Articles for high temperature service and related method

1. An article, comprising:

a substrate; and

a thermal barrier coating disposed on the substrate, wherein the thermal barrier coating comprises a plurality of aluminum-based particles dispersed in an inorganic binder, wherein the aluminum-based particles are substantially spaced apart from each other via the inorganic binder such that the thermal barrier coating is substantially electrically and thermally insulating and the aluminum-based particles comprise aluminum metal, an aluminum alloy or combinations thereof.

2. The article of claim 1 , wherein the article comprises an automotive component, a locomotive component, a marine component, or a medical component.

3. A method of forming a thermal barrier coating on a substrate, the method comprising

(i) contacting a slurry comprising a plurality of aluminum-based particles and an inorganic binder with a surface of the substrate to form a slurry coating; and

(ii) heat-treating the slurry coating under conditions sufficient to cure the slurry coating and form the thermal barrier coating, wherein the aluminum-based particles are substantially spaced apart from each other via the inorganic binder in the thermal barrier coating such that the thermal barrier coating is substantially electrically and thermally insulating, and wherein the aluminum-based particles comprise aluminum metal, an aluminum alloy or combinations thereof.

4. The method of claim 3 , wherein a volume ratio of the aluminum-based particles to the inorganic binder in the slurry is in a range from about 0.67 to about 1.

5. The method of claim 3 , wherein the slurry coating is heat-treated at a temperature lower than a temperature sufficient for diffusing aluminum from the plurality of aluminum-based particles into a surface region of the substrate.

6. The method of claim 5 , wherein the slurry coating is heat-treated at a temperature lower than 300° C.

7. The method of claim 3 , wherein the inorganic binder comprises a chromate, a phosphate, a molybdate, a vanadate, a tungstate, or combinations thereof.

8. The method of claim 3 , wherein the inorganic binder is substantially free of hexavalent chromium.

9. The method of claim 3 , wherein an average domain size of the plurality of aluminum-based particles in the cured slurry coating is in a range from about 0.5 microns to about 30 microns.

10. The method of claim 3 , wherein an average domain size of the inorganic binder in the cured slurry coating is in a range from about 0.5 microns to about 5 microns.

11. The method of claim 3 , wherein the plurality of aluminum-based particles is present in the cured slurry coating in an amount in a range from about 20 volume percent to about 70 volume percent, and the inorganic binder is present in the cured slurry coating in an amount in a range from about 30 volume percent to about 80 volume percent.

12. The method of claim 3 , wherein the inorganic binder comprises a chromate, a phosphate, a molybdate, a vanadate, a tungstate, or combinations thereof.

13. The method of claim 3 , wherein the plurality of aluminum-based particles comprises a core-shell structure.

14. The method of claim 13 , wherein a core of the core-shell structure comprises aluminum metal and a shell of the core-shell structure comprises a complex of the inorganic binder and aluminum.

15. The method of claim 3 further comprising burnishing the cured slurry.

16. The method of claim 3 , wherein the cured slurry coating has an electrical resistivity greater than 1 ohm·m and a thermal conductivity lower than 2.2 W/m-K.

17. The method of claim 3 further comprising disposing a bond coating between the substrate and the thermal barrier coating.