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Proceedings Paper

Accelerated Ageing Tests Of Copper-Oxide And Ni-MgF2-cermet Solar Absorber Coatings
Author(s): M Kohl; K Gindele; M. Mast
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Paper Abstract

Good durability of solar absorber coatings is one of the most important preconditions for their application. Since the lifetime of an absorber should be at least ten years, a prediction of the ageing behaviour by accelerated ageing tests is very desirable. In general the ageing due to temperature loads of the coatings is caused by chemical or diffusion processes. The temperature dependence of the chemical reaction velocities as well as of the diffusion constants is described by Arrhenius'law. Therefore an increase of the test temperature leads to an accelerated ageing. The degradation of the optical properties of the layer (e. g. solar absorptance and thermal emittance) at high temperatures as a function of time, caused by the enhanced temperatures, can be transformed to lower temperatures using Arrhenius'law. Thus an estimation of the ageing behaviour and the lifetime at operating temperatures is possible. This method is applied to copper-oxide coatings and to Ni-MgF2 cermets. The specific ageing processes have been investigated by Auger-electron-spectroscopy combined with energy-dispersive x-ray analysis, which has shown, that the degradation of the copper-oxide layers is caused by chemical processes while the ageing processes in Ni-MgF2 coatings are dominated by diffusion processes.

Paper Details

Date Published: 24 September 1986
PDF: 7 pages
Proc. SPIE 0653, Optical Materials Technology for Energy Efficiency and Solar Energy Conversion V, (24 September 1986); doi: 10.1117/12.938335
Show Author Affiliations
M Kohl, University of Stuttgart (Germany)
K Gindele, University of Stuttgart (Germany)
M. Mast, University of Stuttgart (Germany)

Published in SPIE Proceedings Vol. 0653:
Optical Materials Technology for Energy Efficiency and Solar Energy Conversion V
Claes-Goeran Granqvist; Carl M. Lampert; John J. Mason; Volker Wittwer, Editor(s)

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