Korrosion von polykristallinem Aluminiumoxid (PCA) durch Metalljodidschmelzen sowie deren Benetzungseigenschaften

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.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2009

Author dc:creator

• Fischer, Sarah Christine

Contributors dc:contributor

• Singheiser, Lorenz

• info:eu-repo/classification/ddc/500
• Korundstruktur
• Aluminiumoxide
• Natriumiodid
• Thalliumiodid <Thallium(I)-iodid>
• Calciumiodid
• Finite Element Subsurface Flow and Transport Simulation System
• Transportreaktion
• Randwinkel
• Benetzung
• Mischungsenthalpie
• Rauigkeit
• Naturwissenschaften
• Rauigkeitsmessung
• Ceriodid
• Indiumiodid
• kooperatives Transportmodel
• cerium iodide
• indium iodide
• cooperative transport model

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-113520%22

OAI record oai:identifier

https://publications.rwth-aachen.de/oai2d?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai%3Apublications.rwth-aachen.de%3A51208