Korrosion von PCA durch Metalljodidschmelzen sowie deren Benetzungseigenschaften

Fischer, Sarah Christine

Dissertation / PhD Thesis/Book

Korrosion von PCA durch Metalljodidschmelzen sowie deren Benetzungseigenschaften

Fischer, S. C. (Corresponding author)FZJ*

2009
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
ISBN: 978-3-89336-584-5

Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag, Schriften des Forschungszentrums Jülich : Energie & Umwelt / Energy & Environment 44, 148 S. (2009) = RWTH Aachen, Diss., 2009

Please use a persistent id in citations: http://hdl.handle.net/2128/3722

Abstract: On high-energy discharge lamps with burners consisting of polycrystalline aluminum oxide (PCA) corrosion leads to relocation of the wall material; the extent of the phenomenon depends on the composition and the wetting behaviour of the liquid salt mixture contained in the lamp. The aim of this work was to better comprehend these phenomena. For this the wetting behaviours of several iodides on PCA- and carbon plates in a water-free argon atmosphere was determined in a contact angle measurement apparatus. While pure salts show good or, at high temperatures, complete wetting, the surface wetting of binary salt mixtures is positively worse, even if only small amounts of the second component are present. From the contact angle measurements the surface tension of the pure salts could be determined. By combining the YOUNG-LAPLACE-Equation with the BUTLER-Equation, the excess GIBBS energy could be related to the contact angles of salt mixtures, which makes the estimation of their wetting properties possible. The extent of the corrosion was determined by annealing experiments in a temperature gradient. No corrosion was found in reference experiments without any salt. In addition to diverse corrosion phenomena the formation of cerium aluminate was observed in some cases. All these effects could also be reproduced by computer simulations, for which a special program was developed. This program may lead to the development of advanced software in the future which can calculate the shape and corrosivity of lamp-relevant salt melts.

Note: Record converted from VDB: 12.11.2012
Note: RWTH Aachen, Diss., 2009

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