HYBRID CERAMIC MATERIAL COMPOSED OF INSULATING AND STRUCTURAL CERAMIC LAYERS

• US 20030207155A1
• Filed: 09/26/2001
• Published: 11/06/2003
• Est. Priority Date: 03/27/1998
• Status: Active Grant

• Current Assignee: Siemens Energy Incorporated (Siemens AG)
• Original Assignee: Siemens Westinghouse Power Corporation
• Inventors: Lane, Jay E., Morrison, Jay A., Merrill, Gary B., Burke, Michael A.
• Granted Patent: US 6,733,907 B2
• Time in Patent Office: Days
• US Class Current: 428/699
• CPC Class Codes: B32B 18/00 Layered products essentially comprising ceramics, e.g. refractory products
• CPC Class Codes: C04B 2111/28 Fire resistance, i.e. materials resistant to accidental fires or high temperatures
• CPC Class Codes: C04B 2235/5224 Alumina or aluminates
• CPC Class Codes: C04B 2235/5228 Silica and alumina, including aluminosilicates, e.g. mullite
• CPC Class Codes: C04B 2235/77 Density
• CPC Class Codes: C04B 2235/96 Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
• CPC Class Codes: C04B 2235/9607 Thermal properties, e.g. thermal expansion coefficient
• CPC Class Codes: C04B 2237/06 Oxidic interlayers
• CPC Class Codes: C04B 2237/062 based on silica or silicates
• CPC Class Codes: C04B 2237/34 Oxidic
• CPC Class Codes: C04B 2237/341 Silica or silicates
• CPC Class Codes: C04B 2237/343 Alumina or aluminates
• CPC Class Codes: C04B 2237/345 Refractory metal oxides
• CPC Class Codes: C04B 2237/346 Titania or titanates
• CPC Class Codes: C04B 2237/348 Zirconia, hafnia, zirconates or hafnates
• CPC Class Codes: C04B 2237/36 Non-oxidic
• CPC Class Codes: C04B 2237/361 Boron nitride
• CPC Class Codes: C04B 2237/365 Silicon carbide
• CPC Class Codes: C04B 2237/366 Aluminium nitride
• CPC Class Codes: C04B 2237/368 Silicon nitride
• CPC Class Codes: C04B 2237/38 : Fiber or whisker reinforced
• CPC Class Codes: C04B 2237/584 : the different additives being fibers or whiskers
• CPC Class Codes: C04B 2237/62 : Forming laminates or joined articles comprising holes, channels or other types of openings
• CPC Class Codes: C04B 2237/704 : of one or more of the ceramic layers or articles
• CPC Class Codes: C04B 28/34 : containing cold phosphate binders
• CPC Class Codes: C04B 35/00 : Shaped ceramic products characterised by their composition porous ceramic products C04B38/00; ceramic articles characterised by particular shape, see the relevant classes, e.g. linings for casting ladles, tundishes, cups or the like B22D41/02; ceramic substrates for microelectronic semi-conductors H01L23/15; Ceramics compositions containing free metal bonded to carbides, diamond, oxides, borides, nitrides, silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides or sulfides other than as macroscopic reinforcing agents C22C; shaping of ceramics B28B; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products chemical preparation of powders of inorganic compounds C01; infiltration of sintered ceramic preforms with molten metal C04B41/51
• CPC Class Codes: C04B 35/10 : based on aluminium oxide
• CPC Class Codes: C04B 35/515 : based on non-oxide ceramics
• CPC Class Codes: C04B 35/80 : Fibres, filaments, whiskers, platelets, or the like
• CPC Class Codes: C04B 37/001 : directly with other burned ceramic articles
• CPC Class Codes: C04B 37/005 : consisting of glass or ceramic material
• CPC Class Codes: C04B 38/007 : characterised by the pore distribution, e.g. inhomogeneous distribution of pores
• CPC Class Codes: F01D 5/288 : Protective coatings for blades
• CPC Class Codes: F05D 2230/90 : Coating; Surface treatment manufacture with deposition of material F05D2230/30
• CPC Class Codes: F05D 2300/21 : Oxide ceramics
• CPC Class Codes: F05D 2300/6033 : Ceramic matrix composites [CMC]
• CPC Class Codes: F05D 2300/611 : Coating
• CPC Class Codes: Y02T 50/60 : Efficient propulsion technologies, e.g. for aircraft
• CPC Class Codes: Y10T 428/2495 : Thickness [relative or absolute]
• CPC Class Codes: Y10T 428/30 : Self-sustaining carbon mass or layer with impregnant or other layer

Abstract

A hybrid ceramic structure (10), for use in high temperature environments such as in gas turbines, is made from an insulating layer (12) of porous ceramic that is thermally stable at temperatures up to 1700° C. bonded to a high mechanical strength structural layer (8) of denser ceramic that is thermally stable at temperatures up to 1200° C., where optional high temperature resistant adhesive (9) can bond the layers together, where optional cooling ducts (11) can be present in the structural layer and where hot gas (14) can contact the insulating layer (12) and cold gas (15) can contact the structural layer (8).

Claims

1. A hybrid structure material for use in high temperature applications, comprising:

a ceramic insulating layer having a thickness of >

1 mm, and a low thermal conductivity K_th<

4 W/mK, and having a conductivity/thickness ratio less than 2000 W/m²K, wherein the insulating layer is erosion resistant to high velocity gas and particle impact and thermally stable, non-sinterable and is environmentally stable at temperatures greater than 1200°

C.; and

a structural ceramic layer of monolithic ceramic or reinforced ceramic, and wherein the structural layer has higher mechanical strength and lower temperature capability than the insulating layer, and wherein the ceramic insulating layer and structure ceramic layer are bonded together.

2. The hybrid structure of claim 1 wherein the ceramic insulating layer has a thermal stability greater than 1500°

C. and up to 1700°

C. and the structural ceramic layer has thermal stability greater than 1000°

C. and up to 1400°

C.

3. The hybrid structure of claim 1 wherein the ceramic insulating layer is a non-sinterable structure having an interconnecting phase or phases of non-sinterable material.

4. The hybrid structure of claim 1 wherein the ceramic insulating layer is further characterized by columnar structures wherein the columns are either non-sinterable, non-contacting, or coated with non-sinterable material.

5. The hybrid structure of claim 1 wherein the ceramic insulating layer is further characterized by hollow ceramic geometric shapes individually stabilized and subsequently formed into an interconnecting network.

6. The hybrid structure of claims 1 wherein the ceramic insulating layer is further characterized in that the ceramic insulating layer does not appreciably densify (<

5% change in density) or consolidate (<

0.5% linear shrinkage in free-standing condition) during 100 hours of exposure to its maximum intended surface temperature.

7. The hybrid structure of claim 3 wherein the interconnecting and/or thermally stabilizing phase of the ceramic insulating layer is comprised of either a single or compound stable oxide, selected from the group consisting of:

8. The hybrid structure of claim 7 wherein the structural ceramic layer comprises an oxide from the oxide-based family above and is comprised of single or compound oxides formed by a method or methods selected from the group consisting of hot pressing, pressureless sintering, hot isostatic pressing, sol-gel, slurry processing, vacuum infiltration, pressure casting, chemical vapor deposition, physical vapor deposition, or reaction processing by directed metal oxidation.

9. The hybrid structure of claim 8 wherein the oxide structural ceramic layer comprises a composite whose matrix contains additives selected from the group consisting of whiskers, platelets, elongated grains, discontinuous fibers or continuos fibers.

10. The hybrid structure of claim 9 wherein the structural ceramic layer contains continuous fibers which are comprised of any of the polycrystalline multi-filament tows or single crystal mono-filaments and being formed by a method or methods, selected from the group consisting of slurry impregnation, vacuum infiltration, pressure casting, reaction forming, or chemical vapor infiltration.

11. The hybrid structure of claim 10 wherein the fibers within the structural ceramic layer are selected from the group consisting of alumina, mullite, aluminosilicate, YAG, YAG/alumina eutectics, sapphire, and the fibers comprise >

25% by volume of the total composite volume.

12. The hybrid structure of claims 11 wherein the matrix within the structural ceramic layer is densified in the final product to >

50% theoretical density.

13. The hybrid structure of claims 10 wherein the structural ceramic layer fibers are coated with protective or “

debonding”

interface coatings selected from the group consisting of C, BN, fugitive layers, sheelite structures, monazites, xenotimes, or germanates.

14. The hybrid structure of claims 10 wherein the structural ceramic layer is further characterized having a low through-thickness thermal conductivity (Kth<

4 W/mK at maximum substrate material temperature), a moderate thermal expansion coefficient (CTE>

5 ppm/°

C.), a relatively low elastic modulus (E<

150 GPa), and a moderate mechanical strength (generally σ

<

300 MPa in 2D layups).

15. The hybrid structure of claim 1 wherein the structural ceramic layer is from the non-oxide-based family of ceramics comprised of single or compound metal carbides, nitrides, silicides, or borides and formed by any of a variety of methods select from the group of chemical vapor infiltration, melt infiltration, reaction forming (nitriding, directed metal oxidation), hot pressing, pressureless sintering, hot isostatic pressing, or polymer impregnation &

pyrolysis.

16. The hybrid structure of claim 15 wherein the non-oxide structural ceramic layer comprises a continuous fiber reinforced composite whose matrix contains additives selected from the group consisting of whiskers, platelets, elongated grains, reinforced with discontinuous fibers or continues fibers and being formed by a method or methods, selected from the group consisting of slurry impregnation, vacuum infiltration, pressure casting, reaction forming, or chemical vapor infiltration.

17. The hybrid structure of claim 16 wherein the structural ceramic layer contains continuous fibers which are comprised of any of the polycrystalline multi-filament tows or single crystal mono-filaments.

18. The hybrid structure of claim 16 wherein the structural ceramic layer comprises a continuous fiber reinforced composite whose matrix is a material selected from the group consisting of;

19. The hybrid structure of claim 18 wherein the structural ceramic layer continuous fiber reinforced composite contains fibers comprised of a material selected for the group consisting of;

polycrystalline multi-filament tows or mono-filaments of silicon carbide, silicon carbo-nitride, silicon nitride, with or without small additions of Ti, Zr, or B.

20. The hybrid structure of claim 18 wherein the structural ceramic layer continuous fiber reinforced composite the fibers comprise >

25% by volume of the total composite volume.

21. The hybrid structure of claim 18 wherein the structural ceramic layer continuous fiber reinforced composite the matrix is densified to >

50% theoretical density (<

50% porosity in the matrix phase).

22. The hybrid structure of claim 18 wherein the structural ceramic layer continuous fiber reinforced composite the fibers are coated with protective debonding interface coatings selected from a group consisting of C, BN, layered SiC, SiCBN, or any combination thereof.

23. The hybrid structure of claim 18 wherein the structural ceramic layer continuous fiber reinforced composite such composites having a relatively high through-thickness thermal conductivity of Kth>

4 W/mK, a low thermal expansion coefficient of CTE<

5 ppm/°

C., a high elastic modulus of E>

150 Gpa, and a mechanical strength of σ

>

250 MPa in 2D layups.

24. The hybrid structure of claim 1 having a ratio of in-plane elastic moduli of ceramic insulating layer and structural ceramic layer is between 0.05 and 0.5.

25. The hybrid structure of claims 1 having a ratio of in-plane thermal expansion coefficients of insulating layer and structural layer is between 0.5 and 1.2.

26. The hybrid structure of claims 1 where the insulating layer comprises multiple layers of the ceramic insulating layer.

27. The hybrid structure of claim 26 where the insulating layer has a surface layer modified for improved erosion resistance.

28. The hybrid structure of claim 26 where the insulating layer comprises two or more layers having differing thermal expansions selected so as to minimize differential thermal strains in the layer.

29. The hybrid structure of claim 26 where the insulating layer contains one or more layers which have graded composition and/or porosity.