Micro X-ray diffraction and fluorescence tomography for the study of multilayered automotive paints
Micro X-ray diffraction and fluorescence tomography for the study of multilayered automotive paints
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DOI：
10.1002/sia.3125
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发表时间：
2010-05-01
影响因子：
1.7
通讯作者：
Janssens, Koen
中科院分区：
文献类型：
--
作者：
De Nolf, Wout;Janssens, Koen
显微X射线荧光/显微X射线衍射(MU-XRF/MU-XRD)层析成像是近年来发展起来的一种新方法，它能够以无损的方式显示复杂的、非均质的超厚(毫米范围)材料中化学元素的分布和相关的晶相。本文对汽车涂料多层堆栈中各层的识别精度和分辨率进行了评估，并对其部分性能进行了测量。研究了一个由八层组成的漆层系统，其中鉴定了八种不同的结晶物质，每一层由一种有机合成树脂组成，其中掺入了用作颜料或增强该层的精细研磨的无机化合物。在X射线衍射层析图中，可以直观地区分所有的漆层，并计算它们的平均厚度。在使用滤波反投影法重建断层图像的情况下，获得了与微束大小相当的空间分辨率，表明重建没有明显的模糊。当采用更稳健的重建方法时，例如最大似然期望最大化方法，获得的断层图像显示的伪影较少，但空间分辨率差两倍。在相应的XRF断层图像中，显著的自吸收扭曲了对应于低能量(
Combined microscopic X-ray fluorescence/microscopic X-ray diffraction (mu-XRF/mu-XRD) tomography is a recently developed method that allows the visualization of the distribution of chemical elements and the associated crystalline phases inside complex, heterogeneous materials of extended thickness (millimeter range) in a nondestructive fashion. In this paper, the accuracy and resolution with which the individual layers in a multilayer stack of automotive paints can be distinguished is evaluated, and some of their properties measured. A paint layer system of eight layers was investigated, in which eight different crystalline substances were identified, each layer consisting of an organic, synthetic resin doped with finely milled inorganic compounds that serve as pigments or to strengthen the layer. In the XRD tomograms, all paint layers could be straightforwardly distinguished and their average thickness calculated. In case the filtered back projection method was used for tomogram reconstruction, a spatial resolution comparable to the microbeam size was obtained indicating no significant reconstruction blurring. When a more robust reconstruction method, such as the maximum-likelihood expectation maximization method, was employed, tomograms showing fewer artifacts were obtained, but with a spatial resolution that was two times worse. In the corresponding XRF tomograms, significant self-absorption distorted the element-specific tomograms corresponding to the low-energy (