Evaluation of Photonuclear Reaction Data on Tantalum-181 up to 140MeV

Photonuclear cross sections of ¹⁸¹Ta are evaluated up to an incident photon energy of 140MeV which is the threshold energy for pion production. Re-analyses were performed on the (γ, n) and (γ, 2n) data measured at Saclay and Livermore, and reference data were reconstructed. The absorption cross sections were evaluated with the giant electric dipole resonance (GDR) model below 40MeV. The calculation by the statistical model with preequilibrium correction reproduced the reference data of all the photoneutron cross sections consistently. From 40 to 140 MeV, the quasideuteron model (QDM) was adopted to evaluate photoabsorption cross sections and the results are compared with the measurements. The decaying processes including n, p, d, t, ³He, and α particle emission up to 140MeV were theoretically evaluated by the ALICE-F code.     

Morphological and electrochemical investigation of RuO<Subscript>2</Subscript>–Ta<Subscript>2</Subscript>O<Subscript>5</Subscript> oxide films prepared by the Pechini–Adams method

Preparation methods can profoundly affect the structural and electrochemical properties of electrocatalytic coatings. In this investigation, RuO₂–Ta₂O₅ thin films containing between 10 and 90 at.% Ru were prepared by the Pechini–Adams method. These coatings were electrochemically and physically characterized by cyclic voltammetry, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The composition and morphology of the oxide were investigated before and after accelerated life tests (ALT) by EDX and SEM. SEM results indicate typical mud-flat-cracking morphology for the majority of the films. High resolution SEMs reveal that pure oxide phases exhibit nanoporosity while binary compositions display a very compact structure. EDX analyses reveal considerable amounts of Ru in the coating even after total deactivation. XRD indicated a rutile-type structure for RuO₂ and orthorhombic structure for Ta₂O₅. XPS data demonstrate that the binding energy of Ta is affected by Ru addition in the thin films, but the binding energy of Ru is not likewise influenced by Ta. The stability of the electrodes was evaluated by ALT performed at 750 mA cm⁻² in 80 °C 0.5 mol dm⁻³ H₂SO₄. The performance of electrodes prepared by the Pechini–Adams method is 100% better than that of electrodes prepared by standard thermal decomposition.     

压缩率对钽丝力学性能的影响

研究冷拉拔过程对钽丝室温力学性能的影响及机制,测试了1.28 mm钽丝退火后进行拉拔后各道次的硬态室温抗拉强度、延伸率、硬度等性能指标,以期对选择加工态钽丝的压缩率进行指导。试验表明,钽丝在冷加工时加工硬化效应明显,随着总压缩率的增大,强度指标呈线性上升,延伸率急剧下降。当总压缩率增加到85%时,抗拉强度增加约为65%;当总压缩率增至15%后,延伸率下降趋势急剧减缓,当总压缩率增至60%后,延伸率基本维持在0.5%。研究表明,增加加工变形程度是提高钽丝的强度及延性的主要途径,丝径越细,强度越高。     

钽-铜-不锈钢复合板设备的制造

根据钽材的特性,分析了钽-铜-不锈钢复合板设备的制造难点和控制要点,简述了钽-铜-不锈钢复合板设备相关零部件的加工方法及钽材的焊接注意要点。制造的设备投用后运行正常,满足相关要求。     

钽粉制备新工艺研究进展

文章评述了几种由氧化钽还原制取钽粉的新工艺,并阐述了不同方法的工艺原理、特点和产品特性.同时指出了不同方法生产钽粉的应用方向.     

Easily accessible oxygen‐containing derivatives of niobium pentachloride as catalytic precursors for ethylene polymerization

The low catalytic activity of NbCl₅ as an ethylene polymerization catalyst was significantly increased by the addition of a series of oxygen donors. The novel niobium derivatives NbCl₅(OPh₂) (1), NbCl₅(OEt₂) (3), NbCl₅(O?CPh₂) (5), NbCl₅(O?CHPh) (6), NbCl₅(O?CHMe) (7) and [NbCl₄(dppe)₂](NbCl₆) (18) (dppe is 1,2‐bis(diphenylphosphino)ethane) and the previously reported derivatives NbCl₅(OMePh) (2), NbCl₅(thf) (4) (thf is tetrahydrofuran), NbCl₅(O?CHOMe) (8), NbCl₅(O?CHNMe₂) (9), NbCl₅[O?C(NMe₂)₂] (10), NbCl₅(NCMe) (11), NbCl₄(κ²‐1,2‐OC₆H₄OMe) (12), NbCl₄[κ²‐O?C(Me)CH₂C(Me₂)O] (13), (14), [NbCl₄(O₂CMe)]₂ (15), NbCl₃(dme)(µ‐O)NbCl₅ (16) (dme is 1,2‐dimethoxyethane), [NbCl₄(κ²‐dmm)₂](NbCl₆) (17) (dmm is dimethylmaleate), TaCl₅(O?CMe₂) (19) and [TaCl₄(O₂CMe)]₂ (20) were tested as catalytic precursors in the ethylene polymerization reaction using AlMe₃‐depleted methylaluminoxane as co‐catalyst. Highly linear polyethylene was obtained. Compounds 1, 3, 5, 6 and 8–13 showed catalytic activities in the range 89–116 kg_polymer mol_Nb^?1 h^?1 bar^?1, i.e. comparable with the best performances reached with niobium pre‐catalysts up to now. However, the dinuclear compounds 14–16 and 18 were found to be less active, whereas17 and the tantalum derivatives 19 and 20 did not produce polymer. Relatively high molecular weights were achieved with the mononuclear compounds 1, 2, 8, 9, 10 and 12, the dinuclear 16 and the phosphine ionic 18. Copyright © 2011 Society of Chemical Industry     

钨钽铌粗精矿碱分解液萃取试验研究

低品位钨钽铌粗精矿碱分解液的碱性萃取清洁生产工艺有着较好的产业前景。研究了影响钨萃取效果的萃取剂浓度、极性改质剂浓度、振荡时间、振荡温度等因素。试验采用N263萃取方法分离富集钨,在料液[OH-]浓度为44.1 g·L-1,WO3浓度为132.43 g·L-1,温度为25℃,振荡时间8 min,萃取有机相组成为62%N263(500 g·L-1)+15%仲辛醇+23%磺化煤油,相比O/A=2/1的条件下,测得有机相中WO3饱和容量为122.63 g·L-1。在此条件下,经过4级逆流萃取后,萃余液中WO3浓度可降至0.35 g·L-1以下,钨萃取率达到99.7%以上。     

医用钽丝生产工艺研究

介绍医用钽丝的坯料提纯方法和生产工艺。采用冶金级钽粉经三次熔炼锭坯、电子轰击一次锭坯和二次熔炼锭坯3种方法提纯坯料。给出钽丝生产过程控制要点:(1)压缩率控制在12%¹5%;(2)热处理温度控制在80015%;(2)热处理温度控制在800¹ 100℃;(3)拉拔过程保持模具完全浸泡在润滑油中,防止温度过高产生表面增氧、增碳。经比对可知,采用二次高真空电子束熔炼得到的高纯钽坯制得的医用钽丝纯度可达99.99%,产品延伸率达20.9%,生物相容性较好,广泛应用于医疗领域。     

Blast and tensile properties of tantalum/niobium lined SiC/SiC composite tubes for nuclear cladding

The mechanical performances such as tensile strength and blast property of metal lined SiC/SiC composite cladding tubes were investigated. Nb or Ta was selected as liner material, and the SiC/SiC composite layer was fabricated by winding and different precursor impregnation and pyrolysis (PIP) processes. The tensile strengths of different tube samples were measured at room temperature (RT) and 1200 °C, respectively. The blast property was investigated through the maximum water pressure of tubes. And the fracture microstructures were observed by SEM. The highest tensile strength at RT was 150.7 MPa. The blast strength was enhanced with the PIP process increasing from 1 to 4 cycles and the tube of 4 PIP cycles had the highest water pressure of 34.7 MPa. Compared with the metal tubes, the multi-layer structure improved tensile and blast properties significantly. The different processes such as PIP cycles and pyrolytic carbon (PyC) coating were important factors to enhance the mechanical performances of SiC/SiC-based tubes. However, the retention rate of tensile strength was only 18.5% at 1200 °C.     

一种新型片式固体钽电容器成型粘合剂的研究

新研究出的EOX粘合剂,可取消片式固体钽电容器生产过程的预焙烧工序,并使每批产品生产周期缩短10-12h,可节约电耗、物耗、劳动力消耗;EOX粘合剂的脱除原理简单,其作为杂质蒸发脱除。EOX作粘合剂使用可将产品的漏电流降低50％,60％,提高了产品质量。并随着钽阳极基体结构和内应力的改善,片式固体钽电解电容器的电性能亦得到改善。