Ceramic materials for thermal barrier coatings
First Claim
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 Y3C Al2A Al3D 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.
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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.
57 Citations
13 Claims
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1. A ceramic-metal composite material suitable for use in a high temperature environment comprising:
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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 Y3C Al2A Al3D 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. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A turbine engine component having a thermal barrier coating comprising:
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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 Y3C Al2A Al3D 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. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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Specification