Hybrid multilayer solar selective coating for high temperature solar thermal applications and a process for the preparation thereof
First Claim
1. A hybrid multilayer solar selective coating comprising a tandem stack of layers containing an interlayer of chromium, a first absorber layer of aluminum-titanium nitride (AlTiN), a second absorber layer of aluminum-titanium oxynitride (AlTiON), an antireflection layer of aluminum-titanium oxide (AlTiO) and a barrier layer of organically modified silica (ormosil), wherein said coating exhibits a thermal resistance up to 500°
- C. in air and up to 600°
C. in vacuum with a solar selectivity ratio in the order of 5 to 9.
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Abstract
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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Citations
13 Claims
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1. A hybrid multilayer solar selective coating comprising a tandem stack of layers containing an interlayer of chromium, a first absorber layer of aluminum-titanium nitride (AlTiN), a second absorber layer of aluminum-titanium oxynitride (AlTiON), an antireflection layer of aluminum-titanium oxide (AlTiO) and a barrier layer of organically modified silica (ormosil), wherein said coating exhibits a thermal resistance up to 500°
- C. in air and up to 600°
C. in vacuum with a solar selectivity ratio in the order of 5 to 9. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
- C. in air and up to 600°
Specification