Methoden zur Analyse der Beständigkeit von Aluminium-Solarspiegeln

Kurzfassung

With the beginning of operation of first commercial solar thermal power plants, questions about the durability and cost reduction potential of components become a more and more important issue. In this thesis, the degradation of aluminum- based solar reflectors, which offer economic benefits compared to thick-glass mirrors, has been analyzed. The optical degradation of outdoor weathered samples has been examined with a newly developed reflectometer, which enables to measure the specular reflectance spatially resolved wihtin a certain acceptance angle. In that way, the influence of corrosion on the reflectance properties of the reflector could be analyzed. Additionally to nanocomposite layer have been tested at outdoor weathering test standards. The quick degradation of the uncoated samples permitted to derive a model to describe the corrosion expansion. In order to estimate the life-time of coated samples, these laws have been extrapolated to samples with nanocomposite layer. The modeled specular reflectance losses served as input-parameters for the development of a new, accelerated testing procedure, which consists in a combination of an abrasion and a corrosion test. By means of this accelerated aging procedure a newly developed nanocomposite coating by the manufacturer has been tested and the resulting specular reflectance losses after ten years of outdoor weathering have been estimated.