氧化物电解法制备钕铁合金的研究

在溶有氧化钕和钕富集物的NdF_3—LiF二元氟化物和NdF_3—LiF—BaF_2三元氟化物熔盐中,以工业纯铁为自耗阴极,电解纯度大于99%的氧化钕和氧化钕含量大于68%的钕富集物制备了钕铁合金。电解纯度大于99%的氧化钕,电流效率可达到85.21%。电解氧化钕含量大于68%的钕富集物电流效率随钐和铕变价元素含量的增加而降低。试验条件下,制备了铁含量11～21%的钕铁合金。     

氧化钕电解的阴极过程及钕的溶解行为

本文用循环伏安法和重差法分别测定了 NdF_3-LiF-CaF_2熔体中氧化钕电解的阴极过程;金属钕在该熔体中的溶解损失;在120～300安培级电解槽中进行了氧化钕电解试验,并将所得的电解指标与氯化钕电解法进行了对比分析。     

富镧钕金属在RECl3-KCl和RECl3-KCl-CaF2体系中溶解损失研究

利用差重分析,研究了富镧钕金属在RECl3-KCl和RECl3-KCl-CaF2体系中溶解损失及添加剂CaF2对其的影响,得到了数学模型,绘制了各因素与溶解损失的关系曲线,并进行了讨论.     

富镧钕金属在RECl3-KCl和RECl3-KCl-CaF2体系中溶解损失研究

利用差重分析 ,研究了富镧钕金属在 RECl3 - KCl和 RECl3 - KCl- Ca F2 体系中溶解损失及添加剂Ca F2 对其的影响 ,得到了数学模型 ,绘制了各因素与溶解损失的关系曲线 ,并进行了讨论     

制取金属钕全流程工艺新技术

氟化钕制备采用氯化钕直接氟化工艺,流程最短,且较好地解决了沉淀过滤问题;碳酸氢铵作沉淀剂所得氧化钕成本最低;氟化物体系熔盐电解氧化物在熔盐熔化、阴极保护和实现低电流自热等方面有所创新,炉型结构合理,工艺稳定,投资少,实用性强。全流程对金属镧、铈、镨以及某些稀土合金生产。有参考价值。     

金属钕工业生产中氧化钕利用率的探讨

在氟化体系氧化物电解金属钕的工业产中,针对Ｍｄ２Ｏ３在熔盐中溶解度低的情况下,尤其是以氟酸铈矿提取的ｎｄ２Ｏ３为原料电解时易发生沉底现象时,采取调整熔盐配比和适当提高氧化钕利用率的方法,可改善金属钕产品的表面质量,防止熔盐夹杂,降低产品中的碳含量,并可达到减少炉渣（废旧溶盐）生成、稳定炉况生产和节能降耗的目的。     

熔盐电解钕中金属的溶解和泥渣的形成探讨

采用金属质量差法,对金属钕在NdF3与LiF质量比为10∶1.2的NdF3-LiF电解质中的溶解度进行测定,分析了金属钕在电解质中溶解损失随温度的变化情况,使用X射线衍射分析法测定了溶解度实验后的金属外层包裹物以及钕电解槽中泥渣中的物相,对泥渣的成因和如何提高电流效率进行了探讨。结果表明,钕的溶解度随温度升高而增大,金属溶解后生成NdOF和NdF2,溶解产物参与了渣泥的生成;通过降低电解温度到1040±10℃,并以95 g.min^-1的加料速度控制好加料,可以提高电流效率。     

熔盐电解富镨钕氧化物合成NdPrFe合金的研究

测定了稀土氧化物在氟化物熔盐中的溶解度、氟化物熔盐的密度和粘度，分析了电沉积钕的阴极过程，确定了电解富镨钕氧化物合成ＮｄＰｒＦｅ合金的工艺条件，讨论了工业规模生产的一些规律。     

金属钕工业生产中氧化钕利用率的探讨

在氟化体系氧化物电解金属钕的工业生产中,采用调整熔盐酯比和适应提高氧化钕利用率的方法,可改善金属钕产品的质量。     

金属镧,钕分别在KCl＋NaCl熔盐中的溶解行为

金属溶解于熔盐中的行为表现为溶解的金属与熔盐中的离子发生了不同程度的相互作用。稀土金属在含有自身熔盐中的溶解,前人已作了一些研究,其溶解机理归结起来主要有以下几种:生成了低价稀土离子;体系形成了胶体溶液以及离子-电子液     

氯化钕熔盐电解制取钕铁中间合金

本文简要评述了制取Nd及富Nd合金的方法,分析讨论了用消耗性Fe阴极电解NdCl_3-KCl熔盐制取Nd-Fe合金的原理及选择技术条件的原则。实验室电解试验获得了含Fe仅13％的优质Nd-Fe合金,69％的合金电流效率(按纯Nd计为60％),Nd直收率大于90％。试验结果表明,本法是技术上合理、经济上有利的制取Nd-Fe合金的简便有效方法。     

A Study on the Dissolving Loss of Nd in the NdCl_3-Containing Systems

The Dissolving loss of Nd in the systems NdCl_3-MCl_n(M=Li,Na,K,Ca,Sr,Ba;n=1 or 2)and the NdCl_3-rich NdCl_3-LiF motlen salts,and in the system of NdCl_3-(90 wt% KCl,10 wt%MCl_n) wasdetermined.It was found that the dissolving loss of Nd (B_(Nd)) in the NdCl_3-KCl,NdCl_3-CaCl_2 andNdCl_3-(90 wt%KCl,10 wt%CaCl_2) melts is rather insignificant.The dissolving loss of Nd in theNdCl_3-KCl system increases with temperature,yet it is only 1/3 of that in pure NdCl_3 when the content ofNdCl_3 was less than 50 wt% in the mixture.Addition of LiF to NdCl_3 can diminish the dissolving loss ofNd.The nature of interaction between metallic Nd and its salts was also discussed.     

Observations on Dissolution of La and Nd into Their Halide Melts in a See-through Cell

Visual observations on dissolution of La in LaCl_3-KCl and Nd in NdCl_3-KCl as well as La,Nd inKCl-NaCl melt respectively is first made by means of a see-through cell.It is found that black metal fog isformed as the dissolution of La,Nd in their melts.There is a little resistance to the dissolution and diffusion ofLa and Nd into their halide melts under electrolysis.The dissolution and diffusion rate of Nd in its halide melt ismt(?)h faster than that of La.The metal fog of La and Nd consists mainly of their lower valence ions and partiallyof metal particles.     

Preparation of high-purity neodymium chloride by solvent extraction in the mixer-settlers:A pilot-scale investigation

A novel purification process based on mixer-settlers for high-purity NdCl_3 was developed. Acidic solution and pure NdCl_3 solution were compared to scrub the less-extractable rare earths(REs)(La, Ce, and Pr)from loaded organic phase. The extractant with low-degree saponification was evaluated to remove the more-extractable element(Sm). Then the RE impurities(La, Ce, Pr, and Sm) in Nd were purified by an integrated process. Furthermore, effect of smuggling behavior on the purification of NdCl_3 in mixersettlers was studied. Based on the investigation mentioned above, the pilot-scale purification process for NdCl_3 with a purity of 99.999% was developed, and the total recovery was about 99%.     

氧化镁在镁电解质中的溶解度

测定了MgO在电解质MgCl_2-NaCl-KCl-CaF_2(MgF_2/NaF)以及MgCl_2-NaCl-KCl-NdCl_3等体系中的溶解度,并利用正交试验设计和响应面分析研究了熔盐各组分对MgO溶解度的影响；对MgCl_2 -NaCl-KCl-CaF_2(MgF_2/NaF)体系,得到了MgO溶解度随组分MgCl_2与CaF_2含量的变化规律模型和等值面图及响应面分析图；对MgCl_2-NaCl-KCl-NdCl_3体系,研究了添加稀土氯化物对氧化镁溶解过程的影响。试验结果表明,熔盐MgCl_2-NaCl-KCl-CaF_2(MgF_2/NaF)体系中,MgCl_2与CaF_2的含量对MgO的溶解的影响显著,但体系中对氧化镁的溶解度并不大(＜0．2％)；而MgCl_2-NaCl-KCl- NdCl_3体系中,MgO有较大的溶解度,而且NdCl_3的添加量直接决定着MgO的溶解度。对MgO在不同组分熔盐中的溶解过程也作了热力学研究,结果表明：MgO在熔盐中的溶解主要是氧化镁与熔盐中组分相互作用,生成络合离子所致。     

Effects of Nd on microstructure and mechanical properties of as-cast Mg-8Li-3Al alloy

Effects of Nd on microstructure and mechanical properties of as-cast Mg-8Li-3Al alloy were investigated by OM,X-ray diffraction(XRD),EPMA,scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS).The results showed that the dendrites sizes of α phase were decreased by the Nd addition.When the amount of addition Nd was 1.6 wt.%,the alloy with the smallest α phase was obtained.The refining mechanism mainly owed to the increasing constitutional supercooling at the solidification front.Furthermore,the compound Al 2 Nd generated by the reaction of Al and Nd,which distributed at the phase boundary and inside β phase,could also restrain the growth of α phase.Nd could improve the tensile strength and elongation of Mg-8Li-3Al alloy,however,excessive Al 2 Nd might also become crack source and decrease the elongation.     

镁锶合金的电化学还原制备

提出了一种电化学还原制备Mg-Sr合金的新方法。通过理论与实验研究,获得了工艺流程及工艺参数。研究结果表明,以Mg-9Al为阴极,以LiCl-16SrCl2为电解质,可实现阴极下沉电解,直接获得Mg-Al-Sr合金;LiCl的分解电压与SrCl2相近,电解过程中析出Sr的同时会析出Li,Sr以溶入Mg基熔体为主,Li以浮于熔盐表面为主;电解还原获得的Mg-Al-Sr的微观组织中,存在大量片状组织。     

Microstructural Characterization of Novel Ni-Containing Nd-Fe-B Strips by Strip Casting

The characteristics of novel Nd-Fe （Ni, Co, Al ）-B microstructure prepared by strip casting technique were studied. The novel microstructure was observed using scanning electron microscope （SEM） and transmission electron microscope （TEM）. Along the direction of heat flow, there are two kinds of different microstructures. Close to the wheel side, there is a thick layer containing many polygonal Nd2Fe14B grains. Near the free surface side, however, there are relative uniform platelike Nd2Fe14B grains whose growth direction is not completely the direction of the heat flow during solidification. The formation of the novel microstructure is presumed to be the contribution of the special temperature field and Ni component.     

Grain Growth Behavior in Sintered Nd-Fe-B Magnets

The Nd2Fe14B grain growth behavior in sintered Nd-Fe-B magnets was quantitatively described.The effects of sintering temperature and time,and alloy powder size and its distribution on grain growth process were analyzed.Hence,possible grain growth mechanisms in these magnets were qualitatively discussed.The Nd2Fe14B grain growth proceeded at quite a high rate in the initial 0~1 h of sintering and from then onwards the grain growth rate decreased.A large average particle size or a wide particle size distribution of initial alloy powders was found to remarkably accelerate the grain growth process and even result in the occurrence of abnormal grain growth.On the basis of experimental results,two grain growth mechanisms were considered to operate during sintering of Nd-Fe-B magnets,that is,dissolution and re-precipitation of Nd2Fe14B particles,and Nd2Fe14B particle growth by coalescence.It was believed that Nd2Fe14B particle growth by coalescence not only produced a large average grain size and a wide grain size distribution,but also was the fundamental reason for the formation of abnormally large grains in the microstructure of sintered Nd-Fe-B magnets.     

添加Nd元素对Ti-6Al-4V-2Cr合金组织细化的影响

采用冷等静压–真空烧结法制备Ti-6Al-4V-2Cr-1Nd合金,然后进行固溶及时效热处理,通过实验与最小错配度理论计算,研究Nd元素对该合金组织细化的影响,并分析细化机理。结果表明,添加1%(质量分数)的稀土元素Nd后,析出相Nd2O3能有效促进晶粒细化。二维错配度的计算结果证明析出相Nd2O3是有效的形核剂,可促进非均匀形核,增加形核率,从而使晶粒细化。通过对合金试样薄区进行高分辨率观察,发现另一种絮状的、非常细小的、弥散分布的Nd2Ti4O11相,由于其界面错配度较低,也可作为非均匀形核的核心,促进形核,起到细化晶粒的作用。