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.