The present invention describes a hybrid multilayer solar selective coating having high thermal stability useful for high temperature solar thermal power generation. The hybrid multilayer solar selective coating of the present invention has been deposited using a novel combination of sputtering and sol-gel methods on metallic and non-metallic substrates, preferably on SS 304 and 321 with chrome interlayer. The hybrid multilayer solar selective coating of the present invention consists of stacks of Ti/chrome interlayer, aluminum titanium nitride (AlTiN), aluminum titanium oxynitride (AlTiON), aluminum titanium oxide (AlTiO) and organically modified silica (ormosil) layers. The chrome interlayer was deposited using an electroplating method, whereas, Ti, AlTiN, AlTiON and AlTiO layers were prepared using a four-cathode reactive unbalanced pulsed direct current magnetron sputtering technique. The ormosil layer was deposited using a sol-gel technique, which provides the enhanced absorptance and improved long term thermal stability in air and vacuum. The present invention provides a hybrid multilayer solar selective coating having absorptance 0.950, emittance 0.11 (SS substrate with chrome interlayer) and long term high thermal stability (in the order of 1000 hrs under cyclic heating conditions at 500°C in air and 600°C in vacuum). The hybrid multilayer solar selective coating of the present invention exhibits higher solar selectivity ratio in the order of 5-9 on metal and non-metal substrates. The hybrid multilayer solar selective absorber coating of the present invention has high oxidation resistance, stable microstructure, high adherence and graded composition particularly suitable for applications in concentrating collectors like evacuated receiver tubes and Fresnel receiver tubes useful for solar steam generation.
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