High durability solar absorptive coating and methods for making same
View Patent ↗The present invention relates to solar absorptive coatings including a ceramic material. In particular, the coatings of the invention are laser-treated to further enhance the solar absorptivity of the material. Methods of making and using such materials are also described.
1. A method of forming a solar absorptive coating on a surface, the method comprising:
i. applying a ceramic material to the surface to form a coated surface, wherein the ceramic material comprises chromium oxide or a lanthanum-based perovskite; and
ii. treating the coated surface with a pulsed laser source, wherein the pulsed laser source is selected from the group consisting of a nanosecond laser and femtosecond laser, thereby forming the solar absorptive coating on the surface.
2. The method of claim 1 , further comprising, before step ii, curing the ceramic material on the coated surface.
3. The method of claim 1 , further comprising, after step ii, re-treating the solar absorptive coating with a pulsed laser source.
4. The method of claim 1 , wherein the solar absorptive coating has a solar absorptance of greater than about 0.94 and/or is a high-temperature solar selective coating.
5. The method of claim 1 , wherein the solar absorptive coating comprises a plurality of microstructures and a plurality of nanostructures.
6. The method of claim 5 , wherein the microstructure comprises a trench having a width of from about 5 μm to about 30 μm and/or a spacing between trenches of from about 20 μm to about 70 μm.
7. The method of claim 1 , wherein the pulsed laser source has a pulse width from about 100 fs to about 1000 ns.
8. The method of claim 7 , wherein the pulse width is from about 1 ns to about 500 ns.
9. The method of claim 1 , wherein the pulsed laser source has a wavelength from about 750 nm to about 1200 nm.
10. The method of claim 1 , wherein the pulsed laser source has a pulse energy of more than about 1 mJ.
11. The method of claim 1 , wherein the pulsed laser source has an average power of more than about 20 watts.
12. The method of claim 1 , wherein the pulsed laser source has a repetition rate of between about 1 kHz to about 500 kHz.
13. The method of claim 1 , wherein the pulsed energy source is a nanosecond laser.
14. The method of claim 13 , wherein the nanosecond laser has a pulse duration of between about 1 ns to about 400 ns, a wavelength of about 1064 nm, an average power of more than about 20 watts, and/or a repetition rate of about 15 kHz to about 300 kHz.
15. The method of claim 1 , wherein the pulsed energy source is a femtosecond laser.
16. The method of claim 15 , wherein the femtosecond laser has a pulse energy of more than about 1 mJ, a repetition rate of between about 1 kHz to about 100 kHz, and/or a wavelength of about 800 nm.
17. The method of claim 1 , wherein the surface is a substrate for absorption of solar energy selected from the group consisting of a concentrating solar power receiver, a solar tower, a trough, a Stirling engine, a heat absorber, and a solar collector, or a portion thereof.
18. A solar absorptive coating formed by the method of claim 1 .