Analysis of particle rolling and intrinsic rotations in copper powder during sintering
Analysis of particle rolling and intrinsic rotations in copper powder during sintering
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DOI：
10.1007/s10853-012-6558-0
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发表时间：
2012-10-01
影响因子：
4.5
通讯作者：
Kraft, T.
中科院分区：
文献类型：
--
作者：
Kieback, B.;Noethe, M.;Kraft, T.
描述烧结过程的常用理论模型是双颗粒模型。该模型全面描述了由拉普拉斯压力驱动的颗粒间接触的生长。在三维中，该模型作为合作材料运输（即，粉末颗粒的运动）发生。对这些过程的基本理解仍然相当粗略，并且来自于对1D或2D样品的观察。为了观察和量化合作物质传输，需要新的实验方法，例如高分辨率计算机断层扫描结合摄影测量图像分析。通过在每个颗粒的表面钻孔来标记单晶铜球，并使用标记的粉末制备两个样品。一个样品在石英毛细管中连续加热至1，050 A ℃，并在格勒诺布尔的欧洲同步辐射设施中通过原位同步计算机断层扫描（SCT）进行分析。在柏林的Bessy II通过非原位SCT研究了自由烧结。在球体表面钻孔的新技术允许通过摄影测量来量化固有旋转和颗粒滚动。所观察到的内禀旋转超过滚动到目前为止，我们得出结论，晶界能的各向异性导致晶界滑动。此外，我们提出了第一个计算机模拟的烧结过程的基础上测量的SCT的初始颗粒位置。
The common theoretical model used to describe the sintering process is the two particle model. This model describes comprehensively the growth of inter-particle contacts driven by the Laplace pressure. In three dimensions this model fails as cooperative material transport (i.e., movements of powder particles) occurs. The fundamental understanding of these processes is still rather sketchy and is derived from the observation of 1D or 2D samples. To observe and quantify cooperative material transport new experimental methods are needed, for example high resolution computer tomography in conjunction with photogrammetric image analysis. Single-crystal copper spheres were marked by drilling holes into the surface of each particle and two samples were prepared using the marked powder. One sample was heated continuously to 1,050 A degrees C in a silica capillary and was analyzed by in situ synchrotron computer tomography (SCT) at the European synchrotron radiation facility in Grenoble. Free sintering was investigated by ex-situ SCT at Bessy II in Berlin. The novel technique of drilling holes into the sphere surfaces allows for the quantification of both intrinsic rotations and particle rolling by photogrammetry. The observed intrinsic rotations exceed the rolling by far and we conclude that the anisotropy of grain boundary energies results in grain boundary sliding. Furthermore, we present first computer simulations of sintering processes based on initial particle positions measured by SCT.