Thermal and environmental barrier coating compositions and methods of deposition

1. A coated component, comprising:

a metal substrate;

a barrier coating comprising a compound having the formula:

Ln 2 AMo x W 1-x O 8

where Ln comprises scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, or mixtures thereof;

A comprises Si, Ti, Ge, Sn, Ce, Hf, Zr, or a combination thereof; and

0<x≤0.5.

2. The coated substrate as in claim 1 , wherein Ln is selected from the group consisting of scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), and mixtures thereof.

3. The coated substrate as in claim 1 , wherein Ln comprises yttrium.

4. The coated substrate as in claim 1 , wherein A comprises Si.

5. The coated substrate as in claim 1 , wherein the compound has the formula:

Ln 2 Si y A 1-y Mo x W 1-x O 8

where

0<y≤0.5; and

A is Ti, Ge, Sn, Ce, Hf, Zr, or a combination thereof.

6. The coated substrate as in claim 1 , wherein A comprises Hf and/or Zr.

7. The coated substrate as in claim 1 , wherein the compound comprises a zircon crystal structure or a scheelite structure.

8. The coated substrate as in claim 1 , wherein the metal substrate comprises a nickel-based superalloy, a cobalt-based superalloy, a titanium-based superalloy, or an iron-based superalloy, and wherein the barrier coating defines an external surface of a multi-layer thermal barrier coating system formed on the metal substrate.

9. The coated substrate as in claim 8 , wherein the multi-layer thermal barrier coating system includes an aluminide or silicide bond coat layer on the metal substrate, an oxide layer, and the barrier coating as the outermost layer defining the external surface.

10. The coated substrate as in claim 1 , further comprising an outer coat layer on the barrier coating, and wherein the outer coat layer comprises Ln 2 SiO 5 , where Ln is scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), or mixtures thereof.

11. The coated substrate as in claim 1 , wherein the coated substrate is a component of a gas turbine engine with the barrier coating facing a hot gas stream within the gas turbine engine.

12. A gas turbine engine defining a hot gas stream, the gas turbine engine comprising the coated substrate of claim 1 , wherein the barrier coating faces the hot gas stream within the gas turbine engine.

13. A method of forming a coated substrate, the method comprising:

applying a barrier coating over a substrate; wherein the barrier coating comprises a compound having the formula:

Ln 2 AMo x W 1-x O 8

where Ln comprises scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, or mixtures thereof;

A comprises Si, Ti, Ge, Sn, Ce, Hf, Zr, or a combination thereof; and

0<x≤0.5.

14. The method of claim 13 , wherein the barrier coating is applied to form the external exposed surface of the coated substrate.

15. The method of claim 14 , wherein the barrier coating is applied as a pattern of dense abradable ridges.