing it to expand, burst and break, and crack along the Nd-rich phase layer, thereby ensuring the integrity of the main phase grains and the boundary phase between the Nd-rich grains; the HDI process makes the NdFeB flakes very loose, improves the powder making efficiency of the airflow mill, and reduces the production cost;

[0028] Step 4, air flow milling: In step 4, the material is crushed by high-speed collision in the air flow chamber, without abrasion to the inner wall of the mill, and powder can be prepared quickly;

[0029] Step 5, molding; in step 5, the magnetic powder is mixed with the adhesive, heated and mixed, granulated, dried, and then sent to the heating chamber by a spiral guide rod for heating, injected into the mold cavity for molding, and the finished product is obtained after cooling; generally, nylon 6, polyamide, polyester and PVC are added in an amount of 20% to 30% (volume fraction), combined with a rigid adhesive permanent magnet with a complex shape;

[0030] Step 6: static pressure, gradually release the pressure to the object to gradually reduce the density of the product to meet the predetermined requirements;

[0031] Step 7, oil stripping, is to remove the static pressed product packaging and prepare for sintering;

[0032] Step 8, put the product into a specific sintering furnace for a series of sintering, and the small steps can be divided into: entering the furnace, sintering, taking out of the furnace, demagnetizing, and reverse firing, and then the rough product can be obtained; in step 8, the sintering process is divided into two stages of sintering and aging. The sintering temperature is about 1040℃~1070℃ for hydrogen-stripped crushed materials, about 1080℃~1200℃ for hydrogen-cast ingots, and 1090℃~1140℃ for ingots. The aging is divided into two stages of aging mechanism at 880℃~910℃ and 510℃~620℃. The whole process from sintering and aging to taking out of the furnace takes 22~40 hours;

[0033] Step nine, the sintered blank material is put on the grinding machine, wire cutting, slicing, punching, electroplating, and finally magnetizing, packaging and shipping; in step nine, a slicer is used for cutting, and a double-sided grinder is required for processing for higher precision or CPK requirements.

[0034] By adding samarium, nickel and chromium to replace praseodymium, dysprosium and terbium, the remanence of the NdFeB in the present invention can reach 1.35T and the temperature coefficient is low; the temperature coefficient is -0.02% / ℃, and the use temperature can reach 680℃; it has a high magnetic energy product, and at a working temperature of 180℃, its magnetic energy product, temperature stability and chemical stability are greater than those of NdFeB magnetic materials; it has excellent plasticity and ductility, and can also be made into semi-hard magnetic alloys, and has better characteristics than other magnetic materials, is more resistant to high temperatures, and can maintain magnetic properties without decay when used at a temperature of 400°C. It has good mechanical processing performance, whether it is drilling, cutting, planing, stamping, etc. or making some thinner heterosexual magnets, it can meet the effect of avoiding the brittleness, fragility and cracking of other magnetic magnetic materials. Example

[0035] A method for preparing a neodymium iron boron magnet, step 1, ingredients; including the following selected materials, such as rare earth metal neodymium, metal element iron, non-metallic element boron, and added samarium, niobium, aluminum, copper, nickel and chromium; the mass percentage content of each component is respectively 28% of rare earth metal neodymium, 62% of metal element iron, 1.1% of non-metallic element boron, and 0.5% of added samarium, 0.4% of niobium, 0.3% of aluminum, 0.05% of copper, 0.2% of nickel and 0.2% of chromium;

[0036] Step 2, smelting; in step 2, the pre-treated raw materials are mixed according to the proportion, added into a vacuum melting furnace, and smelted at high temperature under the protection of argon gas, and then spun; so that the product composition is uniform, the crystal orientation is high, the organization consistency is good, and the formation of a-Fe is avoided;

[0037] Step 3, hydrogen crushing; In step 3, the hydrogen absorption property of rare earth intermetallic compounds is used to place the NdFeB alloy in a hydrogen environment, and the hydrogen enters the alloy along the Nd-rich phase thin layer, causing it to expand, burst and break, and crack along the Nd-rich phase layer, thereby ensuring the integrity of the main phase grains and the boundary phase between the Nd-rich grains; the HDI process makes the NdFeB flakes very loose, improves the powder making efficiency of the airflow mill, and reduces the production cost;

[0038] Step 4, air flow milling: In step 4, the material is crushed by high-speed collision in the air flow chamber, without abrasion to the inner wall of the mill, and powder can be prepared quickly;

[0039] Step 5, molding; in step 5, the magnetic powder is mixed with the adhesive, heated and mixed, granulated, dried, and then sent to the heating chamber by a spiral guide rod for heating, injected into the mold cavity for molding, and the finished product is obtained after cooling; generally, nylon 6, polyamide, polyester and PVC are added in an amount of 20% by volume, and a rigid adhesive permanent magnet with a complex shape is used;

[0040] Step 6: static pressure, gradually release the pressure to the object to gradually reduce the density of the product to meet the predetermined requirements;

[0041] Step 7, oil stripping, is to remove the static pressed product packaging and prepare for sintering;

[0042] Step 8, put the product into a specific sintering furnace for a series of sintering, and the small steps can be divided into: entering the furnace, sintering, taking out of the furnace, demagnetizing, and reverse firing, and then the rough product can be obtained; in step 8, the sintering process is divided into two stages of sintering and aging. The sintering temperature is about 1040℃ for the hydrogen-stripped material, about 1080℃ for the hydrogen-stripped material, and about 1090℃ for the ingot material. The aging is divided into two stages of aging at 880℃ and 510℃. The whole process from sintering and aging to taking out of the furnace takes 22 hours;

[0043] Step nine, the sintered blank material is put on the grinding machine, wire cutting, slicing, punching, electroplating, and finally magnetizing, packaging and shipping; in step nine, a slicer is used for cutting, and a double-sided grinder is required for processing for higher precision or CPK requirements.

[0044] By adding samarium, nickel and chromium to replace praseodymium, dysprosium and terbium, the remanence of the NdFeB in the present invention can reach 1.35T and the temperature coefficient is low; the temperature coefficient is -0.02% / ℃, and the use temperature can reach 680℃; it has a high magnetic energy product, and at a working temperature of 180℃, its magnetic energy product, temperature stability and chemical stability are greater than those of NdFeB magnetic materials; it has excellent plasticity and ductility, and can also be made into semi-hard magnetic alloys, and has better characteristics than other magnetic materials, is more resistant to high temperatures, and can maintain magnetic properties without decay when used at a temperature of 400°C. It has good mechanical processing performance, whether it is drilling, cutting, planing, stamping, etc. or making some thinner heterosexual magnets, it can meet the effect of avoiding the brittleness, fragility and cracking of other magnetic magnetic materials. Example

[0045] A method for preparing a neodymium iron boron magnet, step 1, ingredients; including the following selected materials, such as rare earth metal neodymium, metal element iron, non-metallic element boron, and added samarium, niobium, aluminum, copper, nickel and chromium; the mass percentage content of each component is respectively 29.5% of rare earth metal neodymium, 64% of metal element iron, 1.15% of non-metallic element boron, and 0.85% of added samarium, 0.5% of niobium, 0.4% of aluminum, 0.1% of copper, 0.1% of nickel and 0.1% of chromium;

[0046] Step 2, smelting; in step 2, the pre-treated raw materials are mixed according to the proportion, added into a vacuum melting furnace, and smelted at high temperature under the protection of argon gas, and then spun; so that the product composition is uniform, the crystal orientation is high, the organization consistency is good, and the formation of a-Fe is avoided;

[0047] Step 3, hydrogen crushing; In step 3, the hydrogen absorption property of rare earth intermetallic compounds is used to place the NdFeB alloy in a hydrogen environment, and the hydrogen enters the alloy along the Nd-rich phase thin layer, causing it to expand, burst and break, and crack along the Nd-rich phase layer, thereby ensuring the integrity of the main phase grains and the boundary phase between the Nd-rich grains; the HDI process makes the NdFeB flakes very loose, improves the powder making efficiency of the airflow mill, and reduces the production cost;

[0048] Step 4, air flow milling: In step 4, the material is crushed by high-speed collision in the air flow chamber, without abrasion to the inner wall of the mill, and powder can be prepared quickly;

[0049] Step 5, molding; in step 5, the magnetic powder is mixed with the adhesive, heated and kneaded, granulated, dried, and then sent to the heating chamber by a spiral guide rod for heating, injected into the mold cavity for molding, and the finished product is obtained after cooling; generally, nylon 6, polyamide, polyester and PVC are added in an amount of 25% by volume, and a rigid adhesive permanent magnet with a complex shape is used;

[0050] Step 6: static pressure, gradually release the pressure to the object to gradually reduce the density of the product to meet the predetermined requirements;

[0051] Step 7, oil stripping, is to remove the static pressed product packaging and prepare for sintering;

[0052] Step 8, put the product into a specific sintering furnace for a series of sintering, and the small steps can be divided into: entering the furnace, sintering, taking out of the furnace, demagnetizing, and reverse firing, and then the rough product can be obtained; the sintering process in step 8 is divided into two stages of sintering and aging. The sintering temperature is about 1050℃ for the hydrogen-stripped material, about 1090℃ for the hydrogen-stripped material, and about 1120℃ for the ingot material. The aging is divided into two stages of aging mechanism at 895℃ and 565℃. The whole process from sintering and aging to taking out of the furnace takes 30 hours;

[0053] Step nine, the sintered blank material is put on the grinding machine, wire cutting, slicing, punching, electroplating, and finally magnetizing, packaging and shipping; in step nine, a slicer is used for cutting, and a double-sided grinder is required for processing for higher precision or CPK requirements.

[0054] By adding samarium, nickel and chromium to replace praseodymium, dysprosium and terbium, the remanence of the NdFeB in the present invention can reach 1.35T and the temperature coefficient is low; the temperature coefficient is -0.02% / ℃, and the use temperature can reach 680℃; it has a high magnetic energy product, and at a working temperature of 180℃, its magnetic energy product, temperature stability and chemical stability are greater than those of NdFeB magnetic materials; it has excellent plasticity and ductility, and can also be made into semi-hard magnetic alloys, and has better characteristics than other magnetic materials, is more resistant to high temperatures, and can maintain magnetic properties without decay when used at a temperature of 400°C. It has good mechanical processing performance, whether it is drilling, cutting, planing, stamping, etc. or making some thinner heterosexual magnets, it can meet the effect of avoiding the brittleness, fragility and cracking of other magnetic magnetic materials. Example

[0055] A method for preparing a neodymium iron boron magnet, step 1, ingredients; including the following selected materials, such as rare earth metal neodymium, metal element iron, non-metallic element boron, and added samarium, niobium, aluminum, copper, nickel and chromium; the mass percentage content of each component is 31% of rare earth metal neodymium, 66% of metal element iron, 1.2% of non-metallic element boron, and added elements of 1.1%, 0.6% of niobium, 0.5% of aluminum, 0.15% of copper, 0.3% of nickel and 0.3% of chromium;

[0056] Step 2, smelting; in step 2, the pre-treated raw materials are mixed according to the proportion, added into a vacuum melting furnace, and smelted at high temperature under the protection of argon gas, and then spun; so that the product composition is uniform, the crystal orientation is high, the organization consistency is good, and the formation of a-Fe is avoided;

[0057] Step 3, hydrogen crushing; In step 3, the hydrogen absorption property of rare earth intermetallic compounds is used to place the NdFeB alloy in a hydrogen environment, and the hydrogen enters the alloy along the Nd-rich phase thin layer, causing it to expand, burst and break, and crack along the Nd-rich phase layer, thereby ensuring the integrity of the main phase grains and the boundary phase between the Nd-rich grains; the HDI process makes the NdFeB flakes very loose, improves the powder making efficiency of the airflow mill, and reduces the production cost;

[0058] Step 4, air flow milling: In step 4, the material is crushed by high-speed collision in the air flow chamber, without abrasion to the inner wall of the mill, and powder can be prepared quickly;

[0059] Step 5, molding; in step 5, the magnetic powder is mixed with the adhesive, heated and mixed, granulated, dried, and then sent to the heating chamber by a spiral guide rod for heating, injected into the mold cavity for molding, and the finished product is obtained after cooling; generally, nylon 6, polyamide, polyester and PVC are added in an amount of 30% by volume, and a rigid adhesive permanent magnet with a complex shape is used;

[0060] Step 6: static pressure, gradually release the pressure to the object to gradually reduce the density of the product to meet the predetermined requirements;

[0061] Step 7, oil stripping, is to remove the static pressed product packaging and prepare for sintering;

[0062] Step 8: Put the product into a specific sintering furnace for a series of sintering. The small steps can be divided into: entering the furnace, sintering, taking out of the furnace, demagnetizing, and reverse firing to obtain the rough product; the sintering process in step 8 is divided into two stages of sintering and aging. The sintering temperature is about 1070℃ for hydrogen-strip crushing, about 1200℃ for hydrogen-strip crushing, and about 1140℃ for ingots. The aging is divided into two stages of aging at 910℃ and 620℃. The whole process from sintering and aging to taking out of the furnace takes 40 hours.

[0063] Step nine, the sintered blank material is put on the grinding machine, wire cutting, slicing, punching, electroplating, and finally magnetizing, packaging and shipping; in step nine, a slicer is used for cutting, and a double-sided grinder is required for processing for higher precision or CPK requirements.

[0064] By adding samarium, nickel and chromium to replace praseodymium, dysprosium and terbium, the remanence of the NdFeB in the present invention can reach 1.35T and the temperature coefficient is low; the temperature coefficient is -0.02% / ℃, and the use temperature can reach 680℃; it has a high magnetic energy product, and at a working temperature of 180℃, its magnetic energy product, temperature stability and chemical stability are greater than those of NdFeB magnetic materials; it has excellent plasticity and ductility, and can also be made into semi-hard magnetic alloys, and has better characteristics than other magnetic materials, is more resistant to high temperatures, and can maintain magnetic properties without decay when used at a temperature of 400°C. It has good mechanical processing performance, whether it is drilling, cutting, planing, stamping, etc. or making some thinner heterosexual magnets, it can meet the effect of avoiding the brittleness, fragility and cracking of other magnetic magnetic materials.

[0065] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a neodymium iron boron magnet, characterized in that: The method comprises the following steps: Step 1, ingredients; the selected materials are rare earth metal neodymium, metal element iron, non-metal element boron, samarium, niobium, aluminum, copper, nickel and chromium; the mass percentage content of each component is respectively 28%-31% of rare earth metal neodymium, 62%-66% of metal element iron, 1.1%-1.2% of non-metal element boron, 0.5%-1.1% of samarium, 0.4%-0.6% of niobium, 0.3%-0.5% of aluminum, 0.05%-0.15% of copper, 0.2%-0.3% of nickel and 0.2%-0.3% of chromium; Step 2, smelting; in the step 2, the raw materials after pretreatment are mixed according to proportion, added into a vacuum melting furnace, smelted at high temperature under argon protection, and then spun off; so that the product composition is uniform, the crystal orientation is high, the organization consistency is good, and the formation of a-Fe is avoided; Step 3, hydrogen crushing; in the step 3, the hydrogen absorption property of rare earth intermetallic compounds is utilized to place the NdFeB alloy in a hydrogen environment, and the hydrogen enters the alloy along the Nd-rich phase thin layer, causing it to expand, burst and break, and crack along the Nd-rich phase layer, thereby ensuring the integrity of the main phase grains and the boundary phase between the Nd-rich grains; the HDI process makes the NdFeB flakes become very loose, thereby improving the powder making efficiency of the airflow mill and reducing the production cost; Step 4, air flow milling: In step 4, the material is crushed by high-speed collision in the air flow chamber, without abrasion to the inner wall of the mill chamber, and powder is prepared quickly; Step 5, molding; in the step 5, the magnetic powder is mixed with the adhesive, heated and mixed, granulated, dried, and then sent to the heating chamber by a spiral guide rod for heating, injected into the mold cavity for molding, and the finished product is obtained after cooling; the amount of the adhesive added is 20% to 30% by volume, and a rigid bonded permanent magnet is prepared; Step 6: static pressure, gradually release the pressure to the object to gradually reduce the density of the product to meet the predetermined requirements; Step 7, oil stripping, is to remove the static pressed product packaging and prepare for sintering; Step 8, putting the product into the sintering furnace for a series of sintering, the small steps can be divided into: entering the furnace, sintering, taking out of the furnace, demagnetization, reverse firing, and then the blank product can be obtained; the sintering process in the step 8 is divided into two stages of sintering and aging, the sintering temperature is between 1040℃~1070℃, and the aging is divided into two stages of aging mechanism 880℃~910℃ and 510℃~620℃. The whole process from sintering and aging to taking out of the furnace takes 22~40 hours; Step nine, the sintered blank material is put on a grinder, wire cut, sliced, punched, electroplated, and finally magnetized, packaged and shipped as required; in the step nine, a slicer is used for cutting, and a double-sided grinder is required for processing for higher precision or CPK requirements.