Analytische Chemie
Larger high pressure die castings (HPDC) and decreasing wall thicknesses are raising the issue of casting defects like pores in aluminum structures. Properties of components are often strongly influenced by inner porosity. As these products are being established more and more in lightweight construction (e.g. automotive and other transport areas), non-destructive testing methods, which can be applied fast and on-site, are required for quality assurance. In this contribution, the application of active thermography for the direct detection of larger pores is demonstrated. The analysis of limits and accuracy of the method are completed by numerical simulation and the method is validated using computed
tomography.
Numerical measurement uncertainty determination for dimensional measurements of microparts with CT
(2016)
Up to now, the only standardized method to determine the measurement uncertainty for computed tomography (CT) is to use calibrated workpieces as specified in the Guideline VDI/VDE 2630 Part 2.1. This paper discusses a promising numerical method for uncertainty determination with help of a virtual metrological CT (VMCT). It gives an explanation of the adjustments, the input parameters and the execution of the simulation. Furthermore, it discusses the first results of uncertainty determination compared to the method of using calibrated workpieces with the aid of two example cases.
In this paper we present the results of imaging studies of ancient Egyptian metallic artifacts using micro-Computed Tomography (micro-CT). Micro-CT is a non-destructive imaging method with high spatial resolution, which enables the examination of the internal structure of objects. It is thus especially suitable for the investigation of cultural heritage and archaeological findings, when it is not possible to sample or difficult to manipulate the object. Using specialized software for 3D visualization and segmentation, data sets of two objects were analyzed. We gained a clear view of the inner structure of a metallic archaeological artifact from the necropolis of Abusir el-Meleq, which is believed to be very ancient in the Egyptian archaeological context (from the Predynastic Era), and were able to distinguish its different omponents under the thick layers of external concretions. These components give hints about the production technology of the object. We also investigated the contents of a closed metal box found near Abusir dated to the Late/Greco-Roman Period. The identified Content corresponds either to sediments or to mineral remains of the original content of the box. Both artifacts are from excavations conducted in Egypt and are part of the archeological collection of the Ägyptisches Museum und Papyrussammlung in Berlin.