Turbine engine components with environmental protection for interior passages
Turbine airfoil components with protective layers and methods therefore. The components are each formed to have a platform, an airfoil extending upwardly from the platform, and a shank extending downwardly from the platform. The shank has an exterior wall and an internal passage, and the airfoil has a cooling flow channel inside the airfoil for flowing a cooling flow therethrough. The component has an interior chromide coating contacting at least a portion of an interior surface of the shank and interdiffused with a base metal thereof, and an exterior chromide coating contacting at least a portion of an exterior surface of the shank and interdiffused with the base metal thereof. The interior and exterior chromide coatings do not have an aluminide coating deposited thereon.
1. A gas turbine blade, comprising:
a base metal;
a platform;
an airfoil extending upwardly from the platform, the airfoil having a cooling flow channel located inside the airfoil for flowing a cooling flow therethrough;
a shank extending downwardly from the platform, the shank having an exterior surface and an internal passage located inside the shank for flowing a cooling flow therethrough to the cooling flow channel of the airfoil;
a dovetail extending downwardly from the shank, the dovetail having an exterior surface and having an internal passage located therein for flowing a cooling flow therethrough to the internal passage of the shank;
a first interior chromide coating contacting the base metal of at least a portion of an interior surface of the internal passage within the shank and contacting at least a portion of an interior surface of the internal passage within the dovetail and interdiffused therewith;
a second interior chromide coating contacting the base metal of at least a portion of an interior surface of the airfoil and interdiffused therewith; and
a protective layer on at least a portion of an exterior surface of the airfoil, the protective layer being chosen from the group consisting of diffusion aluminide and diffusion platinum aluminide coatings;
wherein the first and second interior chromide coatings and the exterior surfaces of the shank and dovetail do not have an aluminide coating deposited thereon; and
wherein the exterior surfaces of the airfoil, shank and dovetail do not have a chromide coating deposited thereon.
2. A gas turbine blade according to claim 1 , wherein the first interior chromide coating comprises an average of about 20 to about 50 percent by weight chromium.
3. A gas turbine blade according to claim 1 , wherein the first interior chromide coating has a thickness of from about 0.0005 to about 0.002 inch.
4. A gas turbine blade according to claim 1 , wherein the second interior chromide coating comprises an average of about 20 to about 50 percent by weight chromium.
5. A gas turbine blade according to claim 1 , wherein the second interior chromide coating has a thickness of from about 0.0005 to about 0.002 inch.
6. A gas turbine blade according to claim 1 , wherein the base metal has a composition, in weight percent, of from about 4 to about 20 percent cobalt, from about 1 to about 10 percent chromium, from about 5 to about 7 percent aluminum, from 0 to about 2 percent molybdenum, from about 3 to about 8 percent tungsten, from about 4 to about 12 percent tantalum, from 0 to about 2 percent titanium, from 0 to about 8 percent rhenium, from 0 to about 6 percent ruthenium, from 0 to about 1 percent niobium, from 0 to about 0.1 percent carbon, from 0 to about 0.01 percent boron, from 0 to about 0.1 percent yttrium, from 0 to about 1.5 percent hafnium, balance nickel and incidental impurities.
7. A gas turbine blade according to claim 1 , further comprising a ceramic layer overlying at least a portion of the protective layer.