The effects of the pulse current electrolysis on the optical characteristics of black chrome solar selective coatings: Influence Statistics

The effects of the pulse current electrolysis on the optical characteristics of black chrome solar selective coatings

Abstract

The effects of pulse current (PC) electrolysis during electrodeposition of black chrome oxide (Cr2O3) on the optical properties and surface microstructure of the solar selective coatings were investigated in this study. For this investigation, the new chromic-propionic acid bath solution has been prepared, and black chrome coatings were electrodeposited onto the bright nickel substrates from this solution using PC electrolysis. This method enabled us to achieve good optical properties (α=0.973, ϵ=0.17) for PC-applied initial (as-deposited) black chrome coatings. It was found that the direct current (DC) electrolysis method versus PC-applied deposits varied in their optical values, and that the PC-applied coatings were superior to DC-mode coating. Thermal stability tests associated with the change in optical properties and microstructure of PC-applied coatings were performed. SEM photomicrographs indicated that thermal degradation does not change significantly the optical properties and surface microstructure of coatings obtained by the PC electrolysis. In AES composition depth profiles an increase in oxygen signal in films was not observed upon heating to 300°C for 24 h; however, this oxygen signal drastically increased after thermal aging at 450°C for 24 hours. This study concludes that thermally stable black chrome coatings with good optical properties can be produced by the pulse current electrolysis process from a chronic-propionic acid bath solution.