Solar receiver, selectively absorbing material, and associated fabrication methods
A selectively-absorbing material includes a silicone polymer and transition-metal oxide nanoparticles dispersed therein. Each of the transition-metal oxide nanoparticles includes manganese. A solar receiver includes (i) a metal substrate including an etched surface having a microroughness between 0.05 micrometers and two micrometers; (ii) a polymer matrix disposed on the etched surface; and (iii) transition-metal oxide nanoparticles dispersed within the polymer matrix. A method for producing transition-metal oxide nanoparticles includes recrystallizing a plurality of two-element nanoparticles at a temperature between 300 and 700° C. The plurality of two-element nanoparticles includes at least two of (i) copper oxide nanoparticles, (ii) manganese oxide nanoparticles, and (iii) iron oxide nanoparticles. A method for fabricating a selective-absorber includes etching a top surface of a metal substrate; depositing a polymer-matrix composite on the etched top surface; and interdiffusing the polymer-matrix composite and the metal substrate. The polymer-matrix composite includes transition-metal oxide nanoparticles dispersed therein.
1. A selectively-absorbing material comprising:
a silicone polymer; and
a plurality of transition-metal oxide nanoparticles dispersed within the silicone polymer, each of the plurality of transition-metal oxide nanoparticles including manganese, copper, and a non-stoichiometric proportion of chromium.
2. The selectively-absorbing material of claim 1 , the silicone polymer having a kinematic viscosity between 0.5 and 500 square-millimeters per second.
3. The selectively-absorbing material of claim 1 , a diameter of each of the plurality of transition-metal oxide nanoparticles being between six and sixty nanometers.
4. The selectively-absorbing material of claim 1 , a volume fraction of the plurality of transition-metal oxide nanoparticles being between 0.1 and ten percent.
5. The selectively-absorbing material of claim 1 , a weight fraction of the plurality of transition-metal oxide nanoparticles being between 0.1 percent and ten percent.
6. The selectively-absorbing material of claim 1 , further comprising a plurality of non-stoichiometric Mn 1−x Fe 2+y O 4 nanoparticles dispersed within the silicone polymer, wherein −0.3<x<0.3 and −0.3<y<0.3, wherein each of the non-stoichiometric Mn 1−x Fe 2+y O 4 nanoparticles does not include zinc.
7. The selectively-absorbing material of claim 1 , the plurality of transition-metal oxide nanoparticles including a plurality of Cu y Cr x Mn 2−x O 4 nanoparticles, wherein 0.05≤x<1.0 and 0.5≤y≤1.5.
8. A solar receiver comprising:
a metal substrate including an etched surface having a root-mean-square microroughness between 0.05 micrometers and two micrometers;
a polymer matrix disposed on the etched surface; and
a plurality of transition-metal oxide nanoparticles dispersed within the polymer matrix, each of the plurality of transition-metal oxide nanoparticles including manganese, copper, and a non-stoichiometric proportion of chromium.
9. The solar receiver according to claim 8 , the metal substrate including a transition metal.
10. The solar receiver of claim 8 , a thickness of the polymer matrix being between one and fifty micrometers.
11. A method of producing a plurality of transition-metal oxide nanoparticles comprising:
recrystallizing a plurality of nanoparticles at a temperature between 30° and 700° C., each of the plurality of nanoparticles including manganese, copper, and a non-stoichiometric proportion of chromium.
12. The method of claim 11 , further comprising synthesizing the plurality of nanoparticles.
13. A method for forming a polymer-matrix composite comprising:
producing a plurality of transition-metal oxide nanoparticles according to the method of claim 11 ; and
forming a polymer matrix from a silicone polymer having a kinematic viscosity between 0.5 and 500 square-millimeters per second.
14. The method of claim 13 , further comprising dispersing the plurality of transition-metal oxide nanoparticles in the polymer matrix to yield the polymer-matrix composite.
15. A method for forming a polymer-matrix composite comprising:
producing a plurality of transition-metal oxide nanoparticles according to the method of claim 11 ; and
dispersing the plurality of transition-metal oxide nanoparticles in a polymer matrix to yield the polymer-matrix composite.
16. A method for fabricating a selective-absorber, comprising:
etching a top surface of a metal substrate;
depositing a polymer-matrix composite on the etched top surface, the polymer-matrix composite including a plurality of transition-metal oxide nanoparticles dispersed therein, each of the plurality of transition-metal oxide nanoparticles including manganese, copper, and a non-stoichiometric proportion of chromium; and
interdiffusing the polymer-matrix composite and the metal substrate.
17. The method of claim 16 , the step of interdiffusing including annealing the polymer-matrix composite for at least twenty-four hours at a service temperature exceeding 500° C.
18. The method of claim 16 , the step of etching comprising etching the metal substrate with a solution that includes hydrogen chloride and hydrogen peroxide.
19. The solar receiver of claim 8 , each of the plurality of transition-metal oxide nanoparticles including a non-stoichiometric proportion of at least two of manganese, copper, and chromium.
20. The selectively-absorbing material of claim 1 , each of the plurality of transition-metal oxide nanoparticles including a non-stoichiometric proportion of at least two of manganese, copper, and chromium.