Ceramic materials for thermal barrier coatings

• US 6,015,630 A
• Filed: 04/10/1997
• Issued: 01/18/2000
• Est. Priority Date: 04/10/1997
• Status: Expired due to Fees

• Current Assignee: University of Connecticut (State of Connecticut)
• Original Assignee: University of Connecticut (State of Connecticut)
• Inventors: Gell, Maurice, Klemens, Paul G., Padture, Nitin P.
• Primary Examiner(s): Zimmerman, John J.
• Application Number:
  US08/835,411
• Time in Patent Office: 1,013 Days
• Field of Search: 428/632, 428/633, 428/469, 416/241 B
• US Class Current: 428/632
• CPC Class Codes: B32B 15/04 comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material next to a bituminous or tarry layer B32B11/08; next to a water-setting substance layer B32B13/06; next to a glass layer B32B17/061; next to a cellulosic plastic layer B32B23/042
• CPC Class Codes: C23C 28/00 Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
• CPC Class Codes: F01D 5/288 Protective coatings for blades
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft
• CPC Class Codes: Y10T 428/12611 Oxide-containing component

Abstract

A method for identifying ceramics suitable for use as thermal barrier coatings is presented, based on parameters associated with thermal conductivity, oxygen diffusivity, thermal expansion coefficient, maximum temperature capability, hardness, elastic modulus, density, and chemical reactivity. A ceramic thermal barrier coating and method of manufacture is further presented, the ceramic comprising yttrium aluminum garnet (Y₃ Al₅ O₁₂, or YAG)-based ceramics. Such ceramics are based on yttrium aluminum garnet or other ceramics with the garnet structure and alloys thereof. The ceramics in accordance with the present invention have low thermal conductivity, and are more potentially durable than prior art zirconia based ceramics.

Claims

1. A ceramic-metal composite material suitable for use in a high temperature environment comprising:

a metal substrate having disposed thereon an optional metallic bond coat; and

a YAG-based ceramic thermal barrier coating disposed on the metal substrate or on the optional metallic bond coat, wherein the YAG-based ceramic thermal barrier coating is selected from the group consisting of Y₃^C Al₂^A Al₃^D O₁₂, wherein C, A, and D are sites on the crystal structure, and further wherein all or part of the Al³⁺ on the A sites, D sites, or A and D sites are substituted in an amount effective to provide the YAG-based ceramic thermal barrier coating with a thermal conductivity less than or equal to about 3 Wm^-1 K^-1 at about 1000°

C., an oxygen diffusivity less than or equal to about 10^-15 m² s^-1 at about 1000°

C., a thermal coefficient of expansion greater than or equal to about 9×

10^-6 °

C.^-1, a maximum temperature capability greater than or equal to about 1400°

C., a hardness greater than or equal to about 14 GPa, an elastic modulus less than or equal to about 280 GPa, or a density less than or equal to about 6.4 gcm^-3.

2. The ceramic-metal composite material of claim 1, wherein all or part of the Al³⁺ on the A sites, D sites, or A and D sites are substituted by an element selected from the group consisting of transition elements and mixtures thereof.

3. The ceramic-metal composite material of claim 2, wherein all or part of the Al³⁺ on the A sites, D sites, or A and D sites are substituted by an element selected from the group consisting of iron, gallium, scandium, and mixtures thereof.

4. The ceramic-metal composite material of claim 1, wherein all or part of the Y^3- on the C site is substituted by an element selected from the group consisting of rare earth elements and mixtures thereof.

5. The ceramic-metal composite material of claim 2, wherein all or part of the Y³⁺ on the C site is substituted by an element selected from the group consisting of cerium, neodymium, terbium, ytterbium, and mixtures thereof.

6. The ceramic-metal composite material of claim 2, wherein the metallic bond coat is omitted and the YAG-based ceramic thermal barrier coating is disposed directly upon the metal substrate.

7. A turbine engine component having a thermal barrier coating comprising:

a turbine engine component having disposed thereon an optional metallic bond coat; and

a thermal barrier coating disposed on the optional metallic bond coat or on the turbine engine component, wherein the thermal barrier coating comprises a YAG-based ceramic selected from the group consisting of Y₃^C Al₂^A Al₃^D O₁₂, wherein C, A, and D are sites on the crystal structure, and further wherein all or part of the Al³⁺ on the A sites, D sites, or A and D sites are substituted in an amount effective to provide the YAG-based ceramic thermal barrier coating with a thermal conductivity less than or equal to about 3 Wm^-1 K^-1 at about 1000°

C., an oxygen diffusivity less than or equal to about 10^-15 m² s^-1 at about 1100°

C., a thermal coefficient of expansion greater than or equal to about 9×

10^-6 °

C.^-1, a maximum temperature capability greater than or equal to about 1400°

C., a hardness greater than or equal to about 14 GPa, an elastic modulus less than or equal to about 280 GPa, or a density less than or equal to about 6.4 gcm^-3.

8. The turbine engine component of claim 7, wherein all or part of the aluminum Al³⁺ on the A and/or D sites are substituted by an element selected from the group consisting of transition elements and mixtures thereof.

9. The turbine engine component of claim 8, wherein all or part of the aluminum Al³⁺ on the A sites, D sites or A and D sites are substituted by an element selected from the group consisting of iron, gallium or scandium and mixtures thereof.

10. The turbine engine component of claim 7 wherein, all or part of the Y³⁺ on the C site is substituted by an element selected from the group consisting of rare earth elements and mixtures thereof.

11. The turbine engine component of claim 10 wherein, wherein all or part of the aluminum Al³⁺ on the A and/or D sites are substituted by an element selected from the group consisting of cerium, neodymium, erbium, ytterbium, and mixtures thereof.

12. The turbine engine component of claim 7, further comprising a metallic bond coat disposed between the YAG-based ceramic thermal barrier and the turbine engine component.

13. The turbine engine component of claim 7, wherein the turbine engine component is a blade or a vane.