Claims
- 1. A method for applying a diffusion barrier coating to a substrate comprising the steps of:
providing a metal substrate; cleaning the substrate of foreign material; coating the metal substrate with a layer of metal containing paint, said paint comprising substantially metal, solvents, and binders, wherein said metal is selected from the group consisting of chromium, aluminum, zirconium, hafnium, platinum, yttrium, silicon, alloys thereof and combinations thereof; baking the layer of metal containing paint to a temperature for a period of time sufficient to volatilize the solvents in the layer of metal containing paint; baking the layer of metal containing paint to a second temperature for a second period of time sufficient to volatilize the binders in the layer of metal containing paint, the remaining layer being substantially contiguous on the substrate surface and comprising substantially metal of sufficient thickness; heating the metal substrate and layer of metal to a third temperature for a third period of time sufficient to diffuse the metal into the substrate to form a diffusion metal layer; and cooling the substrate.
- 2. The method of claim 1 further comprising the step of applying an outer coating over the diffusion metal layer after cooling the substrate.
- 3. The method of claim 1, wherein the paint contains a metal selected from the group consisting of chromium, aluminum, zirconium, hafnium, platinum, yttrium, silicon, alloys thereof, and combinations thereof.
- 4. The method of claim 3, wherein the metal is chromium.
- 5. The method of claim 3, wherein the metal is a chromium and aluminum alloy, wherein the percentage of the metal that is chromium is in the range of about 5 weight percent to about 25 weight percent.
- 6. The method of claim 5, wherein the percentage of the alloy that is chromium is about 20 weight percent.
- 7. The method of claim 4 wherein the first temperature is in the range of about 300° F. to about 485° F., the first time is in the range of about one hour to about three hours, the second temperature is in the range of about 750° F. to about 930° F., the second time is in the range of about one hour to about three hours, the third temperature is in the range of about 1200° F. to about 2010° F. and the third time is in the range of about one hour to about four hours.
- 8. The method of claim 7 wherein the first temperature is about 400° F., the first time is about two hours, the second temperature is about 750° F. and the second time is about two hours, the third temperature is about 1830° F. and the third time is about two hours.
- 9. The method of claim 5 wherein the first temperature is in the range of about 300° F. to about 485° F., the first time is in the range of about one hour to about three hours, the second temperature is in the range of about 750° F. to about 930° F., the second time is in the range of about one hour to about three hours, the third temperature is in the range of about 1200° F. to about 1830° F. and the third time is in the range of about one hour to about four hours.
- 10. The method of claim 9 wherein the first temperature is about 400° F., the first time is about two hours, the second temperature is about 750° F. and the second time is about two hours, the third temperature is about 1600° F. and the third time is about two hours.
- 11. The method of claim 6 wherein the first temperature is in the range of about 300° F. to about 485° F., the first time is in the range of about one hour to about three hours, the second temperature is in the range of about 750° F. to about 930° F., the second time is in the range of about one hour to about three hours, the third temperature is in the range of about 1200° F. to about 1830° F. and the third time is in the range of about one hour to about four hours.
- 12. The method of claim 11 wherein the first temperature is about 400° F., the first time is about two hours, the second temperature is about 750° F. and the second time is about two hours, the third temperature is about 1600° F. and the third time is about two hours.
- 13. The method of claim 8 further comprising the step of applying an outer coating over the diffusion metal layer after cooling the substrate.
- 14. The method of claim 12 further comprising the step of applying an outer coating over the diffusion metal layer after cooling the substrate.
- 15. The method of claim 3, wherein the metal is an aluminum and zirconium alloy.
- 16. The method of claim 3, wherein the metal is an aluminum and hafnium alloy.
- 17. The method of claim 3, wherein the metal is an aluminum and platinum alloy.
- 18. The method of claim 3, wherein the metal is an aluminum, platinum and hafnium alloy.
- 19. A low pressure turbine blade coated with a diffusion barrier using the method of claim 1.
- 20. A high pressure turbine blade coated with a diffusion barrier using the method of claim 1.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This Application is related to application Ser. No. ______, Attorney Docket No. 13DV-14160 filed contemporaneously with this Application on Dec. 27, 2002, entitled “LOW COST ALUMINIDE PROCESS FOR MODERATE TEMPERATURE APPLICATIONS” assigned to the assignee of the present invention, and which is incorporated herein by reference.