MULTI-CONSTITUENT ENVIRONMENTAL BARRIER COATING

Abstract

Environmental barrier coatings or coating systems that contain a bond coat, the bond coat containing an oxide matrix, and dispersed throughout the oxide matrix an oxidant gettering phase, a SiO.sub.2 based phase, that may be amorphous or crystalline, a crystalline phase, and an amorphous oxide phase, which is a self-healing phase having the ability to soften or melt and flow into cracks formed in the oxide matrix at predetermined temperatures that are below the melting temperature of the oxide matrix, where the amorphous oxide phase contains an alkaline earth alumino-silicate, and the crystalline phase contains Al.sub.6Si.sub.2O.sub.13, ZrSiO.sub.4, HfSiO.sub.4, Ca.sub.2ZrSi.sub.4O.sub.12, Ca.sub.2HfSi.sub.4O.sub.12, CaAl.sub.2Si.sub.2O.sub.8, CaSiO.sub.3, Al.sub.2TiO.sub.5, Mg.sub.2Al.sub.4Si.sub.5O.sub.18, BaAl.sub.2Si.sub.2O.sub.8, BaZrSi.sub.3O.sub.9, Y.sub.2Si.sub.2O.sub.7, Yb.sub.2Si.sub.2O.sub.7, and/or Al.sub.2O.sub.3, and methods for protecting ceramic matrix composite materials.

Claims

1. An environmental barrier coating having a bond coat layer, and comprising in said bond coat layer an oxide matrix, and dispersed throughout said oxide matrix: i) an oxidant gettering phase that forms silicon oxide, ii) a SiO.sub.2 based phase, that may be amorphous or crystalline, iii) a crystalline phase, and iv) an amorphous oxide phase, which is a self-healing phase having the ability to soften or melt and flow into cracks formed in the oxide matrix at predetermined temperatures that are below the melting temperature of the oxide matrix, wherein the amorphous oxide phase comprises an alkaline earth alumino-silicate glass, and the crystalline phase comprises Al.sub.6Si.sub.2O.sub.13, ZrSiO.sub.4, HfSiO.sub.4, Ca.sub.2ZrSi.sub.4O.sub.12, Ca.sub.2HfSi.sub.4O.sub.12, CaAl.sub.2Si.sub.2O.sub.8, CaSiO.sub.3, Al.sub.2TiO.sub.5, Mg.sub.2Al.sub.4Si.sub.5O.sub.18, BaAl.sub.2Si.sub.2O.sub.8, BaZrSi.sub.3O.sub.9, Y.sub.2Si.sub.2O.sub.7, Yb.sub.2Si.sub.2O.sub.7 and/or Al.sub.2O.sub.3, and in case the SiO.sub.2 based phase of ii) is amorphous, the crystalline phase may additionally include among the options above crystalline SiO.sub.2.

2. The environmental barrier coating according to claim 1, wherein the amorphous oxide phase comprises a calcium alumino-silicate glass with an incipient melting point between 115 and 1300 C. and viscosity between 200 and 20,000 Pa.Math.s at 1300 C. and 1 and 500 Pa.Math.s at 1500 C., which calcium alumino-silicate glass is optionally doped with one or more rare earth elements or transition metal elements.

3. The environmental barrier coating according to claim 1, wherein the amorphous oxide phase comprises a barium-magnesium alumino silicate glass.

4. The environmental barrier coating according to claim 1, which contains in the bond coat layer the oxide matrix in an amount of 1 to 25 vol. %, i) the oxidant gettering phase in an amount of 25 to 75 vol. %, ii) the crystalline phase in an amount of 5 to 50 vol. %, and iii) the amorphous oxide phase in an amount of 1 to 10 vol. %.

5. The environmental barrier coating according to claim 1, wherein the oxide matrix is SiO.sub.2.

6. The environmental barrier coating according to claim 1, wherein the oxidant gettering phase is Si.sub.xO.sub.yC.sub.z where 0.5x<1; 0y<2; 0z<2, or is Si.sub.3N.sub.4 or SiCN.

7. The environmental barrier coating according to claim 1, wherein the oxidant gettering phase is SiC.

8. The environmental barrier coating according to claim 1, wherein the bond coat layer comprises 50% vol. % SiC gettering phase, 25 vol. % ZrSiO.sub.4, 20 vol. % SiO.sub.2 matrix phase, and 5 vol. % self-healing phase composed of a calcium alumino-silicate glass with an incipient melting point between 115 and 1200 C. and viscosity between 1,000 and 50,000 Pa.Math.s at 1260 C. and 10 and 500 Pa.Math.s at 1482 C.

9. The environmental barrier coating according to claim 1, wherein the bond coat layer comprises 50% vol. % SiC gettering phase, 25 vol. % Ca.sub.2HfSi.sub.4O.sub.12, 20 vol. % SiO.sub.2 matrix phase, and 5 vol. % self-healing phase composed of a calcium alumino-silicate glass with an incipient melting point between 115 and 1200 C. and viscosity between 1,000 and 50,000 Pa.Math.s at 1260 C. and 10 and 500 Pa.Math.s at 1482 C.

10. The environmental barrier coating according to claim 1, wherein the bond coat layer comprises 40-70 vol. % SiC gettering phase, 10-30 vol. % ZrSiO.sub.4, 10-30 vol. % SiO.sub.2 matrix phase, and 5-10 vol. % self-healing phase composed of a calcium alumino-silicate glass with an incipient melting point between 115 and 1200 C. and viscosity between 1,000 and 50,000 Pa.Math.s at 1260 C. and 10 and 500 Pa.Math.s at 1482 C.

11. The environmental barrier coating according to claim 1, wherein the bond coat layer comprises 40-70% vol. % SiC gettering phase, 5-50 vol. % ZrSiO.sub.4, 5-20 vol. % SiO.sub.2 matrix phase, and 1-10 vol. % self-healing phase composed of a calcium alumino-silicate glass with an incipient melting point between 115 and 1200 C. and viscosity between 1,000 and 50,000 Pa.Math.s at 1260 C. and 10 and 500 Pa.Math.s at 1482 C.

12. The environmental barrier coating according to claim 1, wherein the bond coat layer comprises 50% vol. % SiC gettering phase, 25 vol. % Al.sub.6Si.sub.2O.sub.13, 20 vol. % SiO.sub.2 matrix phase, and 5% self-healing phase composed of a calcium alumino-silicate glass with an incipient melting point between 115 and 1200 C. and viscosity between 1,000 and 50,000 Pa.Math.s at 1260 C. and 10 and 500 Pa.Math.s at 1482 C.

13. The environmental barrier coating according to claim 1, wherein the bond coat layer comprises 50% vol. % SiC gettering phase, 20-25 vol. % Al.sub.6Si.sub.2O.sub.13 20-25 vol. % SiO.sub.2 matrix phase, and 3-5 vol. % self-healing phase composed of a rare earth aluminate silicate glass with an incipient melting point between 115 and 1200 C. and viscosity between 1,000 and 50,000 Pa.Math.s at 1260 C. and 10 and 500 Pa.Math.s at 1482 C.

14. The environmental barrier coating according to claim 1, wherein the bond coat layer comprises 40-70% vol. % SiC gettering phase, 5-50 vol. % ZrSiO.sub.4, 5-20 vol. % SiO.sub.2 matrix phase, and 1-10 vol. % self-healing phase composed of a ytterbium aluminum silicate glass with an incipient melting point between 135 and 1500 C. and viscosity between 1,000 and 50,000 Pa.Math.s at 1260 C. and 10 and 500 Pa.Math.s at 1482 C.

15. The environmental barrier coating according to claim 1, wherein the oxidant gettering phase, the crystalline phase and/or the amorphous oxide phase are dispersed in the oxide matrix in the form of discrete particles.

16. A turbine vane or blade or turbine engine component, comprising thereon the coating according to claim 1.

17. An environmental coating system on a silicon containing material, which coating system contains as a bond coat layer, and on top thereof a protective top coat, wherein the bond coat layer comprises an oxide matrix, and dispersed throughout said oxide matrix: i) an oxidant gettering phase that forms silicon oxide, ii) a SiO.sub.2 based phase, that may be amorphous or crystalline, iii) a crystalline phase, and iv) an amorphous oxide phase, which is a self-healing phase having the ability to soften or melt and flow into cracks formed in the oxide matrix at predetermined temperatures that are below the melting temperature of the oxide matrix, wherein the amorphous oxide phase comprises an alkaline earth alumino-silicate glass, and the crystalline phase comprises Al.sub.6Si.sub.2O.sub.13, ZrSiO.sub.4, HfSiO.sub.4, Ca.sub.2ZrSi.sub.4O.sub.12, Ca.sub.2HfSi.sub.4O.sub.12, CaAl.sub.2Si.sub.2O.sub.8, CaSiO.sub.3, Al.sub.2TiO.sub.5,Mg.sub.2Al.sub.4Si.sub.5O.sub.18, BaAl.sub.2Si.sub.2O.sub.8, BaZrSi.sub.3O.sub.9, Y.sub.2Si.sub.2O.sub.7, Yb.sub.2Si.sub.2O.sub.7, and/or Al.sub.2O.sub.3, and in case the SiO.sub.2 based phase of ii) is amorphous, the crystalline phase may additionally include among the options above crystalline SiO.sub.2.

18. The environmental barrier coating system according to claim 17, wherein the silicon containing material is a ceramic matrix composite material.

19. The environmental barrier coating system according to claim 17, wherein the top coat comprises binary or multicomponent oxides, HfO.sub.2, ZrO.sub.2, Gd.sub.2Hf.sub.2O.sub.7, Gd.sub.2Zr.sub.2O.sub.7, refractory metal oxides, silicates, rare earth-monosilicates or disilicates, alkaline earth alumino silicates, or silicates of hafnium or zirconium.

20. A method for protecting a ceramic matrix composite material comprising applying thereon a bond coat layer and on top thereof a top coat, wherein the bond coat layer comprises an oxide matrix, and dispersed throughout said oxide matrix: i) an oxidant gettering phase that forms silicon oxide, ii) a SiO.sub.2 based phase, that may be amorphous or crystalline, iii) a crystalline phase, and iv) an amorphous oxide phase, which is a self-healing phase having the ability to soften or melt and flow into cracks formed in the oxide matrix at predetermined temperatures that are below the melting temperature of the oxide matrix, wherein the amorphous oxide phase comprises an alkaline earth alumino-silicate glass, and the crystalline phase comprises Al.sub.6Si.sub.2O.sub.13, ZrSiO.sub.4, HfSiO.sub.4, Ca.sub.2ZrSi.sub.4O.sub.12, Ca.sub.2HfSi.sub.4O.sub.12, CaAl.sub.2Si.sub.2O.sub.8, CaSiO.sub.3, Al.sub.2TiO.sub.5, Mg.sub.2Al.sub.4Si.sub.5O.sub.18, BaAl.sub.2Si.sub.2O.sub.8, BaZrSi.sub.3O.sub.9, Y.sub.2Si.sub.2O.sub.7, Yb.sub.2Si.sub.2O.sub.7, and/or Al.sub.2O.sub.3, and in case the SiO.sub.2 based phase of ii) is amorphous, the crystalline phase may additionally include among the options above crystalline SiO.sub.2.

Description

BRIEF DESCRIPTION OF DRAWING

[0159] Implementations of the inventive concepts disclosed herein may be better understood when consideration is given to the following detailed description thereof. Such descriptions make reference to the included drawings, which are not necessarily to scale, and which some features may be exaggerated and some features may be omitted or may be represented schematically in the interest of clarity. Like reference numerals in the drawings may represent and refer to the same or similar element, feature, or function.

[0160] FIG. 1 illustrates a coating system,

[0161] FIG. 2 illustrates the phase constitution of specific embodiment #2 in Table 1 as a function of temperature,

[0162] FIG. 3 illustrates of the viscosity as a function of temperature for the slag (molten oxide) present in embodiment #2 in Table 1,

[0163] FIG. 4 illustrates the phase constitution of specific embodiment #2 in Table 2 as a function of temperature

[0164] FIG. 5 illustrates of the viscosity as a function of temperature for the slag (molten oxide) present in embodiment #2 in Table 1

[0165] In more detail, FIG. 1 shows a coating system (100) on a CMC component/substrate (130), where the bond coat (120) contains, in a matrix (128), particles of a crystalline phase (124), a self-healing glass (126) as well as gettering particles (122). On top of the bond coat is a top coat (110), which may have a porosity (112).

[0166] FIG. 2 shows a mole fraction of the phases present in embodiment 2 in Table 1 above, where with increasing temperature the phases of various components change. The slag contains mostly SiC, SiO.sub.2, ZrSiO.sub.4 and a molten oxide.

[0167] FIG. 3 shows a viscosity graph of embodiment 2 in T able 1.

[0168] FIG. 4 shows a mole fraction of the phases present in embodiment 2 in Table 2 above, where with increasing temperature the phases of various components change. The slag contains mostly SiC, SiO.sub.2, ZrSiO.sub.4, mullite and a molten oxide

[0169] FIG. 5 shows a viscosity graph of embodiment 2 in Table 2.

LEGEND FOR FIGURES

[0170] FIG. 1: [0171] 100Coating System [0172] 110Top Coat [0173] 112Porosity [0174] 120Bond Coat [0175] 122Gettering Particle [0176] 124Crystalline Phase [0177] 126Self-healing Glass [0178] 128Bond Coat Matrix [0179] 130CMC [0180] FIG. 2: [0181] 200Graph of the phase constitution diagram of specific embodiment #2 in Table 1 as a function of temperature [0182] 202Ca.sub.2ZrSi.sub.4O.sub.12 [0183] 204CaAl.sub.2Si.sub.2O.sub.8 [0184] 206Slag [0185] 208SiO.sub.2 [0186] 210ZrSiO.sub.4 [0187] 212SiC [0188] FIG. 3: [0189] 300Graph of the viscosity as a function of temperature for the slag (molten oxide) present in embodiment #2 in Table 1 [0190] 302Slag [0191] FIG. 4: [0192] 400Graph of the phase constitution of specific embodiment #2 in Table 2 as a function of temperature [0193] 402Al.sub.6Si.sub.2O.sub.13 [0194] 403Mg.sub.2Al.sub.4Si.sub.2O.sub.18 [0195] 404BaAl.sub.2Si.sub.2O.sub.8 [0196] 406Slag [0197] 408SiO.sub.2 [0198] 410ZrSiO.sub.4 [0199] 412SiC [0200] FIG. 5: [0201] 500Graph of the viscosity as a function of temperature for the slag (molten oxide) present in embodiment #2 in Table 1 [0202] 502Slag

Example of Method of Preparation

[0203] The bond coating can be fabricated using a slurry coating method. The appropriate slurries can be prepared by mixing components, such as, silicon carbide, hafnium silicate, barium-magnesium alumino-silicate, and powder of silicon oxide in a carrier fluid, such as water. The slurry can be mixed by a ball milling and the resulting slurry can be sprayed onto an underlying substrate. The slurry can be dried at room temperature and cured at 200 C. for 1 hour. The coating can then be sintered at 1500 C. for 1 hour in air.

[0204] As will be appreciated by one skilled in the art, the embodiments described herein may be embodied as a method of use or preparation, a product, including a part for use in various assemblies, or use per se.

[0205] The description of the embodiments described herein has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill without departing from the scope and spirit of the invention. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for embodiments with various modifications as are suited to the particular use contemplated.

[0206] Modifications and equivalents may be made to the features disclosed without departing from the spirit or scope of the invention. Thus, it is intended that the embodiments described herein covers the modifications and variations disclosed above, including changes that lead to equivalents, i.e., modifications and equivalents may be made to the features of the claims without departing from the scope of the invention.