Effect of Growth Condition on Mechanical Properties of Zirconium Carbonitride Absorber-Based Spectrally Selective Coatings
Zirconium carbonitride (ZrC–ZrN) absorber layer has been optimized for the maximum absorptivity α ~ 0.9 in ZrOx/ZrC–ZrN/Zr reflector–absorber tandem structures on stainless steel (SS) and aluminum (Al) substrates, using reactive DC/RF magnetron sputtering process and varying reactive nitrogen during the deposition. The mechanical properties such as hardness and Young’s modulus values increase from ~19.63 to ~38.53 GPa and ~36.39 to ~58.67 GPa, respectively, with increasing nitrogen flow rate during ZrC–ZrN absorber layer deposition on SS substrate. These values also increase with increasing load up to a critical limit and saturates thereafter with further increase in load values. The films with moderate hardness and Young’s modulus exhibit enhanced solar thermal performance (α ~ 0.9) against films with lower and higher values of these mechanical properties, suggesting optimal nitrogen concentration for desired solar thermal performance.
KeywordsSpectrally selective coatings Nanoindentation Young’s modulus Hardness Absorptance Emittance
Authors gratefully acknowledge the financial assistance, from the Ministry of New and Renewable Energy (MNRE), India through grant 15/40/2010-11/ST, to carry out experimental work.
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