Materials Chemistry and Physics, Vol.163, 478-484, 2015
Fabrication and characterization of silver/nickel sulphide solar absorber coatings on stainless steel by chemical bath deposition
Metal chalcogenide (silver/nickel sulphide) thin film absorber coatings on AISI SS 321 substrates were deposited using a chemical bath deposition technique. An aqueous solution of silver nitrate (AgNO3) and sodium thiosulphate pentahydrate (Na2S203.5H20) was used as the chemical bath. A systematic study of the growth of silver/nickel sulphide thin films was carried out by varying the composition, temperature of the chemical bath in addition to the deposition time. Optimization of process parameters was carried out in order to achieve high solar selectivity. Depending on the ratio of AgNO3:Na2S2O3.5H2O used, either silver sulphide or nickel sulphide films were formed on SS 321. The silver/nickel sulphide films were characterized for their solar absorbance, thermal emissivity, phase purity and surface morphology. Thermal stability analysis and corrosion testing of the silver and nickel sulphide thin films confirmed that they were stable up to 300 degrees C in air and corrosion resistant, thus making them suitable for midtemperature (<400 degrees C) solar heating and power generation applications without evacuation of the annular space between the absorber tube and the borosilicate cover glass tube. (C) 2015 Elsevier B.V. All rights reserved.