Development and degradation behavior of protective multilayer coatings for aluminum reflectors for solar thermal applications

Publication date: 30 November 2016
Source:Thin Solid Films, Volume 619
Author(s): S.K. Mishra, Vikash Kumar, S.K. Tiwari, T. Mishra, Gopal Angula, Saikat Adhikari
The fabrication of multilayers Al-SiO2, Al-SiO2-TiO2, Al-Ni-Ag-SiO2, Al-Ni-Ag-SiO2-TiO2 on anodized aluminum sheet by the combination of physical vapor deposition sputtering and sol-gel coating process has been done. The multilayers of very high reflectivity (95% or more) could be developed on Al. The Al mirror reflectivity has been enhanced to 95% by a thin coating of Ag on aluminum in between the substrate and transparent and protective layers of SiO2 and SiO2-TiO2 The degradation behavior of these multilayers in accelerated weathering condition and under salt spray with different hours of exposure vis a vis reflectance is investigated. These coatings showed higher reflectance and sustenance in accelerated weathering and salt spray environment making it potential multilayered coating for solar thermal applications.