2019年9月稀土市场分析

<正>1稀土市场运行概况进入9月,传统旺季来临。稀土企业核查、指令性计划未下发,原料供应偏紧,因此月初分离厂商持货惜售挺价情绪升温,氧化镨钕价格上调,冶炼厂金属报价同步上调。但下游对市场持谨慎观望态度,实际成交量有限。中重稀土方面,由于受泛亚拍卖影响和对商储、国储的期待,镝铽市场形势趋于谨慎,整体市场基本稳定,交投气氛相对冷清。进入9月第2周,受北方稀土氧化镨钕、镨钕金     

溶剂选择对PVDF-HFP膜的耐甲醇渗透性能的影响

通过相转化法,采用不同溶剂制备了多孔聚偏氟乙烯-六氟丙烯(PVDF-HFP)共聚物膜,采用计时电流法考察了膜的耐甲醇渗透性能。实验结果表明:以低沸点溶剂如丙酮和四氢呋喃作为溶剂时得到的膜多孔性较为明显,甲醇渗透较为严重,而以高沸点溶剂如N,N-二甲基乙酰胺和N-甲基吡咯烷酮作为溶剂时,形成的膜甲醇渗透较小,耐甲醇渗透性能较好。     

Impurities especially titanium in the rare earth metal gadolinium— before and after solid state electrotransport

Gadolinium was prepared by conventional procedures of fluorination, reduction, distillation and solid state electrotransport（SSE）. The electronegativities of the metals were found to have an important influence on the electrotransport process and result of the impurity element. Meanwhile, titanium particles in the distilled gadolinium as major metallic impurities were studied by high resolution transmission electron microscopy（HRTEM） before and after solid state electrotransport. The results showed that impurities especially titanium transported from anode to cathode during SSE. In the metal before SSE, there were impurities of titanium in strip shape or embedded round shape. After SSE processing, titanium particles in the metal smaller than 50 nm in the cathode, but existed 6 to 10 times bigger in the anode.     

基于激光剥蚀-电感耦合等离子体质谱法的金属镝棒统计分布分析初探

高效、高灵敏度的原位微区分析技术开发对于固态电迁移等稀土提纯工艺具有重要意义。实验以固态电迁移提纯后金属镝棒为研究对象,将激光剥蚀-电感耦合等离子体质谱法(LA-ICP-MS)应用于高纯稀土金属的微区分布分析。研究了激光剥蚀速率对样品覆盖率和分析时间的影响,确定了剥蚀速率为50μm/s;考察了剥蚀池及ICP-MS载气流量对待测元素信号强度、氧化物产率及元素分馏效应的影响,确定了载气流量分别为0.60L/min(He)和1.0L/min(Ar)。采用线扫描方式,以基体元素~(158)Dy为内标,获得了不同电迁移区域各杂质元素的二维相对强度分布图,初步探究了各杂质元素的迁移规律。结果显示:在电迁移过程中,Al、Si、Ti、Fe、Mo、W元素从阴极向阳极迁移;Ni、Cu元素从中间区域向两极迁移。这一迁移趋势与辉光放电质谱法(GD-MS)分析结果相一致。同时,LA-ICP-MS还得到更丰富的微区统计分布信息。不同电迁移区域各杂质元素最大偏析度、相对标准偏差(RSD)值及最大偏析位置进一步揭示了各元素的迁移状态,可能与固态电迁移工艺相联系。因此,LA-ICPMS有望为稀土金属提纯工艺解析及优化提供一种新的有效分析手段。     

Effect of samarium on microstructure and corrosion resistance of aged as-cast AZ92 magnesium alloy

The effects of samarium（Sm） on microstructure and corrosion resistance of AZ92 magnesium alloy were characterized and analyzed by scanning electronic microscopy, X-ray diffraction, mass loss test, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy and potentio-dynamic polarization test. The results showed that the added Sm could promote continuous precipitation of β-Mg17Al12 phase in grains, and meanwhile restrain discontinuous precipitation of the same phase along the grain boundaries. Thus, the precipitations distributed more uniformly in the aged AZ92 magnesium alloys. When the content of Sm was 0.5 wt.%, the corrosion resistance of aged AZ92 alloy tended to be the best, which was due to the β-phase distributes more homogeneous reducing the galvanic corrosion. The corrosion product film had more integrality and compactness than AZ92 alloys without Sm. However, it resulted in worse corrosion resistance of AZ92 alloy because of the formation of mass cathodic Al2 Sm phase coming from excess Sm in AZ92 alloy.