WO2018040299A1 - 一种制备稀土永磁材料的方法 - Google Patents

一种制备稀土永磁材料的方法 Download PDF

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WO2018040299A1
WO2018040299A1 PCT/CN2016/106318 CN2016106318W WO2018040299A1 WO 2018040299 A1 WO2018040299 A1 WO 2018040299A1 CN 2016106318 W CN2016106318 W CN 2016106318W WO 2018040299 A1 WO2018040299 A1 WO 2018040299A1
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ndfeb
rare earth
powder
magnet
pressure sintering
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PCT/CN2016/106318
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English (en)
French (fr)
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郝忠彬
韩相华
洪群峰
章晓峰
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浙江东阳东磁稀土有限公司
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Publication of WO2018040299A1 publication Critical patent/WO2018040299A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/10—Sintering only
    • B22F3/1003—Use of special medium during sintering, e.g. sintering aid
    • B22F3/1007—Atmosphere
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/12—Both compacting and sintering
    • B22F3/14—Both compacting and sintering simultaneously
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/24—After-treatment of workpieces or articles
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/24—After-treatment of workpieces or articles
    • B22F2003/248—Thermal after-treatment

Definitions

  • the invention relates to the technical field of magnetic materials, in particular to a method for preparing rare earth permanent magnet materials.
  • NdFeB permanent magnet material is the most excellent permanent magnetic material with comprehensive magnetic properties. It is known as “Magnetic King” and is of great significance for miniaturization, integration and high efficiency of devices.
  • the NdFeB magnets are mainly divided into sintered, bonded, hot-pressed/thermally deformed magnets, in which the amount of sintered NdFeB is the largest.
  • the preparation process of the sintered NdFeB magnet is mainly obtained by a rapid setting process to obtain a NdFeB alloy, and then the alloy is ground to obtain 3-5 ⁇ m single crystal particles, and the single crystal magnetic powder particles are placed in a magnetic field to form a green body, which will be obtained.
  • the green body is sintered at a temperature of 1040-1100 ° C to obtain a sintered NdFeB billet, and the blank is mechanically processed to finally obtain a sintered NdFeB product.
  • the radiation-oriented magnetic field having a high magnetic field strength (above 1T) cannot be obtained due to the limitation of the saturation of the iron core, thereby limiting the development of the radiation magnetic ring.
  • the hot pressing/thermal deformation NdFeB magnet is prepared by quenching nanocrystals with a particle size of about 200 ⁇ m.
  • the NdFeB magnetic powder is densified at 500-600 ° C to obtain an isotropic magnet, and then subjected to thermal deformation at 850-950 ° C to obtain an anisotropic NdFeB magnet.
  • the coercive force of the hot-pressed/thermally deformed magnet is slightly higher than that of the sintered NdFeB, because the temperature used for hot pressing/thermal deformation is lower than the sintering temperature, and the time is short, so the crystal grains are finer. .
  • the hot-pressed/heat-deformed magnet can be formed into a net size or a near-net shape, and the deformation and cracking of the magnet can be effectively suppressed, so that the material utilization rate is high.
  • the main disadvantage of hot pressed/thermally deformed magnets is their high cost.
  • the nanocrystalline quick-quenching magnetic powder used for hot pressing has a higher price; at the same time, the thermal deformation process has a low production efficiency, so the production cost is high.
  • Bonded NdFeB magnets are also prepared by using nanocrystalline quenched magnetic powder to bond magnetic powder into a magnet by adding a certain proportion of adhesive.
  • the material utilization rate of the bonded NdFeB magnet is very high, close to 100%, and the preparation of the shaped product can be realized.
  • the biggest disadvantage of bonding NdFeB is that the magnetic properties are low, and the magnetic energy product of the bonded NdFeB magnets is mostly 60-90 kJm -3 .
  • the advantages of the sintered NdFeB magnet are that the magnetic powder is cheap, the production process is simple, the efficiency is high, and the cost is low; the disadvantage is that the material utilization rate is low, and the deformation is easy to crack.
  • the advantage of the hot-pressed/heat-deformed magnet is that the magnet crystal is fine and the material utilization rate is high; the disadvantage is that the magnetic powder (hot-pressing/heat-deformation special quick-quenching powder) has high price, low heat deformation efficiency and high cost.
  • the advantage of bonding NdFeB magnets is that the material utilization rate is high, and the production of shaped magnets can be realized; the main disadvantage is that the magnetic properties are low, and the magnetic energy products of the bonded NdFeB magnets are all in the range of 60-90 kJm -3 .
  • the present invention is to overcome the above-mentioned deficiencies in the prior art, and to provide a method for preparing a rare earth permanent magnet material capable of improving material utilization rate and achieving sustainable development.
  • a method for preparing a rare earth permanent magnet material comprising the steps of:
  • the pressure-sintered magnet is placed in a vacuum furnace for secondary tempering heat treatment, and is kept at 850-950 ° C for 1-8 hours, and then heated at 350-650 ° C for 0.5-6 hours to obtain NdFeB magnet.
  • the sintered NdFeB blank, the waste NdFeB magnet or the NdFeB scrap after washing and drying is used for the powdering, the material utilization rate can be improved, and the waste NdFeB magnet can be efficiently recycled.
  • the prepared NdFeB powder has a particle size significantly higher than that of the conventional sintered NdFeB magnetic powder, so the magnetic powder has good fluidity; the required orientation magnetic field is low, and mass stable production of a special oriented magnet such as a radiation ring can be realized;
  • the mold is pressure sintered so that the outer dimensions of the magnet are close to the size of the final product, and the material utilization rate is high.
  • the sintered NdFeB blank, the waste NdFeB magnet or the NdFeB scrap which has been washed and dried is broken into a polycrystalline powder of NdFeB powder of 10 ⁇ m or more.
  • the magnet is prepared by using polycrystalline large particle magnetic powder, so that the magnetic powder has good fluidity, high production efficiency, and small deformation and cracking of the product.
  • the average particle size range of the produced NdFeB powder is controlled at 50-300. Mm.
  • the NdFeB powder in this particle size range has better fluidity, higher production efficiency, and less cracking of the product.
  • the rare earth-rich alloy powder is added, and the composition of the rare earth-rich alloy powder is one or more of the rare earth elements lanthanum, cerium, lanthanum and cerium.
  • the other non-rare earth elements are one or more of aluminum, copper, gallium and iron, and the sum of the mass percentages of the rare earth elements lanthanum, cerium, lanthanum and cerium is more than 50%; the proportion of the rare earth-rich alloy powder is ferroniobium 0-30% of the boron alloy powder, the average particle size range of the rare earth-rich alloy powder is controlled to be 0.3 to 10 ⁇ m.
  • the pressure sintering mold is in a closed space, and is heated to 650 to 850 ° C under vacuum or inert gas, pressurized at 3 to 100 MPa, and pressure is pressed for 10 seconds to 10 minutes for pressure sintering. And then cooled out.
  • the second tempering heat treatment is performed by holding at 880 ° C for 2 to 6 hours, and then holding at 450 to 620 ° C for 2 to 4 hours.
  • the magnetic powder has good fluidity, high production efficiency, and less deformation and cracking of the product
  • the orientation magnetic field is low, and the batch stable production of special oriented magnets such as radiation rings can be realized;
  • the pressure sintering mold is used for pressure sintering.
  • the outer shape of the magnet is close to the size of the final product, the material utilization rate is high, the cost is low, and the magnetic performance is high.
  • the sintered NdFeB blank having the composition of Nd 26.25 Pr 8.75 Fe 64 B 1 (mass percentage) is mechanically broken into particles having an average particle diameter of 200 ⁇ m;
  • the pressure sintering mold is in a closed space, first evacuated to 8 ⁇ 10 -3 Pa, refilled with argon gas to 8 ⁇ 10 4 Pa, and then heated to 850 ° C. Pressing 200 MPa along the thickness direction of the sintered NdFeB green body, holding it for 6 minutes, and then cooling it out;
  • the pressure-sintered magnet is placed in a vacuum furnace for heat treatment, and the hot-pressed blank is heat-treated by heat-treating at 900 ° C for 4 hours and at 500 ° C for 4 hours, and the specification is R8.1 ⁇ R3.6 ⁇ 5.3.
  • the magnet has a material utilization rate of 100%, no corner cracking, and a yield of 100%.
  • a sintered NdFeB blank having a composition of Nd 26.25 Pr 8.75 Fe 64 B 1 (mass percentage) was mechanically broken into particles having an average particle diameter of 50 ⁇ m.
  • a 5% Nd 70 Cu 30 (mass percent) rare earth-rich alloy powder was added to the polycrystalline NdFeB particles, wherein the beryllium copper alloy powder had an average particle diameter of 3 ⁇ m.
  • the temperature at the time of pressure sintering was 700 ° C, and other processes were the same as in Example 1.
  • the scrap of sintered NdFeB is washed and dried to be crushed into 300 ⁇ m polycrystalline particles, and then 5% Nd 70 Cu 30 (mass percent) rare earth alloy powder is added.
  • the average particle size of the beryllium copper alloy powder is 3 ⁇ m. .
  • a circular green body of ⁇ 30 ⁇ ⁇ 24 ⁇ 20 was obtained by using a 0.5T radiation magnetic field orientation.
  • the temperature at the time of pressure sintering was 650 ° C, and the other processes were the same as in Example 1.
  • Example 2 The same batch of magnetic powder orientation molding as in Example 1 was used, and the green size was 43.56 ⁇ 39.6 ⁇ 29.82, which was sintered and densified at 1068 ° C according to a conventional sintering process, and heat-treated in the same manner as in Example 1.
  • the sintered blank has a size of 33 ⁇ 30 ⁇ 2, and is cut into a black sheet of R8.1 ⁇ R3.6 ⁇ 5.5 and subjected to internal and external arc grinding to obtain a magnet of R8.1 ⁇ R3.6 ⁇ 5.3.
  • the material utilization rate is 76%.
  • the machining cost is 0.3 yuan/only, and there is a drop in the processing process, and the yield rate is 98%.
  • Example 1 basically achieved net size molding, and the product with low tolerance requirement was free from processing, and the material utilization rate was close to 100%, but the product HAST weight loss of Example 1 was slightly larger.
  • Example 2 improves the grain boundary structure by adding a rare earth-rich alloy powder through grain boundaries, and increases the density of the magnet to improve the HAST weight loss and yield of the magnet.
  • Comparative Example 1 was prepared by a conventional method, and the product required a process such as wire cutting and grinding to greatly reduce the material utilization rate and increase the processing cost.
  • Example 3 can achieve the preparation of a high performance thin wall magnetic ring product.
  • Example 3 has a significant price advantage over comparable thin walled magnetic rings on the market.
  • the magnetic powder particles are large, the fluidity is good, and the required orientation magnetic field is low, which is advantageous for mass production.
  • Example 1 From the comparison of Example 1, Example 2, Example 3 and Comparative Example 1 in Tables 1 and 2 above, it can be seen that, in comparison with the conventional process, the present invention uses a polycrystalline large particle magnetic powder to prepare a magnet, particularly a special oriented magnet, High material utilization, low cost and high magnetic performance.

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  • Crystallography & Structural Chemistry (AREA)
  • Inorganic Chemistry (AREA)
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Abstract

一种制备稀土永磁材料的方法，包括如下步骤：选取烧结钕铁硼毛坯、废旧钕铁硼磁体或者经过清洗和烘干后的钕铁硼边角料，破碎成钕铁硼粉末；对钕铁硼粉末施加取向磁场，制成钕铁硼生坯；将钕铁硼生坯置于压力烧结模具的腔体内，压力烧结模具处于一个密闭的空间，在真空或惰性气体保护下，加热加压进行压力烧结，然后冷却取出；将压力烧结后的磁体置入真空炉内进行二次回火热处理，制得钕铁硼磁体。该方法磁粉流动性好，生产效率高，产品变形小开裂少；取向磁场低，可以实现辐射环等特殊取向磁体的批量稳定生产；采用压力烧结模具进行压力烧结，磁体外形尺寸接近最终成品的尺寸，材料利用率高，成本低，磁性能高。

Description

一种制备稀土永磁材料的方法 技术领域
本发明涉及磁性材料相关技术领域，尤其是指一种制备稀土永磁材料的方法。
背景技术
自上世纪80年代钕铁硼磁体问世以来，由于其优异的磁性能迅速在电子、通讯、交通运输、自动化、医疗和新能源等领域获得广泛的应用。到目前为止，钕铁硼永磁材料是综合磁性能最优异的永磁材料，被誉为“磁王”，对器件小型化、集成化和高效率具有重要意义。
按制备方法分，钕铁硼磁体主要分为烧结、粘结、热压/热变形磁体，其中以烧结钕铁硼用量最大。烧结钕铁硼磁体的制备工艺主要是采用速凝工艺得到钕铁硼合金，然后将合金磨碎得到3-5μm的单晶颗粒，将单晶磁粉颗粒放入磁场中取向成型得到生坯，将生坯在1040-1100℃温度烧结得到烧结钕铁硼毛坯，毛坯再经过机械加工最终得到烧结钕铁硼产品。在生产中，除了少部分大规格产品可以通过单片成型制得以外，其他大部分烧结钕铁硼产品都需要机械加工，综合材料利用率约为66％，而对于一些薄片和异形产品来说材料利用率不到50％。特别是磁环或磁瓦等异形薄壁产品，由于磁粉流动性差造成生坯密度不均匀，在烧结过程中的收缩比差异造成了产品的变形甚至开裂，从而影响产品的成品率和材料利用率。另外，制备辐射环等特殊取向产品时，由于受铁芯饱和的限制，无法获得磁场强度很高(1T以上)的辐射取向磁场，从而限制了辐射磁环的发展。
热压/热变形钕铁硼磁体的制备工艺是将粒度约为200μm的纳米晶快淬 钕铁硼磁粉在500-600℃热压致密得到各向同性磁体，然后再经过850-950℃下热变形得到各向异性钕铁硼磁体。一般来说，热压/热变形磁体的内禀矫顽力要比烧结钕铁硼的略高，这是因为热压/热变形采用的温度比烧结温度低，时间短，所以晶粒更细小。而且热压/热变形磁体可以实现净尺寸或接近净尺寸成型，同时也可以有效地抑制磁体的变形开裂，所以材料利用率较高。热压/热变形磁体的主要缺点是成本高。首先热压所用的纳米晶快淬磁粉价格较高；同时热变形工艺生产效率很低，所以生产成本高。
粘结钕铁硼磁体也是采用纳米晶快淬磁粉制备的，通过添加一定比例的粘接剂将磁粉粘结成的磁体。粘结钕铁硼磁体的材料利用率很高，接近100％，而且可以实现异形产品的制备。粘结钕铁硼的最大缺点是磁性能低，粘结钕铁硼磁体磁能积大都在60-90kJm-3。
综上所述，烧结钕铁硼磁体的优点是磁粉便宜，生产工艺简单，效率高，成本低；缺点是材料利用率低，易变形开裂。热压/热变形磁体的优点是磁体晶粒细小，材料利用率高；缺点是磁粉(热压/热变形专用快淬粉)价格高，热变形效率低，成本高。粘结钕铁硼磁体的优点是材料利用率高，可以实现异形磁体的生产；主要缺点是磁性能低，粘结钕铁硼磁体磁能积大都在60-90kJm-3。
发明内容
本发明是为了克服现有技术中存在上述的不足，提供了一种能够提高材料利用率且实现可持续发展的制备稀土永磁材料的方法。
为了实现上述目的，本发明采用以下技术方案：
一种制备稀土永磁材料的方法，包括如下步骤：
(1)磁粉准备：选取烧结钕铁硼毛坯、废旧钕铁硼磁体或者经过清洗和烘干后的钕铁硼边角料，破碎成10μm以上的钕铁硼粉末；
(2)取向成型：对钕铁硼粉末施加0.2-1.5T的取向磁场，制成钕铁硼生坯；
(3)压力烧结：将钕铁硼生坯置于压力烧结模具的腔体内，压力烧结模具处于一个密闭的空间，在真空或惰性气体保护下，升温至450～900℃，加压1～200MPa，保压10秒～10分钟进行压力烧结，然后冷却取出；
(4)热处理：将压力烧结后的磁体置入真空炉内进行二次回火热处理，采用850～950℃保温1～8小时，再采用350～650℃保温0.5～6小时，制得钕铁硼磁体。
本发明中，选取烧结钕铁硼毛坯、废旧钕铁硼磁体或者经过清洗和烘干后的钕铁硼边角料进行制粉，可以提高材料利用率，同时还可以实现废旧钕铁硼磁体高效循环利用，从而实现稀土永磁产业的可持续发展。所制得的钕铁硼粉末粒径明显高于传统的烧结钕铁硼磁粉，所以磁粉流动性好；所需要的取向磁场低，可以实现辐射环等特殊取向磁体的批量稳定生产；通过压力烧结模具进行压力烧结，使得磁体外形尺寸接近最终成品的尺寸，材料利用率高。
作为优选，在步骤(1)中，选取烧结钕铁硼毛坯、废旧钕铁硼磁体或者经过清洗和烘干后的钕铁硼边角料破碎成10μm以上的钕铁硼粉末为多晶粉末。采用多晶大颗粒磁粉制备磁体，使得磁粉流动性好，生产效率高，产品变形小开裂少。
作为优选，在步骤(1)中，制得钕铁硼粉末的平均粒径范围控制在50-300 μm。处于该粒径范围内的钕铁硼粉末流动性更好，生产效率更高，产品变形更小开裂更少。
作为优选，在步骤(1)中，在制得钕铁硼粉末之后，加入富稀土合金粉末，富稀土合金粉末的组成成分为：稀土元素镨、钕、镝、铽中的一种或多种，其他非稀土元素是铝、铜、镓、铁中的一种或多种，且稀土元素镨、钕、镝、铽的质量百分比之和大于50％；富稀土合金粉末的添加比例为钕铁硼合金粉末的0-30％，所述的富稀土合金粉末平均粒径范围控制在0.3-10μm。这样可以降低压力烧结的温度，有助于抑制晶粒长大并延长压力烧结模具使用寿命，提高生产效率；同时通过晶界添加富稀土合金粉末改善晶界结构，提高磁体致密度，从而改善了磁体的HAST失重和成品率。
作为优选，在步骤(3)中，压力烧结模具处于一个密闭的空间，在真空或惰性气体保护下，升温至650～850℃，加压3～100MPa，保压10秒～10分钟进行压力烧结，然后冷却取出。
作为优选，在步骤(4)中，二次回火热处理：采用880℃保温2～6小时，再采用450～620℃保温2～4小时。
本发明的有益效果是：
1、磁粉流动性好，生产效率高，产品变形小开裂少；
2、取向磁场低，可以实现辐射环等特殊取向磁体的批量稳定生产；
3、采用压力烧结模具进行压力烧结，磁体外形尺寸接近最终成品的尺寸，材料利用率高，成本低，磁性能高。
具体实施方式
下面结合具体实施方式对本发明做进一步的描述。
实施例1：
1、将成分为Nd26.25Pr8.75Fe64B1(质量百分含量)的烧结钕铁硼毛坯机械破碎成平均粒径为200μm的颗粒；
2、施加1T的磁场，生坯尺寸R8.1×R3.6×10，生坯重量29.97g；
3、将生坯置于压力烧结模具的腔体内，压力烧结模具处于一个密闭的空间，先抽空至8×10-3Pa，再充氩气到8×104Pa，然后升温至850℃，沿烧结钕铁硼生坯的厚度方向加压200MPa，保压6分钟后冷却取出；
4、将压力烧结后的磁体置入真空炉内进行热处理，分别采用900℃保温4小时以及500℃保温4小时工艺对热压毛坯进行热处理，制得规格为R8.1×R3.6×5.3的磁体，材料利用率100％，无掉角开裂，成品率100％。
实施例2：
将成分为Nd26.25Pr8.75Fe64B1(质量百分含量)的烧结钕铁硼毛坯机械破碎成平均粒径为50μm的颗粒。在多晶钕铁硼颗粒中添加5％Nd70Cu30(质量百分含量)富稀土合金粉末，其中钕铜合金粉末的平均粒径为3μm。压力烧结时的温度为700℃，其他工艺与实施例1相同。
实施例3：
将烧结钕铁硼的边角料经过清洗和烘干后破碎成300μm的多晶颗粒，然后添加5％Nd70Cu30(质量百分含量)富稀土合金粉末，钕铜合金粉末的平均粒径为3μm。采用0.5T辐射磁场取向制得φ30×φ24×20的环形生坯。压力烧结时的温度为650摄氏度，其他工艺与实施例1相同。
比较例1：
采用与实施例1同批磁粉取向成型，生坯规格43.56×39.6×29.82，按传统烧结工艺在1068℃烧结致密化，与实施例1相同工艺热处理。
烧结毛坯规格33×30×2，线切割成R8.1×R3.6×5.5的黑片并进行内外弧磨加工，最终得到R8.1×R3.6×5.3的磁体，材料利用率76％，机械加工费用0.3元/只，加工过程中有掉角，成品率98％。
实施例1、实施例2与比较例1的制备工艺及产品特性对比见表1。实施例1基本达到净尺寸成型，对于公差要求不高的产品可以免加工，材料利用率接近100％，但实施例1的产品HAST失重略大。实施例2通过晶界添加富稀土合金粉末改善晶界结构，提高磁体致密度从而改善了磁体的HAST失重和成品率。比较例1采用传统方法制备，产品需要经过线切割磨加工等工序，大大降低了材料利用率，同时增加了加工成本。
表1实施例1、实施例2与比较例1的制备工艺及产品特性
  致密化温度 材料利用率 HAST失重 机械加工费 成品率
实施例1 850℃ ～100％ 2mg/cm2 0 99％
实施例2 700℃ ～100％ 0.5mg/cm2 0 ～100％
比较例1 1068℃ 76％ 1mg/cm2 0.3元/只 97％
采用不同工艺制备的钕铁硼磁体各项磁性能指标见表2。实施例3可以实现高性能薄壁磁环产品的制备。与市场上同类薄壁磁环相比，实施例3具有明显价格优势。而且实施例3中磁粉颗粒较大，流动性好，需要的取向磁场低，有利于批量生产。
表2不同工艺制备的钕铁硼磁体各项磁性能指标
Figure PCTCN2016106318-appb-000001
从上述表1和表2中实施例1、实施例2、实施例3和对比例1的比较可知，与传统工艺对比，本发明采用多晶大颗粒磁粉制备磁体特别是特殊取向磁体时，具有材料利用率高，成本低，磁性能高等优势。

Claims (6)

  1. 一种制备稀土永磁材料的方法，其特征是，包括如下步骤：
    (1)磁粉准备：选取烧结钕铁硼毛坯、废旧钕铁硼磁体或者经过清洗和烘干后的钕铁硼边角料，破碎成10μm以上的钕铁硼粉末；
    (2)取向成型：对钕铁硼粉末施加0.2-1.5T的取向磁场，制成钕铁硼生坯；
    (3)压力烧结：将钕铁硼生坯置于压力烧结模具的腔体内，压力烧结模具处于一个密闭的空间，在真空或惰性气体保护下，升温至450～900℃，加压1～200MPa，保压10秒～10分钟进行压力烧结，然后冷却取出；
    (4)热处理：将压力烧结后的磁体置入真空炉内进行二次回火热处理，采用850～950℃保温1～8小时，再采用350～650℃保温0.5～6小时，制得钕铁硼磁体。
  2. 根据权利要求1所述的一种制备稀土永磁材料的方法，其特征是，在步骤(1)中，选取烧结钕铁硼毛坯、废旧钕铁硼磁体或者经过清洗和烘干后的钕铁硼边角料破碎成10μm以上的钕铁硼粉末为多晶粉末。
  3. 根据权利要求1或2所述的一种制备稀土永磁材料的方法，其特征是，在步骤(1)中，制得钕铁硼粉末的平均粒径范围控制在50-300μm。
  4. 根据权利要求1或2所述的一种制备稀土永磁材料的方法，其特征是，在步骤(1)中，在制得钕铁硼粉末之后，加入富稀土合金粉末，富稀土合金粉末的组成成分为：稀土元素镨、钕、镝、铽中的一种或多种，其他非稀土元素是铝、铜、镓、铁中的一种或多种，且稀土元素镨、钕、镝、铽的质量百分比之和大于50％；富稀土合金粉末的添加比例为钕铁硼合金粉末的0-30％，所述的富稀土合金粉末平均粒径范围控制在0.3-10μm。
  5. 根据权利要求1所述的一种制备稀土永磁材料的方法，其特征是，在步骤(3) 中，压力烧结模具处于一个密闭的空间，在真空或惰性气体保护下，升温至650～850℃，加压3～100MPa，保压10秒～10分钟进行压力烧结，然后冷却取出。
  6. 根据权利要求1所述的一种制备稀土永磁材料的方法，其特征是，在步骤(4)中，二次回火热处理：采用880℃保温2～6小时，再采用450～620℃保温2～4小时。
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