阅读说明：本技术 一种各向同性热压钕铁硼快淬磁粉及其制备方法 (Isotropic hot-pressed neodymium iron boron quick-quenched magnetic powder and preparation method thereof ) 是由 蔺继荣 *** 王瑞刚 *** 于 2019-09-06 设计创作，主要内容包括：本发明公开了一种各向同性热压钕铁硼快淬磁粉及其制备方法,涉及稀土永磁材料应用领域,该各向同性热压钕铁硼快淬磁粉的制备方法包括：将原料放入中频真空感应炉中在高真空充氩气条件下熔炼和精炼,去除合金中的有害杂质；然后将合金溶液浇铸成合金锭；之后将制得的合金锭放入真空感应快淬炉中,在流动的氩气保护下感应加热熔化,合金熔液在重力作用下经铜或铜镍导流棒引导从氧化铝坩锅底部氮化硼喷嘴的小孔喷射到高速旋转的水冷快淬轮表面瞬间凝固成钕铁硼快淬合金片；最后将合金片放入万能破碎机,在氩气保护下破碎,经过40目振动筛筛分；通过该方法制得的磁粉可用于制造热压各向同性钕铁硼磁体和热挤压各向异性钕铁硼磁体。(The invention discloses isotropic hot-pressed neodymium iron boron quick-quenched magnetic powder and a preparation method thereof, and relates to the field of rare earth permanent magnet material application, wherein the preparation method of the isotropic hot-pressed neodymium iron boron quick-quenched magnetic powder comprises the following steps: putting the raw materials into an intermediate frequency vacuum induction furnace, smelting and refining under the condition of filling argon in high vacuum, and removing harmful impurities in the alloy; then casting the alloy solution into an alloy ingot; then placing the prepared alloy ingot into a vacuum induction quick quenching furnace, carrying out induction heating and melting under the protection of flowing argon, and leading the alloy melt to be sprayed from a small hole of a boron nitride nozzle at the bottom of an alumina crucible to the surface of a water-cooling quick quenching wheel rotating at a high speed under the action of gravity through a copper or copper-nickel guide rod to be instantly solidified into a neodymium-iron-boron quick quenching alloy sheet; finally, placing the alloy sheet into a universal crusher, crushing the alloy sheet under the protection of argon, and screening the crushed alloy sheet by a 40-mesh vibrating screen; the magnetic powder prepared by the method can be used for manufacturing hot-pressing isotropic neodymium iron boron magnets and hot-extrusion anisotropic neodymium iron boron magnets.)

1. The isotropic hot pressed Nd-Fe-B fast quenched magnetic powder features its atomic ratio general expression as

（Nd_1-w-xPr_wDy_x）_α(Fe_1-y-zCo_yGa_z)_100-α-βB_β，

In the formula: nd is neodymium element, Pr is praseodymium element, Dy is dysprosium element, Fe is iron element, Co is cobalt element, Ga is gallium element, B is boron element, alpha is any number between 12 and 16, beta is any number between 4 and 7, x is any number between 0 and 0.2, y is any number between 0 and 0.1, z is any number between 0 and 0.01, and w is any number between 0 and 1, the unit being atomic ratio.

2. The method for preparing the isotropic hot-pressed neodymium-iron-boron quick-quenched magnetic powder according to claim 1, which is characterized by comprising the following steps:

s1 alloy smelting

Preparing raw materials according to the atomic ratio of each element in the atomic ratio general formula, wherein the raw materials are metals or alloys containing the elements in the general formula, putting the raw materials into a medium-frequency vacuum induction furnace, smelting and refining under the condition of filling argon in high vacuum at the smelting temperature of 1500 ℃, and then refining for 20-30 minutes under the atmosphere of 1450 ℃ and 200 Pa to remove harmful impurities in the alloys; measuring alloy components by using an ICP (inductively coupled plasma spectrometer), comparing the alloy components with the atomic ratio of each element which is initially set, if the difference is larger, indicating that operation errors exist in the production process, at the moment, remelting is needed, and if the measured alloy components are basically the same as the atomic ratio of each element which is initially set, casting the alloy solution into an alloy ingot;

s2 alloy quick quenching

Placing the alloy ingot prepared in the step S1 into a vacuum induction quick quenching furnace, carrying out induction heating and melting under the protection of flowing argon, wherein the pressure of the argon is 2000-3000 Pa, the temperature is 1420 ℃, the alloy melt is guided by a copper or copper-nickel guide rod to be sprayed from a small hole of a boron nitride nozzle at the bottom of an alumina crucible to the surface of a water-cooling quick quenching wheel rotating at high speed under the action of gravity to be instantly solidified into a neodymium-iron-boron quick quenching alloy sheet, the diameter of the small hole of the boron nitride is 0.6-2.0 mm, and the linear velocity of the outer surface of the water-cooling quick quenching wheel is 20-50 m/S; the water-cooling quick quenching wheel is made of molybdenum or TZM alloy;

s3 crushing and sieving

And (4) putting the alloy sheet prepared in the step S2 into a universal crusher, crushing under the protection of argon, sieving by a 40-mesh vibrating screen, and returning and crushing the powder larger than 40 meshes to obtain the neodymium iron boron quick quenching magnetic powder.

3. The method for preparing isotropic hot-pressed neodymium-iron-boron quick-quenched magnetic powder as claimed in claim 2, wherein the atomic ratio formula is w =0.2556, x =0, α =13.4875, β =5.4723, y =0.0479, and z =0.0052, and the raw materials include:

praseodymium-neodymium alloy, its neodymium content is 74.4%, the surplus is praseodymium;

ferroboron, the boron content of which is 19.4 percent, and the balance being iron;

the purity of the metal cobalt is 99.99 percent;

gallium metal with a purity of 99.99%;

raw material pure iron of 99.9% purity.

4. The method for preparing isotropic hot-pressed neodymium-iron-boron quick-quenched magnetic powder as claimed in claim 2, wherein the atomic ratio formula is w =0, x =0, α =13.8248, β =5.5946, y =0.0554, and z =0.0053, and the raw materials used include:

metallic neodymium of 99.9% purity;

ferroboron, with a boron content of 19.4%, the balance being iron;

the purity of the metal cobalt is 99.99 percent;

gallium metal with a purity of 99.99%;

raw material pure iron of 99.9% purity.

5. The method for preparing isotropic hot-pressed neodymium-iron-boron rapidly quenched magnetic powder as claimed in claim 2, wherein the atomic ratio formula is w =0, x =0, α =14.2610, β =5.4420, y =0.0154, and z =0.0063, and the raw materials used comprise:

metallic neodymium of 99.9% purity;

ferroboron, with a boron content of 19.4%, the balance being iron;

the purity of the metal cobalt is 99.99 percent;

gallium metal with a purity of 99.99%;

raw material pure iron of 99.9% purity.

6. The method for preparing isotropic hot-pressed neodymium-iron-boron quick-quenched magnetic powder as claimed in claim 2, wherein the atomic ratio formula is w =0.5849, x =0.0616, α =13.7731, β =5.5236, y =0.0538, and z =0.0055, and the raw materials used include:

praseodymium-neodymium alloy, its neodymium content is 74.4%, the surplus is praseodymium;

metal praseodymium of 99.9% purity;

dysprosium-iron alloy with dysprosium content of 80% and the balance of iron;

ferroboron, with a boron content of 19.4%, the balance being iron;

the purity of the metal cobalt is 99.99 percent;

gallium metal with a purity of 99.99%;

raw material pure iron of 99.9% purity.

7. The method for preparing isotropic hot-pressed neodymium-iron-boron fast-quenched magnetic powder according to claim 2, wherein in the atomic ratio general formula, w =0, x =0.1074, α =13.5513, β =5.6505, y =0.0276, and z =0.0064, and the raw materials include:

dysprosium-iron alloy with dysprosium content of 80% and the balance of iron;

metallic neodymium of 99.9% purity;

ferroboron, the boron content of which is 19.4 percent, and the balance being iron;

the purity of the metal cobalt is 99.99 percent;

gallium metal with a purity of 99.99%;

raw material pure iron of 99.9% purity.

Technical Field

The invention relates to the field of application of rare earth permanent magnet materials, in particular to isotropic hot-pressed neodymium iron boron quick-quenched magnetic powder and a preparation method thereof.

Background

The existing neodymium iron boron rare earth magnetic materials are divided into four types according to the production process; the first is sintered neodymium iron boron magnet of powder metallurgy technology, the second is bonded neodymium iron boron magnet of magnetic powder and thermosetting resin mould pressing solidification technology, the third is injection moulding neodymium iron boron magnet of magnetic powder and thermoplastic resin granulation injection moulding technology, the fourth is hot pressing neodymium iron boron magnet of magnetic powder cold pressing, hot pressing and hot extrusion moulding technology; the hot-pressed neodymium iron boron magnet has the advantages of high magnetic performance, good heat resistance, excellent corrosion resistance, no or little use of rare element dysprosium, capability of being extruded into a thin-wall cylinder shape, high material utilization rate and the like, is particularly suitable for being used for miniature motors, and develops rapidly in recent years.

The basic raw materials of the hot-pressed neodymium-iron-boron magnet are called isotropic hot-pressed neodymium-iron-boron quick-quenched magnetic powder, the basic raw materials of the isotropic hot-pressed neodymium-iron-boron quick-quenched magnetic powder are rare earth praseodymium neodymium, metal iron and boron, and other elements are added for modification; the process can be summarized as follows: alloy smelting, alloy quick quenching, quick quenching alloy sheet crushing and screening, magnetic powder mixing and packaging; the production process of the isotropic hot-pressed neodymium iron boron quick-quenched magnetic powder is very complex, relates to technical foundation and industrial foundation in many aspects, and the production technology of the isotropic hot-pressed neodymium iron boron quick-quenched magnetic powder is monopolized by foreign companies all the time.

On the basis of a process method for producing neodymium iron boron bonded magnetic powder, a component composition of high-performance isotropic hot-pressed neodymium iron boron quick-quenched magnetic powder and a production process for producing the high-performance quick-quenched neodymium iron boron magnetic powder in a large scale are independently developed by the company; the produced magnetic powder has excellent magnetic performance.

Disclosure of Invention

The invention aims to provide a composition of high-performance isotropic hot-pressed neodymium iron boron quick-quenched magnetic powder and a production process for producing the high-performance quick-quenched neodymium iron boron magnetic powder in a large scale.

The technical scheme adopted by the invention is as follows: the isotropic hot pressed Nd-Fe-B fast quenched magnetic powder features its atomic ratio general expression as

（Nd_1-w-xPr_wDy_x）_α(Fe_1-y-zCo_yGa_z)_100-α-βB_β，

In the formula: nd is neodymium element, Pr is praseodymium element, Dy is dysprosium element, Fe is iron element, Co is cobalt element, Ga is gallium element, B is boron element, alpha is any number between 12 and 16, beta is any number between 4 and 7, x is any number between 0 and 0.2, y is any number between 0 and 0.1, z is any number between 0 and 0.01, and w is any number between 0 and 1, the unit being atomic ratio.

A preparation method of isotropic hot-pressed neodymium iron boron quick-quenched magnetic powder is characterized by comprising the following steps:

s1 alloy smelting

Preparing raw materials according to the atomic ratio of each element in the atomic ratio general formula, wherein the raw materials are metals or alloys containing the elements in the general formula, putting the raw materials into a medium-frequency vacuum induction furnace, smelting and refining under the condition of filling argon in high vacuum, wherein the raw materials can be prevented from being oxidized under the condition of filling argon, the smelting temperature is 1500 ℃, and then refining is carried out for 20-30 minutes under the atmosphere of 1450 ℃ and 200 Pa argon to remove harmful impurities in the alloys; measuring alloy components by using an ICP (inductively coupled plasma spectrometer), comparing the alloy components with the atomic ratio of each element which is initially set, if the difference is larger, indicating that operation errors exist in the production process, at the moment, remelting is needed, and if the measured alloy components are basically the same as the atomic ratio of each element which is initially set, casting the alloy solution into an alloy ingot;

s2 alloy quick quenching

Placing the alloy ingot prepared in the step S1 into a vacuum induction quick quenching furnace, carrying out induction heating and melting under the protection of flowing argon, wherein the pressure of the argon is 2000-3000 Pa, the temperature is 1420 ℃, the alloy melt is guided by a copper or copper-nickel guide rod to be sprayed from a small hole of a boron nitride nozzle at the bottom of an alumina crucible to the surface of a water-cooling quick quenching wheel rotating at high speed under the action of gravity to be instantly solidified into a neodymium-iron-boron quick quenching alloy sheet, the diameter of the small hole of the boron nitride is 0.6-2.0 mm, and the linear velocity of the outer surface of the water-cooling quick quenching wheel is 20-50 m/S; the water-cooling quick quenching wheel is made of molybdenum or TZM alloy;

s3 crushing and sieving

And (4) putting the alloy sheet prepared in the step S2 into a universal crusher, crushing under the protection of argon, sieving by a 40-mesh vibrating screen, and returning and crushing the powder larger than 40 meshes to obtain the neodymium iron boron quick quenching magnetic powder.

Further, one of the preparation methods is as follows: in the general formula of atomic ratio, w =0.2556, x =0, α =13.4875, β =5.4723, y =0.0479, and z =0.0052, the raw materials used include:

praseodymium-neodymium alloy, its neodymium content is 74.4%, the surplus is praseodymium;

ferroboron, the boron content of which is 19.4 percent, and the balance being iron;

the purity of the metal cobalt is 99.99 percent;

gallium metal with a purity of 99.99%;

raw material pure iron of 99.9% purity.

Further, one of the preparation methods is as follows: in the general formula of atomic ratio, w =0, x =0, α =13.8248, β =5.5946, y =0.0554, and z =0.0053, the raw materials used include:

metallic neodymium of 99.9% purity;

ferroboron, with a boron content of 19.4%, the balance being iron;

the purity of the metal cobalt is 99.99 percent;

gallium metal with a purity of 99.99%;

raw material pure iron of 99.9% purity.

Further, one of the preparation methods is as follows: in the general formula of atomic ratio, w =0, x =0, α =14.2610, β =5.4420, y =0.0154, and z =0.0063, the raw materials used include:

metallic neodymium of 99.9% purity;

ferroboron, with a boron content of 19.4%, the balance being iron;

the purity of the metal cobalt is 99.99 percent;

gallium metal with a purity of 99.99%;

raw material pure iron of 99.9% purity.

Further, one of the preparation methods is as follows: in the general formula of atomic ratio, w =0.5849, x =0.0616, alpha =13.7731, beta =5.5236, y =0.0538, and z =0.0055, the raw materials used include:

praseodymium-neodymium alloy, its neodymium content is 74.4%, the surplus is praseodymium;

metal praseodymium of 99.9% purity;

dysprosium-iron alloy with dysprosium content of 80% and the balance of iron;

ferroboron, with a boron content of 19.4%, the balance being iron;

the purity of the metal cobalt is 99.99 percent;

gallium metal with a purity of 99.99%;

raw material pure iron of 99.9% purity.

Further, one of the preparation methods is as follows: in the general atomic ratio formula, w =0, x =0.1074, α =13.5513, β =5.6505, y =0.0276, and z =0.0064, the raw materials used include:

dysprosium-iron alloy with dysprosium content of 80% and the balance of iron;

metallic neodymium of 99.9% purity;

ferroboron, the boron content of which is 19.4 percent, and the balance being iron;

the purity of the metal cobalt is 99.99 percent;

gallium metal with a purity of 99.99%;

raw material pure iron of 99.9% purity.

The invention has the beneficial effects that: the invention provides a composition of high-performance isotropic hot-pressed neodymium iron boron quick-quenched magnetic powder and a production process for producing the high-performance quick-quenched neodymium iron boron magnetic powder in a large scale; the produced magnetic powder has excellent magnetic performance, and Br measured by VSM (vibration sample magnetometer) is between 720 and 784mT, Hci is between 1492 and 1834KA/m, and (BH) max is between 84 and 99KJ/m³To (c) to (d); the powder can be directly used for producing the hot-pressed magnet without further treatment, and the magnet has high magnetic property, heat resistance, corrosion resistance and uniform magnetism.

Specifically, the powder can be used for hot-pressing isotropic neodymium iron boron magnets and hot-extrusion anisotropic neodymium iron boron magnets; the magnetic powder is hot pressed to obtain high-density isotropic magnet with the density equal to that of the original alloy, the magnet is upset and extruded at high temperature to produce thermoplastic deformation, crystal grains are arranged in the processing direction to obtain anisotropic magnet, and the anisotropic magnet is very suitable for manufacturing radiation-oriented thin-wall magnetic rings.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The isotropic hot-pressed neodymium iron boron rapidly quenched magnetic powder and the preparation method thereof according to the embodiment of the invention are specifically described below.

An isotropic hot-pressed Nd-Fe-B fast-quenched magnetic powder with an atomic ratio general formula

（Nd_1-w-xPr_wDy_x）_α(Fe_1-y-zCo_yGa_z)_100-α-βB_β，

In the formula: nd is neodymium element, Pr is praseodymium element, Dy is dysprosium element, Fe is iron element, Co is cobalt element, Ga is gallium element, B is boron element, alpha is any number between 12 and 16, beta is any number between 4 and 7, x is any number between 0 and 0.2, y is any number between 0 and 0.1, z is any number between 0 and 0.01, and w is any number between 0 and 1, the unit being atomic ratio.

A preparation method of the isotropic hot-pressed neodymium iron boron quick-quenched magnetic powder comprises the following steps:

s1 alloy smelting

Preparing raw materials according to the atomic ratio of each element in the atomic ratio general formula, wherein the raw materials comprise metal neodymium, praseodymium-neodymium alloy, metal praseodymium, dysprosium-iron alloy, raw material pure iron, metal cobalt, metal gallium and ferroboron alloy;

more specifically, the rare earth metal neodymium and the metal praseodymium with the purity of 99.9 percent are used, and the carbon content of the compositions is less than 300ppm, the silicon, manganese and aluminum content is less than 500ppm, and the iron content is less than 1000 ppm; the praseodymium-neodymium alloy used comprises 75 +/-2% of neodymium, the balance of praseodymium, the carbon content of less than 300ppm, the silicon, manganese and aluminum content of less than 500ppm and the iron content of less than 1000ppm, and the volatilization loss compensation of metal neodymium, metal praseodymium and the praseodymium-neodymium alloy is required to be considered during material use; the dysprosium-iron alloy used comprises 80 +/-2% of dysprosium, the balance of iron, the carbon content is less than 300ppm, and the contents of silicon, manganese and aluminum are less than 500 ppm; using raw material pure iron with the purity of 99.9 percent, wherein the carbon content is less than 50ppm, the manganese content is less than 200ppm, and the silicon content is less than 500 ppm; the boron-iron alloy used comprises 20 +/-1% of boron, the balance of iron and carbon, the content of manganese and aluminum is less than 1000ppm, and the content of silicon is less than 3000 pm; using metal cobalt with the purity of 99.99 percent; gallium metal with a purity of 99.99% was used.

180 kg of materials are prepared in each batch, the materials are put into a 200kg medium frequency vacuum induction furnace to be smelted and refined under the condition of filling argon in high vacuum, the oxidation can be prevented under the condition of argon, the smelting temperature is 1500 ℃, and then the materials are refined for 20 to 30 minutes under the atmosphere of 1450 ℃ and 200 Pa argon, so that harmful impurities in the alloy are removed; and measuring the alloy components by using an ICP (inductively coupled plasma spectrometer), comparing the alloy components with the atomic ratio of each element which is initially set, if the difference is large, indicating that operation errors exist in the production process, at the moment, remelting is needed, and if the measured alloy components are basically the same as the atomic ratio of each element which is initially set, casting the alloy solution into about 4 alloy ingots of 45 kg.

S2 alloy quick quenching

The alloy ingot prepared in the step S1 is sequentially placed into a 50 kg vacuum induction quick quenching furnace, induction heating and melting are carried out under the protection of flowing argon, the pressure of the argon is 2000-3000 Pa, the temperature is 1420 ℃, the alloy melt is guided by a copper or copper-nickel guide rod to be sprayed from a small hole of a boron nitride nozzle at the bottom of an alumina crucible to the surface of a water-cooling quick quenching wheel rotating at high speed under the action of gravity to be instantly solidified into a neodymium iron boron quick quenching alloy sheet, the diameter of the small hole of boron nitride is 0.6-2.0 mm, and the linear velocity outer surface of the water-cooling quick quenching wheel is 20-50 m/S; the material of the water-cooling quick quenching wheel is molybdenum or TZM (molybdenum, titanium, zirconium and carbon) alloy.

S3 crushing and sieving

Placing the alloy sheet prepared in the step S2 into a universal crusher, crushing under the protection of argon, sieving by a 40-mesh vibrating screen, and returning and crushing powder larger than 40 meshes to obtain the neodymium iron boron quick quenching magnetic powder; magnetic properties were then measured with a VSM (vibrating sample magnetometer).