纳米粉对烧结钕铁硼抗腐蚀性能的影响

发布时间：2018-01-12 22:27

本文关键词：纳米粉对烧结钕铁硼抗腐蚀性能的影响　出处：《沈阳工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：烧结NdFeB磁体卓越的磁性能而被广泛的应用在各种电子设备中。但是,由于NdFeB磁体富Nd相与主相之间大的电位差使磁体容易发生晶间腐蚀,富Nd相比较活泼,在湿热环境中与H2O反应造成晶界区域体积膨胀产生晶界应力,导致晶界相破坏。这些原因的存在严重限制了烧结NdFeB在重要领域中的应用,晶界相的微观结构与NdFeB磁体的腐蚀性能密切相关。目前,通过晶界添加改变晶界相的结构是一种有效的改善烧结NdFeB磁体抗腐蚀性能的方法之一。本文为了提高烧结钕铁硼磁体的磁性能和抗腐蚀性能,采用二元合金法添加Mg纳米粉制备NdFeB材料。利用扫描电子显微镜、X射线衍射仪和AMT-4永磁特性测试仪对烧结NdFeB磁体(PrNd)29.9Dy0.1B1Co1Cu0.15Febal+x%Mg(质量分数))的微观结构和磁性能进行了分析。添加Mg纳米粉的量分别为0.0wt.%、0.1wt.%、0.2wt.%、0.3wt.%和0.4wt.%。结果表明:当添加了0.1wt%Mg纳米粉时,娇顽力(Hcj)达到最大值999.1kA/m,剩磁(Br)达到最大值1.436T,最大磁能积(BH)max达到最大值396.9kJ/m3,磁体密度为7.42g/cm3,增加了0.27%。磁性能的提高与晶界的微观结构和磁体密度的改变密切相关。采用电化学工作站和加速腐蚀试验对烧结NdFeB磁体的抗腐蚀性能进行检测,动电位极化曲线分别在3.5%NaCl和0.005%H2SO4溶液中测得,曲线平台对应的纵坐标为相应的腐蚀电位,阳极曲线的切线与自腐蚀电位的交点的横坐标为相应的腐蚀电流密度。在酸性腐蚀介质中,当Mg添加量从0.0wt.%增加到0.4wt.%,腐蚀电位由-0.618V升高到-0.470V,腐蚀电流密度由193.1μA/cm~2降低到46.5μA/cm~2。在湿热环境中腐蚀96h后,添加0.0wt.%和0.1wt.%Mg的磁体的质量损失分别为42.3 mg/cm~2和5.3 mg/cm~2,表明晶界添加Mg纳米粉能够提高磁体的抗腐蚀性能。进一步的研究表明磁体抗腐蚀性能的提高与Mg-Nd晶界相的形成有关。
[Abstract]:Sintered NdFeB magnets have been widely used in various electronic devices due to their excellent magnetic properties. However, due to the large potential difference between Nd-rich and main phases of NdFeB magnets, the magnets are prone to intergranular corrosion. Nd-rich phase is relatively active, and the volume expansion of grain boundary region results in grain boundary stress due to the reaction with H _ 2O in humid and thermal environment. These reasons seriously limit the application of sintered NdFeB in important fields. The microstructure of grain boundary phase is closely related to the corrosion properties of NdFeB magnets. It is one of the effective ways to improve the corrosion resistance of sintered NdFeB magnets by adding grain boundary to change the structure of grain boundary phase. In order to improve the magnetic properties and corrosion resistance of sintered NdFeB magnets. The NdFeB material was prepared by adding mg nano-powder by binary alloy method. Scanning electron microscope (SEM) was used. X-ray diffractometer and AMT-4 permanent Magnet characteristic Tester for Sintered NdFeB Magnet PrNdlr 29.9Dy0.1B1Co1Cu0.15Febal xMg(. The content of mg nano-powder was 0.0wt.%. 0.3wt.% and 0.4wt.s. the results showed that when 0.1 wtmg nano-powder was added. The maximum value of coercive force (HCJ) is 999.1 Ka / m, the maximum value of remanent magnetic energy is 1.436 T, and the maximum value of BHN max is 396.9 KJ / m3. The density of magnets is 7.42 g / cm3. The improvement of magnetic properties is closely related to the change of grain boundary microstructure and density of magnets. The corrosion resistance of sintered NdFeB magnets was tested by electrochemical workstation and accelerated corrosion test. Test. The potential polarization curves were measured in 3.5 NaCl and 0.005H _ 2SO _ 4 solutions, respectively. The corresponding vertical coordinates of the curve platform are the corresponding corrosion potentials. The transverse coordinates of the tangent line of the anode curve and the intersection point of the self-etching potential are the corresponding corrosion current density. In acidic corrosion medium, the mg content increases from 0.0wt.% to 0.4wt.%. The corrosion potential increased from -0.618 V to -0.470 V, and the corrosion current density decreased from 193.1 渭 A / cm ~ (2) to 46.5 渭 A / cm ~ (2). The mass loss of magnets added 0.0wt.% and 0.1wt.mg were 42.3 mg/cm~2 and 5.3 mg/cm~2, respectively. The results show that the corrosion resistance of magnets can be improved by adding mg nano-powder to grain boundary, and the further research shows that the improvement of corrosion resistance of magnets is related to the formation of Mg-Nd grain boundary phase.
【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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