A comparative study of high resolution cone beam X-ray tomography and synchrotron tomography applied to Fe- and Al-alloys

Upper Austria University of Applied Sciences, Stelzhamerstrasse 23, 4600 Wels, Austria.
NDT & E international : independent nondestructive testing and evaluation 10/2010; 43(7-3):599-605. DOI: 10.1016/j.ndteint.2010.06.004
Source: PubMed

ABSTRACT X-ray computed tomography (XCT) has become a very important method for non-destructive 3D-characterization and evaluation of materials. Due to measurement speed and quality, XCT systems with cone beam geometry and matrix detectors have gained general acceptance. Continuous improvements in the quality and performance of X-ray tubes and XCT devices have led to cone beam CT systems that can now achieve spatial resolutions down to 1 μm and even below. However, the polychromatic nature of the source, limited photon flux and cone beam artefacts mean that there are limits to the quality of the CT-data achievable; these limits are particularly pronounced with materials of higher density like metals. Synchrotron radiation offers significant advantages by its monochromatic and parallel beam of high brilliance. These advantages usually cause fewer artefacts, improved contrast and resolution.
Tomography data of a steel sample and of two multi-phase Al-samples (AlSi12Ni1, AlMg5Si7) are recorded by advanced cone beam XCT-systems with a μ-focus (μXCT) and a sub-μm (nano-focus, sub-μXCT) X-ray source with voxel dimensions between 0.4 and 3.5 μm and are compared with synchrotron computed tomography (sXCT) with 0.3 μm/voxel. CT data features like beam hardening and ring artefacts, detection of details, sharpness, contrast, signal-to-noise ratio and the grey value histogram are systematically compared. In all cases μXCT displayed the lowest performance. Sub-μXCT gives excellent results in the detection of details, spatial and contrast resolution, which are comparable to synchrotron-XCT recordings. The signal-to-noise ratio is usually significantly lower for sub-μXCT compared with the two other methods. With regard to measurement costs “for industrial users”, scanning volume, accessibility and user-friendliness sub-μXCT has significant advantages in comparison to synchrotron-XCT.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Nowadays, X-ray tube-based high-resolution CT systems are widely used in scientific research and industrial applications. Compact XCT systems are available that can reach resolutions down to 1 µm and below. But the potential, convenience and economy of these lab systems is often underestimated. The present paper shows the comparison of sophisticated conventional µCT with synchrotron radiation-based µCT (SRµCT). The different aspects and characteristics of both approaches like spatial and density resolution, penetration depth, scanning time or sample size is described in detail. Beside this, the advances in technology of industrial high resolution CT systems are shown. The paper also presents recent advances in the area of industrial high resolution CT systems from phoenix product line of General Electric. All major parts are designed to make the system extremely stable during the data acquisition process. So, the system is equipped with granite base and very precise rotation unit. The unique nanofocus tube technology with build-in cooling system stabilizes the tube and at the same time the diamond based target allows high photon flux at very small focal spot sizes. The unique detector with excellent contrast resolution and SNR is also thermally stabilized. Also, the user friendliness is increased through the fully automated process chain starting with detector calibration and going through acquisition and data reconstruction process with automated volume data evaluation The application results of this new technology show its high potentials for usage of the state of the art laboratory systems in the industrial and scientific application fields of material research, metrology, petro-industry, etc. To compare the potentials of laboratory based CT with synchrotron based CT, different samples were used: e.g. a low-carbon steel sample, and an aluminium multi-phase sample (AlMg5Si7) and some other. Concerning measurement costs, scanning volume, accessibility and user-friendliness sub-µXCT has significant advantages in comparison to synchrotron-XCT.
  • Source
    International Geophysical Conference and Exhibition, Brisbane, Australia; 02/2012
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Today's high-resolution X-ray CT with its powerful tubes and great detail detectability lends itself naturally to geological and petrological applications. Those include the non-destructive interior examination and textural analysis of rocks and their permeability and porosity, the study of oil occurrences in reservoir lithologies, and the analysis of morphology and density distribution in sediments – to name only a few. Especially spatial distribution of pores, mineral phases and fractures are important for the evaluation of reservoir properties. The possibility to visualize a whole plug volume in a non-destructive way is undoubtedly the most valuable feature of this type of rock analysis and is a new area for routine application of high resolution X-ray CT. All presented geological CT volume evaluations were performed with GE's phoenix nanotom, a 180 kV/15 W nanofocus CT system tailored specifically for extremely high-resolution scans of samples weighing up to 3 kg with voxel-resolutions down to < 300 nm. In our first sample we will show a typical reservoir rock scanned with 1 µm voxel size to characterize the pore space and to extract information about the distribution of mineral components. The segmented in-situ porosity could be easily used for fluid flow modelling purposes, to predict permeability and complex flow processes within these structures. Next, two very porous pyroclastic rock samples have been examined at a resolution of 1 and 5 µm. One data set has been analysed with the Avizo software tool XLab Hydro. Besides permeability tensor, porosity and pressure drop, the resulting velocity field of the fluid particles can be directly visualized whereas the colour mapping indicates the velocity's magnitude. The resulting volume data can be used to produce surface data for any computer-aided design (CAD) application and furthermore for FEM modelling for hydrogeological purposes.
    Annual Symposium of the Society of Core Analysts, Napa Valley, USA; 09/2013

Full-text (2 Sources)

Available from
May 22, 2014