Ceramic matrix composite / environmental barrier coating bonding layer integrated preparation method

Abstract

The invention relates to a ceramic-based composite material / environmental barrier coating bonding layer integrated preparation method, which is characterized in that an EBC bonding layer is introduced in the preparation process of a composite material through dipping-curing-cracking process treatment, so that the composite material is prevented from being subjected to high temperature again, the mechanical property of the composite material is ensured, and the preparation efficiency of a coating is improved; a SiBCX ceramic coating is prepared on the surface of a composite material by adopting a ceramic precursor containing silicon and boron, and an EBC coating bonding layer with the thermal expansion coefficient close to that of the composite material is formed. The bonding layer is prepared from the ceramic precursor, so that thermal mismatching of the bonding layer can be effectively avoided, the temperature resistance level of the environmental barrier coating is improved, and meanwhile, the preparation efficiency of the environmental barrier coating can also be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of surface engineering, and in particular relates to an integrated preparation method for a ceramic-based composite material / environmental barrier coating bonding layer. Background Art

[0002] With the development of aerospace technology, the development of aircraft engines with higher thrust-to-weight ratio and higher combustion efficiency has become a hot topic in current research. The components in the combustion system of high thrust-to-weight ratio aircraft engines need to withstand higher temperatures and higher stresses, which requires the component materials to have higher strength, toughness and heat resistance. In recent years, SiC fiber reinforced SiC ceramic matrix composites (SiC f / SiC-CMC) has become a key material for the hot end components of the next generation of high thrust-to-weight ratio aviation gas turbine engines due to its good high-temperature mechanical properties, corrosion resistance and high-temperature oxidation resistance.

[0003] Under high temperature and dry air atmosphere conditions, SiC f / SiC-CMC reacts with oxygen to form a protective SiO2 layer. The dense SiO2 glass phase can effectively prevent oxygen from entering SiC f / SiC-CMC internal diffusion is conducive to the stability of CMC's high temperature performance. However, the fuel gas environment of aircraft engines is very harsh, containing water vapor, oxygen, molten salt impurities (Na, K, V, S, etc.) and oxidizing and corrosive media such as volcanic ash, coupled with high pressure, high temperature, high-speed fuel gas scouring (fuel gas flow rate of 1-2Mah) and complex stress. The harsh fuel gas environment will seriously limit SiC f / The service life of SiC-CMC is the key to limiting its large-scale application in gas turbines and aircraft engines. In order to solve this problem, scientists have proposed to prepare an environmental barrier coating (EBC) on the surface of CMC to isolate it from these harsh service environments, thereby improving its service performance.

[0004] Environmental barrier coatings (EBC) are generally designed as three-layer structures, including a top layer, a middle layer and a bonding layer from the outside to the inside. The ceramic-based composite material substrate to be protected is in direct contact with the bonding layer. The three layers of EBC coatings have different functions: the top layer is directly exposed to the external environment, providing the first layer of heat insulation and corrosion protection; the middle layer is used as a transition layer to adjust the matching of the thermal expansion coefficient and chemical compatibility between the top layer and the bonding layer, and can further protect the bonding layer. The bonding layer can improve the matching of the modulus and CTE of the coating system and the substrate, and enhance the bonding strength between the substrate and the entire coating system.

[0005] Si is a commonly used EBCs bonding layer material with a melting point of 1414°C and a CTE of 2.6-3.5×10 -6 ℃-1 ) and SiC (4.5×10 -6 ℃ -1 ) is relatively close, and has a low Young's modulus and good bonding properties. These advantages make it a widely used bonding layer material. Under the condition of temperature below the softening point (below 1400℃), Si is oxidized to SiO2, and the diffusion rate of oxygen in SiO2 is low, which can slow down the further oxidation of the bonding layer. However, SiO2 in the cristobalite phase undergoes a β-α phase transition at about 277℃ during cooling, accompanied by a volume shrinkage of about 5%, and the CTE of α-cristobalite is 9.6×10 -6 ℃ -1 , an order of magnitude higher than the CTE of the CMC substrate, all of which can lead to stress concentrations, crack formation, and coating failure during repeated heating and cooling cycles.

[0006] The preparation process of the bonding layer mainly follows the traditional coating preparation technology. Currently, the commonly used preparation methods include low-pressure plasma spraying (LPPS), supersonic flame spraying (HVOF), plasma spraying (APS), etc. These preparation processes all require high-temperature treatment at 5000℃-10000℃. When the composite material experiences high temperature again, the SiC matrix will crystallize, resulting in a decrease in the mechanical properties of the composite material. Summary of the invention

[0007] In order to overcome the shortcomings of the prior art, the present invention provides an integrated preparation method for a ceramic-based composite material / environmental barrier coating bonding layer. An EBC bonding layer is introduced during the preparation of the composite material to prevent the composite material from experiencing high temperature again, thereby ensuring the mechanical properties of the composite material and improving the preparation efficiency of the coating. A silicon-boron-containing ceramic precursor is used to prepare a SiBCX ceramic coating on the surface of the composite material to form an EBC coating bonding layer whose thermal expansion coefficient is close to that of the composite material.

[0008] The above-mentioned purpose of the present invention is mainly achieved through the following technical solutions:

[0009] A method for preparing an integrated ceramic matrix composite material / environmental barrier coating bonding layer comprises the following steps:

[0010] (1) mixing a ceramic precursor and a powder, adding a powder dispersant, and stirring until the mixture is uniform to obtain a precursor impregnation solution;

[0011] (2) immersing the composite material in the precursor impregnation solution obtained in step (1) at 25-100° C. for 2-6 hours;

[0012] (3) subjecting the impregnated composite material obtained in step (2) to thermal curing;

[0013] (4) placing the cured composite material obtained in step (3) in a cracking furnace for cracking treatment;

[0014] (5) Repeating the impregnation-curing-cracking process of step (2), step (3) and step (4) for 1 to 4 times on the composite material obtained in step (4);

[0015] (6) performing static oxidation treatment on the composite material obtained in step (5) to obtain a ceramic-based composite material / environmental barrier coating bonding layer integrated material;

[0016] The ceramic precursor includes at least one of a silicon-boron-carbon-nitride ceramic precursor, a zirconium boride-silicon carbide ceramic precursor or a hafnium boride-silicon carbide ceramic precursor.

[0017] The composite material comprises C f / SiC、SiC f / SiC、SiC f / SiCN or SiC f / SiBCN at least one.

[0018] The powder in the precursor impregnation solution is zirconium silicide powder, yttrium oxide powder or titanium silicide powder.

[0019] The powder content in the precursor impregnation liquid is 10-50wt%, the powder particle size range is 5-30μm, and the viscosity of the precursor impregnation liquid is 20-300cP.

[0020] The heat curing treatment process conditions in step (3) are as follows: the curing treatment temperature is 100-300°C and the time is 1-3h.

[0021] The cracking treatment process conditions of step (4) are as follows: cracking at 900-1300°C in an argon environment, with a heating rate of 5-20°C / min and a time of 1-4h.

[0022] The static oxidation treatment process conditions of step (6) are as follows: pyrolysis at 800-1500°C in an air environment, a heating rate of 10-50°C / min, and a time of 0.5-3h.

[0023] The thickness of the bonding layer in the ceramic-based composite material / environmental barrier coating bonding layer integrated material is 50-500 μm.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] (1) The present invention simplifies the preparation process of the EBC coating by introducing an EBC bonding layer during the preparation of the composite material, avoids the composite material from experiencing high temperature again, ensures the mechanical properties of the composite material, and improves the preparation efficiency of the coating.

[0026] (2) The present invention uses a ceramic precursor containing silicon and boron to prepare a SiBCX ceramic coating on the surface of the composite material, making it a bonding layer of the EBC coating. The bonding layer can withstand a temperature of 2000°C and has a thermal expansion coefficient of 4.5×10 -6 ℃ -1 Close to composite materials.

[0027] (3) The bonding layer of the present invention forms SiO2-B2O3 borosilicate glass after 1100°C. The borosilicate glass has appropriate viscosity and high saturated vapor pressure at high temperatures, and forms liquid borosilicate glass with stable structure on the surface of the composite material, which can effectively fill the cracks on the surface of the composite material and effectively prevent oxygen from entering.

[0028] (4) The present invention can adjust the content ratio of silicon to boron, thereby regulating the viscosity and temperature resistance of SiO2-B2O3 borosilicate glass.

[0029] (5) The present invention adds powder to a ceramic precursor, and the volume expansion of the powder during oxidation offsets the high-temperature cracking and shrinkage of the ceramic precursor, thereby obtaining a densified bonding layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention is a process flow chart for preparing the surface bonding layer of the composite material;

[0031] Figure 2 This is a microscopic photograph of the bonding layer in Example 3 of the present invention. DETAILED DESCRIPTION

[0032] The present application is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] like Figure 1 The process flow chart of preparing the surface bonding layer of the composite material of the present invention is shown in the figure. The present invention adopts the PIP method to prepare the bonding layer of the ceramic-based composite material. 2 The composite material has been processed through multiple rounds of "impregnation-curing-cracking" process, so that the density of the composite material reaches 1.8-2.2g / cm 3 , and at the same time, a bonding layer with a thickness of 50-500μm is obtained, realizing the integrated preparation of the ceramic-based composite material / environmental barrier coating bonding layer.

[0034] Example 1

[0035] Place 200g of SiBCN precursor impregnation liquid (viscosity 60cP, temperature 25°C, mixed with 40wt% of 10μm zirconium silicide powder) in the impregnation chamber and immerse for 4 hours. Then place the impregnated composite material in an oven and cure it at 150°C for 2 hours. Place the cured composite material in a high-temperature cracking furnace and pyrolyze it at 1200°C for 2 hours with a heating rate of 15°C / min. Repeat the above process 4 times. Static oxidation at 1400°C for 1 hour with a heating rate of 10°C / min. Until a bonding layer of about 200μm is prepared on the surface of the composite material. The density of the composite material is 2.01g / cm 3 At 1200°C, the thermal expansion coefficient of the bonding layer is 6.2×10 -6 K -1 .

[0036] Example 2

[0037] Place 200g of SiBCN ceramic precursor (viscosity 20cP, temperature 50℃, mixed with 50wt% of 30μm titanium silicide powder) in an impregnation chamber for 4 hours, then place the impregnated composite material in an oven and cure it at 200℃ for 3 hours. Place the cured composite material in a high-temperature cracking furnace and perform high-temperature cracking at 1300℃ for 1 hour with a heating rate of 10℃ / min. Repeat the above process 4 times. Static oxidation at 1400℃ for 1 hour with a heating rate of 20℃ / min. Until a bonding layer of about 250μm is prepared on the surface of the composite material. The density of the composite material is 2.13g / cm 3 At 1200°C, the thermal expansion coefficient of the bonding layer is 5.3×10 - 6 K -1 .

[0038] Example 3

[0039] Place 200g of zirconium boride-silicon carbide ceramic precursor (viscosity 70cP, temperature 80°C, mixed with 20wt% of 10μm zirconium silicide powder) in an impregnation chamber and immerse for 2 hours. Then place the impregnated composite material in an oven and cure it at 250°C for 2 hours. Place the cured composite material in a high-temperature cracking furnace and pyrolyze it at 1000°C for 3 hours with a heating rate of 20°C / min. Repeat the above process 3 times. Static oxidation at 1200°C for 2 hours with a heating rate of 10°C / min. Until a bonding layer of about 200μm is prepared on the surface of the composite material. Figure 2 The density of the composite material is 1.88 g / cm 3 At 1200°C, the thermal expansion coefficient of the bonding layer is 4.7×10 -6 K -1 .

[0040] Example 4

[0041] Place 200g of hafnium boride-silicon carbide ceramic precursor (viscosity 80cP, temperature 80°C, mixed with 20wt% of 20μm zirconium silicide powder) in an impregnation chamber and immerse for 2 hours. Then place the impregnated composite material in an oven and cure it at 220°C for 2 hours. Place the cured composite material in a high-temperature cracking furnace and pyrolyze it at 1300°C for 3 hours with a heating rate of 10°C / min. Repeat the above process twice. Static oxidation at 1500°C for 3 hours with a heating rate of 20°C / min. Until a bonding layer of about 150 microns is prepared on the surface of the composite material. The density of the composite material is 1.92g / cm 3 At 1200°C, the thermal expansion coefficient of the bonding layer is 4.7×10 -6 K -1 .

[0042] The above description is only the best specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

[0043] The contents not described in detail in the specification of the present invention belong to the common knowledge of the professionals in this field.

Claims

1. A method for preparing an integrated ceramic matrix composite material / environmental barrier coating bonding layer, characterized in that: The following steps are involved: (1) mixing a ceramic precursor and a powder, adding a powder dispersant, and stirring until the mixture is uniform to obtain a precursor impregnation solution; (2) immersing the composite material in the precursor impregnation solution obtained in step (1) at 25-100° C. for 2-6 hours; (3) subjecting the impregnated composite material obtained in step (2) to thermal curing; (4) placing the cured composite material obtained in step (3) in a cracking furnace for cracking treatment; (5) Repeating the impregnation-curing-cracking process of step (2), step (3) and step (4) for 1 to 4 times on the composite material obtained in step (4); (6) performing static oxidation treatment on the composite material obtained in step (5) to obtain a ceramic-based composite material / environmental barrier coating bonding layer integrated material; The ceramic precursor includes at least one of a silicon-boron-carbon-nitride ceramic precursor, a zirconium boride-silicon carbide ceramic precursor or a hafnium boride-silicon carbide ceramic precursor.

2. The method for preparing an integrated ceramic matrix composite material / environmental barrier coating bonding layer according to claim 1, characterized in that: The composite material comprises C f / SiC、SiC f / SiC、SiC f / SiCN or SiC f / SiBCN at least one.

3. The method for preparing an integrated ceramic matrix composite material / environmental barrier coating bonding layer according to claim 1, characterized in that: The powder in the precursor impregnation solution is zirconium silicide powder, yttrium oxide powder or titanium silicide powder.

4. The method for preparing an integrated ceramic matrix composite material / environmental barrier coating bonding layer according to claim 1, characterized in that: The powder content in the precursor impregnation liquid is 10-50wt%, the powder particle size range is 5-30μm, and the viscosity of the precursor impregnation liquid is 20-300cP.

5. The method for preparing an integrated ceramic matrix composite material / environmental barrier coating bonding layer according to claim 1, characterized in that: The heat curing treatment process conditions in step (3) are as follows: the curing treatment temperature is 100-300°C and the time is 1-3h.

6. The method for preparing an integrated ceramic matrix composite material / environmental barrier coating bonding layer according to claim 1, characterized in that: The cracking treatment process conditions of step (4) are as follows: cracking at 900-1300°C in an argon environment, with a heating rate of 5-20°C / min and a time of 1-4h.

7. The method for preparing an integrated ceramic matrix composite material / environmental barrier coating bonding layer according to claim 1, characterized in that: The static oxidation treatment process conditions of step (6) are as follows: pyrolysis at 800-1500°C in an air environment, a heating rate of 10-50°C / min, and a time of 0.5-3h.

8. A ceramic matrix composite material / environmental barrier coating bonding layer integrated material, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 7.

9. The ceramic matrix composite material / environmental barrier coating bonding layer integrated material according to claim 8, characterized in that: The thickness of the bonding layer in the ceramic-based composite material / environmental barrier coating bonding layer integrated material is 50-500 μm.

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