US 6,887,595 B1Granted

Thermal barrier coatings having lower layer for improved adherence to bond coat

AssigneeGeneral Electric Company

InventorsRamgopal Darolia, Irene Spitsberg, Brett Allen Boutwell, Mark Daniel Gorman, Robert William Bruce

Life of this patent

Estimating the term…

Loading patent…

Abstract

A thermal barrier coatings for the underlying substrate of articles that operate at, or are exposed to, high temperatures. The thermal barrier coating includes a zirconia-containing upper layer wherein the zirconia is stabilized in the cubic crystalline phase to reduce the thermal conductivity of the coating. The thermal barrier coating further includes a zirconia-containing lower layer stabilized in the tetragonal crystalline phase that increases the adherence of the upper layer to the bond coat layer that overlies the substrate of the article to improve the resistance of the coating to spallation.

Claims25

Dependent claims

A thermal barrier coating, which comprises:

A. a zirconia-containing upper layer wherein the zirconia is stabilized in the cubic crystalline phase, and which comprises:
1. at least about 50 mole % zirconia;
and
2. a stabilizing amount up to about 49 mole % of a stabilizer component comprising:
a. a first metal oxide selected from the group consisting of ytterbia, neodymia, mixtures of ytterbia and neodymia, mixtures of ytterbia and lanthana, mixtures of neodymia and lanthana, and mixtures of ytterbia, neodymia and lanthana in an amount of from about 5 to about 49 mole % of the upper layer;
and
b. a second metal oxide selected from the group consisting of yttria, calcia, ceria, scandia, magnesia, india and mixtures thereof in an amount of about 4 mole % or less of the upper layer;
and
3. one or more of a third metal oxide selected from the group consisting of:
a. hafnia in an amount from about 0.5 to about 40 mole % of the upper layer;
and
b. tantala in an amount of from about 0.5 to about 10 mole % of the upper layer;
and
B. a zirconia-containing lower layer wherein the zirconia is stabilized in the tetragonal crystalline phase, and which comprises:
1. at least about 80 mole % zirconia;
2. a stabilizing amount up to about 10 mole % of a stabilizer component, which comprises:
a. a first metal oxide selected from the group consisting of yttria, calcia, ceria, scandia, magnesia, india and mixtures thereof in an amount of from about 1.5 to about 6 mole %;
and
b. a second metal oxide selected from the group consisting of lanthana, neodymia, ytterbia and mixtures thereof in an amount of from about 0.5 to about 8.5 mole %.

16 more elements

A thermally protected article, which comprises:

I. a substrate;
II. a bond coat layer adjacent to and overlaying the substrate;
and
III. a thermal barrier coating adjacent to and overlaying the bond coat layer, the thermal barrier coating comprising:
A. a zirconia-containing upper layer wherein the zirconia is stabilized in the cubic crystalline phase, and which comprises:
1. at least about 50 mole % zirconia;
and
2. a stabilizing amount up to about 49 mole % of a stabilizer component comprising:
a. a first metal oxide selected from the group consisting of ytterbia, neodymia, mixtures of ytterbia and neodymia, mixtures of ytterbia and lanthana, mixtures of neodymia and lanthana, and mixtures of ytterbia, neodymia and lanthana in an amount of from about 5 to about 49 mole % of the upper layer;
b. a second metal oxide selected from the group consisting of yttria, calcia, ceria, scandia, magnesia, india and mixtures thereof in an amount of about 4 mole % or less of the upper layer;
and
3. one or more of a third metal oxide selected from the group consisting of:
a. hafnia in an amount from about 0.5 to about 40 mole % of the upper layer;
and
b. tantala in an amount of from about 0.5 to about 10 mole % of the upper layer;
and
B. a zirconia-containing lower layer adjacent to and overlaying the bond coat layer, wherein the zirconia is stabilized in the tetragonal crystalline phase, and which comprises:
1. at least about 80 mole % zirconia;
and
2. a stabilizing amount up to about 10 mole % of a stabilizer component, which comprises:
a. a first metal oxide selected from the group consisting of yttria, calcia, ceria, scandia, magnesia, india and mixtures thereof in an amount of from about 1.5 to about 6 mole %;
and
b. a second metal oxide selected from the group consisting of lanthana, neodymia, ytterbia and mixtures thereof in an amount of from about 0.5 to about 8.5 mole %.

20 more elements

A method for preparing thermal barrier coating on a metal substrate having a bond coat layer, the method comprising the step of:

A. forming a zirconia-containing lower layer wherein the zirconia is stabilized in the tetragonal crystalline phase by depositing on the a bond coat layer a first zirconia-containing ceramic composition, which comprises:
1. at least about 80 mole % zirconia;
and
2. a stabilizing amount up to about 10 mole % of a stabilizer component, which comprises:
a. a first metal oxide selected from the group consisting of yttria, calcia, ceria, scandia, magnesia, india and mixtures thereof in an amount of from about 1.5 to about 6 mole %;
and
b. a second metal oxide selected from the group consisting of lanthana, neodymia, ytterbia and mixtures thereof in an amount of from about 0.5 to about 8.5 mole %;
and
B. forming a zirconia-containing upper layer wherein the zirconia is stabilized in the cubic crystalline phase by depositing on the lover layer a second zirconia-containing ceramic composition, which comprises:
1. at least about 50 mole % zirconia;
and
2. a stabilizing amount up to about 49 mole % of a stabilizer component comprising:
a. a first metal oxide selected from the group consisting of ytterbia, neodymia, mixtures of ytterbia and neodymia, mixtures of ytterbia and lanthana, mixtures of neodymia and lanthana, and mixtures of ytterbia, neodymia and lanthana in an amount of from about 5 to about 49 mole % of the second composition;
and
b. a second metal oxide selected from the group consisting of yttria, calcia, ceria, scandia, magnesia, india and mixtures thereof in an amount of about 4 mole % or less of the second composition;
and
3. one or more of a third metal oxide selected from the group consisting of:
a. hafnia in an amount from about 0.5 to about 40 mole % of the second composition;
and
b. tantala in an amount of from about 0.5 to about 10 mole % of the second composition.

17 more elements

Dependencies are inferred from the claim text.