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Synthesis and Characterization of Multilayered CrAlN/Al2O3 Tandem Coating Using HiPIMS for Solar Selective
Miriam Sanchez-Perez1, Teresa Cristina Rojas1, Daniel F Reyes1,2
1Instituto de Ciencia de Materiales de Sevilla (CSIC-Univ. Sevilla), Avda. Américo Vespucio 49, E-41092 Sevilla, Spain.
ACS Applied Energy Materials
|January 26, 2024
Summary
Applying a negative bias to multilayer solar selective absorber coatings enhances their density and durability. This improved coating demonstrates superior thermal stability and higher solar-to-mechanical energy conversion efficiency at elevated temperatures.
Area of Science:
- Materials Science
- Renewable Energy
- Thin Film Technology
Background:
- Solar selective absorber coatings are crucial for efficient solar thermal energy conversion.
- Optimizing coating properties like density, thermal stability, and optical performance is essential for high-temperature applications.
- Previous designs of chromium aluminum nitride-based coatings require further enhancement for demanding conditions.
Purpose of the Study:
- To investigate the effect of applying a negative bias during the deposition of a multilayer solar selective absorber coating.
- To evaluate the impact of bias application on film density, optical performance, thermal stability, and oxidation resistance.
- To compare the performance of bias-assisted coatings with unbiased counterparts and a commercial reference.
Main Methods:
- Fabrication of multilayer solar selective coatings (CrAlN/Al2O3) on 316L stainless steel and Inconel 625 substrates using RF, DC, and HiPIMS sputtering.
- Application of a simultaneous DC-pulsed bias (-100 V, 250 kHz) during deposition to enhance film density.
- Evaluation of optical properties (absorptance, emittance), thermal stability (annealing at 600-800 °C), oxidation resistance, and solar-to-mechanical energy conversion efficiency.
Main Results:
- Bias application significantly increased film density, leading to improved durability and thermal stability.
- Coated samples remained stable after 200 h annealing at 600 °C, showing high solar absorptance (93-92%) and low thermal emittance (18%).
- Bias-assisted coatings exhibited up to 2 times higher solar-to-mechanical energy conversion efficiency at 800 °C compared to Pyromark paint.
Conclusions:
- Applying a negative bias during deposition is an effective method to enhance the performance and durability of multilayer solar selective absorber coatings.
- The bias-assisted coatings demonstrate superior thermal stability and higher operating temperature limits.
- These enhanced coatings hold significant potential for advanced solar thermal energy applications.
