Coating layer with slow SIO2 crystallization rate
An article having a coating system configured to inhibit or prevent crystallization of a thermally grown oxide (TGO) layer at the operating temperature of the article. An article includes a substrate defining a surface and a coating layer that includes a dopant configured to inhibit crystallization of a thermally grown oxide layer comprising amorphous silicon dioxide at an interface of the coating layer at the operating temperature of the article. The dopant includes an oxide or a nitride. By inhibiting or preventing TGO crystallization, the described coating systems may increase a useable life of the component.
1 . An article comprising:
a substrate defining a surface; and
a coating layer overlying the substrate, wherein the coating layer comprises a dopant configured to inhibit crystallization of a thermally grown oxide layer comprising amorphous silicon dioxide at an interface of the coating layer at an operating temperature of the article,
wherein the dopant comprises both lanthanum oxide and silicon nitride, and wherein the dopant is included in the coating layer in a range of from about 1 weight percent to about 5 weight percent.
2 . The article of claim 1 , wherein the coating layer is a bond coat layer.
3 . The article of claim 1 , wherein the coating layer comprises an environmental barrier coating (EBC) further comprising at least one rare-earth monosilicate or rare-earth disilicate.
4 . The article of claim 1 , further comprising a bond coat on the surface of the substrate and between the coating layer and the surface of the substrate.
5 . The article of claim 1 , wherein the dopant further comprises aluminum nitride.
6 . The article of claim 1 , wherein the coating layer is a bond coat layer comprising at least two regions, wherein the first region is closer to the substrate than the second region, and wherein the second region of the bond coat includes a greater amount of the dopant than the first region.
7 . The article of claim 1 , further comprising an abradable coating on the coating layer, wherein the abradable coating comprises at least one rare-earth monosilicate or rare-earth disilicate.
8 . The article of claim 1 , wherein the coating layer comprises graded chemistry, a graded porosity, or a graded chemistry and a graded porosity.
9 . The article of claim 1 , wherein the article is a high temperature component of a gas turbine engine.
10 . The article of claim 1 , wherein the dopant increases a glass transition temperature of the thermally grown oxide layer.
11 . A gas turbine engine component comprising:
a ceramic matrix composite (CMC) substrate defining at least a portion of the gas turbine engine component, wherein the CMC substrate comprises a silicon-containing material; and
a coating layer overlying the CMC substrate, wherein the coating layer comprises a dopant configured to inhibit crystallization of a thermally grown oxide layer comprising amorphous silicon dioxide at an interface of the coating layer at an operating temperature of the gas turbine engine component,
wherein the dopant comprises both lanthanum oxide and silicon nitride, and wherein the dopant is included in the coating layer in a range of from about 1 weight percent to about 5 weight percent.
12 . A method comprising:
depositing a coating layer formulation on a substrate defining a surface to form a coating layer,
wherein the coating layer comprises a dopant configured to inhibit crystallization of a thermally grown oxide layer comprising amorphous silicon dioxide at an interface of the coating layer at an operating temperature of an article;
wherein the dopant comprises both lanthanum oxide and silicon nitride, and wherein the dopant is included in the coating layer in a range of from about 1 weight percent to about 5 weight percent.
13 . The method of claim 12 , wherein depositing the coating layer comprises thermal spraying.
14 . The method of claim 13 , wherein thermal spraying comprises feeding a ceramic feedstock into a heating zone of a thermal spray apparatus, wherein the ceramic feedstock includes the dopant.
15 . The method of claim 13 , wherein thermal spraying comprises:
feeding a ceramic feedstock into a heating zone of a thermal spray apparatus, and
feeding a dopant composition with a dopant feed apparatus into a heated gas stream of the thermal spray apparatus downstream of the heating zone.
16 . The method of claim 15 , wherein the ceramic feedstock comprises at least one rare earth silicate.
17 . The method of claim 15 , wherein the ceramic feedstock comprises a first ceramic feedstock comprising a rare earth (RE) monosilicate and a second ceramic feedstock comprising a RE disilicate.
18 . The method of claim 15 , wherein the dopant composition is fed into the heated gas stream in the form of a powder entrained in a carrier gas.
19 . The method of claim 15 , wherein feeding the dopant composition comprises varying a feed rate of dopant relative to the feed rate of ceramic feedstock.