穆斯堡尔谱测量的多丝正比室探测器

穆斯堡尔谱的测量通常有透射法和背散射法,使用的探测器有闪烁计数器和正比计数器等。如常用~(57)Co作穆斯堡尔源时,透射法是用闪烁计数器或正比计数器测量无反冲吸收后被吸收体~957)Fe核放出的X射线。背散射法是用正比计数器,可测量放出的K壳层X射线或内转换电子,测量背散射穆斯堡尔谱是研究固体表面物理性能的有用方法,近几年来发展很快,应用在簿膜的结构和性质的研究,表面化学和冶金、扩散、腐蚀和离子注入等诸方面的研究。     

带有透射窗的背散射式探测器

本文提出了用于~(57)Fe穆斯堡尔谱测量的带有透射窗的高分辨、背散射式探测器的设计,用它可测内转换电子或6.3keV的转换X射线。探测器对6.3keV X射线的能量分辨率是18％,对14.4keV的γ光子能量分辨率是13％,并且对较低能量粒子呈现出更高的检测效率。 这种在样品盒内设置透射铍窗的探测器结构非常适于组成双通道穆斯堡尔谱仪,有利于同时进行吸收谱与背散射谱的测量。     

双通道穆斯堡尔谱仪的两种接法

使用双通道穆斯堡尔谱仪同时测得两个穆斯堡尔谱是提高工作效率的一种有效途径。如果在通常的单通道穆斯堡尔谱仪的驱动器两端各加一个放射源,用两个探测器分别测取两个样品的穆斯堡尔谱,同时存储于一台多道分析器中,则组成了所说的双通道穆斯堡尔谱仪。如果使用带有透射窗的背散射探测器,使用一个放射源就可组成另一种形式的双通道穆斯堡尔谱仪,且有利于吸收谱与背散射谱同时测量。可见,把单通道穆斯堡尔谱仪改装     

低合金钢在人造海水中腐蚀过程的穆斯堡尔谱学研究

钢铁的腐蚀是一个严重的普遍现象,因此人们研究其发生原因和防护具有十分重要的意义。而穆斯堡尔谱学是新发展起来的对腐蚀产物进行定性、定量相分析的重要工具。本工作测量了低合金钢样在实验室人造海水中,二个月内不同腐蚀阶段,不同层锈层的CEMs、X射线散射谱及变温的透射穆斯堡尔谱,并与同钢样在实际海域经腐蚀后的锈层谱进行比较。结果表明:腐蚀一开始钢样表层即生成粒度很小的铁氧氢氧化物(FeOOH),     

用离子注入法制备~(57)Fe穆斯堡尔样品

~(57)Fe是在常温下就能测量穆斯堡尔谱的最常用和方便的同位素之一。应用同位素分离器把~(57)Fe同位素注入待测样品,然后测量样品中~(57)Fe受激发后的内转换电子(或X,γ射线)的穆斯堡尔谱,这是近年来己发展起来的一种新的穆斯堡尔实验技术。由于它可以对不含有穆斯堡尔核素的样品进行所需穆斯堡尔核素的离子注入,并可对样品进行非破坏性测量,从而扩大了穆斯堡尔效应的应用范围。     

穆斯堡尔谱、X射线波长色散谱和X射线衍射技术联合研究乙苯脱氢铁催化剂

本工作用穆斯堡尔谱(MS)、X射线波长色散谱(WDS)及X射线衍射(XRD)联合观察了一种以钾铬为助剂的乙苯脱氢铁催化剂。 新制备的铁催化剂的穆斯堡尔谱如图EB。它是由多组六线磁分裂谱叠加而成的复杂谱。它与已知的部分倒置尖晶石的穆斯堡尔谱十分相似。研究还表明,Cr很可能处于Fe八面体的近邻A位。     

背射式穆斯堡尔谱仪用的β共振探测器

本文叙述了背射式穆斯堡尔谱仪用的β共振探测器的工作原理、特点、结构和它的性能,通过实测得到了不锈钢、铁板、α铁的穆斯堡尔背散射谱。     

非晶Fe-Zr-B薄膜穆斯堡尔谱学研究

用X射线衍射分析、X射线光电子能谱(XPS)和穆斯堡尔谱学研究了直流磁控溅射法制备的Fe-Zr-B薄膜。X射线衍射分析结果表明制备态的薄膜是非晶的;X射线光电子能谱(XPS)结果表明样品表面氧化较明显,深层部分Fe, Zr, B结合占主导地位;穆斯堡尔谱学结果表明薄膜中Fe原子周围Zr、B原子的存在使Fe原子核内场值有所下降并导致超精细场分布P(H)出现双峰结构,薄膜中存在两种不同的局域微结构。     

穆斯堡尔效应应用的一些已有探索

发现穆斯堡尔效应已有二十几年历史。目前,穆斯堡尔效应已发展为在物理学、化学、生物医学、地质学、冶金学和磁学等方面获得广泛应用的穆斯堡尔谱学。穆斯堡尔谱学已是一门非常成熟的谱学技术。本文简要地回顾几种非常规的谱学方面的应用,着重讨论了γ射线激光器和利用同步光源的穆斯堡尔效应实验,分析了它     

一种直接测量穆斯堡尔谱小能量移位和弱线的方法

本文描述了一种利用穆斯堡尔色散结合共振过滤的简易方法,直接测量穆斯堡尔谱小能量移位和弱线成份。用不同厚度的吸收体作吸收补偿,可从穆斯堡尔色散谱中直接测得较精确的谱线小能量移位(可小至0.01mm/s)和从强的背景谱中直接分离出弱相的谱线(小于5％的相成分)。这种方法适宜于辐照样品、非化学计量的化合物、组分不同或有少量杂质的合金和腐蚀样品的穆斯堡尔测量。     

铀表面脉冲偏压MSIP铝镀层的电化学腐蚀行为

采用脉冲偏压磁控溅射离子镀（MSIP）技术在贫铀表面制备铝镀层,利用电化学测试技术、扫描电镜（SEM）及X射线能谱（EDS）对铝镀层在50μg/gCl－水溶液中的电化学腐蚀行为进行研究。结果表明：铝镀层的腐蚀电位－534.8mV高于贫铀的腐蚀电位－641.2mV,它对贫铀是一种阴极性镀层;镀铝贫铀样品的极化电阻和电化学阻抗幅值远大于贫铀,腐蚀电流远小于贫铀,铝镀层对贫铀基体具有良好的防腐蚀性能;镀铝贫铀样品的腐蚀特征为局部腐蚀,并出现镀层破裂、剥落,抗腐蚀性能变差;铝/铀界面伪扩散层具有一定的抗腐蚀能力。     

Fission product behaviour and graphite corrosion under accident conditions in the HTR

This paper primarily gives an overview of methods and data in source term estimations for the HTR with pebble bed core. For medium size HTRs the risk dominating accidents are tied to core heat-up events, where a significant portion of the fission product inventory may be released from the coated fuel particles. Here the research mainly is focused on temperature-induced coated particle failure and the interaction of metallic fission products with the core graphite. For small HTRs, with their limitation of maximum temperatures below coated particle failure limits, core heat-up accidents virtually play no role with respect to source terms. Here the risk is dominated by accidents like water ingress or rapid depressurization which may lead to a partial release of fission products accumulated on primary circuit surfaces like the steam reformer. Deposition of fission products and remobilization under the conditions mentioned above are predominant research areas. It can be expected that the ongoing and planned improvements of models and data base, in particular for the medium size HTR, will result in a further reduction of the already low source terms.A principal possibility for core degradation and hence destruction of fission product barriers is graphite corrosion caused by massive air ingress. The research effort in this field as well as for graphite corrosion during water ingress accidents is described in Part B of this paper. From the viewpoint of risk for this type of accident no significant contribution to that of present reactor concepts was found.     

Corrosion-resistant coating technique for oxide-dispersion-strengthened ferritic/martensitic steel

Oxide-dispersion-strengthened (ODS) steels are attractive materials for application as fuel cladding in fast reactors and first-wall material of fusion blanket. Recent studies have focused more on high-chromium ferritic (12–18 wt% Cr) ODS steels with attractive corrosion resistance properties. However, they have poor material workability, require complicated heat treatments for recrystallization, and possess anisotropic microstructures and mechanical properties. On the other hand, low-chromium ferritic/martensitic (8–9 wt% Cr) ODS steels have no such limitations; nonetheless, they have poor corrosion resistance properties. In our work, we developed a corrosion-resistant coating technique for a low-chromium ferritic/martensitic ODS steel. The ODS steel was coated with the 304 or 430 stainless steel, which has better corrosion resistances than the low-chromium ferritic/martensitic ODS steels. The 304 or 430 stainless steel was coated by changing the canning material from mild steel to stainless steel in the conventional material processing procedure for ODS steels. Microstructural observations and micro-hardness tests proved that the stainless steels were successfully coated without causing a deterioration in the mechanical property of the low-chromium ferritic/martensitic ODS steel.     

TBM testing in ITER: Requirements for the development of predictive tools to describe corrosion-related phenomena in HCLL blankets towards DEMO

Compatibility testing of RAFM-steels in Pb–15.7Li environment has shown that liquid metal corrosion is always present and dissolution of steel elements in hot areas of non-isothermal systems takes place whereas a transport of the corrosion products and formed precipitates has to be considered in the TBM design.It is clear that for the design of a HCLL breeding blanket system for DEMO and to ensure the safety over a fusion power plant lifetime, a good knowledge of the corrosion behavior including the dominating mechanisms is required. Simulation tools predicting the corrosion behavior of bare and coated Eurofer in Pb–15.7Li must be implemented and validated in a real fusion environment where numerous physical phenomena are additionally present, compared to the state of the art corrosion knowledge, such as neutron flux, H, T permeation, MHD effects, temperature field with steep gradients.The state of the art will be shown and discussed using some of the main fundamental corrosion data selected from own testing campaigns and published literature regarding corrosion behavior of TBMs.On this basis a test matrix for TBM testing in ITER is presented in the paper and the deficits in present knowledge are outlined deviating future development needs in corrosion.     

Corrosion of single layer thin film protective coatings on steel substrates for high level waste containers

Single-layer thin film coatings have been deposited on steel substrates and tested for their corrosion resistance. These coatings include TiN, ZrO₂, TiO₂, Al₂O₃, and MoS₂, and it is proposed that they will act as barriers to provide protection to the steel canisters that are part of the dry cask storage system for high level nuclear waste. Corrosion testing was completed using electrochemical potentiodynamic polarization techniques in aerated 1 M NaCl solution. Results show an exponential increase in corrosion rate with increasing temperature and an exponential decrease in the passive breakdown overpotential, which is directly related to the ability of a material to form and sustain a corrosion-inhibiting passive film in a given environment. Additionally, kinetic activation parameters have been experimentally determined for each material, leading to predictive equations for corrosion rates. The bare and coated samples corrode analogously, indicative of pores allowing the coating and substrate to corrode simultaneously. The samples were also placed in circulating salt brines of varying pH as a supplementary corrosion testing mechanism to explore their corrosivity over extended time. Negligible weight change was experienced by the bare and coated steel samples over a period of 5 months. Increasing the coating thickness and the number of layers may provide higher resistance to uniform and localized corrosion.     

一种Zr基非晶/晶体复合型核材料的力学性能与耐腐蚀性能的研究

采用Zr65Cu35和Nb双靶直流共溅射方法,通过调节Nb靶的溅射功率,制备了不同Nb含量的Zr Cu Nb非晶薄膜。分别使用能谱仪、X射线衍射仪、高分辨透射电子显微镜观察Zr Cu Nb非晶薄膜的成分与结构,最终选择具有优异非晶形成能力的Zr53Cu38Nb9成分溅射到纯Zr基片上,以制备锆基非晶复合材料。研究测试Zr53Cu38Nb9非晶复合材料的力学性能与耐腐蚀性能。结果表明:与纯Zr基片相比,复合材料在弹性阶段力学性能无明显差异;而在塑性变形阶段,由于非晶薄膜与纯Zr基片的变形与断裂机制不同,该复合材料具有更好的拉伸塑性,其表现为非晶膜厚为280 nm、640 nm和960 nm的复合材料的最大拉伸塑性形变较纯Zr基片分别提高了2.72%、5.22%、4.27%;在耐腐蚀性能方面,非晶膜厚为640 nm的复合材料与纯Zr基片相比,具有较小的自腐蚀电流密度icorr、较正的腐蚀电位Ecorr以及较大的容抗弧半径,表现出更优异的耐腐蚀能力。因此,该新型Zr基复合材料在核材料领域具有潜在的应用。     

The role of SIMS in cultural heritage studies

Secondary ion mass spectrometry (SIMS) is a highly sensitive chemical analysis technique available in variants, which are top monolayer specific (static SIMS) or which can extract micro-volume analyses or depth profiles (dynamic SIMS). The technique offers ppm or even ppb atomic sensitivity for the consumption of extremely small sample volumes. In the area of cultural heritage, SIMS has been applied to a diverse range of problems including technology and authenticity, origin and provenance, degradation processes, such as corrosion and weathering, and conservation. In this paper, the basic attributes and limitations of the technique are described. An outline is given of applications to glasses (obsidian dating, conservation of stained glass and Venetian glass), metals (simulated archaeological bronzes), pigments and human remains, focusing on conservation problems such as the assessment and suppression of corrosion, other degrading processes, identification of materials using speciation. The topic of ultra low energy SIMS, newly applied to cultural heritage materials, is briefly described.     

Tarnish Testing of Copper-Based Alloys Coated with SiO_2-Like Films by PECVD

The tarnishing test in the presence of hydrogen sulfide（H2S） vapors has been used to investigate the tarnish resistance capability of copper-based alloys coated with Si02-like films by means of plasma-enhanced chemical vapor deposition（PECVD） fed with a tetraethoxysilane/oxygen mixture.The chemical and morphological properties of the films have been characterized by using infrared absorption spectroscopy（IR） and scanning electron microscopy（SEM）with energy disperse spectroscopy（EDS）.The corrosion products of the samples after the tarnishing test have been identified by X-ray diffraction analysis（XRD）.It has been found that SiO2-like films formed via PECVD with a high O2 flow rate could protect copper-based alloys from H2S vapor tarnishing.The alloys coated at the O2 flow rate of 20 sccm remain uncorroded after 54days of H2S vapor tarnish testing.The corrosion products for the alloys deposited at a low O2flow rate after 54 days of tarnish testing are mainly composed of brochantite.     

金属铀与铝薄膜界面的俄歇电子能谱研究

以磁控溅射沉积方法 ,采用循环氩离子轰击镀和未循环轰击镀工艺在金属铀上制备了铝薄膜。俄歇电子能谱分析结果表明 :循环氩离子轰击镀获得的铝薄膜和铀基体的界面扩散比未循环轰击镀的显著增强 ,且界面发生化学反应 ,生成了UAl3和Al2 O3相。     

HTR-PM两根一回路连接管断裂的进气事故分析

进气事故是模块式高温气冷堆关注的超设计基准事故之一,石墨氧化腐蚀反应可能导致反射层结构强度减弱、燃料元件完整性和包容裂变产物能力被破坏,以及产生可燃气体等较严重后果。进气事故的分析研究对进一步掌握高温气冷堆的事故特性以及提高反应堆的安全设计具有重要意义。本文基于200MWe球床模块式高温气冷堆示范工程（HTR-PM）的初步设计,假设与一回路压力边界上、下相连的燃料元件进料管和卸料管同时发生断裂,从而形成烟囱效应并导致空气进入堆芯,利用高温气冷堆专用系统分析软件TINTE对自然循环建立及后续的进气腐蚀过程进行了研究,分析了自然循环流量、堆内石墨腐蚀速率、舱室氧气消耗量、燃料元件温度等关键参数的变化。结果表明,即使考虑腐蚀反应的不均匀性,事故后约60h时才会出现首个燃料包覆颗粒裸露现象,燃料元件最高温度峰值低于1620℃的设计限值,保持完好的燃料包覆颗粒仍具有包容放射性裂变产物的能力。同时,如果在相应的时间内采取措施切断进气源,使石墨腐蚀反应不能继续发展,将不会对反应堆的安全造成严重的影响。