Dy、Co纳米颗粒掺杂烧结Nd-Fe-B的永磁研究

发布时间：2018-12-13 09:19

【摘要】：自20世纪80年代钕铁硼问世以来,其以优异的磁性能被广泛应用于新能源汽车、医疗、风能发电等高新领域。是当今发展最为迅捷、应用领域最广、市场规模发展潜力最大的永磁材料。作为基础性功能材料钕铁硼有着不可替代的重要性,但随着市场需求的不断扩大,大家对钕铁硼的技术参数有了进一步需求,这不仅是取决于材料成分本身,而且还与材料的组织结构、制备工艺有着密不可分的联系。尽管人们对烧结钕铁硼做了大量实验研究,但由于添加的稀土材料成本过高或者企业的生产设备过于老旧,工艺陈腐,导致产品在国际市场上无竞争力。因此如何在降低成本的同时又可以最大限度的提高钕铁硼磁性能一直是国内外科研工作者研究的热点课题。本文采用二元合金法掺杂少量镝(Dy)、钴(Co)纳米粉制备高矫顽力烧结钕铁硼磁体,在避免钕铁硼剩磁和磁能积大幅下降的同时,容许适量减少Dy、Co纳米粉的添加量,从而降低钕铁硼磁体的生产成本。在工业生产线上制备出(Pr-Nd)31.5B0.98Co0.5Nb0.3Ga0.2Cu0.15Al0.1Febal+x wt%Dy(x=0、0.4、0.8、1.2、1.6)烧结磁体。利用扫描电子显微镜、X射线衍射仪、粒度分布仪、磁滞回线测试仪、维氏硬度仪对烧结钕铁硼磁体的形貌、微观结构及成分、磁性能和力学性能进行了分析。结果表明:随着Dy元素质量分数的增加,磁体矫顽力大幅提高,剩磁和最大磁能积略有下降。当x为1.6wt%时,磁体矫顽力达到最大值15.23KOe,矫顽力提升了1.2%,剩磁和最大磁能积分别下降了2.7%和3.4%,维氏硬度值为522.01HV,下降了4%;当x为0.8wt%时,磁体矫顽力达到14.29KOe,矫顽力提升了5.4%,剩磁和最大磁能积分别下降了1.3%、1.5%,维氏硬度值为583.47HV,上升了7.1%,综合磁性能最优。在工业生产线上制备出(Pr-Nd)31.5-xB0.98CoxNb0.3Ga0.2Cu0.15Al0.1Febal(x=0、0.4、0.8、1.2)烧结磁体。分析了磁体的微观结构、磁性能、力学性能和温度稳定性与Co添加量的关系。结果显示:添加一定量的Co可以有效抑制铸锭中的α-Fe的形成,同时形成了晶间杂相,这有助于减弱钕铁硼晶粒间交换耦合作用,从而提高矫顽力。随着Co质量分数的增加,磁体的矫顽力、剩磁、最大磁能积都是先增大后减小,当x=0.8时,磁体矫顽力从13.56KOe提高到14.44KOe;剩磁从14.29KGs提升到14.35KGs;最大磁能积从49.32MGOe提升到49.55MGOe,但当继续添加Co元素到x=1.2时,磁体磁性能均小幅下降。因此当x=0.8时,磁体综合磁性能最优。
[Abstract]:Since the advent of NdFeB in the 1980s, NdFeB has been widely used in new energy vehicles, medical treatment, wind power generation and other high-tech fields with excellent magnetic properties. Is the most rapid development, the most extensive application, market scale development potential of permanent magnet materials. As a basic functional material, NdFeB is of irreplaceable importance, but with the expansion of market demand, there is a further demand for NdFeB technical parameters, which depends not only on the composition of the material, but also on the composition of NdFeB. Moreover, it is closely related to the structure of the material and the preparation process. Although a lot of experiments have been done on the sintered NdFeB, the products are not competitive in the international market because of the high cost of the rare earth materials or the old production equipment and the obsolete process. Therefore, how to reduce the cost and improve the magnetic properties of NdFeB at the same time has been a hot topic for researchers at home and abroad. In this paper, the high coercivity sintered NdFeB magnets were prepared by doping a small amount of dysprosium (Dy), Cobalt (Co) nano-powder by binary alloy method. The NdFeB magnetization and magnetic energy product were avoided while the amount of Dy,Co nanocrystalline powder was reduced at the same time. Thus, the production cost of NdFeB magnets is reduced. The sintered (Pr-Nd) 31.5B0.98Co0.5Nb0.3Ga0.2Cu0.15Al0.1Febal x wt%Dy (x0. 0 0. 4 0. 8 + 1. 21. 6) sintered magnets were prepared in an industrial production line. The morphology, microstructure, composition, magnetic properties and mechanical properties of sintered NdFeB magnets were analyzed by scanning electron microscope, X-ray diffractometer, particle size distribution, hysteresis loop tester and Vickers hardness tester. The results show that the coercivity of the magnets increases significantly with the increase of the mass fraction of Dy elements, and the remanent magnetism and the maximum magnetic energy product decrease slightly. When x is 1.6 wt%, the coercivity of the magnet reaches the maximum value of 15.23KOe. the coercivity increases by 1.2%, the remanent magnetism and the maximum magnetic energy product decrease by 2.7% and 3.4%, respectively, and the Vickers hardness is 522.01 HVV, which decreases by 4. When x is 0.8wt%, the coercivity of the magnet reaches 14.29KOe. the coercivity increases by 5.4. the remanence and the maximum magnetic energy product decrease by 1.3and 1.5, respectively, and the Vickers hardness is 583.47HV, up 7.1 percent. The comprehensive magnetic performance is optimal. The sintered (Pr-Nd) 31.5-xB0.98CoxNb0.3Ga0.2Cu0.15Al0.1Febal magnets were prepared on an industrial production line. The relationship between the microstructure, magnetic properties, mechanical properties and temperature stability of magnets and the addition of Co was analyzed. The results show that the addition of a certain amount of Co can effectively inhibit the formation of 伪-Fe in the ingot and form intergranular impurity, which is helpful to weaken the interaction between NdFeB grains and improve the coercivity. With the increase of Co mass fraction, the coercivity, remanence and maximum magnetic energy product of the magnets all increased first and then decreased. When x0. 8, the coercivity of the magnets increased from 13.56KOe to 14.44KO, and the remanence increased from 14.29KGs to 14.35KGs. The maximum magnetic energy product is increased from 49.32MGOe to 49.55MGOE, but the magnetic properties of the magnets decrease slightly when the Co element is added to XG 1.2. Therefore, the comprehensive magnetic properties of the magnets are optimal when XG is 0.8.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM273

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