Spectrally selective solar absorbers

• US 4,098,956 A
• Filed: 08/11/1976
• Issued: 07/04/1978
• Est. Priority Date: 08/11/1976
• Status: Expired due to Term

• Current Assignee: The United States of America as represented by the Secretary of the Interior
• Original Assignee: The United States of America as represented by the Secretary of the Interior
• Inventors: Blickensderfer, Robert, Lincoln, Russell L., Deardorff, Donald K.
• Primary Examiner(s): Steiner, Arthur J.
• Application Number:
  US05/713,452
• Time in Patent Office: 692 Days
• Field of Search: 428/632, 428/633, 428/627, 428/687, 428/661, 428/432, 428/433, 428/450, 428/434, 428/469, 428/336, 428/926, 204/192 P, 136/89 PC, 136/89 CC, 126/270, 126/271
• US Class Current: 428/627
• CPC Class Codes: F24S 70/225 for spectrally selective absorption
• CPC Class Codes: F24S 70/25 Coatings made of metallic material
• CPC Class Codes: Y02E 10/40 Solar thermal energy, e.g. solar towers
• CPC Class Codes: Y10S 126/908 Particular chemical
• CPC Class Codes: Y10S 428/926 Thickness of individual layer specified
• CPC Class Codes: Y10T 428/12576 Boride, carbide or nitride component
• CPC Class Codes: Y10T 428/12611 Oxide-containing component
• CPC Class Codes: Y10T 428/12618 Plural oxides
• CPC Class Codes: Y10T 428/12812 Diverse refractory group metal-base components: alternative to or next to each other

Abstract

Thin film absorber stacks consisting of an absorptive film of titanium, zirconium or hafnium suboxide, subcarbide or subnitride superposed on a reflective film of silver, aluminum or copper display spectrally selective characteristics. The absorptive film may be prepared by reactively sputtering the metal or the metal carbide in argon or other inert gas with small amounts of gas containing carbon, oxygen or nitrogen or their combinations, or by reaction of the metal film in air or other gas.

Claims

1. An absorber stack consisting of a substrate having coated thereon a reflective metal film and having a solar energy absorptive film superposed upon said reflective metal film;

said reflective metal film having a thickness of about 1500 Angstroms and consisting of a metal selected from the group consisting of gold, copper, silver, aluminum, beryllium, molybdenum and tungsten, and said absorptive film having a thickness of about 800 to 2400 Angstroms and consisting of a compound of the formula MC_x O_y N_z wherein M is selected from the group consisting of titanium, zirconium and hafnium and mixtures thereof and wherein the sum of x+y+z is greater than 0 but less than 2.

2. The absorber stack of claim 1 wherein the value of x is 0.

3. The absorber stack of claim 1 wherein the value of y is 0.

4. The absorber stack of claim 1 wherein the value of z is 0.

5. The absorber stack of claim 1 wherein the values of both x and y are 0.

6. The absorber stack of claim 1 wherein the values of both x and z are 0.

7. The absorber stack of claim 1 wherein the values of both y and z are 0.