微焦点X射线数字成像系统中的放大倍数

概述了微焦点X射线数字成像系统放大倍数的定义,分析了微焦点X射线数字成像系统几个关键部分的放大原理,分别提出了使用搭载图像增强器与CCD相机、平板探测器的参数来计算微焦点X射线成像装置的系统放大倍数的公式。结合试验数据,验证了公式的正确性,该公式可以用在成像方式相类似的,包括直接和间接的数字成像系统上。     

航空发动机涡轮叶片气膜孔微裂纹检测

以加工人工模拟缺陷的涡轮叶片及含微裂纹缺陷的涡轮导向叶片为对象,研究微焦点射线成像方法对气膜孔微裂纹的检出能力。通过光学显微镜对涡轮叶片人工模拟缺陷标定实际尺寸,使用微焦点射线成像方法能有效检出涡轮叶片中7条人工模拟缺陷。对人工模拟缺陷进行尺寸测量,微焦点射线成像检测尺寸测量结果与标定结果一致。另外,设计了涡轮导向叶片微焦点射线成像检测试验,采用微焦点放大成像方法能够检出涡轮导向叶片后缘中长度为392μm、宽度为21μm的微裂纹。结果表明,微焦点成像方法能满足气膜孔微裂纹工程检测需要。     

DR检测技术在制冷压力容器制造检验中的研究与应用

针对制冷压力容器的特点简述了X射线数字成像检测技术应用的技术难点和解决方案,重点介绍了胶片检测和X射线数字成像技术在检测工艺上的差别和检测控制指标的不同。     

基于PLC的微焦点X射线源控制系统设计

X射线显微分析技术利用X射线的穿透能力,结合精密定位和数据反演技术,可以在微米甚至亚微米尺度上展现被测样品的内部结构、密度和缺陷等特征信息。该技术已然成为一种重要的物理分析方式,且被广泛应用于生命科学、材料学和先进制造等领域。微焦点X射线源是X射线显微分析系统的核心部件之一,其性能直接影响着系统的测试分辨率和效率。针对微焦点 X 射线源使用中安全防护升级、工作效率提升、控制精度提高的需求,设计一套基于PLC的微焦点X射线源控制系统,并介绍该系统具体的实现过程。采用JIMA分辨测试卡进行分辨率成像实验,实现了3 μm线对的分辨率,证实了该控制系统性能良好,能够满足使用需求。     

X射线数字实时成像检测技术在浅海钢管铺设中的应用

针对浅海钢管铺设中X射线数字实时成像检测技术的应用,专门研制设计了钢管自动X射线实时成像检测系统,包括X射线检测单元、机械传动系统、专用软件与控制系统和辐射防护系统等,开展了钢管对接焊缝X射线实时成像检测试验与工程应用。研制的浅海船舶钢管对接焊缝X射线数字实时成像检测系统能够适应复杂恶劣的工作条件,具有移动定位精度高、适用性强、大幅提高效率和节省成本等优点。     

电力系统的冷阴极X射线管数字成像检测

在简要分析冷阴极X射线管和数字射线成像检测原理的基础上,进一步介绍了冷阴极X射线管数字成像检测在电力行业的应用。通过对小径管、水冷壁管、埋地电缆等部件的检测,验证了该项技术在电力行业应用的可行性,也对冷阴极X射线数字成像系统的未来应用前景进行了展望。     

关于将X射线实时成像检测技术纳入无损检测人员资格鉴定专业项目的建议

鉴于我国焊接气瓶、焊接钢管、汽车铝合金轮毂等行业越来越多地应用X射线实时成像检测技术，从事工业X射线实时成像检测的无损检测人员迫切需要进行资格鉴定认证，以适应WTO的需要和ISO认证的需要，同时也是工业X射线实时成像检测技术规范化、标准化的需要，建议尽快将工业X射线实时成像检测纳入无损检测人员资格鉴定专业项目。     

X射线数字化实时成像系统在无损检测中的应用

无损检测在航空航天、机械、石油、化工等部门有广泛的应用。X射线胶片照相法是目前常用的无损检测方法之一，它不可避免地存在检测周期长、检测成本高、污染环境等缺点。随着计算机技术的发展，新兴的计算机X射线数字化实时成像技术已在无损检测中得到了广泛应用。概述了计算机数字化实时成像技术原理及其在X射线无损检测中的应用情况。     

X射线实时成像在焊缝探伤中的应用

X射线实时成像是一项新兴的无损检测技术,它具有快速、准确、直观、成本低廉等优点,可以代替常规的X射线胶片照相探伤方法.概述了X射线实时成像技术的要点和在焊缝探伤中的应用情况.     

焊缝X射线检测及其结果的评判方法综述

分析了焊缝X射线检测方法的现状，指出了目前存在的主要问题；介绍了焊缝X射线检测结果的人工评定和计算机辅助评定方法，论述了国内外焊缝X射线检测结果计算机辅助识别的研究现状，研究结果表明，X射线数字实时成像技术是焊缝射线检测的发展方向，焊缝射线数字图像的计算机自动分析与识别技术是射线实时成像技术成功应用的基础。     

金属缺陷的分辨率研究

根据微小焦点X射线成像检测的基本原理,建立系统点扩展函数模型,并推导出检测系统的分辨率关系,最佳放大倍数以及最小检测缺陷公式。对成像检测具有指导作用。并给出在金属缺陷检测中的实际应用。     

Gap width determination by microfocus X-ray film radiography coupled with microdensitometry of the image

Microfocus X-ray film radiography was applied to image submillimetre gaps formed by an accurate micrometer. Optical density profiles of the images were measured by a microdensitometer. Gap widths as well as the focal spot size were determined. Measured width results were compared with true values and the agreement is of the order of 2% for gaps in the range of 0.05 mm to 0.20 mm.     

X-ray images of defect formation in porcelain ceramics during drying

The drying phase during the manufacture of ceramic pieces is often the point of failure owing to the formation of cracks. In this study, non-destructive microfocus X-ray imaging has been employed to study the onset of cracking in porcelain and correlate it with the moisture content. Samples of moist porcelain paste were extruded through dies of 30 and 50 mm diameter. Sections of the extrudate were placed into an X-ray transparent oven and imaged while drying at constant temperature and low humidity. The time to the onset of cracking was found to be a function of temperature. The mode of failure was consistent across the temperature range 40–120 °C.The higher the drying temperature, the shorter the time to failure and the higher the moisture loss at failure. For a particular paste consistency and sample geometry there was found to be a critical moisture content below which cracking began to occur. This moisture threshold was observed to be weakly temperature dependent; it appears to be more sensitive to sample geometry and paste consistency. A safe drying curve has been constructed which provides a boundary for the process parameters which prevent cracking. The implication is that during the drying of a ceramic piece, different sections may have different safe parameter boundaries and the process must be designed to keep all sections within the safe region.     

<Emphasis Type="Italic">In Situ</Emphasis> Characterization of Porosity Evolution in A356 Alloy Directionally Solidified Under Different Solidification Velocities

The effect of solidification velocity on nucleation and growth of porosity in a directionally solidified A356 alloy was investigated in situ using microfocus x-ray imaging and directional solidification technology. Increasing solidification velocity produces high hydrogen solute segregation in the solidification front, leading to a considerable reduction of nucleation temperature for porosity formation. When the solidification velocity increases from 0.1 mm/s to 0.2 mm/s, the average nucleation temperature decreases from 634.0°C to 614.6°C. The increased solidification velocity also increases the rate and fluctuation of pore growth. As a result, the average pore size in the fast solidified specimen is smaller than that with a slow velocity.     

Application of microfocus X-ray radiography in materials and medical research

The advantages of real-time microfocus radiography are evaluated for several applications. These advantages are mainly the small focal spot size (5 μm) leading to a very low geometrical unsharpness (0.1 mm) for a magnification of 21 ×; the positioning of the specimen very close to the source (15 mm) leading to high magnifications (100 ×) and the minimal scattered radiation recorded on film. This radiographic technique was used to study the electrolytic codeposition of a Cu-layer on a metal substrate. Enlarged radiographic images of archaeological findings revealed the smallest detail. This helps in the restoration of pieces contaminated outside and remaining intact inside. For medical research microfocus X-ray radiography provided useful information on the reaction of bone tissue on specific osteoporosis medication, on the vascular changes in experimentally induced liver tumours and on the sequential deterioration of kidney stones.     

微焦点工业CT在大功率微波器件阴极检测中的应用

介绍计算机断层扫描(CT)的成像基本原理和设备基本组成，并用微焦点工业CT系统分析大功率微波器件阴极的内部微细结构以及它与支撑筒的焊接情况，结果证明微焦点工业CT系统在大功率微波器件阴极检测中有着良好的应用前景。     

Optimization of geometrical characteristics and image intensifier response in microfocus radiographic system

Radiogarphic microfocus system with image intensifier is presently applied as a reliable NDT real-time method for failure detection in the millimetric and submillimetric range. The major advantage of the x-ray's microfocus is the magnification up to more than 40 times of the photon image projected on the image intensifier. At high magnifications every deviation from the optimal setup geometric alignment, any change in beam's uniformity and deviations from isoplanaric response of the image intensifier may cause misinterpretations of the image response. At a further step it may lead to erroneous diagnostic conclusions.The aim of the present paper is to present a method developed for a systematic examination and control of the system's response characteristics. The continuous control will reduce misinterpretations of the generated images. The method identifies the subsystem causing the deviation and improvements may be initiated.     

Macromolecular microcrystallography

Over a decade has passed since pioneering diffraction experiments on macromolecular microcrystals were performed at the European Synchrotron Radiation Facility. Since then the measurement of high-quality diffraction data for the purpose of structure determination has been transformed from a specialized experiment into routine practice at dedicated microfocus macromolecular crystallography beamlines at synchrotron facilities. In this article, we review the evolution of microfocus macromolecular crystallography over the past two decades, and explore the instrumentation and methodologies that have evolved to enable structure determination in the face of unfavourable odds. Several case studies are reviewed in depth illustrating the power of microcrystallography and microfocus instruments and their application in answering important biological questions. Challenges and limitations currently facing the community and areas of future development and problems that must be addressed in the future are also discussed.     

射线数字成像（DR）技术在电力工业检测中的应用

由于电磁式电流互感器是全封闭式的结构,在出现故障的情况下,利用常规方法不能对其内部缺陷实现直观地展现。笔者利用X射线数字成像技术对35kV电磁式电流互感器的内部结构进行透照,能够发现其存在的物理缺陷。在解体后,对所判定的缺陷类型进行验证。试验结果表明,相比其他常规检测方法,X射线数字成像技术能够更直观地发现缺陷的位置,并能够在不解体、主绝缘不破坏的情况下,实现对35kV电流互感器内部结构的可视化分析并准确地确定缺陷性质、程度和类型。     

Observation of dendritic growth and fragmentation in Ga–In alloys by X-ray radioscopy

Abstract

Capabilities of the X-ray attenuation contrast radioscopy were utilised to provide a real time diagnostic technique for observations of dendritic growth and fragmentation during solidification of a Ga–30In (wt-%) alloy. The solidification process was visualised by means of a microfocus X-ray tube providing shadow radiographs at spatial resolutions of about 10 μm. Experiments have been carried out to solidify the Ga–In alloy unidirectionally either starting from the bottom or the top of the specimen. The first case is significantly affected by solutal convection, which governs a redistribution of solute concentration. A detachment of dendrite side arms, which is unambiguously caused by melt flow, was not observed. Dendritic fragmentation occurs during the solidification in the reverse top down direction. Variations of the applied cooling rate excited a transition from a columnar to an equiaxed dendritic growth (CET).