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Proceedings Paper

Sol-Gel Protective Coatings For Black Chrome Solar Selective Films
Author(s): R. B. Pettit; C. J. Brinker
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Paper Abstract

Electrodeposited black chrome solar selective films degrade rapidly when heated to temperatures above 300°C in air. The application of sol-gel protective coatings to the black chrome films has been investigated as a possible means to improve the oxidation resistance of black chrome at high temperatures. The sol-gel coating process consists of applying an alcoholic solution containing polymeric glass precursors. After the coating is fired for about one-half hour at a moderate temperature (-450°C), a glass layer is obtained. Because of the wide range of sol-gel processing parameters, initial studies have concentrated on determining the effect of the following variables on the thermal stability of sol-gel coated black chrome: (1) sol-gel composition; (2) firing temperature; (3) firing atmosphere; (4) sol-gel coating thickness; (5) pre-aging of the black chrome films. Of the compositions studied, only Si02/B203 and Si02/B203/Al203/Na20/Ba0 resulted in improved thermal stability. Of the other processing parameters, the firing temperature had the most significant effect on the resulting black chrome thermal stability, with 500°C firing being optimum. For the best combination of process variables studied to date, the solar absorptance of a sol-gel coated sample decreased from 0.97 to 0.95 after 100 hrs at 400°C, while, for an uncoated control sample, the solar absorptance decreased to 0.89. For most of the solgel coated films, continued aging at 400°C resulted in continued protection of the black chrome film.*

Paper Details

Date Published: 12 April 1982
PDF: 8 pages
Proc. SPIE 0324, Optical Coatings for Energy Efficiency and Solar Applications, (12 April 1982); doi: 10.1117/12.933271
Show Author Affiliations
R. B. Pettit, Sandia National Laboratories (United States)
C. J. Brinker, Sandia National Laboratories (United States)

Published in SPIE Proceedings Vol. 0324:
Optical Coatings for Energy Efficiency and Solar Applications
Carl M. Lampert, Editor(s)

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