Solar Energy Materials and Solar Cells, Vol.157, 733-741, 2016
Impact of corrosion on microstructure and mechanical properties of ZrOx/ZrC-ZrN/Zr absorber-reflector tandem solar selective structures
We investigated the impact of corrosion on pristine and thermally treated ZrOx/ZrC-ZrN/Zr absorber reflector tandem solar selective coatings (ARTSSCs) on stainless steel (SS) and copper (Cu) substrates using microstructure, electrochemical and nanoindentation measurements. Electrochemical measurements are carried out in 3.5 wt% NaCl solution, emulating the corrosion environments, under potentiodynamic polarization states. The corrosion treated samples exhibit strong correlations among microstructural, mechanical properties and their solar thermal responses. The thermally treated ZrOx/ZrC-ZrN/Zr structures on SS substrates show degraded corrosion resistance from 1379 K Omega to 104 K Omega for vacuum and 435 K Omega for air thermal conditions. The measured mechanical properties, such as Young's modulus and hardness, substantiate the observed corrosion mediated degradation of thermally treated structures under both vacuum and air environmental conditions. The solar thermal performance shows degradation for both pristine and thermally treated sample after corrosion and room temperature after corrosion emissivity 'epsilon(27) (degrees C)' values are similar to 0.28, 0.35, 0.42 for pristine and thermally treated ZrOx/ZrC-ZrN/Zr structures respectively. (C) 2016 Elsevier B.V. All rights reserved.
Keywords:Solar selective coatings;Sputtering;Corrosion behavior. Microstructure;Emittance;Hardness;Young's modulus