Spectrally selective CuO particulate thin solid coatings on stainless steel and glass substrate: structural and optical properties

摘要

Abstract: CuO thin solid coatings on glass and on stainless steel substrates have been prepared by the dip-coating technique. Sols have been made from a cupric acetate precursor using citric acid as a chelating agent. Scanning electron microscopy (SEM) was used for the determination of the structure of the coatings. These consist of particles with the narrow size distribution. The size of particles is around 0.14 $mu@m. Specularly reflecting CuO films on stainless steel and glass substrates were prepared in the thickness range from 0.04 $mu@m to 0.7 $mu@m. The spectral selectivity of the CuO/stainless steel tandem coating was in the range a$-s$/ $LS 0.90 - 0.85 and e$-T$/ $GRT 0.10 -0.30. Due to the high refractive index of the CuO film the reflectance of the coatings was diminished by the introduction of fumed silica particles in the initial sols which gave a mat appearance to the coatings and increases their solar absorptance for 5%. The CuO coatings produced on glass exhibit a reddish-purple color with chromaticity coordinates which values change as a function of the film thickness. The structural features of the gel and xerogel from which the final oxide coating has been made are discussed on the basis of their FT-IR spectra. !8