晶界添加MgO/Mg纳米粉对烧结钕铁硼磁性和抗腐蚀性的影响

Effect of MgO/Mg nanopowders added to grain boundary on magnetic properties and corrosion resistance of sintered Nd-Fe-B

摘要:

为了提高烧结Nd-Fe-B磁体的磁性能和抗腐蚀性能,采用二元合金法,通过晶界添加MgO/Mg纳米粉烧结成(PrNd)_15.5B₆Cu_0.1Fe_balMg_x(wt%,x=0.1-0.3)永磁体。利用永磁特性自动测量仪、扫描电子显微镜、X射线衍射仪和CHI660E电化学工作站对不同添加量的MgO/Mg(质量比为1:2)纳米粉的烧结Nd-Fe-B磁体的磁性能、微观结构及抗腐蚀性能进行了研究。结果表明：当MgO/Mg纳米粉添加量为0.1wt%时,磁体综合磁性能表现最好,此时磁体矫顽力1183kA/m,剩磁1.22T,最大磁能积288kJ/m^₃。由塔菲尔曲线可知,随着MgO/Mg纳米粉添加量的增多,腐蚀电位从-1.093V提高到-0.929V；腐蚀电流密度从223.87μA/cm^₂降低到42.66μA/cm^₂；由电化学阻抗谱图可知,添加了适量的MgO/Mg纳米粉的磁体的高频容抗弧的半径大于未添加磁体的高频容抗弧的半径,增大了电荷迁移阻力。因此晶界添加适量的MgO/Mg纳米粉提高了烧结Nd-Fe-B磁体的磁性能和抗腐蚀性能。

Abstract:

In order to improve the magnetic properties and corrosion resistance of sintered Nd-Fe-B magnets, (PrNd)_15.5B₆Cu_0.1Fe_balMg(wt%, x=0.1-0.3)permanent magnet was sintered by binary alloy method with adding MgO/Mg nanopowders at grain boundary.The magnetic properties, microstructures and corrosion resistance of sintered Nd-Fe-B magnets with different amounts of MgO/Mg (mass ratio 1:2) nanopowders were studied by means of permanent magnet automatic measuring instrument, scanning electron microscopy, X-ray diffractometer and CHI660E electrochemical workstation. The results show that when the content of MgO/Mg nanopowders is 0.1wt%, the comprehensive magnetic properties of the magnet are the best. At this time, the coercivity of the magnet is 1183 kA/m, the remanence is 1.22T, and the maximum magnetic energy product is 288 kJ/m^₃. The Tafel curve shows that the corrosion potential increases from -1.093V to -0.929V and the corrosion current density decreases from 223.87μA/cm^₂ to 42.66μA/cm^₂ with the increase of MgO/Mg nanopowders content. The electrochemical impedance spectroscopy shows that the radius of the high frequency capacitive arc of the magnet with appropriate amount of MgO/Mg nanopowders is larger than that of the high frequency capacitive arc of the magnet is not added, increasing the charge transfer resistance.Therefore, the magnetic properties and corrosion resistance of sintered Nd-Fe-B magnets are improved by adding appropriate amount of MgO/Mg nanocomposite powder at grain boundaries.