Additive manufacturing of Sm-Fe-N magnets

Isotropic Sm-Fe-N bonded magnets were obtained by additive manufacturing(AM). The technique used was the so-called powder bed fusion(PBF) and the feedstock was composed of a polymeric binder(PA-12) and Sm-Fe-N flake particles(Nitroquench-P). The AM set-up equipment uses a computer-controlled CO_2 laser beam to melt the binder and constructs magnets layer-by-layer. In order to develop this study, a cylinder with 10 mm of both height and diameter was selected as the shape of samples. Specimens were analyzed by scanning electron microscopy(SEM) and X-ray diffraction(XRD). Magnetic properties were measured in a hysteresis graph. XRD results indicate that there is no degradation of the main magnetic phase(SmFe_7 N_x). In the AM component, porous regions were identified on SEM micrographs, as well as magnetic particles and polymeric binder. Remanence values(B_r) as great as 0.3 T are achieved, while intrinsic coercivities remain in the range from 616 up to 642 kA/m. An additional isostatic compression of the parts results in greater remanence, which is directly proportional to the density increase. Coercivity is also sensitive to the porosity decrease, probably due to a better interlocking of particles. Current results indicate AM as a promising route for near net-shape manufacturing of Sm-Fe-N permanent magnets, a market niche yet to be widely explored.     

Effect of HD Process on Microstructure and Hard Magnetic Properties of NdFeAlB Magnet

ＨｙｄｒｏｇｅｎＤｅｃｒｅｐｉｔａｔｉｏｎ (ＨＤ)ｐｒｏｃｅｓｓｉｓａｎｅｗｍｅｔｈｏｄｔｏｐｒｏｄｕｃｅｐｏｗｄｅｒｓｏｆｒａｒｅｅａｒｔｈｐｅｒｍａｎｅｎｔｍａｇｎｅｔ.ＴｈｅｉｎｇｏｔｓａｒｅｃｒｕｓｈｅｄｉｎｔｏｓｍａｌｌｐａｒｔｉｃｌｅｓｏｒｐｏｗｄｅｒｓｄｕｒｉｎｇＨＤｐｒｏｃｅｓｓｏｗｉｎｇｔｏｔｒａｎｓｇｒａｎｕｌａｒａｎｄｉｎｔｅｒｇｒａｎｕｌａｒｆｒａｃ ｔｕｒｅ .ＭａｎｙａｕｔｈｏｒｓｒｅｐｏｒｔｅｄｔｈａｔＨＤｐｒｏｃｅｓｓｈａｓａｌｏｔｏｆａｄｖａｎｔａｇｅｓ ,ｓｕｃｈａ…     

稀土永磁材料Sm_2Fe_（17）N_y磁体的最佳工艺

在深入探讨三元稀土铁基化合物Ｓｍ２Ｆｅ１７Ｎｙ的制备工艺和磁性能的基础上，确定熔炼母合金、渗氮、球磨及粘结等制备优化的Ｓｍ２Ｆｅ１７Ｎｙ磁体具体工艺过程的技术参数．制取了居里温度Ｔｃ＝７４６Ｋ，最大磁能积（ＢＨ）ｍａｘ＝１９９ｋＪｍ－３的Ｓｍ２Ｆｅ１７Ｎｙ粉末与粘结体．     

激光表面淬火后铁基烧结凸轮的组织与性能研究

本论文研究了铁基烧结凸轮材料经宽带激光表面淬火前后的显微组织、硬度及其摩擦学特性。研究结果表明：经激光表面淬火后，铁基烧结凸轮材料的耐磨性得到了显著的改善，摩擦系数也明显降低。在摩擦过程中，摩擦表而形成一具有高硬度的表面层，在摩擦表而层的最表层还覆盖着一层表面膜。该表面膜的存在可进一步改善铁基烧结凸轮材料的耐磨性。     

Resin-bonded NdFeB micromagnets for integration into electromagnetic vibration energy harvesters

A micromachining technique is presented for the fabrication of resin-bonded permanent magnets in the microscale. Magnetic paste is prepared from NdFeB powder and an epoxy resin, filled into lithographically defined photoresist molds or metal molds, and formed into resin-bonded magnets after curing at room temperature. A coercivity of 772.4 kA/m, a remanence of 0.27 T, and a maximum energy product of 22.6 kJ/m³ have been achieved in an NdFeB disk micromagnet with dimensions of Φ200 μm×70 μm. Based on the developed micro-patterning of resin-bonded magnets, a fully integrated electromagnetic vibration energy harvester has been designed and fabricated. The dimensions of the energy harvester are only 4.5 mm×4.5 mm×1.0 mm, and those of the micromagnet are 1.5 mm×1.5 mm×0.2 mm. This microfabrication technique can be used for producing permanent magnets tens or hundreds of micrometers in size for use in various magnetic devices.     

晶界扩散Tb对烧结Nd-Fe-B组织与磁性能的影响

用磁控溅射法在烧结Nd-Fe-B磁体表面沉积Tb金属薄膜并进行晶界扩散处理,对比经不同热扩散温度及时间处理后的磁体组织和磁性能变化.结果 表明,925℃×10 h+500℃×2 h为最佳晶界扩散工艺,可将磁体矫顽力提高到1630.9 kA· m-1,较原始磁体提升50％,同时剩磁和磁能积无明显下降,磁体仍具有较高的退磁...     

NdFeB纳米晶双相复合永磁材料研究进展

NdFeB纳米晶双相复合永磁材料，由于其潜在的优异磁性能和商业价值，成为当今材料领域研究的热点。本文就近年来NdFeB纳米晶双相复合永磁材料的发展状况，从该类合金的交换耦合作用、分类以及提高磁性能的方法三个方面为重点，作简要的评述。     

钕铁硼稀土永磁材料室温熔盐电镀铝的研究

在钕铁硼(NdFeB)稀土材料表面直接进行水溶液电镀时,存在镀层分层、易起泡等缺陷.采用AlCl3/EMIC(1-甲基-3-乙基氯化咪唑)室温熔盐电解质在NdFeB永磁材料表面电镀铝,是提高其表面防护质量的有效方法.探讨了NdFeB永磁材料在室温熔盐中电镀铝的可行性、熔盐配比和芳香化合物对电镀铝层组织形态的影响,同时对镀层形成的机理进行了初步探讨.研究表明:采用AlCl3/EMIC室温熔盐电解质可在NdFeB永磁材料表面获得满意的铝镀层;铝镀层纯度很高,较完整平滑;添加芳香化合物可以大大提高镀层的质量,使晶粒细小、致密.     

稀释剂量对反应烧结Si_3N_4陶瓷结构和性能的影响

以工业Si粉为原料,α-Si3N4粉为稀释剂,聚乙烯醇为粘结剂,采用反应烧结工艺制备了Si3N4陶瓷。研究了稀释剂量对反应烧结Si3N4陶瓷的体积密度、开气孔率、相组成、微结构、弯曲强度和抗热震性的影响。结果表明,随稀释剂量的增加,Si3N4陶瓷的体积密度从2.27g/cm3降至2.04g/cm3,开气孔率从23%升至33.8%。Si3N4陶瓷由α-Si3N4、β-Si3N4和少量单质Si组成。Si3N4主要以针状晶形式存在,残留Si呈不规则块体。随着稀释剂量的增加,4组Si3N4陶瓷的三点抗弯强度分别为119MPa、112MPa、146MPa和113MPa;经50次800℃至室温空冷热震后,其强度保持率分别为81.5%、90.2%、87%和88.5%,表现出较好的抗热震性。