C/Al软X射线多层膜反射镜的制备与测量

在λ＝ ２８．５ｎｍ 波长处,我们选择了一种新的多层膜材料对Ｃ／Ａｌ。正入射Ｃ／Ａｌ多层膜在１５．０ｎｍ 附近有很低的二级衍射峰。磁控溅射法制备的Ｃ／Ａｌ多层膜样品,用Ｘ射线小角衍射法对其结构进行了测试,并测得Ｃ／Ａｌ软Ｘ射线多层膜的正入射反射率２２％ ±４％ 。     

膜厚控制误差对软X射线多层膜性能影响的分析

针对影响多层膜性能的关键因素———膜厚控制误差进行了全面的分析计算,指出影响多层膜性能的主要误差是仪器本身的系统偏差,它使多层膜的峰值反射波长偏离设计值,使得制作出的多层膜无法满足要求;镀膜过程中的随机误差使多层膜的反射率降低,但不影响多层膜峰值反射率波长的位置,因此,在制作多层膜过程中,不但要严格控制镀膜时的系统误差,而且要控制随机误差。     

极紫外与软X射线非周期多层膜优化设计及初步研制

以周期膜理论为基础 ,改进了已有的设计方法 ,通过采用随机数的方法 ,发展了一种普适的多层膜设计方法 ,这种方法除可设计一般的周期多层膜 ,更重要的是它可以根据选定评价因子 ,设计不同要求的非周期多层膜。根据实际要求 ,完成了积分反射率最大多层膜、宽带平坦型多层膜、校正光源发射不均匀性多层膜和选波长多层膜等。这些多层膜各有特点 ,可满足不同应用的要求。用磁控溅射方法对一种宽带多层膜进行了制备。最后的 X射线衍射测量和反射率的相对测试表明 ,与周期膜系相比 ,非周期多层膜的带宽展宽 ,反射率积分值增加 ,但峰值反射率略有降低。     

极紫外与软X射线非周期多层膜优化设计及初步研制

以周期膜理论为基础,改进了已有的设计方法,通过采用随机数的方法,发展了一种普适的多层膜设计方法,这种方法除可设计一般的周期多层膜,更重要的是它可以根据选定评价因子,设计不同要求的非周期多层膜.根据实际要求,完成了积分反射率最大多层膜、宽带平坦型多层膜、校正光源发射不均匀性多层膜和选波长多层膜等.这些多层膜各有特点,可满足不同应用的要求.用磁控溅射方法对一种宽带多层膜进行了制备.最后的X射线衍射测量和反射率的相对测试表明,与周期膜系相比,非周期多层膜的带宽展宽,反射率积分值增加,但峰值反射率略有降低.     

极紫外与软X射线非周期多层膜优化设计及初步研制

以周期膜理论为基础,改进了已有的设计方法,通过采用随机数的方法,发展了一种普适的多层膜设计方法,这种方法除可设计一般的周期多层膜,更重要的是它可以根据选定评价因子,设计不同要求的非周期多层膜.根据实际要求,完成了积分反射率最大多层膜、宽带平坦型多层膜、校正光源发射不均匀性多层膜和选波长多层膜等.这些多层膜各有特点,可满足不同应用的要求.用磁控溅射方法对一种宽带多层膜进行了制备.最后的X射线衍射测量和反射率的相对测试表明,与周期膜系相比,非周期多层膜的带宽展宽,反射率积分值增加,但峰值反射率略有降低.     

X射线超反射镜设计

阐述了一种新的X射线超反射镜的设计方法,它是基于经验理论公式的解析设计方法和基于计算机的数值优化设计方法相结合的产物。利用前者提供比较好的初始膜系,再利用后者对该初始膜系进行优化处理,从而获得比较好的设计结果,并大大减少了计算时间。讨论了实际制作出的多层膜存在的表面粗糙度及膜层材料间的相互扩散对多层膜反射性能的影响,并给出了模拟计算的结果。依据上述方法,在比较大的掠入射角情况下,设计出了具有较宽反射带宽的W/CX射线超反射镜。     

Effect of Reynolds number and boundary layer thickness on the performance of V-cone flowmeter using CFD

The effect of Reynolds number and boundary layer thickness on the performance of V-cone flowmeter has been evaluated using computational fluid dynamics (CFD). The shear stress transport k-ω (SST k-ω) turbulence model has been adopted for closure. The performance of two V-cone flowmeters with different beta ratios (β) viz., 0.6 and 0.7 for a fixed vertex angle (ϕ) of 60° has been analysed as a function of Reynolds number (Re). The results show that the coefficient of discharge (C_d) increases with Reynolds number in the laminar and transition flow regimes whereas it is nearly constant in turbulent flow regime. From the results, it can be concluded that C_d is independent of Re for values equal to 4000 and beyond. Further, it is also seen that the performance of the V-cone flowmeter is not affected by the upstream boundary layer thickness if the velocity profiles having different boundary layer thickness are extracted from an axial distance of 10D and more are fed at 5D upstream of the meter. However, the meter is sensitive to the extracted velocity profile from an axial distance of 5D and uniform velocity profile being fed at 5D upstream. The value of C_d may be sensitive as a result of the pressure variation due to the obstruction.     

大型X射线光学仪器:单层镜和多层镜的制造与表征

150~500 mm长度的各种X射线光学元件可用于光束导引,光束调整,以及单色化。本文介绍了两种不同的大型X射线反射镜。第一种为单层反射镜,这种反射镜以2°掠入射角在软X射线区(50~200 eV)起全反射镜作用,可用于自由电子激光器,如德国汉堡的FLASH。第二种是多层镜,由于它的布喇格反射特性,适于作为反射镜以0.4~1°的入射角用于硬X射线区(20~50 keV),如层析光束线的同步辐射存储环中。两种反射镜都用最新物理汽相淀积法制备,并用磁控溅射来实现X射线光学应用所需要的优良光学品质。这一淀积工艺使不同批次的镀膜稳定性良好,有利于实际反射镜在优质衬底上的最后淀积。单层镜和多层镜在它们的相关能量范围内都有很高的反射率,表面粗糙度也很低,且在整个光学波长区这些特性表现均匀。文中所叙相关研究都是借助X射线反射计量(XRR)法,透射电子显微镜(TEM)、光学轮廓仪(OP),以及原子力显微镜(AFM)完成的。     

多层膜Laue透镜对10 keV硬X射线聚焦性能的理论计算

采用NbC/Si材料组合设计多层膜Laue透镜,总膜厚为40μm,利用衍射动力学理论分析多层膜Laue透镜对硬X射线的衍射效率及聚焦分辨率。通过两种方法提高多层膜Laue透镜的分辨率。第一种方式是减小膜层的最外层宽度,该方法要求结构必须是楔型结构,制备极其困难。第二种方法是使用多层膜Laue透镜的高级次,该方法在不增加制备难题的前提下能有效提高分辨率。通过使用多层膜Laue透镜的-3级次,对10keV硬X射线获得了分辨率为6.72nm,衍射效率为49.31%的聚焦光斑。     

基于二维光学相干层析的多层薄膜结构无损定量评价

为了实现对多层薄膜结构厚度进行快速准确的测量和无损定量评价,研制了二维光学相干层析(Optical Coherence Tomography,OCT)系统,避免了传统一维OCT系统逐点扫描导致成像效率低下的问题。阐述了去除OCT共轭镜像理论,采用了五步相移干涉法,具体由压电驱动器驱动参考镜实现,做到了对OCT共轭镜像的去除,避免出现OCT图像的混叠。所研制的OCT系统具有极高的系统分辨率和较好的信噪比,可以实现对手机钢化玻璃薄膜内部四层结构厚度(钢化玻璃、静电胶层1、防爆贴膜和静电胶层2)进行准确测量。实验结果表明:自研制的系统可快速高精度地对多层薄膜结构厚度进行测量,可以推荐使用在多层薄膜的无损定量评价中。     

类镍钽软X射线激光用多层膜反射镜的研制

设计并制备了工作波长为4.48 nm类镍钽软X射线激光用多层膜反射镜。选择C r/C、C r/Sc为多层膜材料对,模拟了多层膜非理想界面对多层膜反射率的影响。采用直流磁控溅射技术在超光滑硅基片上制备了C r/C、C r/Sc多层膜。利用X射线衍射仪测量了多层膜结构,在德国Bessy II同步辐射上测量了多层膜的反射率,C r/C,C r/Sc多层膜峰值反射率分别为7.50%,6.12%。     

The effect of large solid angles of collection on quantitative X-ray microanalysis in the AEM

Increasing the solid angle of X-ray collection is a major factor in improving the analytical sensitivity of X-ray energy-dispersive spectrometry (XEDS) in the analytical electron microscope (AEM). A new scanning transmission electron microscope, the VG HB 603, is equipped with two XEDS detectors with the largest collection angles (0.30 and 0.17 sr) available in commercial AEMs. However, large collection angles result in a large range of take-off angles, from ~ 4° to 36°, and the low angles can cause strong X-ray absorption. In order to investigate possible detrimental effects of the low (and of the range of) take-off angles on quantitative microanalysis of specimens exhibiting significant absorption, a stoichiometric Ni₃Al thin-film, in which the Al Kα line is significantly absorbed, was analysed. Furthermore, the effect of different values of the collection angle on X-ray intensities was theoretically evaluated by numerical calculations and spectral simulation. These theoretical approaches permitted correlation of changes in the X-ray take-off angle (and hence X-ray absorption) with changes in the collection angle. It is demonstrated that ~ 0.30 sr detectors, with minimum take-off angles as small as 4°, only result in maximum errors of 4% in the quantification of Al in Ni₃Al and, therefore, further increases in collection angle can be pursued while maintaining current levels of accuracy of quantification.     

蓝宝石衬底损伤层厚度和折射率的椭偏测量

为了定量测量蓝宝石衬底在化学机械抛光过程中产生的损伤层厚度d和折射率n,提出了一种光谱椭偏测量法。首先,测量蓝宝石衬底反射光谱（波长范围：250~1650 mm）偏振态的改变量（即振幅比和相位差）：然后,通过光学建模和测量数据反演,获得损伤层d和n。实验研究了Al,0。和SiO,两种磨料加工蓝宝石衬底损伤层d和n的变化趋势,前者d呈现波动趋势且最小值（约1.4mm）出现在40min左右,后者d持续下降,在20min接近1mm;二者损伤层n均小于蓝宝石晶体n。另外,实验和仿真分析结果表明相位差与厚度变化趋势一致,因无需建模反演,可作为快速表征损伤层 d变化趋势的参量。总之,所提方法作为光学无损测量模式,适用于加工过程监测。     

Influence of layer thickness on hardness and scratch resistance of Si-DLC/CrN coatings

Abstract

Multifunctional coatings, widely used in tribological applications, have their properties strongly influenced by the interaction of the system coating/substrate. The use of multilayered coatings has been pointed out as a solution for the problem of high internal stresses that can be generated in coated systems, in particular in the case of soft substrates. In multilayered coatings, a decrease in the stress gradient between substrate and coating improves adhesion. Moreover, the thickness of the coating has shown a strong influence on the tribological behaviour of the coated system. This paper, through widely used and efficient techniques, seeks to assess the influence of the thickness of different layers (DLC and CrN) on the response of a multifunctional coating. Si rich DLC and CrN coatings with different thicknesses were deposited on a steel substrate (AISI 1020) by Plasma Enhanced Magnetron Sputtering (PECVD). Scanning electron microscopy (SEM) and Raman spectroscopy (RS) were used in order to characterize the chemical composition and microstructure of the coatings. Instrumented indentation and scratch test techniques were used to measure hardness, elastic modulus, and adhesion of each layer. Critical loads were determined by visual analysis, using SEM in conjunction with the curves obtained in the scratch tests. The evaluation of the effect of the thicknesses of the layers allowed an optimised design of the multifunctional coated systems with improved durability.