18-冠-6/LA/Fe3O4复合磁性纳米粒子的制备及其吸附性能研究

Fe₃O₄磁性纳米粒子（MNPs）比表面积大、吸附能力强,且在外磁场作用下易于液固分离,冠醚具有对铀酰离子选择性配位的能力。本研究制备了兼具两者特点和优势的18-冠-6/LA/Fe₃O₄复合磁性纳米粒子。其结构经红外（IR）、扫描电镜-X射线能谱（SEX/EDX）、振动样品磁强计（VSM）、热综合分析仪（TGA）进行表征,表明18-冠-6/LA/Fe₃O₄复合磁性纳米粒子的粒径为12～23 nm,饱和磁化强度为56.34 emu/g。用制得的复合磁性纳米粒子对溶液中铀酰离子进行初步吸附实验,在选定的条件下,平衡吸附率达95%,操作方法快速简便,吸附后的磁粒子可方便地进行富集和回收。     

Quantitative analysis of the main components in ceramic raw materials based on the desktop LIBS analyzer

The concentrations of SiO₂, Al₂O₃, K2O, Na₂O, CaO, MgO, Fe₂O₃ and TiO₂, and loss on ignition (L.O.I.) are the main inorganic components of geological samples. Concentrations of the eight oxides and L.O.I. are also the main indicators of concern in the production of building ceramics. Quantitative analysis of the eight oxides and L.O.I. was performed using fiber-laser-based laser-induced breakdown spectroscopy (LIBS). A combination of continuous background deduction, full width at half maximum (FWHM) intensity integral and spectral sum normalization was proposed for data processing. After the data processing combined the continuous background deduction, FWHM intensity integral and spectral sum normalization, the mean absolute errors (MAEs) of the calibration of L.O.I., SiO₂, Al₂O₃, K2O, Na₂O, CaO, MgO, Fe₂O3 and TiO₂ was reduced from 2.03%, 12.06%, 4.84%, 1.10%, 0.69%, 0.31%, 0.11%, 0.20% and 0.10% to 1.80%, 9.48%, 2.12%, 0.36%, 0.58%, 0.11%, 0.08%, 0.19% and 0.05%, respectively. This multivariate method was further introduced and discussed to improve the analysis performance. The MAEs of L.O.I., SiO₂, Al₂O₃, K₂O and Na₂O were further reduced to 1.12%, 2.07%, 1.38%, 0.35% and 0.43%, respectively. The results show that the overall prediction error can meet the requirements for the production of building ceramics. The LIBS desktop analyzer has great potential in detection applications on geological samples.     

Fe-Al/Al2O3涂层表面氧化膜的掠入射X射线衍射研究

本文采用掠入射X射线衍射（GXRD）α-2θ扫描模式,进行了掠入射角α为0.1°～5°范围内Fe-Al/Al₂O₃阻氚涂层表面氧化膜的X射线衍射实验。结果表明,随α的增加,表面氧化膜中Al₂O₃相与Fe₃Al相对应的衍射峰强度绝对值增强;α的增加加深了分析区域的深度,引起Al₂O₃相的相对含量下降,导致Al₂O₃相对衍射峰强度降低。对Fe-Al/ Al₂O₃涂层表面氧化膜的掠入射X射线衍射而言,较佳的掠入射角是0.25°,此时对应Al₂O₃相的衍射峰相对强度最高。经比对PDF卡片,表面氧化膜相结构为暂态γ-Al₂O₃（200）。在此基础上建立了GXRD分析Fe-Al/ Al₂O₃涂层表面亚微米氧化膜的相结构组成的快速无损检测方法。     

阻氚用Fe-Al渗铝层表面稳态相Al2O3膜生长机理研究

为阐释Fe-Al渗铝层表面暂态相Al₂O₃膜向稳态相α-Al₂O₃膜的转变机理，探索稳态相α-Al₂O₃膜制备的氧化工艺参数范围，采用掠入射角X射线衍射仪、辉光放电光谱仪、聚焦离子束、透射电镜等，结合热重分析对CLAM钢基体Fe-Al渗铝层在940～980 ℃、1 Pa～20 kPa参数下的氧化生长行为进行了深入表征与机理分析。研究结果表明，在1 Pa～20 kPa氧分压范围内Al₂O₃膜生长初期反应速率常数随着氧分压的升高而增大，而后期反应速率常数反而随之下降；采用掠入射角X射线衍射仪对3～180 min氧化不同时期表面Al₂O₃膜的相结构进行了掠入射角分析，推测Al2O3膜的生长经历了从氧化初期形成暂态相γ-Al₂O₃（15 min）→过渡态相α-（Al_0.948Cr_0.052）₂O₃（30 min）→稳态相α-Al₂O₃（120～180 min）的演变过程，最短相转变时间约60～90 min，连续Al₂O₃膜厚度约2 000 nm；同时，结合聚焦离子束对30、120 min形成的Al₂O₃膜表面进行了精确定向切割制样，并采用透射电镜选区电子衍射分析验证了相转变前Al₂O₃膜结构为过渡态相α-（Al_0.948Cr_0.052）₂O₃（113），转变后为稳态相α-Al₂O₃（113），证实了Cr作为第三组元促进暂态相向稳态相α-Al₂O₃的转变规律。     

Investigation of Stable Al2O3 Scale on Fe-Al Aluminized Coating for Tritium Barrier

It is well known that α-Al₂O₃ phase has stablility performance, high permeation reduction factor and good resistance performance in liquid LiPb, which is considered as the reference tritium barrier coating in future fusion reactor. In order to study the formation mechanism of stable α-Al₂O₃ scales on fusion structure material, the oxidation behavior of Fe-Al aluminized coating on China Low Activated Martensitic （CLAM） steel was investigated under the oxygen partial pressure from 1 Pa to 20 kPa at the temperature of 940-980 ℃. The Al₂O₃ scales were analyzed by thermogravimetric analysis meter, grazing angle X-ray diffractometer, glow discharge spectrometer, focused ion beam and transmission electron microscope. A single continuous Al₂O₃ scales with the maximum thickness of about 2 000 nm was formed on the diffusion Fe-Al aluminized layer. Thermogravimetric analysis results show that the higher oxidation rate constant is achieved while increasing the oxygen partial pressure, and then oxidation rate constant decreases. The phase transformation of Al₂O₃ scales on the surface of Fe-Al aluminized coating was studied during different oxidation time ranges from 3 min to 180 min. The metastable γ-Al₂O₃ and α-（Al0.948Cr0.052）₂O₃ phases is formed in the earlier oxidation process and finally transformed to stable α-Al₂O₃ phase. The features of the transient α-（Al0.948Cr0.052）₂O₃（113） and α-Al₂O₃（113） were detected by GXRD and then confirmed by focused ion beam and transmission electron microscope.     

磁性MOFs材料Fe3O4@SiO2@UiO-66-SO3H对Co(Ⅱ)的吸附性能

通过水热法制备了磁性MOFs材料Fe₃O₄@SiO₂@UiO-66-SO₃H,并利用红外光谱仪（FT-IR）、X射线衍射仪（XRD）、比表面积测试（BET）、振动样品磁强计（VSM）、X射线光电子能谱仪（XPS）等对材料结构、形貌和性能进行表征。考察了溶液pH值、时间、温度、Co(Ⅱ)初始浓度对Fe₃O₄@SiO₂@UiO-66-SO₃H吸附性能的影响。结果表明,在pH=8.3、温度为298 K下,Fe₃O₄@SiO₂@UiO-66-SO₃H对Co(Ⅱ)的理论最大吸附量为106 mg/g;吸附过程符合准二级动力学模型和Langmuir等温模型,吸附是一个自发的吸热过程。Fe₃O₄@SiO₂@UiO-66-SO₃H在外加磁场下易从水溶液中分离,5次循环后仍具有较强的吸附性能。     

316NG不锈钢在硼-锂溶液中的电化学腐蚀行为研究

利用电化学方法获得316NG不锈钢（316NG）在300℃、pH=5~8硼-锂溶液中的极化曲线和交流阻抗（EIS），并绘制相应水化学条件下的电位-pH图。结果表明:碱性条件下钝化区尤其是二次钝化区极化电流急剧减小，pH=7~8时阳极极化表现出3次钝化现象，偏碱性条件极化阻抗显著高于偏酸性和近中性条件，说明碱性条件下316NG表面钝化膜保护效果更佳。pH=5时电化学极化后样品表面主要生成Cr₂O₃和Fe₂O₃；碱性条件下（pH=6~8）样品表面氧化膜为分层结构:最外层为Fe₃O₄，随深度增加开始出现NiFe₂O₄，内层成分主要为FeCr₂O₄。随着电导率升高，溶液电阻、电荷传递电阻和钝化膜电阻均显著降低。依据极化曲线绘制的电位-pH图与文献结果相吻合。      

AP1000一回路氧化膜特性研究

AP1000与一般压水堆不同的是其一回路采用注锌加氢技术,使其一回路氧化膜特性发生变化。试验在高压釜中模拟AP1000一回路水化学工况,研究F304L、F316、690三种反应堆主工艺设备材料表面生成的氧化膜特性。结果表明,氧化膜为双层结构,外层氧化膜成分主要是Fe₂O₃及Fe₃O₄。F304L不锈钢与F316不锈钢内层氧化膜主要是ZnCr₂O₄,注入的Zn元素取代了FeCr₂O₄中的铁元素,形成了致密的ZnCr₂O₄ 氧化层,内层氧化膜存在少量ZnO和ZnFe₂O₄。690合金的氧化膜内层为ZnCr₂O₄,同时存在较高含量的ZnO和ZnFe₂O₄。与前两者不同的是,690合金的氧化膜含少量的二价镍,以NiFe₂O₄和NiCr₂O₄形式存在。加锌加氢使得氧化膜更加致密,也明显变薄。     

Formation mechanism of Al_2O_3/MoS_2 nanocomposite coating by plasma electrolytic oxidation(PEO)

In this study, an Al_2O_3/MoS_2 nanocomposite coating was created on an aluminum 1050 substrate using the plasma electrolytic oxidation method. The zeta potential measurements showed that small MoS_2 particles have negative potential and move toward the anode electrode.The nanoparticles of MoS_2 were found to have a zeta potential of-25 mV, which prevents suspension in the solution. Thus, to produce an Al_2O_3/MoS_2 nanocomposite, one has to use the microparticles of MoS_2. The X-ray diffraction analyses showed that the produced coatings contained α-Al_2O_3, γ-Al_2O_3, and MoS_2, and that the size of MoS_2 particles can be reduced to 30 nm. It was observed that prolonged suspension in the electrolyte results in an enhanced formation of an Al_2O_3/MoS_2 nanocomposite. Using the results, it was hypothesized that the mechanism of the formation of the Al_2O_3/MoS_2 nanocomposite coating on the aluminum 1050 substrate is based on electrical energy discharge.     

磁性富羧基碳复合材料的制备及对Pb(Ⅱ)、Ni(Ⅱ)、Hg(Ⅱ)和U(Ⅵ)的吸附

采用溶剂热法制备了富羧基碳,随后通过化学共沉淀法合成了磁性富羧基碳复合材料。利用透射电子显微镜(TEM)、红外光谱分析(FTIR)、X射线衍射(XRD)、振动样品磁强计(VSM)、热重差热分析(TGA)、zeta电位分析及比表面积(BET)等手段对磁性富羧基碳的形貌、组成、结构、磁性以及表面电荷特性等进行了表征,并考察了富羧基碳和磁性富羧基碳对Pb(Ⅱ)、Ni(Ⅱ)、Hg(Ⅱ)和U(Ⅵ)的吸附性能。结果表明:富羧基碳经磁性改性后表面负载了铁氧化物纳米颗粒,比表面积由29.2m2/g提高到45.4m2/g,热稳定性提高,由磁滞回线可知,磁性富羧基碳的饱和磁化强度为30.68A.m2/kg。Pb(Ⅱ)、Ni(Ⅱ)、Hg(Ⅱ)和U(Ⅵ)在磁性富羧基碳上的平衡吸附容量分别为477.50、23.50、260.20、54.86mg/g,低于富羧基碳,吸附等温线符合Langmuir等温模型。从磁性富羧基碳对Pb(Ⅱ)、Ni(Ⅱ)、Hg(Ⅱ)和U(Ⅵ)均具有较高的吸附容量和不同吸附剂对U(Ⅵ)吸附容量的比较可以看出,该吸附剂是重金属污水和放射性废液处理领域中极具发展前景的吸附材料。     

FCM燃料压水堆弥散可燃毒物中子学分析

为将全陶瓷微胶囊封装（FCM）燃料应用于小型压水堆，对FCM燃料组件开展了可燃毒物中子学设计与分析。通过寿期初引入负反应性、寿期内消耗速率和寿期末残留3个方面，对弥散在SiC基体中的弥散型可燃毒物Gd₂O₃、Er₂O₃、Sm₂O₃、Eu₂O₃、Dy₂O₃及HfO₂进行评价。FCM燃料中TRISO颗粒核芯直径达800 μm，燃料颗粒自屏效应强烈，在RMC程序中引入随机介质计算功能，对FCM燃料进行随机几何建模，保证了反应性计算精度。分析表明：Er₂O₃可作为FCM燃料堆芯的候选可燃毒物，Gd₂O₃和Eu₂O₃需结合堆芯开展进一步研究，Sm₂O₃、Dy₂O₃及HfO₂的反应性惩罚过大，不适合作为FCM燃料可燃毒物。     

IVR中熔融堆芯被牺牲性材料稀释后的传热计算

应用牺牲性材料的堆芯熔融物稀释方案是先进轻水堆中一种新型的严重事故缓解措施。严重事故发生时,掉落的堆芯熔融物被氧化物牺牲性材料（OSM）稀释,导致熔池结构发生翻转,因此计算翻转后熔融池的传热行为是进行牺牲性材料筛选和评价稀释方案可行性的重要研究内容。本文计算了容器内滞留（IVR）中熔融堆芯被Fe₃O₄、TiO₂和Al₂O₃3种候选OSM稀释后压力容器壁面的热流密度分布。研究发现,布置OSM后,上腔室结构在强烈热辐射的作用下会熔化掉落。随着OSM布置量的增大,压力容器壁面最大热流密度减小,当布置15 m³的OSM时,压力容器伸长约2 m,此时壁面最大热流密度较未布置时减小约45%,且当布置相同体积的OSM时,Fe₃O₄导致的壁面最大热流密度减小最多。此外,UO₂-ZrO₂-OSM三元混合物的熔点高低会对氧化物层表面是否结壳产生影响,从而影响壁面最大热流密度。     

堆芯熔融物被牺牲性材料稀释后的热物性计算

在压力容器内滞留熔融堆芯的过程中,应用牺牲性材料的堆芯熔融物稀释方案是先进轻水堆中一种新型的严重事故缓解措施。当堆芯熔融物被牺牲性材料稀释后,会形成三元或三元以上的熔融混合物。计算多元熔融混合物的热物性是进行牺牲性材料筛选、传热计算和评价稀释方案可行性的重要前提。本文比较了Fe₃O₄、TiO₂和Al₂O₃-3种候选氧化物牺牲性材料（OSM）的基本物性,并计算了熔融三元UO₂-ZrO₂-OSM混合物的密度、比热容、热导率和黏度。研究发现,为保证熔融结构发生翻转,需布置的Fe₃O₄材料的质量较大,而TiO₂和Al₂O₃材料的质量较小。混合物的比热容和热导率随着OSM添加量的增加而增大,而黏度随OSM添加量的增加而减小。混合物熔点T_c越小,在相同温度下混合物的黏性也越小。     

含铝奥氏体耐热钢在超临界二氧化碳中的腐蚀行为

研究了20Cr-25Ni合金和一种新型结构材料含铝的奥氏体耐热钢（AFA钢）在600℃/20 MPa的超临界二氧化碳（S-CO₂）环境中的腐蚀行为,并对2种合金的氧化膜形貌、成分和结构进行分析。研究发现,20Cr-25Ni合金出现明显的腐蚀增重增长趋势,表现出“抛物线”上升规律;AFA钢腐蚀增重趋势缓慢,腐蚀1000 h后仅为2.11 mg/dm2。20Cr-25Ni合金表面出现粗大的氧化产物,随腐蚀时间延长,AFA钢的氧化膜始终保持致密、连续。通过氧化膜的截面形貌分析发现,20Cr-25Ni合金腐蚀后具有两层氧化膜结构,主要由Fe₃O₄和FeCr₂O₄氧化层以及少量尖晶石组成。而AFA钢中出现了3层氧化膜结构,中间和最内层分别为Cr₂O₃和Al₂O₃氧化膜,最外层分布了一层不连续的FeCr₂O₄尖晶石氧化物。由于形成了致密的Al₂O₃氧化膜,AFA钢的抗腐蚀性能大幅提升。      

Electronic structure of In_2O_3 nanowires synthesized at low temperature

In₂O₃ nanowires with uniform morphology and single crystalline structure were synthesized at low temperature of 400℃⁴50℃using InSb as the precursor via VLS mechanism.The nanowires have uniform diameter of about 40 nm and are up to tens of micrometres in length and grew along the[100]direction as established by high resolution electron microscopy.The electronic and local structures of ln203 nanowires,compared to that of In203 powder,have been studied with X-ray absorption fine structure（XAFS） at In K-edge and O K-edge.The XAFS results reveal the stronger In-O bonding in In₂O₃ nanowires compared to bulk In₂O₃.     

低活化马氏体钢在ITER水环境中的腐蚀性能研究

低活化马氏体钢作为聚变堆候选的结构材料，其腐蚀性能影响冷却回路辐射场的分布。本文选取CLAM、CNS-1和SCRAM-9 3种钢材，并用T91与3种钢材进行对比，分析4种材料的性能。整个实验回路温度维持在150 ℃，溶氧量小于0.01 mg/kg，pH值为7（20 ℃），电导率小于1 μS/cm，压力为1 MPa，水的流速设为6 m/s。实验后，所有样品均采用失重分析法、XRD、EDS及SEM分析。结果显示，随着时间的增加，材料的失重量增加，腐蚀速率减少。4种材料的失重量均遵循幂函数规律，T91钢的耐腐蚀性较另3种钢好，而3种材料中CLAM的抗腐蚀性能相对更好；样品表面氧化层变得越来越致密且非常薄。氧化层腐蚀产物主要是Fe₂O₃和Fe₃O₄。     

Al_2O_3纯化闪烁液过程中的放射性污染

Al_2O_3可用于纯化闪烁液,但在纯化过程中有可能引入放射性污染。本工作对Al_2O_3纯化闪烁液过程中氡及Al_2O_3本身放射性对闪烁液的污染问题进行了研究。研究结果表明:通过Al_2O_3与闪烁液的混合澄清实验,发现若有细小Al_2O_3颗粒悬浮于闪烁液中会对闪烁液产生污染。但经过滤实验,发现过滤纯化闪烁液过程中的放射性污染主要来源于环境空气中氡的溶解,Al_2O_3过滤柱能阻挡绝大部分Al_2O_3中的放射性核素随着极细颗粒进入闪烁液。排除氡的影响后,在标准偏差范围内,未过滤与经Al_2O_3过滤后的闪烁液的放射性计数率无明显变化,说明Al_2O_3样品中的放射性对闪烁液的影响已低于液闪的探测灵敏度。     

60Fe Sample Preparation and Extraction Method for Measurement with Accelerator Mass Spectrometry

⁶⁰Fe can be used in the study of the outbreak of supernova, the synthesis of celestial bodies in nuclear astrophysics, as well as the metabolism of iron in the organism as a tracer. As the neutron activation production of the reactor, ⁶⁰Fe also plays an important role for nuclear facilities and nuclear safety. In accelerator mass spectrometer, the large negative ion beam and the suppression of isotope⁶⁰Ni are the key steps to improve the measurement sensitivity of⁶⁰Fe. In this work, the process of sample preparation and beam extraction were tested. The beam intensity, suppression of⁶⁰Ni , the relationship between the electron affinity and beam current, the choice of conductive medium, and the problems found in the test process were discussed. The series of experiments showed that the sample chemical form of Fe₂O₃, the ion extraction form of FeO^-, and the conducting medium of Ag powder were the best choices for⁶⁰Fe AMS measurement.     

Interface mixing induced by swift heavy ions at metal-oxide/silicon interfaces

It was observed previously that ceramic/ceramic bilayers were very sensitive with respect to the electronic stopping power S_e, i.e. strong interface mixing, scaling with , occurred if a threshold S_ec was exceeded. The threshold seemed to be determined by the higher track formation threshold of two constituents forming the bilayer. Although no track formation has been observed in crystalline Si even for Uranium projectiles, interface mixing was observed previously for some Si-multilayers.

In this paper we report on the interface mixing of NiO, Fe₂O₃, TiO₂ on Si due to irradiation with 90–350 MeV Ar-, Kr-, Xe- and Au-ions at 80 K at fluences up to 9E15 ions/cm². Interface mixing, analyzed by means of Rutherford Backscattering Spectrometry (RBS), is found for these bilayers, too. But the threshold for intermixing is significantly higher compared to the ceramic/ceramic bilayers. This observation could be an evidence for the threshold being determined by the Si-layer. In contrast to NiO/Si and Fe₂O₃/Si, where an usual random walk mixing Δσ² = kΦ was observed, the interface broadening Δσ² for TiO₂/Si is found to scale nonlinearly with the ion fluence, which indicates that mixing is driven by a chemical solid-state reaction. At higher fluences plateaus form at the low energy Ni-edge of the RBS spectra. The plateaus indicate phase formation. X-Ray diffraction spectra does not show any evidence for new crystalline phases.     

Investigation of metal matrix systems for cosmogenic Al analysis by accelerator mass spectrometry

We report experiments designed to help optimize accelerator mass spectrometry (AMS) of ²⁶Al (in the form of Al₂O₃) for geochronologic and geomorphologic applications. Analysis times are long and the precision of AMS are restricted by counting statistics for ²⁶Al, which are in turn limited by the intensity of Al⁻ beam currents. We show that ion beam currents are affected by the metal matrix in which Al₂O₃ is dispersed, by the matrix-to-Al₂O₃ mixing ratio, and for at least some matrices, such as Ag, by the depth to which the sample is packed in the AMS cathode. Typical instantaneous Al⁺⁷ currents (μA) produced by the LLNL CAMS Cs sputter ion source and measured in a Faraday cup after the accelerator are 2.26 for samples in Ag, 2.17 in Re, 2.00 in Nb, 1.92 in V and 1.73 in Mo. The AMS counting efficiency (Al⁻ ions detected per Al atom loaded in the target) for a constant analysis time (900 s) and for equimolar mixtures of Al₂O₃ and matrix is in the range of 6 × 10⁻⁵–9 × 10⁻⁵ in the order Ag > Re > Nb > V > Mo. Additionally, we observed a correlation between the ion detection efficiency (Al ions detected per Al atoms loaded) and the matrix work function and inverse vaporization enthalpy of the matrix and beam current. Typical currents (μA) obtained with elemental Al are 13.3 for samples in no matrix, 3.23 in V, 3.14 in Nb, 3.07 in Re, 2.85 in Mo, 1.46 in Ag. The ion detection efficiency for elemental Al correlates strongly with matrix electron affinity. Thus, our data indicate that the current practice of mixing Al₂O₃ with Ag is reasonable until a means is found to produce cathodes of elemental Al.