SnO2:Sb dip coated films on anodized aluminum selective absorber plates

In this paper solar selective coatings have been prepared on aluminum substrates using a two phase eloxal technique, Porous anodic films were formed by de anodization in phosphoric acid and followed by black coloration via ac electrolysis in nickel sulfate electrolyte. To increase the thermal, chemical and mechanical stability, and also to provide low emissivity, a protective layer of tin oxide was coated on the surface by the sol-gel process. Conditions required to produce good quality coatings having the best spectral selectivity and thermal stability were determined from spectral reflectance measurements and temperature tests. Microstructure and chemical composition of the best samples were investigated using SEM, EDX, AAS. The resulting technology has been formed into a process which suits the facilities and skills of Turkish industry.