Electrically insulating material for thermal sprayed coatings matching the coefficient of thermal expansion of the underlying body
Compositions and method for preparing thermally sprayed coatings are disclosed. The inventive compositions include at least one component that is electrically-insulating and/or non-subliming at thermal spray temperatures; and at least one component that has a high coefficient of thermal expansion. The invention also provides a compositions and methods for preparing a coating comprising a spinel, from materials that do not comprise a spinel; and also provides non-spinel materials used to prepare coatings comprising spinel. The invention includes coatings made from the materials and methods; and articles comprising the coatings.
1. A material comprising a particle comprising a core portion comprising a first mixture, and an encasing portion comprising a second mixture,
the first mixture comprising at least 50 mol % of a high-CTE material (component B1) and comprising less than 50 mol % of a non-sublimating electrical insulator (component A1);
the second mixture comprising at least 50 mol % of a non-sublimating electrical insulator (component A2) and comprising less than 50 mol % of a high-CTE material (component B2); and
wherein at least one of component A1 and component B1 has an average particle size up to about 100 microns;
at least one of component A2 and component B2 has an average particle size up to about 20 microns; and
component B1 having a coefficient of thermal expansion (CTE) at least about 10 μm/m/K;
wherein the encasing portion at least partially encases the core portion, and wherein the material comprises essentially no spinel.
2. The material of claim 1 , wherein component A1 and component A2 are independently chosen from one or both of a) one or more oxide of trivalent or tetravalent metals, or b) one or more salts with binding properties.
3. The material of claim 1 , wherein component A1 and component A2 are independently chosen from one or more of oxide of Al, In, Ga, Y, Sc, Mg, Si, Ti, Ge, Zr, Hf, Sn, Nb, Mn, or a rare earth metal.
4. The material of claim 1 , wherein component A1 and component A2 comprise Al 2 O 3 .
5. The material of claim 1 , wherein component B2 has a coefficient of thermal expansion at least about 10 μm/m/K.
6. The material of claim 1 , wherein component B1 and component B2 are independently chosen from one or more of a simple oxide, a double oxide, a triple oxide, an alkali metal halide, an alkaline metal halide, or a metal.
7. The material of claim 1 , wherein component B1 and component B2 comprise MgO.
8. The material of claim 1 , comprising a plurality of cores.
9. The material of claim 8 , wherein the cores comprise particles that are at least one of monolithic or an agglomerate of smaller particles.
10. The material of claim 1 , comprising a plurality of agglomerated encased cores.
11. The material of claim 1 , wherein the core further comprises an outer layer that is non-electrically conducting and non-sublimating.
12. The material of claim 11 , wherein the outer layer comprises one or both of a) one or more oxides of trivalent or tetravalent metals, or b) one or more salt with binding properties.
13. The material of claim 1 , further comprising a binder.
14. The material of claim 1 , further comprising a dispersant.
15. A thermal spray coating prepared by thermally spraying the material of claim 1 onto a substrate.
16. The thermal spray coating of claim 15 , the thermal spray coating comprising one or more spinel.
17. The thermal spray coating of claim 15 , wherein the substrate comprises at least one of iron, steel, aluminum, copper, Fe—Cr alloy, Cr-rich steel, cobalt, Co-alloy, nickel, Ni-alloy, bronze, or titanium.
18. A particle comprising a core portion comprising a first mixture, and an encasing portion comprising a second mixture,
the first mixture comprising at least 50 mol % of a high-CTE material having CTE greater than or about 10 μm/m/K (component B1) and comprising less than 50 mol % of a non-sublimating electrical insulator (component A1);
the second mixture comprising at least 50 mol % of in a non-sublimating electrical insulator (component A2) and comprising less than 50 mol % of a high-CTE material (component B2); and
wherein at least one of component A1 and component B1 has an average particle size up to about 100 microns;
at least one of component A2 and component B2 has an average particle size up to about 20 microns; and
wherein the encasing portion at least partially encases the core portion, and wherein the particle comprises essentially no spinel.
19. A method of manufacturing a thermal spray coating comprising:
obtaining a material according to claim 1 ;
obtaining a substrate; and
forming a coating on the substrate by applying the material to the substrate by a thermal spray process.
20. The method of claim 19 , wherein the material does not comprise spinel, and the thermal spray coating comprises a spinel.
21. The method of claim 19 , wherein the material comprises Al 2 O 3 , and the thermal spray coating does not comprise A1 2 O 3 .
22. The method of claim 19 , wherein the substrate comprises at least one of iron, steel, aluminum, copper, Fe—Cr alloy, Cr-rich steel, cobalt, Co-alloy, nickel, Ni-alloy, bronze, or titanium.