Thermal barrier coating resistant to CMAS corrosion and preparation method thereof

Abstract

The present invention discloses a thermal barrier coating resistant to CMAS corrosion and a preparation method thereof, belonging to the technical field of thermal barrier coatings. The preparation method comprises: preparing a bonding layer; preparing a YSZ coating on the bonding layer; preparing the Gd2O3 coating on the YSZ coating by microfluidic extrusion of a Gd2O3 ceramic slurry, wherein the microfluidic extrusion conditions include: an extrusion pressure of 2-3 kPa, an extrusion speed of 6-10 mm / s, and an extrusion temperature of 60-80°C; and heat treating the bonding layer, YSZ coating, and Gd2O3 coating. The thermal barrier coating prepared by the present invention has a dense structure and excellent thermal insulation performance, with a thermal conductivity of 0.85-1.1 W / (m·K) and a coating bonding strength of 35-50 MPa. Compared with conventional thermal barrier coating materials, the thermal barrier coating has superior CMAS corrosion resistance. In a CMAS corrosion test, the coating showed no peeling or cracking after undergoing a molten salt corrosion test at 900°C / 100h.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal barrier coatings, and in particular relates to a thermal barrier coating resistant to CMAS corrosion and a preparation method thereof. Background Art

[0002] Thermal barrier coatings (TBCs) are a key protective technology for high-temperature alloy components. CMAS corrosion refers to the chemical erosion and physical damage to materials, particularly aircraft engine TBCs, caused by the melting of calcium-magnesium-aluminum-silicon oxides (CaO-MgO-Al2O3-SiO2) at high temperatures.

[0003] Currently, 7-8wt% yttria-stabilized zirconia (YSZ) is the core material for commercial TBCs. However, its resistance to CMAS corrosion is poor. YSZ coatings are susceptible to phase transformation in high-temperature CMAS corrosion environments. Upon infiltration of the CMAS melt, the tetragonal phase (t-ZrO2) in the coating partially transforms to the monoclinic phase (m-ZrO2), leading to volume expansion and coating spalling.

[0004] Researchers are currently attempting to dope YSZ coatings with lanthanide oxides (such as Gd2O3) to stabilize the tetragonal phase at high temperatures and reduce the formation of the monoclinic phase, thereby avoiding volume expansion and coating spalling caused by phase transitions. However, while doping with lanthanide oxides can slow the phase transition compared to YSZ systems, it still cannot completely suppress the phenomenon, with corrosion being particularly pronounced at grain boundaries.

[0005] It should be noted that this part of the present invention only provides background technology related to the present invention and does not necessarily constitute prior art or public known technology. Summary of the Invention

[0006] The present invention provides a thermal barrier coating resistant to CMAS corrosion and a preparation method thereof, and the present invention aims to at least solve the problem of poor CMAS corrosion resistance of thermal barrier coatings in the prior art.

[0007] In order to achieve the above objectives, in a first aspect, the present invention provides a method for preparing a thermal barrier coating resistant to CMAS corrosion, comprising:

[0008] S1, preparing a bonding layer;

[0009] S2. preparing a YSZ coating on the bonding layer;

[0010] S3. Gd2O3 coating was prepared on the YSZ coating by microfluidic extrusion of Gd2O3 ceramic slurry. The microfluidic extrusion conditions included: extrusion pressure of 2-3 kPa, extrusion speed of 6-10 mm / s, and extrusion temperature of 60-80°C.

[0011] S4. Heat-treating the bonding layer, the YSZ coating and the Gd2O3 coating.

[0012] Preferably, in S3, the preparation method of Gd2O3 ceramic slurry comprises:

[0013] S31, mixing Gd2O3 ceramic powder, lubricant, dispersant and toughening agent;

[0014] S32, adding a pH adjuster to the mixture obtained in S31 to adjust the pH value to 6-8 and stirring for 20-30 minutes;

[0015] S33, milling the mixed liquid obtained in S32 with zirconia balls, mixing at a speed of 300-550 rpm for 8-15 hours, wherein the mass ratio of zirconia balls to mixed liquid is (10:1)-(20:1);

[0016] S34. After standing for 1 to 2 hours, Gd2O3 ceramic slurry is obtained.

[0017] Preferably, in S31, the mass ratio of Gd2O3 ceramic powder, lubricant, dispersant and toughening agent is (3-6):6:1:1.

[0018] Preferably, the lubricant is a mixture of deionized water and n-octanol, the dispersant is a polycarboxylate compound, and the toughening agent is an epoxy resin.

[0019] Preferably, in S31, the preparation method of Gd2O3 ceramic powder includes: performing high-temperature densification treatment on Gd2O3 powder using plasma spheroidization technology to form Gd2O3 ceramic powder; wherein the conditions of the plasma spheroidization technology include: the working gas is argon and hydrogen, the power is 30~40kW, the carrier gas flow rate is 1slpm~2slpm, and the powder feeding rate is 5g / min~15g / min.

[0020] Preferably, the thickness of the bonding layer is 0.05-0.15 mm, the thickness of the YSZ coating is 0.4-0.5 mm, and the thickness of the Gd2O3 coating is 0.08-0.15 mm.

[0021] Preferably, in S1, the material of the bonding layer is MCrAlY alloy, M is one or a combination of Ni and Co; the bonding layer is prepared by an atmospheric plasma spraying method, and the process parameters include: spraying distance of 130mm~150mm, spraying power of 35kw~40kw, carrier gas flow rate of 3slpm~5slpm, and powder feeding rate of 15g / min~25g / min.

[0022] Preferably, in S2, the YSZ coating is prepared by an atmospheric plasma spraying method, and the process parameters include: spraying distance of 90 mm to 120 mm, spraying power of 43 kW to 47 kW, carrier gas flow rate of 2 slpm to 5 slpm, and powder feeding rate of 10 g / min to 20 g / min.

[0023] Preferably, S4 specifically includes heat treating the bonding layer, the YSZ coating and the Gd2O3 coating at 700-1000°C for 2-3 hours, with a heating rate of 2-5°C / min.

[0024] On the other hand, the present invention also provides a thermal barrier coating resistant to CMAS corrosion, which is prepared by the above preparation method.

[0025] Beneficial effects of the present invention:

[0026] 1. Compared with the powder prepared in the prior art, the Gd2O3 ceramic powder prepared by the plasma spheroidization technology in the present invention has a spherical structure with a smooth surface and a dense interior, which can provide a dense coating and effectively improve the coating's ability to resist CMAS corrosion.

[0027] 2. Compared with the coatings prepared in the prior art, the Gd2O3 coating prepared by the present invention using microfluidic extrusion molding is carried out at a lower temperature, which helps to maintain the chemical stability of Gd2O3 and avoid phase change or performance degradation caused by high temperature. At the same time, the thickness and shape of the coating can be precisely controlled to ensure the uniformity and dimensional accuracy of the coating.

[0028] 3. The present invention also improves the raw materials for microfluidic extrusion molding by optimizing the ratio and selection of each component, thereby regulating the particle dispersion state and slurry rheological properties to ensure the uniformity and structural stability of the coating.

[0029] 4. The thermal barrier coating prepared by the present invention has a dense structure and excellent thermal insulation performance, with a thermal conductivity of 0.85~1.1W / (m·K) and a coating bonding strength of 35~50MPa. In addition, the thermal barrier coating has better resistance to CMAS corrosion than conventional thermal barrier coating materials. In the CMAS corrosion test, after the coating has undergone a molten salt corrosion test of 900℃ / 100h, the coating appearance shows no peeling or cracking. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 This is an electron microscope photograph of the cross-section of the microstructure of the Gd2O3 ceramic powder according to Example 1 of the present invention;

[0032] Figure 2 This is an electron microscope photograph of the microstructure cross-section of the thermal barrier coating resistant to CMAS corrosion according to Example 1 of the present invention. DETAILED DESCRIPTION

[0033] In the present invention, unless otherwise specified, directional words such as "up, down, left, right" are generally understood in conjunction with the directions shown in the drawings and actual applications.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0035] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0036] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined to form one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein. The terms "optional" and "optional" both mean that a range may or may not be included (or may or may not be present).

[0037] The present invention provides a method for preparing a thermal barrier coating resistant to CMAS corrosion, comprising:

[0038] S1, preparing a bonding layer;

[0039] S2. preparing a YSZ coating on the bonding layer;

[0040] S3. Gd2O3 coating was prepared on the YSZ coating by microfluidic extrusion of Gd2O3 ceramic slurry. The microfluidic extrusion conditions included: extrusion pressure of 2-3 kPa, extrusion speed of 6-10 mm / s, and extrusion temperature of 60-80°C.

[0041] S4. Heat-treating the bonding layer, the YSZ coating and the Gd2O3 coating.

[0042] It should be noted that the existing technology usually uses atmospheric plasma spraying to prepare the outer coating. Compared with the existing technology, the Gd2O3 coating prepared by the present invention is prepared by microfluidic extrusion molding at a lower temperature, which helps to maintain the chemical stability of Gd2O3 and avoid phase change or performance degradation caused by high temperature. At the same time, it can accurately control the thickness and shape of the coating, ensure the uniformity and dimensional accuracy of the coating, and thus improve the coating's resistance to CMAS corrosion.

[0043] The following details the improvement principles and advantages of the Gd2O3 coating of the present invention:

[0044] Gd2O3 coatings offer enhanced chemical stability and low reactivity with CMAS melts. Conventional YSZ coatings readily react with the SiO2 in CMAS at high temperatures, consuming the stabilizer Y2O3 and initiating a ZrO2 phase transition (t to m phase), accelerating coating failure. However, the alkaline nature of Gd2O3 allows it to react with acidic components of CMAS (such as SiO2) to form stable, high-melting-point compounds (such as apatite), forming a dense barrier that inhibits CMAS penetration. Compared to widely used zirconium-based coatings (such as La2Zr2O7), while these can reduce CMAS penetration, their thermal expansion coefficients are poorly matched to YSZ, making them susceptible to delamination due to thermal mismatch stress. Gd2O3 coatings offer superior thermal expansion coefficient matching. At the same time, Gd2O3 can react with CaO, SiO2 and other components in CMAS at high temperatures to form high-melting-point compounds (such as Ca2Gd8(SiO4)6O2 or Gd2SiO5). These products have high viscosity and low fluidity, and can form a dense protective layer on the coating surface, hindering further penetration of CMAS.

[0045] The existing technology also has the method of doping lanthanide oxides (such as Gd2O3) in the YSZ coating to improve the coating's resistance to CMAS corrosion. Doping Gd2O3 in the YSZ coating actually makes Gd3+ It enters the ZrO2 lattice in the form of solid solution, mainly playing the role of stabilizing the cubic phase. 3+ The reactivity with CMAS is significantly lower than that of pure Gd2O3. 3+ The doping amount is usually low (such as 3~5mol%), which is not enough to provide sufficient Gd 3+ Reacts with CMAS. And solid-solution Gd 3+ It is locked in the crystal lattice and difficult to diffuse quickly to the coating surface to participate in the reaction at high temperature. The doping system may generate a small amount of Gd-Si-O or Gd-Ca-Si-O compounds, but due to the Gd 3+ Due to the low concentration and slow reaction rate, the products are distributed in a localized, point-like manner and cannot form a continuous, dense layer. Therefore, pure Gd2O3 coating is the best choice for resisting CMAS corrosion due to its high reactivity and dense, continuous protective layer.

[0046] Preferably, the extrusion pressure is 2-3 kPa, and can be 2 kPa, 2.3 kPa, 2.5 kPa, 2.7 kPa, 3 kPa, and any value therebetween.

[0047] The extrusion speed is 6 to 10 mm / s, and can be 6 mm / s, 7 mm / s, 8 mm / s, 9 mm / s, 10 mm / s, and any value therebetween.

[0048] The extrusion temperature is 60-80°C, and can be 60°C, 65°C, 70°C, 75°C, 80°C, and any value therebetween.

[0049] The present application reasonably sets the conditions for microfluidic extrusion molding, which is more conducive to ensuring the uniformity and density of the prepared Gd2O3 coating.

[0050] Preferably, in S3, the preparation method of Gd2O3 ceramic slurry comprises:

[0051] S31, mixing Gd2O3 ceramic powder, lubricant, dispersant and toughening agent;

[0052] S32, adding a pH adjuster to the mixture obtained in S31 to adjust the pH value to 6-8 and stirring for 20-30 minutes;

[0053] S33, milling the mixed liquid obtained in S32 with zirconia balls, mixing at a speed of 300-550 rpm for 8-15 hours, wherein the mass ratio of zirconia balls to mixed liquid is (10:1)-(20:1);

[0054] S34. After standing for 1 to 2 hours, Gd2O3 ceramic slurry is obtained.

[0055] It should be noted that the purpose of adding the pH regulator in S32 is to maintain the stable dispersing performance of the dispersant. S33 Reasonable setting of the process parameters of the mixing ball mill can make the various raw materials mixed more uniformly.

[0056] Preferably, in S31, the mass ratio of the Gd2O3 ceramic powder, lubricant, dispersant, and toughening agent is (3-6):6:1:1, and may be (3:6:1:1), (4:6:1:1), (5:6:1:1), (6:6:1:1), or any value therebetween. Too high a Gd2O3 ceramic powder ratio will cause the powder to agglomerate and become difficult to disperse. Too low a Gd2O3 ceramic powder ratio will result in excessively large pores within the coating.

[0057] Preferably, the lubricant is a mixture of deionized water and n-octanol.

[0058] Preferably, the dispersant is a polycarboxylate compound. More preferably, the dispersant is an acrylic acid-sulfonate copolymer. Sodium polyacrylate is commonly used as a dispersant in the prior art. However, sodium polyacrylate is primarily based on electrostatic repulsion, making it ineffective for dispersing high-concentration or high-surface-energy powders (such as Gd2O3), and is particularly susceptible to failure at high temperatures or high pH. Compared to the commonly used sodium polyacrylate, polycarboxylates offer the advantage of greater adaptability to pH and temperature. Polycarboxylate dispersants are less sensitive to factors such as pH and temperature in the slurry, maintaining stable dispersion properties under a wider range of conditions. Polycarboxylates (such as acrylic acid-sulfonate copolymers) achieve stable dispersion through the dual effects of electrostatic repulsion and steric hindrance. The carboxylic acid and sulfonic acid groups in their molecular chains adsorb onto the surface of Gd2O3 ceramic powders, creating strong electrostatic repulsion. Simultaneously, the long-chain polymer structure provides steric hindrance, preventing particle agglomeration.

[0059] This application rationally controls the components and proportions of the dispersant, thereby regulating the particle dispersion state and slurry rheological properties, ensuring the uniformity and structural stability of the coating, and further improving the coating's resistance to CMAS corrosion.

[0060] Preferably, the toughening agent is epoxy resin. Epoxy resin forms a flexible network structure in the slurry, bonding with ceramic particles through hydrogen bonding or physical entanglement, thereby enhancing the mechanical strength of the green body after drying and reducing the risk of cracking during the extrusion molding process.

[0061] Preferably, in S31, the method for preparing Gd2O3 ceramic powder includes: performing a high-temperature densification treatment on Gd2O3 powder using plasma spheroidization technology to form Gd2O3 ceramic powder; wherein the conditions of the plasma spheroidization technology include: working gases of argon and hydrogen, a power of 30-40 kW, a carrier gas flow rate of 1 slpm-2 slpm, and a powder feeding rate of 5 g / min-15 g / min. The present application solves the problem of internal non-densification of Gd2O3 ceramic powder by rationally controlling the process parameters of the plasma spheroidization technology.

[0062] Preferably, the powder feeding rate can be 5 g / min, 7 g / min, 10 g / min, 12 g / min, 15 g / min, or any value therebetween. If the feeding rate is higher than 15 g / min, voids may form within the powder. If the feeding rate is lower than 5 g / min, the powder may be over-calcined and gasified, resulting in a reduced powder recovery rate.

[0063] It should be noted that the powder used to prepare the coating in the prior art is usually prepared by the sol-gel method. However, the powder prepared by the sol-gel method has disadvantages such as insufficient internal density. If the powder is not dense, cracks and defects will occur after the coating is formed, and it will not be able to play a role in resisting CMAS corrosion.

[0064] Preferably, the thickness of the bonding layer is 0.05-0.15 mm, the thickness of the YSZ coating is 0.4-0.5 mm, and the thickness of the Gd2O3 coating is 0.08-0.15 mm. This application rationally controls the thickness of the bonding layer to improve the adhesion of the overall coating and provide additional resistance to oxidation and corrosion. This application rationally controls the thickness of the YSZ coating to provide insulation and mitigate the mismatch in thermal expansion coefficients between the top layer and the bottom layer. This application rationally controls the thickness of the Gd2O3 coating to improve the coating's resistance to CMAS corrosion.

[0065] Preferably, in S1, the material of the bonding layer is MCrAlY alloy, M is one or a combination of Ni and Co; the bonding layer is prepared by an atmospheric plasma spraying method, and the process parameters include: spraying distance of 130mm~150mm, spraying power of 35kw~40kw, carrier gas flow rate of 3slpm~5slpm, and powder feeding rate of 15g / min~25g / min.

[0066] Preferably, in S2, the YSZ coating is prepared by an atmospheric plasma spraying method, and the process parameters include: spraying distance of 90 mm to 120 mm, spraying power of 43 kW to 47 kW, carrier gas flow rate of 2 slpm to 5 slpm, and powder feeding rate of 10 g / min to 20 g / min.

[0067] Preferably, S4 specifically includes heat treating the bonding layer, the YSZ coating and the Gd2O3 coating at 700-1000°C for 2-3 hours, with a heating rate of 2-5°C / min.

[0068] It is understandable that the decomposition temperature of epoxy resin is generally between 300-500°C, so it can be completely removed by oxidation or pyrolysis during heat treatment at 700-1000°C. The escape of its decomposition products (such as CO2 and H2O) may form temporary pores, but the reasonable control of the heat treatment time (2-3h) in this application can avoid residual pore defects; the application also reasonably controls the heating rate of the heat treatment to avoid rapid decomposition and resulting in cracking of the blank; at the same time, the heat treatment can also alleviate the thermal mismatch between the bonding layer, YSZ coating and Gd2O3 coating, thereby improving the overall CMAS corrosion resistance of the coating.

[0069] It should be noted that, in addition to having excellent resistance to CMAS corrosion, the thermal barrier coating of the present invention also has excellent thermal insulation and anti-stripping capabilities, which is specifically manifested in that the thermal barrier coating of the present invention has low thermal conductivity and high bonding strength.

[0070] It is understood that the plasma spheroidization technology, microfluidic extrusion, and slurry preparation of the present invention are key process steps in the preparation of thermal barrier coatings (TBCs), and their process parameters directly affect the thermal conductivity and bonding strength of the coating. In the plasma spheroidization process, higher power leads to more complete melting, which reduces internal porosity in the coating and thus improves bonding strength. However, reduced porosity increases thermal conductivity. In the microfluidic extrusion process, slurry uniformity enhances bonding strength by reducing interfacial defects (such as microcracks or unmelted particles), while the uniform porous structure reduces thermal conductivity. By rationally controlling the parameters of each process and synergizing multiple processes, the present invention ultimately produces a thermal barrier coating with low thermal conductivity, high bonding strength, and excellent resistance to CMAS corrosion.

[0071] The present invention also provides a thermal barrier coating resistant to CMAS corrosion, which is prepared by the above preparation method.

[0072] The technical effects of the present invention will be described below through specific examples and comparative examples, but they are all exemplary and do not constitute any limitation to the present invention.

[0073] Example 1

[0074] This embodiment provides a method for preparing a thermal barrier coating resistant to CMAS corrosion, comprising:

[0075] Step 1: Using plasma spheroidization technology to perform high-temperature densification treatment on Gd2O3 powder to form Gd2O3 ceramic powder;

[0076] Among them, the conditions of plasma spheroidization technology include: working gases are argon and hydrogen, power is 38kW, carrier gas flow rate is 1.2slpm, and powder feeding rate is 8g / min.

[0077] Step 2: Spray a 0.1mm thick MCrAlY bonding layer and a 0.45mm thick YSZ coating in sequence;

[0078] The bonding layer was produced by atmospheric plasma spraying, with process parameters including a spray distance of 140 mm, a spray power of 37 kW, a carrier gas flow rate of 3.5 slpm, and a powder feed rate of 20 g / min. The YSZ coating was produced by atmospheric plasma spraying, with process parameters including a spray distance of 110 mm, a spray power of 46 kW, a carrier gas flow rate of 2.5 slpm, and a powder feed rate of 15 g / min.

[0079] Step 3: Mix Gd2O3 ceramic powder, lubricant, dispersant and toughening agent; add pH regulator (specifically ammonia water) to the resulting mixture to adjust the pH value to 7 and stir for 25 minutes; mix the resulting mixed liquid through a zirconia ball mill at a speed of 450 rpm for 13 hours, and the mass ratio of zirconia balls to the mixed liquid is 15:1; after standing for 1.5 hours, Gd2O3 ceramic slurry is obtained.

[0080] The mass ratio of Gd2O3 ceramic powder, lubricant, dispersant and toughening agent is 5:6:1:1. The lubricant is a mixture of deionized water and n-octanol, the dispersant is acrylic acid-sulfonate copolymer, and the toughening agent is epoxy resin.

[0081] Step 4: Gd2O3 coating was prepared on the YSZ coating by microfluidic extrusion of Gd2O3 ceramic slurry. The conditions of microfluidic extrusion included: extrusion pressure of 2.5 kPa, extrusion speed of 8 mm / s, and extrusion temperature of 70°C.

[0082] Among them, the thickness of the Gd2O3 coating is 0.1 mm.

[0083] Step 5: Heat treat the bonding layer, YSZ coating and Gd2O3 coating at 900℃ for 2.5h with a heating rate of 4℃ / min.

[0084] Example 2

[0085] This embodiment also provides a method for preparing a thermal barrier coating resistant to CMAS corrosion, which is carried out with reference to the preparation method provided in Example 1. The difference between this method and Example 1 is that in step 1, the powder feeding rate of the plasma spheroidization technology is 15 g / min.

[0086] Example 3

[0087] This embodiment also provides a method for preparing a thermal barrier coating resistant to CMAS corrosion, which is carried out with reference to the preparation method provided in Example 1. The difference between this method and Example 1 is that in step 1, the powder feeding rate of the plasma spheroidization technology is 5 g / min.

[0088] Example 4

[0089] This embodiment also provides a method for preparing a thermal barrier coating resistant to CMAS corrosion, which is carried out with reference to the preparation method provided in Example 1. The difference from Example 1 is that in step three, the mass ratio of Gd2O3 ceramic powder, lubricant, dispersant and toughening agent is 3:6:1:1.

[0090] Example 5

[0091] This embodiment also provides a method for preparing a thermal barrier coating resistant to CMAS corrosion, which is carried out with reference to the preparation method provided in Example 1. The difference from Example 1 is that in step three, the mass ratio of Gd2O3 ceramic powder, lubricant, dispersant and toughening agent is 6:6:1:1.

[0092] Example 6

[0093] This embodiment also provides a method for preparing a thermal barrier coating resistant to CMAS corrosion, which is carried out with reference to the preparation method provided in Example 1. The difference between this method and Example 1 is that in step 4, the extrusion temperature of the microfluidic extrusion molding is 60°C.

[0094] Example 7

[0095] This embodiment also provides a method for preparing a thermal barrier coating resistant to CMAS corrosion, which is carried out with reference to the preparation method provided in Example 1. The difference between this method and Example 1 is that in step 4, the extrusion temperature of the micro-flow extrusion molding is 80°C.

[0096] Example 8

[0097] This embodiment also provides a method for preparing a thermal barrier coating resistant to CMAS corrosion, which is carried out with reference to the preparation method provided in Example 1. The difference between this method and Example 1 is that in step five, the heat treatment time is 2 hours.

[0098] Example 9

[0099] This embodiment also provides a method for preparing a thermal barrier coating resistant to CMAS corrosion, which is carried out with reference to the preparation method provided in Example 1. The difference between this method and Example 1 is that in step five, the heat treatment time is 3 hours.

[0100] Example 10

[0101] This embodiment also provides a method for preparing a thermal barrier coating resistant to CMAS corrosion, which is carried out with reference to the preparation method provided in Example 1. The difference between this method and Example 1 is that in step five, the heating rate of the heat treatment is 2°C / min.

[0102] Example 11

[0103] This embodiment also provides a method for preparing a thermal barrier coating resistant to CMAS corrosion, which is carried out with reference to the preparation method provided in Example 1. The difference between this method and Example 1 is that in step five, the heating rate of the heat treatment is 5°C / min.

[0104] Comparative Example 1

[0105] This comparative example provides a method for preparing a thermal barrier coating, which still uses the preparation method provided in Example 1 to prepare an MCrAlY bonding layer and a YSZ coating. The difference from Example 1 is that a Gd2O3 coating is not prepared, but is replaced by a YSZ coating doped with Gd2O3 commonly used in the prior art. For specific preparation process parameters, please refer to the prior art.

[0106] Comparative Example 2

[0107] This comparative example provides a method for preparing a thermal barrier coating, which still uses the preparation method provided in Example 1 to prepare an MCrAlY bonding layer and a YSZ coating. The difference between it and Example 1 is that: instead of using plasma spheroidization technology to prepare Gd2O3 ceramic powder, the sol-gel method commonly used in the prior art is used to prepare Gd2O3 ceramic powder, and the Gd2O3 ceramic powder is subsequently used to prepare a Gd2O3 ceramic slurry and a Gd2O3 coating. For the specific preparation process parameters of the sol-gel method, please refer to the prior art.

[0108] Comparative Example 3

[0109] This comparative example provides a method for preparing a thermal barrier coating, which still adopts the preparation method provided in Example 1 to prepare an MCrAlY bonding layer and a YSZ coating. The difference between it and Example 1 is that: instead of using micro-flow extrusion molding to prepare the Gd2O3 coating, the atmospheric plasma spraying method commonly used in the prior art is used to prepare the Gd2O3 coating. It should be noted that the atmospheric plasma spraying method does not require the preparation of Gd2O3 ceramic slurry, and the Gd2O3 ceramic powder can be directly used to prepare the Gd2O3 coating. For the specific preparation process parameters of the atmospheric plasma spraying method, please refer to the prior art.

[0110] Comparative Example 4

[0111] This comparative example provides a preparation method of a thermal barrier coating, which is carried out with reference to the preparation method provided in Example 1. The difference between this comparative example and Example 1 is that in step 1, the powder feeding rate of the plasma spheroidization technology is 40 g / min.

[0112] Comparative Example 5

[0113] This comparative example provides a preparation method of a thermal barrier coating, which is carried out with reference to the preparation method provided in Example 1. The difference between this method and Example 1 is that in step three, the mass ratio of Gd2O3 ceramic powder, lubricant, dispersant and toughening agent is 10:6:1:1.

[0114] Comparative Example 6

[0115] This comparative example provides a method for preparing a thermal barrier coating, which is carried out with reference to the preparation method provided in Example 1. The difference between this method and Example 1 is that in step three, the dispersant is sodium polyacrylate.

[0116] Comparative Example 7

[0117] This comparative example provides a preparation method of a thermal barrier coating, which is carried out with reference to the preparation method provided in Example 1. The difference between this comparative example and Example 1 is that in step 4, the extrusion temperature of the micro-flow extrusion molding is 40°C.

[0118] Comparative Example 8

[0119] This comparative example provides a method for preparing a thermal barrier coating, which is carried out with reference to the preparation method provided in Example 1. The difference between this method and Example 1 is that in step 5, the heat treatment time is 1 hour.

[0120] Comparative Example 9

[0121] This comparative example provides a preparation method of a thermal barrier coating, which is carried out with reference to the preparation method provided in Example 1. The difference between this comparative example and Example 1 is that in step five, the heating rate of the heat treatment is 8°C / min.

[0122] Test Case

[0123] The present invention further tested the effectiveness of the thermal barrier coatings prepared in the examples and comparative examples. The test results are shown in Table 1. The thermal conductivity test method is specifically described in GB / T 22588, "Measurement of Thermal Diffusivity or Thermal Conductivity by Flash Method." The coating bond strength test method is specifically described in GB / T 38898, "Nondestructive Ultrasonic Testing of Coating Bond Strength." The CMAS corrosion resistance test method involves attaching the thermal barrier coating to a high-temperature alloy test component and subjecting it to a molten salt corrosion test at 900°C for 100 hours. The thickness of the corrosion in the coating reaction zone is then measured. A coating passing standard is considered acceptable if the corrosion thickness in the reaction zone is no greater than 0.1 mm.

[0124] Table 1

[0125]

[0126] like Figure 1 As shown, the electron microscope image prepared in Example 1 shows that the Gd2O3 ceramic powder prepared by the present invention has a spherical structure with a smooth surface and a dense interior. The Gd2O3 coating formed in this way has no cracks and defects and has strong resistance to CMAS corrosion.

[0127] like Figure 2 As shown, the electron microscope image prepared in Example 1 shows that the thickness of the YSZ coating prepared by the present invention is 0.45 mm, and the thickness of the Gd2O3 coating is 0.1 mm. It can also be seen that the uniformity and density of the Gd2O3 coating prepared by the present invention are very high, which helps to improve the resistance to CMAS corrosion.

[0128] The above results show that, compared with the comparative example, the thermal barrier coating prepared by the embodiment scheme of the present invention has a dense structure and excellent thermal insulation performance, and the thermal barrier coating is more excellent in resisting CMAS corrosion than conventional thermal barrier coating materials.

[0129] Furthermore, according to Example 1 and Examples 2-11, it can be seen that the adoption of the preferred solution of the present invention helps to further improve the thermal insulation performance, coating bonding strength and CMAS corrosion resistance of the thermal barrier coating.

[0130] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing a thermal barrier coating resistant to CMAS corrosion, characterized in that: include: S1, preparing a bonding layer; S2, preparing a YSZ coating on the bonding layer; S3, preparing a Gd2O3 coating on the YSZ coating by micro-flow extrusion of a Gd2O3 ceramic slurry, wherein the conditions of the micro-flow extrusion include: an extrusion pressure of 2-3 kPa, an extrusion speed of 6-10 mm / s, and an extrusion temperature of 60-80°C; S4, heat treating the bonding layer, the YSZ coating and the Gd2O3 coating for 2-3 hours at a heating rate of 2-5°C / min; The Gd2O3 ceramic slurry is prepared from Gd2O3 ceramic powder, a lubricant, a dispersant and a toughening agent, wherein the mass ratio of the Gd2O3 ceramic powder, the lubricant, the dispersant and the toughening agent is (3-6):6:1:1, and the dispersant is a polycarboxylate compound; The Gd2O3 ceramic powder is formed by subjecting Gd2O3 powder to a high-temperature densification treatment using a plasma spheroidization technique, wherein the conditions of the plasma spheroidization technique include a powder feeding rate of 5 g / min to 15 g / min.

2. The method for preparing a thermal barrier coating resistant to CMAS corrosion according to claim 1, characterized in that: In S3, the preparation method of the Gd2O3 ceramic slurry includes: S31, mixing Gd2O3 ceramic powder, lubricant, dispersant and toughening agent; S32, adding a pH adjuster to the mixture obtained in S31 to adjust the pH value to 6-8 and stirring for 20-30 minutes; S33, milling the mixed liquid obtained in S32 with zirconia balls, mixing at a speed of 300-550 rpm for 8-15 hours, wherein the mass ratio of the zirconia balls to the mixed liquid is (10:1)-(20:1); S34, after standing for 1 to 2 hours, the Gd2O3 ceramic slurry is obtained.

3. The method for preparing a thermal barrier coating resistant to CMAS corrosion according to claim 1, characterized in that: The lubricant is a mixture of deionized water and n-octanol, and the toughening agent is epoxy resin.

4. The method for preparing a thermal barrier coating resistant to CMAS corrosion according to claim 1, characterized in that: The conditions of the plasma spheroidization technology also include: the working gas is argon and hydrogen, the power is 30-40 kW, and the carrier gas flow rate is 1 slpm-2 slpm.

5. The method for preparing a thermal barrier coating resistant to CMAS corrosion according to claim 1, characterized in that: The thickness of the bonding layer is 0.05-0.15 mm, the thickness of the YSZ coating is 0.4-0.5 mm, and the thickness of the Gd2O3 coating is 0.08-0.15 mm.

6. The method for preparing a thermal barrier coating resistant to CMAS corrosion according to claim 1, characterized in that: In S1, the material of the bonding layer is MCrAlY alloy, where M is one or a combination of Ni and Co; the bonding layer is prepared by an atmospheric plasma spraying method, and the process parameters include: a spraying distance of 130 mm to 150 mm, a spraying power of 35 kW to 40 kW, a carrier gas flow rate of 3 slpm to 5 slpm, and a powder feeding rate of 15 g / min to 25 g / min.

7. The method for preparing a thermal barrier coating resistant to CMAS corrosion according to claim 1, characterized in that: In S2, the YSZ coating is prepared by an atmospheric plasma spraying method, and the process parameters include: spraying distance of 90 mm to 120 mm, spraying power of 43 kW to 47 kW, carrier gas flow rate of 2 slpm to 5 slpm, and powder feeding rate of 10 g / min to 20 g / min.

8. The method for preparing a thermal barrier coating resistant to CMAS corrosion according to claim 1, characterized in that: S4 specifically includes heat treating the bonding layer, the YSZ coating and the Gd2O3 coating at 700-1000°C.

9. A thermal barrier coating resistant to CMAS corrosion, characterized in that: The compound is prepared by the preparation method according to any one of claims 1 to 8.

Images