Al2O3 modified Yb2Si2O7 material for environmental barrier coating on hot end component surface, preparation method and application thereof

Abstract

The present invention discloses an Al2O3 modified Yb2Si2O7 material for a hot end component surface environmental barrier coating, and its preparation method and application, belonging to the field of environmental barrier coating. The material is synthesized by a solid phase reaction combined with a sintering process. The obtained material contains both Yb2Si2O7 and Yb3Al5O 12 Compared with undoped Yb2Si2O7, the doped material is denser, has lower porosity and higher density, and at the same time, Yb3Al5O will be generated at high temperature after doping. 12 It will effectively improve the high-temperature corrosion resistance of Yb2Si2O7, increase its service life, and has good application prospects.

Description

Technical Field

[0001] The present invention belongs to the field of environmental barrier coatings on the surfaces of aviation engines, and in particular relates to an Al2O3-modified Yb2Si2O7 material for environmental barrier coatings on the surfaces of hot end components, and a preparation method and application thereof. Background Art

[0002] With the continuous improvement of thrust-to-weight ratio requirements for new generation aircraft engines, the service temperature requirements have reached 1400℃ and above, and traditional nickel-based high-temperature alloys have been unable to meet their needs. f / SiC ceramic matrix composites, due to their excellent high-temperature mechanical properties and high specific strength, have become a popular candidate material for the hot end components of the new generation of aircraft engines with a thrust-to-weight ratio of 15-20.

[0003] When serving in an environment with high temperature, gas erosion, high temperature corrosion and interactive coupling of complex stress conditions, SiC f A protective SiO2 film forms on the surface of SiC ceramic-based composites. However, this dense silicon oxide film reacts with water vapor to form volatile silicon hydroxide, primarily Si(OH)4. Continuous volatilization consumes the surface material and leaves behind numerous pores and cracks that facilitate corrosion, impacting the material's performance and lifespan.

[0004] To improve the service reliability of CMCs in this service environment, researchers have proposed the concept of environmental barrier coatings (EBCs). In EBC systems, rare earth monosilicates, represented by ytterbium monosilicate (Yb2SiO5), have low silicon activity and, therefore, excellent high-temperature resistance to water vapor and CMAS corrosion. Unfortunately, the thermal expansion coefficient of rare earth monosilicates differs significantly from that of the substrate and the silicon bonding layer. This causes the coating to crack due to mismatched thermal expansion deformation at high temperatures, affecting service performance. Disilicates, represented by ytterbium disilicate (Yb2Si2O7), although their thermal expansion coefficient matches that of the substrate, their higher silicon activity makes them prone to reaction with corrosive media, leaving fatal holes in the surface, which is not conducive to long-term service. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a preparation method and application of Al2O3-modified Yb2Si2O7 material for environmental barrier coating on the surface of hot end components. Specifically, by doping Al2O3 into Yb2Si2O7, the shortcomings of the ceramic material itself, such as high porosity and poor density, can be improved, and the material's resistance to high-temperature CMAS corrosion can be increased, so that it can play a good role in protecting the substrate under service conditions.

[0006] In order to solve the problems of the prior art, the present invention adopts the following technical solutions:

[0007] A method for preparing an Al2O3-modified Yb2Si2O7 material for an environmental barrier coating on a hot end component surface comprises synthesizing the Al2O3-modified Yb2Si2O7 material by a solid-phase reaction combined with a sintering process, specifically comprising the following steps:

[0008] Step 1, preparation of Yb2Si2O7 powder raw materials:

[0009] Yb2O3 and SiO2 powders were weighed in a weight ratio of 3.2784:1, and then placed in a ball mill with 99.9% pure anhydrous ethanol as the medium for 24 hours to obtain a mixed powder of Yb2O3 and SiO2.

[0010] Step 2, Yb2Si2O7 powder synthesis:

[0011] The ball-milled Yb2O3 and SiO2 mixed powders were placed in a muffle furnace for solid-phase reaction to synthesize Yb2Si2O7 powder;

[0012] Step 3, Yb2Si2O7 powder mixed with Al2O3:

[0013] Yb2Si2O7 powder and Al2O3 powder were weighed in a weight ratio of 97:3, placed in a ball mill, and milled for 24 hours using 99.9% pure anhydrous ethanol to obtain a mixed powder.

[0014] Step 4, preparation of Al2O3 modified Yb2Si2O7 material ceramic block:

[0015] The mixed powder is crushed and passed through a 180-mesh sieve, and then a 5 wt% PVA solution is added after the sieve, so that the concentration of the PVA after mixing is 8 wt%, and the mixture is pressed to obtain a ceramic block;

[0016] Step 5, sintering of Al2O3 modified Yb2Si2O7 ceramic block:

[0017] The ceramic block is first subjected to a debinding treatment in a muffle furnace, and then subjected to high-temperature sintering in the muffle furnace to obtain Al2O3-modified Yb2Si2O7 material.

[0018] As an improvement, the temperature of the solid phase reaction in step 2 is 1500° C. and the reaction time is 10 h.

[0019] As an improvement, the pressing process in step 4 is to pressurize twice, the first pressurization is 200 MPa and maintained for 1 minute, and the second pressurization is 160 MPa and maintained for 30 seconds.

[0020] As an improvement, the process of the debinding treatment in step 5 is to keep the temperature at 550°C for 2.5 hours.

[0021] As an improvement, the high temperature sintering process in step 5 is to keep the temperature at 1400°C for 10 hours.

[0022] The Al2O3 modified Yb2Si2O7 material prepared by the above preparation method is prepared from Yb2O3 powder, SiO2 powder and Al2O3 powder, the powder purity of the powder is ≥99.9%, and the Al2O3 modified Yb2Si2O7 material for the environmental barrier coating on the surface of the hot end component of the aircraft engine contains the phases of Yb2Si2O7 and Yb3Al5O 12 , density is 5.9335g / cm 2 , the porosity is 4.15%.

[0023] The above-mentioned hot end component surface environmental barrier coating uses Al2O3 modified Yb2Si2O7 material in the field of aviation engine environmental barrier coating.

[0024] Beneficial effects:

[0025] Compared with the prior art, the Al2O3-modified Yb2Si2O7 material for the environmental barrier coating on the surface of hot end components of the present invention, as well as its preparation method and application, has the following advantages:

[0026] 1. The Al2O3 modified Yb2Si2O7 material prepared by the present invention is conducive to the formation of ytterbium aluminum garnet (Yb3Al5O 12 ) phase, which promotes the densification of the sample and helps to reduce the porosity of the material.

[0027] 2. After long-term CMAS corrosion at 1300°C, the Al2O3-modified Yb2Si2O7 material prepared by the present invention has low porosity and dispersed dense ytterbium aluminum garnet, which will effectively hinder CAMS penetration and improve its high-temperature corrosion resistance as an EBC layer in harsh service environments.

[0028] 3. The present invention dopes Al2O3 into Yb2Si2O7. Compared with undoped Yb2Si2O7, the doped material is denser, has lower porosity and higher density. At the same time, Yb3Al5O 12 It will effectively improve the high-temperature corrosion resistance of Yb2Si2O7, increase its service life, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The powder XRD pattern of the Yb2Si2O7 powder prepared in step 2 of Example 1;

[0030] Figure 2XRD pattern of the Al2O3 modified Yb2Si2O7 material prepared in Example 1;

[0031] Figure 3 Schematic diagram of the surface morphology of the Al2O3-modified Yb2Si2O7 material prepared in Example 1;

[0032] Figure 4 A comparison chart of the porosity of Example 1 and Comparative Example 1;

[0033] Figure 5 Schematic diagram of the morphology of Example 1 and Comparative Example 1 after 4 hours of CMAS corrosion. DETAILED DESCRIPTION

[0034] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Example 1

[0036] An Al2O3 modified Yb2Si2O7 material for a hot end component surface environmental barrier coating, comprising an Al2O3 modified Yb2Si2O7 material synthesized by a solid phase reaction combined with a sintering process.

[0037] The method for preparing the Al2O3-modified Yb2Si2O7 material for the environmental barrier coating on the surface of the hot end component of the aircraft engine comprises the following steps:

[0038] Step 1, preparation of Yb2Si2O7 powder raw materials:

[0039] Yb2O3 and SiO2 powders were weighed at a weight ratio of 3.2784:1 and then placed in a ball mill using 99.9% pure anhydrous ethanol as the medium for 24 hours.

[0040] Step 2, Yb2Si2O7 powder synthesis:

[0041] The ball-milled Yb2O3 and SiO2 mixed powders were placed in a muffle furnace for solid phase reaction to synthesize Yb2Si2O7 at a reaction temperature of 1500°C and a reaction time of 10 h.

[0042] Step 3, Yb2Si2O7 powder mixed with Al2O3:

[0043] Using an analytical balance, Yb2Si2O7 powder and Al2O3 powder were weighed in a weight ratio of 97:3, and then placed in a ball mill with 99.9% pure anhydrous ethanol as the medium and ball milled for 24 hours;

[0044] Step 4, preparation of Al2O3 modified Yb2Si2O7 material ceramic block:

[0045] The mixed powder is crushed and passed through a 180-mesh sieve. After sieving, a 5wt% PVA solution is weighed and mixed with the powder, and the PVA concentration after mixing is 8wt%. A hydraulic press is then used to prepare ceramic blocks. The specific briquetting process is to apply pressure at 200MPa for 1 minute, followed by a second pressure at 160MPa for 30 seconds. The mixed powder is crushed and passed through a 180-mesh sieve. After sieving, a 5wt% PVA solution is added, and the PVA concentration after mixing is 8wt%. The mixture is then pressurized to obtain ceramic blocks.

[0046] Step 5, sintering of Al2O3 modified Yb2Si2O7 ceramic block:

[0047] The prepared ceramic block is first subjected to a debinding treatment in a muffle furnace with specific process parameters of 550°C and insulation for 2.5 hours; after debinding, it is subjected to high-temperature sintering in a muffle furnace with specific process parameters of 1400°C and insulation for 10 hours.

[0048] Comparative Example 1

[0049] Except that Al2O3 is not added in step 3, the rest is the same as in Example 1.

[0050] Performance Testing

[0051] The materials prepared in each step of Example 1 were analyzed, and the results were as follows: Figure 1-3 As shown, Figure 1 Yb2Si2O7 powder prepared in step 2, Figure 2 This is the XRD pattern of the Al2O3 modified Yb2Si2O7 material prepared in Example 1. Figure 3 This is the surface morphology of the Al2O3 modified Yb2Si2O7 material prepared in Example 1. It can be seen from the figure that the sample surface is dense and has fewer voids and cracks.

[0052] The porosity of the Al2O3 modified Yb2Si2O7 material prepared in Example 1 and the material prepared in Comparative Example 1 was measured. The results are as follows: Figure 4 As shown, the porosity of Comparative Example 1 and Example 1 are 28.7% and 4.15%, respectively.

[0053] The prepared Al2O3 modified Yb2Si2O7 ceramic block was subjected to CMAS corrosion resistance test to observe the morphology after corrosion. The specific operation was as follows: the surface area of ​​the ceramic block was measured with a vernier caliper at 30 mg / cm 2 CMAS powder was weighed and evenly coated on the ceramic block. The sample was placed in a muffle furnace and heated to 1300°C at a rate of 4°C per minute. The temperature was then maintained at this temperature for 4 hours. After the temperature was reduced to room temperature at a rate of 4°C per minute, the sample was removed and the surface morphology was observed.

[0054] The results are as follows Figure 5 As shown, the surface morphology of the material prepared in Example 1 after the CMAS corrosion test is as shown in FIG. Figure 5 (a) shows the cross-sectional morphology. Figure 5 (b) As shown; the surface morphology of the material prepared in Comparative Example 1 after CMAS corrosion test is as shown Figure 5 (c) shows the cross-sectional morphology. Figure 5 (d) shown.

[0055] like Figure 5 (a) Figure 5 As shown in (c), after 4 hours of CMAS corrosion test, a large amount of residual CMAS exists on the surface of Example 1, indicating that the modification of Example 1 can delay the penetration of CMAS; a large amount of corrosion product apatite exists on the surface of Comparative Example 1, and there are a large number of voids, indicating that Comparative Example 1 is severely corroded.

[0056] like Figure 5 (b) Figure 5 (d) After 4 hours of CMAS corrosion test, a residual CMAS layer exists on the top of Example 1, and the reaction layer is relatively thin; in Comparative Example 1, CMAS has fully reacted with the material, and a large number of voids exist.

[0057] In summary, the Al2O3-modified Yb2Si2O7 material for the environmental barrier coating on the surface of the hot end component prepared by the present invention has higher density and better resistance to CMAS corrosion, and can meet the material selection requirements of the environmental barrier coating material.

[0058] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing Al2O3 modified Yb2Si2O7 material for environmental barrier coating on the surface of hot end components, characterized in that: The method includes a solid phase reaction combined with a sintering process to synthesize Al2O3 modified Yb2Si2O7 material, specifically comprising the following steps: Step 1, preparation of Yb2Si2O7 powder raw materials: Yb2O3 and SiO2 powders were weighed in a weight ratio of 3.2784:1 and then placed in a ball mill with 99.9% pure anhydrous ethanol as the medium for 24 h to obtain a mixed powder of Yb2O3 and SiO2. Step 2, Yb2Si2O7 powder synthesis: The ball-milled Yb2O3 and SiO2 mixed powders were placed in a muffle furnace for solid-phase reaction to synthesize Yb2Si2O7 powder; Step 3, Yb2Si2O7 powder mixed with Al2O3: Yb2Si2O7 powder and Al2O3 powder were weighed in a weight ratio of 97:3, placed in a ball mill, and milled for 24 h using 99.9% pure anhydrous ethanol to obtain a mixed powder. Step 4, preparation of Al2O3 modified Yb2Si2O7 material ceramic block: The mixed powder was crushed and passed through a 180-mesh sieve, and then a 5 wt % PVA solution was added after sieving, so that the concentration of PVA after mixing was 8 wt %, and the mixture was pressed to obtain a ceramic block; Step 5, sintering of Al2O3 modified Yb2Si2O7 ceramic block: The ceramic block is first subjected to a debinding treatment in a muffle furnace, and then subjected to high-temperature sintering in the muffle furnace to obtain Al2O3-modified Yb2Si2O7 material.

2. The method for preparing an Al2O3-modified Yb2Si2O7 material for an environmental barrier coating on a hot end component surface according to claim 1, characterized in that: The temperature of the solid phase reaction in step 2 is 1500°C and the reaction time is 10 h.

3. The method for preparing an Al2O3-modified Yb2Si2O7 material for an environmental barrier coating on a hot end component surface according to claim 1, characterized in that: The pressing process in step 4 is two pressurizations, the first pressurization is 200 MPa and maintained for 1 min, and the second pressurization is 160 MPa and maintained for 30 s.

4. The method for preparing an Al2O3-modified Yb2Si2O7 material for an environmental barrier coating on a hot end component surface according to claim 1, characterized in that: The debinding process in step 5 is to keep the temperature at 550°C for 2.5 hours.

5. The method for preparing an Al2O3-modified Yb2Si2O7 material for an environmental barrier coating on a hot end component surface according to claim 1, characterized in that: The high temperature sintering process in step 5 is to keep the temperature at 1400°C for 10 hours.

6. Al2O3 modified Yb2Si2O7 material prepared by any one of the preparation methods according to claims 1-5, characterized in that: It is prepared from Yb2O3 powder, SiO2 powder and Al2O3 powder. The powder purity of the powder is ≥99.9%. The Al2O3 modified Yb2Si2O7 material contains the phases of Yb2Si2O7 and Yb3Al5O 12 , with a density of 5.9335 g / cm 2 , the porosity is 4.15%.

7. Application of the Al2O3 modified Yb2Si2O7 material according to claim 6 in the field of environmental barrier coatings for aircraft engines.

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