含Ce低成本烧结钕铁硼的腐蚀行为研究

发布时间：2019-06-19 02:34

【摘要】：由于烧结钕铁硼具有超高的永磁性能,在信息技术、通讯电子、风力发电等领域得到了广泛的应用。但因其耐蚀性能差,使其应用范围受到了限制。随着烧结钕铁硼磁体的应用快速增长,稀土钕的需求越来越多,价格也日益上涨,因此开发低成本的烧结钕铁硼磁体并研究其耐蚀性能具有重要的研究价值。根据这一情况,本文成功制备出低成本含Ce磁体,并系统的研究了含Ce磁体及商业用磁体N33和N45磁体在不同腐蚀环境中的腐蚀行为,分析并比较了磁体在不同腐蚀环境中腐蚀机理及显微结构,研究了磁体在不同电化学介质中的腐蚀行为,分析并比较了磁体在不同电化学介质中的腐蚀机理。希望为高耐蚀低成本烧结钕铁硼永磁体的制备及其应用奠定了理论基础。获得的主要研究结果如下： (1)通过高压加速实验(HAST)研究了不同成分的磁体在在130℃、100%RH的湿热环境中的腐蚀行为和腐蚀机理。研究发现,此条件下N33的失重率达到83.192%,N45的失重率达到0.3846%,含Ce磁体的失重率达到0.08813%。因而Ce磁体的耐蚀性能优于N45磁体和N33磁体。 (2)通过盐雾实验(NSS)研究了不同成分的磁体在中性盐雾中的腐蚀行为和腐蚀机理。研究发现烧结钕铁硼磁体在中性盐雾中的腐蚀反应以氧化剥落为主。当腐蚀时间达到168h时,含Ce磁体的失重率达到1.6357%,N45磁体的失重率达到2.2636%,N33磁体的失重率为2.9873%。因此,含Ce磁体的耐蚀性能优于N45磁体和N33磁体。通过显微组织分析研究了含Ce磁体具有良好耐蚀的原因,一是由于含Ce磁体的主相晶粒较小,发生氧化剥落反应时,剥落的磁体颗粒较小,因而磁体的失重率最小；二是Ce磁体的富稀土相均匀分布于磁体主相周围,不存在有富稀土相在主相角隅处的富集,使磁体的腐蚀通道变窄,降低了富稀土相的活性。进一步的研究表明,基体在腐蚀介质中的耐蚀性能对镍镀层破裂时间起着至关重要的作用,含Ce磁体由于具有低的失重率,因此电镀Ni/Cu/Ni后,表现出最好耐蚀性。 (3)通过测量烧结钕铁硼磁体在不同溶液(NaOH、NaCl、自来水)中的极化曲线及阻抗曲线,发现Ce磁体在NaOH、NaCl、自来水溶液中的腐蚀电位最正、腐蚀电流最小,阻抗最大,进一步解释了Ce磁体的耐蚀性能最好的根本原因；同时磁体在这三种溶液中的腐蚀行为,说明了当磁体处于NaOH溶液中时,其耐蚀性能最好；当磁体处于NaCl溶液中时,其耐蚀性能最差。
[Abstract]:Because of its ultra-high permanent magnetic properties, sintered ND-Fe-B has been widely used in information technology, communication electronics, wind power generation and other fields. However, because of its poor corrosion resistance, its application scope is limited. With the rapid growth of the application of sintered ND-Fe-B magnets, the demand for rare earth ND-Fe-B magnets is increasing, and the price is also rising day by day. Therefore, it is of great value to develop low-cost sintered ND-Fe-B magnets and study their corrosion resistance. According to this situation, low cost Ce magnets were successfully prepared, and the corrosion behavior of Ce magnets and commercial magnets N33 and N45 magnets in different corrosion environments was systematically studied. The corrosion mechanism and microstructure of magnets in different corrosion environments were analyzed and compared. The corrosion behavior of magnets in different electrochemical media was studied, and the corrosion mechanism of magnets in different electrochemical media was analyzed and compared. It is hoped that it will lay a theoretical foundation for the preparation and application of ND-Fe-B permanent magnets with high corrosion resistance and low cost. The main results are as follows: (1) the corrosion behavior and corrosion mechanism of magnets with different components in hot and humid environment at 130 鈩，

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