粘结NdFeB制备工艺参数的优化研究

采用正交设计法,对粘结NdFeB磁体模压成型的制备工艺参数进行了优化研究.讨论了粒度配比、粘结剂含量、偶联剂含量、成型压力及固化温度对粘结NdFeB磁体磁性能的影响,在此基础上,得出了一套较优的工艺参数.     

NdFeB/酚醛树脂原位复合材料研究

采用原位聚合法制备了NdFeB/酚醛树脂(PF)母料,并进一步制备了粘结磁体.采用红外分析了NdFeB/PF母料的结构,并用多种方法对粘结磁体的磁性能和力学性能进行了研究.研究表明:在原位制备过程中,PF的聚合倾向于在NdFeB的表面进行,形成PF包覆的NdFeB,NdFeB磁粉进入了PF的生成体系,形成了海岛结构.比较三种工艺制备的磁体综合性能可知,采用NdFeB/PF母料粉料作粘结剂制备的磁体的综合性能最好.     

磁粉表面改性及粒度对注射成形粘结NdFeB磁体性能的影响

注射成形粘结NdFeB磁体满足了市场时磁体小型化、轻型化及高性能化的要求,因而有着广泛的应用前景。本文研究了磁粉特性对注射成形粘结磁体性能的影响,结果表明：采用硅烷对磁粉进行表面改性,能有效提高NdFeB磁粉的抗氧化性及相应粘结磁体的磁学及力学性能;同时NdFeB磁粉粒径太粗太细均不利于磁体性能的提高 其最佳粒径范围是60～100μm。     

各向异性粘结NdFeB磁体PTFE耐高温粘结剂的研究

研究了聚四氟乙烯(PTFE)在高温条件下的物理及化学变化以及其作为各向异性粘结NdFeB的粘结剂时不同含量对磁体的磁性能、热退磁效果、尺寸精度、力学性能的影响,同时考察了PTFE粘结NdFeB和环氧树脂(epoxy resin)粘结NdFeB的温度稳定性.认为PTFE由于其优异的耐高温性能,能够满足磁体热退磁对粘结剂的要求,而当PTFE含量为3%(质量分数)时磁体在保证小的尺寸变化率的基础上,可以使表面剩磁降到适于防腐处理的程度,但是其强度较低.同时,PTFE各向异性粘结NdFeB在高温条件下的不可逆损失hirr,剩磁的温度系数α和矫顽力的温度系数β都较epoxy resin粘结NdFeB的大.     

粘结NdFeB磁体用预混料的时效性能研究

粘结NdFeB预混料的时效性能是影响制备粘结磁体性能的关键因素.选取一种树脂粘结剂制备预混料,分析了预混料时效对粘结磁体磁性能及力学性能的影响,发现预混料中粘结剂在时效期部分交联固化对制备的粘结磁体磁性能影响较大,而对力学性能影响小,预混料的有效存储期限应由其粘结磁体磁性能降低程度判定.     

HDDR各向异性NdFeB温压混炼过程

研究了在HDDR各向异性NdFeB粘结磁体温压成形过程中粘结剂和润滑剂的添加量以及二者同磁粉的混炼工艺对磁体磁性能及机械强度的影响。利用B－H回线仪和扫描电子显微镜对磁体的磁特性和显微组织结构进行了分析测试，同时测试了不同工艺条件下处理的磁体的机械强度。结果表明，粘结剂的适量添加能够保证磁体同时具有较好的磁性能和机械强度。润滑剂的加入既降低了磁粉之间的摩擦力，又减小了磁粉在压制过程中的损伤度，从而使粘结磁体获得良好的磁粉填充率、磁取向度和磁性能。而粘结剂和润滑剂与磁粉之间的混炼方式决定了磁体中粘结剂的结合效果，从而决定了磁体最终的机械强度。采用合理的混炼工艺，可以使粘结磁体同时获得最佳的磁性能和机械强度。     

不同包覆处理工艺对粘结NdFeB永磁体性能的影响

采用干混、湿混、硅烷 (KH5 5 0 )包覆处理等工艺对快淬NdFeB磁粉进行包覆处理 ,研究了包覆处理前后快淬NdFeB磁粉的抗氧化性 ,并初步研究了用包覆处理前后的快淬NdFeB磁粉制得的粘结NdFeB永磁体的力学性能及磁性能。结果表明 ,湿混及硅烷包覆处理都能提高快淬NdFeB磁粉及磁体的性能 ,而硅烷包覆处理的效果更明显     

Fe基纳米晶粘结软磁材料的研究

采用快淬法制备了Fe74Cu1Nb3Si13B9非晶薄带,然后将薄带晶化,粉碎成不同粒度的磁性粉末.选择固态环氧树脂作为粘结剂,按一定比例将粘结剂与磁粉混合,在不同的压力下将其压制成Fe基纳米晶环形粘结磁体.分析了不同的磁粉粒度和模压压力对粘结磁体磁性能的影响,结果表明,随着磁粉粒度的减小,μj,μm,Bs,Br,Hc也随之减小;当压力增加到180kN时,再增加压力,磁性能变化不大.     

混杂粘结磁体研究

采用将不同性质的NdFeB磁粉和锶铁氧体磁粉混杂的方法制备粘结磁体,研究了锶铁氧体质量分数对混杂粘结NdFeB/锶铁氧体磁体的磁性能、温度稳定性等的影响规律,并建立了混杂磁体磁能积与锶铁氧体组分之间的经验关系式,实现了混杂磁体性能在一定范围内连续可调.     

注射工艺对高磁粉装载量PPS/NdFeB粘结磁体磁性能的影响

高磁粉装载量PPS/NdFeB注射磁体的制备是目前国内外研究的重点.成功制备出磁粉装载量90％(质量分数)左右的PPS/NdFeB粘结磁体以及可实际应用永磁元器件,应用DSC、SEM和磁化曲线测量仪等表征了注射磁体微观结构和磁性能,并分析注射温度、速度和压力等工艺参数对粘结磁体微观结构和磁性能的影响规律和机理,结果表明...     

酚醛树脂粘结钕铁硼磁体温压制备技术研究

用温压成型工艺制备了酚醛树脂粘结钕铁硼磁体,通过对磁体密度、剩磁、矫顽力、磁能积和抗弯强度的分析,研究了耦联表面处理对磁粉抗氧化性能的影响及成型工艺对磁体性能的影响.结果表明:偶联处理可以明显提高磁粉的抗氧化能力;在压力为620MPa,温压温度为180℃且不进行二次固化条件下获得了性能最佳的磁体,其密度为6.12g/cm3,抗弯强度为59.25MPa,剩磁为0.6824T,内禀矫顽力为730kA/m,最大磁能积为78.2kJ/m3.     

Surface modification of spherical NdFeB magnetic powders by a fluid-bed nickel electrodeposition

The spherical NdFeB magnetic powders were coated with Ni using a fluid-bed electrodeposition device. The oxidations of rich Nd phase or Fe phase were restrained after Ni coating. After annealing at 300 °C for 30 min, the magnetic properties of both coated and uncoated magnets were decreased. However, the Ni-coated powders showed better magnetic properties than the uncoated powders after the annealing. The compressive strength of bonded magnets improved after annealing due to enhancement of the adhesion between the adhesive and the surface of the magnetic powders.     

表面宏微处理对塑料粘结NdFeB永磁性能的影响

本文研究了偶联剂处理ＮｄＦｅＢ磁粉及环氧树脂涂层对塑料粘结ＮｄＦｅＢ永磁体性能的影响，结果表明：（１）ＫＨ５５０包覆处理ＮｄＦｅＢ磁粉可改善Ｎｄ－ＦｅＢ磁粉的抗氧化性，提高塑料粘结ＮｄＦｅＢ的磁性能和压缩强度；（２）用偶联剂微观保护ＮｄＦｅＢ磁粉和环氧树脂涂层宏观保护相结合的办法可显著地提高塑料粘结ＮｄＦｅＢ永磁体的耐蚀性和抗高温氧化性     

Direct-write 3D printing of NdFeB bonded magnets

We report a method to fabricate Nd–Fe–B (NdFeB) bonded magnets of complex shape via extrusion-based additive manufacturing (AM), also known as 3D-printing. We have successfully formulated a 3D-printable epoxy-based ink for direct-write AM with anisotropic MQA NdFeB magnet particles that can be deposited at room temperature. The new feedstocks contain up to 40 vol.% MQA anisotropic NdFeB magnet particles, and they are shown to remain uniformly dispersed in the thermoset matrix throughout the deposition process. Ring, bar, and horseshoe-type 3D magnet structures were printed and cured in air at 100°C without degrading the magnetic properties. This study provides a new pathway for fabricating NdFeB bonded magnets with complex geometry at low temperature, and presents new opportunities for fabricating multifunctional hybrid structures and devices.     

粘结剂对注射成型钕铁硼粘结磁体性能的影响

为了制备出高性价比的注射成型粘结钕铁硼永磁材料,系统地研究了粘结剂对注射成型磁体的加工性能、磁性能和力学性能等的影响。用国产的快淬钕铁硼磁粉和尼龙6粘结剂制备出了磁性能为Br:0．5158T,Hcb：321kA／m,Hcj：730kA／m,(BH)m：40kJ／m^3的注射钕铁硼磁体。     

The properties of aluminium coating on sintered NdFeB by DC magnetron sputtering

Pure aluminium coating was deposited on sintered NdFeB magnets by direct current (DC) magnetron sputtering to improve the corrosion resistance. The corrosion behaviour of sintered NdFeB coated with aluminium was characterized by potentiodynamic polarization measurement. The adhesive strength between the aluminium coating and the sintered NdFeB was characterised by vertical tensile test and high-low temperature shock test. The influence of the coating on the magnetic properties of the sintered NdFeB was also characterised. It was found that the aluminium coating can improve the corrosion resistance of the sintered NdFeB evidently. The aluminium coating was well adhesive with the substrate and did not deteriorate the magnetic properties of the sintered NdFeB magnets. These two characters may overcome the disadvantages of NiCuNi coating which is usually electroplated on NdFeB in industry.