Thermal control coatings

Patent metadata

Field	Value
Publication number	US-10100203-B2
Application number	US-201515324276-A
Country	US
Kind code	B2
Filing date	Jul 7, 2015
Priority date	Jul 7, 2014
Publication date	Oct 16, 2018
Grant date	Oct 16, 2018

Abstract

A curable coating composition comprising: (a) a silicate, such as sodium silicate, potassium silicate or lithium silicate; (b) a phosphate, such calcium phosphate, magnesium phosphate or sodium phosphate; and (c) a metal oxide, such as magnesium oxide, aluminum (III) oxide, scandium (III) oxide, yttrium (III) oxide, or zirconium oxide. Such curable coating compositions may be used as non-thermochromic (tailored based on expected operating environment) thermal control coating compositions for application to spacecraft and components thereof. As an alternative metal oxide component, for use in lower temperature applications, or in applications for which thermochromism at elevated temperatures is not a concern, the metal oxide may comprise zinc oxide. Also provided is a curable coating composition comprising: (a) a silicate (e.g. as above); (b) a phosphate (e.g. as above); and (c) a metal sulphate, such as a barium sulphate. Cured coatings are also provided, as are thermal control coatings, thermal control paints, and processes for making coated substrates.

First claim

The invention claimed is:

1. A curable coating composition comprising:
(a) from about 30% to about 90% by weight of a silicate;
(b) a calcium phosphate; and
(c) a metal oxide comprising magnesium oxide, aluminum (III) oxide, scandium (III) oxide, yttrium (III) oxide, zirconium oxide, or a combination thereof;
wherein the composition is a white thermal control paint; and
wherein the composition, when cured, is non-thermochromic at a temperature up to 500° C.

2. A curable coating composition according to claim 1 , which comprises:
from about 2% to about 60% by weight of the calcium phosphate; and
from about 2% to about 60% by weight of the metal oxide;
the percentages by weight being percentages by weight of the total curable coating composition.

3. A curable coating composition according to claim 1 , wherein the calcium phosphate comprises a tricalcium phosphate, a tetracalcium phosphate, hydroxyapatite or a derivative thereof, or a combination thereof.

4. A curable coating composition according to claim 3 , wherein the calcium phosphate is a tricalcium phosphate selected from α-tricalcium phosphate (α-TCP) and β-tricalcium phosphate (β-TCP), or a combination thereof.

5. A curable coating composition according to claim 4 , wherein the calcium phosphate is β-TCP.

6. A curable coating composition according to claim 2 , wherein the calcium phosphate is present in an amount of from about 5% to about 40%, by weight of the curable coating composition.

7. A curable coating composition according to claim 1 , wherein the calcium phosphate has a particle size in the range of from about 0.1×10 −6 m to about 5×10 −6 m.

8. A curable coating composition according to claim 7 , wherein the calcium phosphate has a particle size in the range of from about 0.2×10 −6 m to about 0.5×10 −6 m.

9. A curable coating composition according to claim 1 , wherein the metal oxide comprises scandium (III) oxide or yttrium (III) oxide.

10. A curable coating composition according to claim 9 , wherein the metal oxide comprises yttrium (III) oxide.

11. A curable coating composition according to claim 2 , wherein the silicate is present in an amount of from about 40% to about 80%, by weight and the metal oxide is present in an amount of from about 10% to about 50%, by weight of the curable coating composition.

12. A curable coating composition according to claim 1 , wherein the metal oxide has a particle size in the range of from about 0.1×10 −6 m to about 5×10 −6 m.

13. A curable coating composition according to claim 1 , wherein the silicate comprises an alkali metal silicate.

14. A curable coating composition according to claim 13 , wherein the silicate comprises an alkali metal silicate selected from sodium silicate, potassium silicate and lithium silicate, or a combination thereof.

15. A curable coating composition according to claim 1 , wherein the composition, when cured, is UV reflective with an optical absorbance less than or equal to 0.20.

16. A curable coating composition comprising:
(a) a silicate;
(b) β-tricalcium phosphate (β-TCP); and
(c) a metal oxide comprising scandium (III) oxide, yttrium (III) oxide, or zirconium oxide;
wherein the composition is a white thermal control paint; and
wherein the composition, when cured, is non-thermochromic at a temperature up to 500° C. and has an optical absorbance less than or equal to 0.20.

17. A curable coating composition according to claim 16 , wherein the composition has a weight ratio of metal oxide to β-TCP of 3:1.

18. A curable coating composition according to claim 16 , wherein the composition has a weight ratio of silicate to a sum of metal oxide and β-TCP of 1:1.

19. A curable coating composition comprising:
(a) sodium silicate;
(b) β-tricalcium phosphate (β-TCP) particles ranging from 0.2×10 −6 m to 0.5×10 −6 m in diameter; and
(c) a metal oxide comprising scandium (III) oxide or yttrium (III) oxide;
wherein the composition is a white thermal control paint; and
wherein the composition, when cured, is non-thermochromic at a temperature up to 1000° C. and has an optical absorbance less than or equal to 0.20.

Assignees

• Univ College Dublin Nat Univ Ireland Dublin
• Univ College Dublin National Univ Of Ireland

Inventors

• Doherty Kevin A J
• Twomey Barry
• Stanton Kenneth

Classifications

• C09D7/61 Primary

  inorganic · CPC title

• C09D1/02 Primary

  alkali metal silicates · CPC title

• C09D5/004 Primary

  Reflecting paints; Signal paints · CPC title

• C09D7/68

  Particle size between 100-1000 nm · CPC title

• C09D5/32

  Radiation-absorbing paints {(protection against X-, gamma- or corpuscular radiation G21F)} · CPC title