Comparing different analytical techniques for the characterization of alloys for a possible sensor sorting approach


Comparing different analytical techniques for the characterization of alloys for a possible sensor sorting approach

Ebert, D.; Möckel, R.; Seidel, P.; Raatz, S.

The so called down cycling effect denotes the unwanted mixing of different materials in the recycling stream resulting in materials with lower quality and functionality than the single parts that where introduced to the recycling process. In a project dealing with different analytical methods a sensor strategy for a desired sorting technique was tested. The methods that were applied on different alloys including steel samples, brass and aluminium included: X-ray fluorescence techniques (handheld XRF, WDXRF), laser induced breakdown spectroscopy (LIBS), and spark-OES but also neutron activation.
Spark-OES was used as benchmark, which was verified by using certified reference materials, suitable for the alloys we investigated. The actual tests were done on nine different, commercially available test alloys with known compositions (given ranges of elemental concentrations, though). Initially, they were tested for homogeneity using spatially resolved EDXRF measurements. Deviations to the mean composition were generally lower than 0.2 wt.%. Nevertheless few inhomogeneities were found including impurities and general inhomogenous areas which are attributed to quality issues during manufacturing (probably with no effect on the desired function).
Summarizing the results of this comparative study, it turned out that for specific elements-matrix combinations, like e.g. Si in steels and Cu in Al alloys, LIBS show more accurate results, whereas the XRF techniques exhibit better performances for the main metal quantification due to its direct quantification of the main element (Seidel et al. 2021). Besides the main elements, we tested for Al, Fe, Cu, Si, Mn, Mg, Cr, Ni, Zn depending on the alloy type.
The results were used to simulate a first approximation on a possible sorting result of real scrap metal samples derived from a magnetic separated fraction, on which we applied LIBS, pXRF and WDXRF. These preliminary calculation considered the analytical deviation, different chemical compositions and the elements of interest vs. analytical method.

References:

Seidel, P., Ebert, D., Schinke, R., Möckel, R., Raatz, S., Chao, M., Niederschlag, E., Kreschel, T., Gloaguen, R., Renno, A. D. (2021). Comparison of Elemental Analysis Techniques for the Characterization of Commercial Alloys. Metals, 11(5), 736.

  • Poster
    AOFKA - Applied Surface and Solid State Analytics, 06.-08.10.2021, Freiberg, Deutschland

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Publ.-Id: 33692