WO2012041244A1 - 一种应力场取向的各向异性可挠性粘结钕铁硼磁体及其制备方法 - Google Patents

一种应力场取向的各向异性可挠性粘结钕铁硼磁体及其制备方法 Download PDF

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WO2012041244A1
WO2012041244A1 PCT/CN2011/080393 CN2011080393W WO2012041244A1 WO 2012041244 A1 WO2012041244 A1 WO 2012041244A1 CN 2011080393 W CN2011080393 W CN 2011080393W WO 2012041244 A1 WO2012041244 A1 WO 2012041244A1
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magnetic powder
rubber
magnet
stress field
ndfeb
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French (fr)
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汪小明
杨应彬
戴雨兰
饶钦盛
罗毅
张科元
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广州金南磁性材料有限公司
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/02—Permanent magnets [PM]
    • H01F7/0205—Magnetic circuits with PM in general
    • H01F7/021—Construction of PM
    • H01F7/0215—Flexible forms, sheets
    • 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
    • H01F1/0572—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 with a protective layer
    • 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
    • H01F1/09—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 mixtures of metallic and non-metallic particles; metallic particles having oxide skin
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
    • H01F41/0266—Moulding; Pressing
    • 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
    • H01F1/0578—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 bonded together

Definitions

  • the invention belongs to the field of preparation of bonded NdFeB magnetic materials, in particular to an anisotropic flexible bonded NdFeB magnet with stress field orientation and a manufacturing method thereof.
  • Nd 2 Fe 14 B-based NdFeB permanent magnets which were introduced in the 1980s, have the most excellent magnetic properties. They are mainly classified into sintered NdFeB and bonded NdFeB. Two major categories. Since the 1990s, with the strong demand of computer-based information industry, isotropic rigid bonded NdFeB magnets represented by quenching NdFeB have been widely used.
  • the isotropic bonded NdFeB magnet processing method mostly uses hard plastic, resin, etc. as a binder and NdFeB magnetic powder after mixing and granulation, molding, injection or extrusion molding, and the obtained magnets are all Rigid, brittle, inflexible, and the use of molding, injection molding process to produce different specifications of the product requires different molds, higher development costs, longer cycle.
  • the rigid magnet has high magnetic properties and a certain degree of shape freedom, it is fragile, has the disadvantages of inconvenient transportation and assembly, and is made into an ultra-thin thickness (less than 0.6 mm) and a large-length (greater than 500 mm) magnet. very difficult.
  • NdFeB magnets which are different from rigid bonded NdFeB magnets. They are made of rubber as a binder and are produced by rubber processing. They do not require a large amount of mold development costs and production. High efficiency, free bending and no cracking, product size can be arbitrarily changed, thickness can be less than 0.6mm, easy for customers to assemble and use, has been widely used in home appliances, sensors, office automation and other fields, the demand is very large.
  • This technique is disclosed in the applicant's patent ZL 200410052150.3. However, this patent uses isotropic quenched NdFeB magnetic powder. The maximum magnetic energy product of the flexible magnet is 18 kJ/m3-68 kJ/m 3 , which is lower than the rigid molded bond. The highest performance of the magnet is 88kJ/m 3 .
  • ultra-thin, ultra-light, stable, high-power requirements for components such as concert halls, plazas, and homes, high-fidelity planar speakers that require larger areas, thinner thickness, and farther sounds;
  • Laptop computers need thinner and more powerful fan motors to meet the heat dissipation requirements of high-speed processing chips; washing machines, fans and other home appliances also need smoother and more torque direct-drive motors; mobile phones, MP3, MP4 and other multimedia devices
  • An ultra-thin, ultra-light flexible sensor is required.
  • magnetic materials are required to have higher performance, so anisotropic NdFeB materials have entered the field of researchers.
  • anisotropic NdFeB magnetic powders there are mainly two kinds of anisotropic NdFeB magnetic powders, one is anisotropic NdFeB magnetic powder prepared by HDDR process; the other is anisotropic NdFeB magnetic powder prepared by hot piercing process.
  • HDDR NdFeB magnetic powder When HDDR NdFeB magnetic powder is used as raw material to prepare flexible bonded magnet, HDDR magnetic powder only has magnetocrystalline anisotropy, and its Hcj is much higher than ferrite. Therefore, it is necessary to design a strong orientation magnetic field during molding. Complex, the size of the magnet cannot be made large, and the application range is limited.
  • the anisotropic NdFeB magnetic powder prepared by the hot piercing process is obtained by coarse-breaking the isotropic NdFeB MQIII magnet, and then modified by a sand mill or a stirring mill, and has magnetocrystalline anisotropy. And an anisotropic sheet-like magnetic powder, and the easy magnetization axis coincides with the direction of the thickness of the magnetic powder.
  • the sheet-like NdFeB magnetic powder passes between the two press rolls of the calender, the sheet-like magnetic powder rotates in the rubber base, and the flat surface of the sheet is regularly arranged perpendicular to the direction of the external force, and the roller is regularly arranged.
  • the orientation of the easy magnetization axis is formed in the pressure direction, thereby realizing the orientation.
  • This orientation does not require any external magnetic field, and is completely realized by the mechanical force between the twin rolls of the calender.
  • the process is simple and can be made into ultra-thin, super long and super. Wide sheets, strips, and articles of various shapes, which are not achievable with magnetic field orientation.
  • the MQIII anisotropic NdFeB magnet is thickened by a full-density isotropic MQ ⁇ magnet hot pier.
  • the MQ neodymium magnet is deformed by hot pressing at 700-750 °C, the Nd-rich phase of the Nd 2 Fe 14 B grain boundary has melted, and the Nd 2 Fe 14 B crystal grain is immersed in the Nd-rich liquid phase and subjected to a compressive stress.
  • the Nd 2 Fe 14 B grain has anisotropy of strain energy, and the grain strain energy of the grain axis whose axis of easy magnetization is parallel with the pressure is low, and the grain strain energy of the magnetization axis and the pressure at a certain angle is high.
  • the grain with high strain energy is unstable, and it will dissolve in the Nd-rich boundary layer liquid, so that the solid phase saturation of the Nd-rich liquid phase increases relative to 2:14:1, forming a concentration gradient and diffusing through the liquid phase.
  • the Nd 2 Fe 14 B grain with low strain energy grows, and the preferred direction of growth is a 2:14:1 base plane, and finally those grains whose axis of easy magnetization is parallel to the pressure direction grow into pieces along the base plane.
  • the physical model of the anisotropic neodymium iron boron magnet MQIII texture is shown in Fig. 1.
  • the above irregular magnetic powder is added to a sand mill or a stirring mill, and when the flattening is optimized under the protection of the liquid medium, the slurry is pumped from the bottom of the cylinder to the upper part of the cylinder, and is subjected to the falling process.
  • the friction, impact, etc. of the grinding ball are continuously pumped to the upper part of the cylinder by the pump, and the cycle is repeated several times.
  • the steel ball and the slurry are multi-dimensional cyclic motion and rotation motion.
  • the steel ball and the material are exchanged in the cylinder up and down, inside and outside, because the tangential force of the sand mill or the stirring mill is large, the normal force is weak, plus The Nd-rich phase of the Nd 2 Fe 14 B grain boundary in the magnetic powder is brittle, so this method can achieve perfect flattening requirements.
  • the force analysis of the logistics in different grinding modes is shown in the following table.
  • the object of the present invention is to provide a stress field oriented anisotropic flexible bonded NdFeB magnet and a manufacturing method thereof, so as to meet the high-end application requirements of high-performance micro-motors, ultra-thin sensors, electroacoustic equipment and the like.
  • the magnetic powder used in the magnet of the present invention is a shape anisotropic NdFeB flat magnetic powder which is crushed by an MQIII magnet and then subjected to a special flattening treatment to obtain an easy magnetization axis and a magnetic powder thickness direction.
  • the flattening treatment is to put the magnetic powder with the particle size of -80 mesh obtained by crushing the MQIII magnet into a sand mill or a stirring mill, and treat it under the protection of a liquid medium to obtain a flat having an average particle diameter D50 to an average thickness ratio of more than 10.
  • Magnetic powder, the easy magnetization axis of the magnetic powder coincides with the thickness direction of the magnetic powder.
  • the coating of organic or inorganic materials by sol coating, chemical or physical deposition, reactive passivation of organic or inorganic surface coating, forming a coating on the surface of the flattened magnetic powder to improve the corrosion resistance of the flexible bonded NdFeB magnet Sex and flame retardant.
  • the surface-coated flat magnetic powder is added to a resin or rubber-based binder and other auxiliary agents, and after being uniformly mixed, orientation molding is performed under a stress field to realize alignment of the magnetic powder in the bonding system to form an anisotropy.
  • the flexible magnetic sheet is cross-linked and surface-treated.
  • the ratio of magnetic powder to resin or rubber-based binder and auxiliary agent is 75-95% of magnetic powder, 5-20% of binder, and 0-5% of other additives.
  • the rubber-based binder used in the present invention is selected from the group consisting of chlorinated polyethylene, nitrile rubber, ethylene propylene rubber, neoprene rubber, butadiene rubber, urethane rubber, styrene butadiene rubber, butyl rubber, polyisobutylene rubber, and poly Sulfur rubber, silicone rubber, hydrogenated nitrile rubber, polyisoprene rubber, thermoplastic polymers, and combinations thereof.
  • one or more of nitrile rubber, chlorinated polyethylene, butyl rubber, and thermoplastic polymer are used.
  • the processing aid used in the present invention includes one or more of an antioxidant, a crosslinking agent, a coupling agent, a plasticizer, a lubricant, a solvent, and an antioxidant.
  • the invention provides a stress field oriented anisotropic flexible bonded NdFeB magnet by adding a flattened and surface coated anisotropic magnetic powder to a resin or rubber adhesive.
  • the additive is uniformly mixed, and the mixing method adopts a mixing method, an opening method, and then the mixed compound is pressed or extruded to form a flexible magnet of a certain thickness.
  • the crosslinking method may be one of the following: electron beam irradiation, infrared radiation, hot air heating, bubbling bed, microwave irradiation, radiation irradiation, flat plate heating, etc. In a more preferred embodiment, a flat plate or hot air heating method is used.
  • the invention relates to a method for manufacturing a stress field oriented anisotropic flexible bonded NdFeB magnet, and further comprising: the prepared magnet is subjected to surface protection treatment, and the treatment method comprises one of spraying, vapor deposition, and coating protective paint. Or several.
  • the stress field oriented anisotropic flexible bonded NdFeB magnets of the present invention have higher performance and can satisfy higher end applications.
  • a flexible bonded NdFeB magnet prepared by anisotropic HDDR NdFeB magnetic powder a flexible bonded NdFeB magnet prepared by flattening NdFeB having an anisotropy of shape, due to magnetic powder It has shape anisotropy and the easy magnetization axis coincides with the direction of the thickness of the magnetic powder.
  • the sheet-like NdFeB magnetic powder passes between the two press rolls of the calender, the sheet-like magnetic powder rotates in the rubber base, and the flat surface of the sheet is regularly arranged perpendicular to the direction of the external force, and the roller is regularly arranged.
  • the assembly of the easy magnetization axis in the pressure direction realizes the orientation, and the orientation does not require any external magnetic field, and is completely realized by the mechanical force between the twin rolls of the calender, so the process is simple, the preparation is large, and the production efficiency is high.
  • the advantages, but also the good magnetic properties of the flexible magnet the magnet can be wound on a shaft 10 times its thickness without cracking.
  • the maximum performance of the magnet can reach 120kJ/m 3 , even exceeding the performance of the isotropic rigid molded magnet, further expanding the application field of the flexible magnet, meeting the global market demand, filling the gaps at home and abroad, and changing the rare earth permanent magnet industry in China. status quo.
  • the magnetic powder obtained by crushing the MQIII magnet (particle size -80 mesh, grade 37-11) 2000g was added to an appropriate amount of pure alcohol to form a liquid slurry ⁇ flattened in a stirring mill for 3 hours (ball ratio 10:1, ⁇ 2) And the balls of ⁇ 4 each accounted for 50%) ⁇ baked in an oven at 60 ° C for 2 h ⁇ flattened flaky magnetic powder (the ratio of the average particle diameter D50 to the average thickness was 10).
  • the mixture was made into a magnetic sheet with a thickness of 2 mm on a calender, and heat-cured at 150 ° C for 20 min.
  • the magnetic sheet was wound around a round rod of ⁇ 20 without cracks.
  • the highest magnetic energy product of the obtained magnet was 100 kJ/m. 3 .
  • the test tube has a flame retardant rating of V-2 of the UL94 standard.
  • the magnetic powder (particle size -80 mesh, grade 37-11) 2000g obtained by crushing MQIII magnet was added to an appropriate amount of pure alcohol to form a liquid slurry ⁇ flattened in a stirring mill for 6 hours (ball ratio 7:1, ⁇ 2) And the balls of ⁇ 4 each accounted for 50%) ⁇ baked in an oven at 60 ° C for 2 h ⁇ flattened flaky magnetic powder (the ratio of the average particle diameter D50 to the average thickness was 11).
  • the mixture was made into a magnetic sheet with a thickness of 2 mm on a calender, and heat-cured at 150 ° C for 20 min.
  • the magnetic sheet was wound around a round rod of ⁇ 20 without cracks.
  • the highest magnetic energy product of the obtained magnet was 106 kJ/m. 3 .
  • the magnet has a flame retardant rating of V-2 of the UL94 standard.
  • the magnetic powder (particle size -80 mesh, grade 37-11) 2000g obtained by crushing MQIII magnet was added to an appropriate amount of pure alcohol to form a liquid slurry ⁇ flattened in a stirring mill for 6 hours (ball ratio 7:1, ⁇ 2) And ⁇ 4 balls each accounted for 50%) ⁇ baked in an oven at 60 ° C for 2 h ⁇ flattened flaky magnetic powder.
  • the magnetic powder (particle size -80 mesh, grade 37-11) 2000g obtained by crushing MQIII magnet was added to an appropriate amount of pure alcohol to form a liquid slurry ⁇ flattened in a stirring mill for 6 hours (ball ratio 7:1, ⁇ 2) And ⁇ 4 balls each accounted for 50%) ⁇ baked in an oven at 60 ° C for 2 h ⁇ flattened flaky magnetic powder.
  • the magnet was subjected to a neutral salt spray test (5% NaCl solution / 35 ° C * 72 h) and observed with a 5x magnifying glass without rust.
  • the magnetic sheet was wound around a round rod of ⁇ 10 without cracks, and the highest magnetic energy product of the obtained magnet was found to be 105 kJ/m 3 .

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Description

一种应力场取向的各向异性可挠性粘结钕铁硼磁体及其制备方法
技术领域
本发明属于粘结钕铁硼磁性材料制备领域，具体地，涉及一种应力场取向的各向异性可挠性粘结钕铁硼磁体及其制造方法。
背景技术
在永磁材料的大家族中，上世纪80年代问世的以Nd2Fe14B为基体的钕铁硼永磁体具有最优异的磁性能，它主要分为烧结钕铁硼和粘接钕铁硼两大类。上世纪90年代以来，随着计算机为主体的信息产业的强劲需求，以快淬钕铁硼为代表的各向同性刚性粘结钕铁硼磁体得到广泛的应用。
以往的各向同性粘结钕铁硼磁体加工方法多采用硬质塑料、树脂等作为粘结剂和钕铁硼磁粉混炼造粒后模压、注射或者挤出成型，所制得的磁体都是刚性、易脆、不能弯曲的，而且采用模压、注射成型工艺生产不同规格的产品则需要不同的模具，开发成本较高，周期较长。同时刚性磁体虽然具有较高的磁性能和一定的形状自由度，但因为易碎，存在运输、装配不便的缺点，而且制作成超薄厚度(小于0.6mm)，超大长度（大于500mm）的磁体非常困难。
为此人们设计开发出可挠性粘结钕铁硼磁体，其不同于刚性粘结钕铁硼磁体，它以橡胶为粘结剂，采用橡胶加工工艺生产，不需要大量的模具开发费用、生产效率高、可自由弯曲不开裂、制品尺寸可任意变更、厚度可小于0.6mm、便于客户装配使用，已广泛应用于家电、传感器、办公自动化等领域，需求量很大。此项技术已在申请人的专利ZL 200410052150.3中得到揭示。但是此专利采用的是各向同性快淬钕铁硼磁粉，制备出的可挠性磁体的最大磁能积范围为18 kJ/m3-68 kJ/m3，这个性能低于刚性模压粘结粘结磁体的最高性能88kJ/m3。
随着应用领域对元器件不断提出超薄、超轻、稳定、大功率的要求，比如音乐厅、广场、家庭等需要面积更大、厚度更薄、声音传得更远的高保真平面喇叭；手提电脑中需要更薄、更大功率的风扇马达以满足高速处理芯片的散热要求；洗衣机、风扇等家电中也需要更平稳、更大力矩的直驱电机；手机、MP3、MP4等多媒体设备用需要超薄、超轻的可挠性传感器等。为了满足上述需求，需要磁性材料具备更高的性能，所以各向异性钕铁硼材料进入了研究人员的视野。目前各向异性钕铁硼磁粉主要有两种，一种是采用HDDR工艺制备的各向异性钕铁硼磁粉；另外一种是采用热墩粗工艺制备的各向异性钕铁硼磁粉。其中采用HDDR钕铁硼磁粉为原料制备可挠性粘结磁体时，因为HDDR磁粉只具有磁晶各向异性，而且它的Hcj相对铁氧体高很多，所以成型时需要设计强大的取向磁场，工艺复杂，无法把磁体的尺寸做大，应用范围受限。
采用热墩粗工艺制备的各向异性钕铁硼磁粉，是通过向异性钕铁硼MQIII磁体经过粗破以后，再用砂磨机或者搅拌磨修饰而得来的、同时具有磁晶各向异性和形状各向异性的片状磁粉，而且易磁化轴与磁粉厚度方向重合。此种片状钕铁硼磁粉在压延过程中，通过压延机的两条压辊之间时，片状磁粉会在橡胶基体中转动，其片的平板面垂直于外力方向而规则排列，在辊子压力方向上形成易磁化轴的聚集，从而实现了取向，此取向不需要任何外加磁场，完全依靠压延机的双辊之间的机械力实现，工艺简单，可以制成超薄、超长、超宽的片材、带材和各种形状的制品，这种尺寸的制品用磁场取向无法实现。
MQIII各向异性钕铁硼磁体是经过全密度的各向同性的MQІІ磁体热墩粗而来。当MQІІ磁体在700-750℃热压变形时，其间的Nd2Fe14B晶界的富Nd相已融化，Nd2Fe14B 晶粒浸泡在富Nd液相中，并受到一个压应力的作用，由于Nd2Fe14B 晶粒具有应变能的各向异性，晶粒的易磁化轴与压力平行的那些晶粒应变能低，易磁化轴与压力成一定角度的那些晶粒应变能高；应变能高的晶粒是不稳定的，它将溶解于富Nd晶界液中，使富Nd液相相对2：14：1固相饱和度增加，形成一个浓度梯度，通过液相扩散，应变能低的Nd2Fe14B 晶粒长大，长大的择优方向是2：14：1的基平面，最终导致易磁化轴与压力方向平行的那些晶粒沿基平面长大成片。各向异性钕铁硼磁体MQIII织构形成的物理模型图如图1。
当 MQIII被破碎成粗磁粉时，大多数是沿着晶界断裂，所以得到的不规则片状粉的易磁化轴就是垂直于片状粉平面的。
上述不规则片状磁粉加入放到砂磨机或者搅拌磨内，在液体介质的保护下进行处理扁平化优化时，由于物料浆从筒体底部用泵抽取到筒体上部，在下落过程中受到磨球的摩擦、冲撞等，到底后继续用泵抽取到筒体上部，如此循环多次。在筒体内，钢球和浆料作多维循环运动和自转运动，钢球和物料在筒体内上下、内外相互交换，因为砂磨机或者搅拌磨的切向力大，法向力弱，加上磁粉中Nd2Fe14B 晶界的富Nd相是脆性的，所以此种方式可以达到完美的扁平化要求。不同研磨方式时物流的受力分析如下表。
表1.各种磨机中物料的受力分析
磨机种类 法向力
（冲击力、撞击力）		 切向力
（剪切力、摩擦力）		 磨球直径 功率输入方式
滚筒球磨机 大 小 大 滚动
振动磨 大 小 较大 振动
搅拌磨 小 大 较小 搅拌滚动
砂磨机 很小 很大 很小 搅拌转动
发明内容
本发明的目的在于提供一种应力场取向的各向异性可挠性粘结钕铁硼磁体及其制造方法，以满足高性能微特电机、超薄传感器、电声器材等高端应用需求。
本发明磁体所采用的磁粉是用MQIII磁体破碎后，再经过专门的扁平化处理得到易磁化轴与磁粉厚度方向重合的形状各向异性钕铁硼扁平磁粉。扁平化处理是把MQIII磁体破碎得到的、粒度为-80目的磁粉放到砂磨机或者搅拌磨内，在液体介质的保护下进行处理，得到平均粒径D50与平均厚度之比大于10的扁平磁粉，该磁粉的易磁化轴与磁粉厚度方向重合。
通过有机-无机材料溶胶包覆、化学或者物理沉积、反应钝化有机或者无机的表面包覆，在扁平化磁粉的表面形成一层包覆层，提高可挠性粘结钕铁硼磁体的防腐性和阻燃性。
把表面包覆好的扁平磁粉加入到树脂或橡胶类粘结剂以及其它助剂中，混合均匀后，在应力场下取向成型，实现磁粉在粘结体系中的定向排列，制成各向异性可挠性磁片，再经过交联，表面处理而成。磁粉与树脂或橡胶类粘结剂、助剂的比例按照质量百分比为磁粉75-95%、粘结剂5-20%、其它助剂0-5%。
不同的高分子材料由于内聚能、加工粘度、密度等的不同，对无机材料的填充性是相差很大的，在可挠性稀土磁体的开发中，如何选择粘结剂以及对粘结剂进行改性以期在保证取向度的前提下获得的尽可能高的磁粉填充性是一个关键的工作。本发明所采用的橡胶类粘结剂选自：氯化聚乙烯、丁腈橡胶、乙丙橡胶、氯丁橡胶、顺丁橡胶、聚氨酯橡胶、丁苯橡胶、丁基橡胶、聚异丁烯橡胶、聚硫橡胶、硅橡胶、氢化丁腈橡胶、聚异戊烯橡胶、热塑性聚合物和它们的组合。在优选的实施方式中选用丁腈橡胶、氯化聚乙烯、丁基橡胶、热塑性聚合物中的一种或者几种。
本发明所采用的加工助剂包括抗氧剂、交联剂、偶联剂、增塑剂、润滑剂、溶解剂和防老剂中的一种或几种。
本发明提供的一种应力场取向的各向异性可挠性粘结钕铁硼磁体的制造方法是：将扁平化并表面包覆处理后的各向异性磁粉加入到树脂或橡胶类粘结剂、助剂里面混合均匀，混合方法采用密炼法、开炼法、然后将混合均匀后的胶料采用压制或者挤出成型制成一定厚度的可挠性磁体。
通常情况下，橡胶制品的强度较低，在很多的使用条件下是不能满足的，为此柔稀性钕铁硼磁体在有强度使用要求的情况下，要对磁体进行交联处理，使橡胶形成网状交联结构以获得更高的强度。交联方式可以采用以下的一种：电子束辐射、红外辐射、热空气加热、沸腾床、微波辐射、放射线辐射、平板加热等，在更优选的实施方式中选用平板或者热空气加热法。
本发明应力场取向的各向异性可挠性粘结钕铁硼磁体的制造方法，还包括所制得的磁体进行表面防护处理，处理方法有喷涂、气相沉积、涂布防护漆中的一种或者几种。
与现有的同性可挠性粘结钕铁硼磁体相比，本发明应力场取向的各向异性可挠性粘结钕铁硼磁体具有更高的性能，可以满足更高端的用途。与用各向异性HDDR钕铁硼磁粉制备的可挠性粘结钕铁硼磁体相比，采用具有形状各项异性的扁平化钕铁硼制备的可挠性粘结钕铁硼磁体，由于磁粉具有形状各向异性，而且易磁化轴与磁粉厚度方向重合。此种片状钕铁硼磁粉在压延过程中，通过压延机的两条压辊之间时，片状磁粉会在橡胶基体中转动，其片的平板面垂直于外力方向而规则排列，在辊子压力方向上形成易磁化轴的聚集，从而实现了取向，此取向不需要任何外加磁场，完全依靠压延机的双辊之间的机械力实现，所以具有工艺简单，容易制备大尺寸、生产效率高的优点，而且兼顾了可挠性磁体的良好曲扰性，磁体可以卷绕在其厚度10倍的轴上不断，不开裂。磁体最高性能可达到120kJ/m3 ，甚至超过了各向同性的刚性模压磁体的性能，进一步扩大了可挠性磁体的应用领域，满足全球市场需求，填补国内外空白，改变中国稀土永磁行业现状。
具体实施方式
实施例1
1、扁平化处理工艺：
将MQIII磁体破碎得到的磁粉（粒度为-80目，牌号为37-11)2000g加入到适量纯酒精中形成液态浆料→在搅拌磨中扁平化处理3小时（球料比例10:1，Φ2和Φ4的球各占50％）→在烘箱中加热60℃烘烤2h→扁平化良好的片状磁粉（其平均粒径D50与平均厚度之比为10）。
2、磁粉包覆工艺：
取上述磁粉200g，纳米二氧化硅4g，加入到用甲苯溶解的硅酮树脂12g中混合均匀（温度80℃），直到溶剂挥发完全→在真空烘箱中加热260℃*2h固化。把该磁粉进行盐水浸泡实验（3％的NaCl溶液/25℃*72h）后用5倍放大镜观察没出现锈迹。
3、磁体制备工艺：
取上述磁体100g，丁腈橡胶5.5g，硅烷偶联剂0.2g，交联剂0.03g，硬脂酸钡0.15g，防老剂0.2g，增塑剂0.25g等组分采用混炼、开练至均匀，再将混合物在压延机上制成厚度为2mm的磁片，在150℃条件下热硫化20min，磁片绕在Φ20的圆棒上不出现裂纹，测所得磁体最高磁能积为100kJ/m3 。测试磁体的阻燃等级可达到UL94标准的V-2。
实施例2
1、扁平化处理工艺：
将MQIII磁体破碎得到的磁粉（粒度为-80目，牌号为37-11)2000g加入到适量纯酒精中形成液态浆料→在搅拌磨中扁平化处理6小时（球料比例7:1，Φ2和Φ4的球各占50％）→在烘箱中加热60℃烘烤2h→扁平化良好的片状磁粉（其平均粒径D50与平均厚度之比为11）。
2、磁粉包覆工艺：
取上述磁粉200g，纳米二氧化硅4g，加入到用甲苯溶解的硅酮树脂12g中混合均匀（温度80℃），直到溶剂挥发完全→在真空烘箱中加热260℃*2h固化。
3、磁体制备工艺：
取上述磁体100g，丁腈橡胶5.5g，硅烷偶联剂0.2g，交联剂0.03g，硬脂酸钡0.15g，防老剂0.2g，增塑剂0.25g等组分采用混炼、开练至均匀，再将混合物在压延机上制成厚度为2mm的磁片，在150℃条件下热硫化20min，磁片绕在Φ20的圆棒上不出现裂纹，测所得磁体最高磁能积为106kJ/m3 。该磁体阻燃等级可以达到UL94标准的V-2。
实施例3
1、扁平化处理工艺：
将MQIII磁体破碎得到的磁粉（粒度为-80目，牌号为37-11)2000g加入到适量纯酒精中形成液态浆料→在搅拌磨中扁平化处理6小时（球料比例7:1，Φ2和Φ4的球各占50％）→在烘箱中加热60℃烘烤2h→扁平化良好的片状磁粉。
2、磁粉包覆工艺：
取上述磁粉200g，纳米二氧化硅3g，加入到用甲苯溶解的硅酮树脂9g中混合均匀（温度80℃），直到溶剂挥发完全→在真空烘箱中加热260℃*2h固化。
3、磁体制备工艺：
取上述磁体100g，氯化聚乙烯4.0g，丁基胶硅1.0g，烷偶联剂0.2g，交联剂0.02g，硬脂酸钡0.15g，防老剂0.2g，增塑剂0.2g等组分采用混炼、开练至均匀，再将混合物在压延机上制成厚度为2mm的磁片，在150℃条件下热硫化20min，磁片绕在Φ20的圆棒上不出现裂纹，测所得磁体最高磁能积为110kJ/m3 。
实施例4
1、扁平化处理工艺：
将MQIII磁体破碎得到的磁粉（粒度为-80目，牌号为37-11)2000g加入到适量纯酒精中形成液态浆料→在搅拌磨中扁平化处理6小时（球料比例7:1，Φ2和Φ4的球各占50％）→在烘箱中加热60℃烘烤2h→扁平化良好的片状磁粉。
2、磁粉包覆工艺：
取上述磁粉200g，加入到用丙酮溶解的KH550硅烷偶联剂（0.1g）、环氧树脂硅（5g）中混合均匀（温度80℃），直到溶剂挥发完全→在真空烘箱中加热120℃*2h固化。
3、磁体制备工艺：
取上述磁体100g，氯化聚乙烯4.0g，丁基胶硅1.0g，烷偶联剂0.2g，交联剂0.02g，硬脂酸钡0.15g，防老剂0.2g，增塑剂0.2g等组分采用混炼、开练至均匀，再将混合物在压延机上制成厚度为1.0mm的磁片，在150℃条件下热硫化15min后，在磁体表面气相沉积一层对二甲苯树脂的异构体涂层（parylene处理）。该磁体进行中性盐雾实验（5％的NaCl溶液/35℃*72h）后用5倍放大镜观察没出现锈迹。磁片绕在Φ10的圆棒上不出现裂纹，测所得磁体最高磁能积为105kJ/m3。

Claims (9)

  1. 一种应力场取向的各向异性可挠性粘结钕铁硼磁体，包括具有形状各向异性的钕铁硼磁粉，树脂或橡胶类粘结剂以及其它助剂。其中，各组分的重量百分比为：形状各向异性钕铁硼磁粉75-95%、粘结剂5-20%、其它助剂0-5%。
  2. 根据权利要求1所述的应力场取向各向异性可挠性粘结钕铁硼磁体，其中，具有形状各向异性的钕铁硼磁粉是扁平形状，其平均粒径D50与平均厚度之比大于10。
  3. 根据权利要求2所述的具有形状各向异性的钕铁硼磁粉，其特征在于易磁化轴与磁粉厚度方向重合。
  4. 根据权利要求2所述的具有形状各向异性的钕铁硼磁粉，是用MQIII磁体破碎后，再经过扁平化处理得到的，扁平化处理所用设备选自砂磨机或者搅拌磨，研磨介质是液体保护介质。
  5. 根据权利要求1所述的应力场取向各向异性可挠性粘结钕铁硼磁体，其中，具有形状各向异性的钕铁硼磁粉是经过表面处理的，在磁粉表面生成包覆层，达到磁体防腐和阻燃的目的。表面处理的方法选自有机-无机材料溶胶包覆、化学或者物理沉积、反应钝化和它们的组合。
  6. 根据权利要求1所述的应力场取向各向异性可挠性粘结钕铁硼磁体，其特征在于所述的橡胶类粘结剂选用氯化聚乙烯、丁腈橡胶、乙丙橡胶、氯丁橡胶、顺丁橡胶、聚氨酯橡胶、丁苯橡胶、丁基橡胶、聚异丁烯橡胶、聚硫橡胶、硅橡胶、氢化丁腈橡胶、聚异戊烯橡胶和热塑性聚合物中的一种或几种。
  7. 根据权利要求1所述的应力场取向各向异性可挠性粘结钕铁硼磁体，其特征在于采用压延或者挤出的方法取向成型，使磁粉在粘结剂中定向排列。
  8. 根据权利要求1所述的应力场取向各向异性可挠性粘结钕铁硼磁体，其特征在于交联的方式采用电子束辐射、红外辐射、热空气加热、沸腾床、微波辐射、放射线辐射或平板加热。
  9. 根据权利要求1所述的应力场取向各向异性可挠性粘结钕铁硼磁体，其特征在于对磁体进行表面防护处理的方法选自喷涂、气相沉积、涂布防护漆中的一种或它们的组合。
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