Preparation method of rare earth zirconate powder for thermal barrier coating

Abstract

The application belongs to the technical field of thermal barrier coatings, and particularly relates to a preparation method of rare earth zirconate powder for thermal barrier coatings. The preparation method comprises the following steps: dissolving a zirconium source and rare earth raw materials respectively with nitric acid, mixing, diluting with water, and adding a dispersing agent to obtain a rare earth mixture; passing carbon dioxide gas through ammonia water to adjust the pH of the solution to obtain a precipitant; making the rare earth mixture and the precipitant flow in parallel, and passing into a reactor to react to obtain rare earth zirconate slurry; adding an inhibitor to the rare earth zirconate slurry to perform a crystallization reaction, and performing solid-liquid separation, washing, drying, and high-temperature calcination to obtain rare earth zirconate powder. The rare earth zirconate powder obtained by the application has fine particle size, high absolute purity, and low calcination temperature, and can be directly used for spray granulation.

Description

Technical Field

[0001] This invention belongs to the field of thermal barrier coating technology, and specifically relates to a method for preparing rare earth zirconate powder for thermal barrier coating. Background Technology

[0002] Thermal barrier coatings (TBCs) are multifunctional ceramic protective systems deposited on the surfaces of hot-end metal components in aircraft engines and gas turbines (hereinafter referred to as "engines"). By isolating the high-temperature airflow from the metal substrate, they significantly increase the engine operating temperature (up to 1500°C or higher). Their core function relies on the ultra-low lattice thermal conductivity of the ceramic layer, which inhibits heat transfer to the substrate, thereby extending component service life, reducing pollutant emissions, and achieving a breakthrough increase in thermal engine efficiency.

[0003] Currently, both turbofan and turbine engines are evolving towards higher thrust-to-weight ratios and higher thermal efficiency. The continuously increasing turbine inlet temperature poses fundamental limitations to traditional yttrium-stabilized zirconia (YSZ) coatings. YSZ undergoes phase decomposition at temperatures above 1200 °C, leading to coating failure. Accelerated sintering and crack propagation severely restrict the lifespan of high-temperature components. Finding thermal barrier coating materials with lower thermal conductivity and higher coefficients of thermal expansion has become a key issue in improving the efficiency of thermal engines.

[0004] Rare earth zirconates belong to the cubic crystal system, according to Ln 3+ and Zr 4+ The radius ratio can form an ordered pyrochlore / disordered fluorite structure with cations and oxygen vacancies. Therefore, rare earth zirconates have ultra-low lattice thermal conductivity, high temperature thermal stability and controllable thermal expansion coefficient, making them the most promising thermal barrier coating materials for current applications.

[0005] Patent (CN 118420358 A) involves mixing rare earth salt solution and zirconium salt solution in a molar ratio and stirring until homogeneous. Ammonia is used as a precipitant to prepare a precipitate. The precipitate is then separated by a ceramic membrane and filtered under pressure. After slurry preparation with nitric acid, it is granulated and finally heat-treated to obtain high-entropy rare earth zirconate powder with a spherical nanostructure. This method uses ammonia as a precipitant, resulting in a slurry that is difficult to filter and agglomerates after drying. Patent (CN 110563035 A) involves mixing rare earth oxides, zirconium oxide, molten salt, and anhydrous ethanol to obtain a mixture. This mixture is then calcined to obtain the rare earth zirconate nanoparticles. This method involves molten salt solid-phase sintering, and the sodium chloride, potassium chloride, and lithium chloride used will ultimately be incorporated into the product, making it unsuitable for industrial production. The patent (CN 112661511 A) involves adding rare earth nitrate or rare earth chloride to ammonia water, precipitating it as hydroxide, then filtering, washing, drying, and calcining for 12 hours, followed by ball milling and freeze drying to obtain rare earth zirconate powder. This method results in a long calcination time for the powder, and the calcined product requires ball milling and freeze drying, leading to high costs. Summary of the Invention

[0006] This invention provides a multi-rare earth zirconate powder for thermal barrier coatings and its preparation method, which solves the problems of difficult filtration of nanoparticles in industrial production, as well as the problem of substandard impurity elements such as Fe, Si, and Al. It can obtain multi-rare earth zirconate powder with fine particle size and high absolute purity.

[0007] According to a specific embodiment of the present invention, a rare earth zirconate powder for thermal barrier coatings has the structural formula (RE... 1 1-x RE 2 x )2(Zr 1-y Ce y )2O7, where 0≤x≤1, 0≤y≤1, RE 1 and RE 2 Each element is independently selected from one of the rare earth elements.

[0008] According to a specific embodiment of the present invention, the rare earth zirconate powder for thermal barrier coating is lanthanum, cerium, samarium, gadolinium or ytterbium.

[0009] The phase structure of the rare earth zirconate powder obtained by this invention is a pyrochlore structure with ordered oxygen vacancies / a fluorite structure with disordered oxygen vacancies.

[0010] According to a specific embodiment of the present invention, a method for preparing rare earth zirconate powder for thermal barrier coatings includes the following steps:

[0011] (1) Weigh the zirconium source and rare earth raw materials according to the structural formula of rare earth zirconate, dissolve the zirconium source and rare earth raw materials separately with nitric acid, mix them, dilute with water, and add dispersant to obtain rare earth mixture;

[0012] (2) Carbon dioxide gas is passed through ammonia water to adjust the pH of the solution and obtain a precipitant;

[0013] (3) The rare earth mixture and the precipitant are flowed in parallel into the reactor to react and obtain a rare earth zirconate slurry containing crystal nuclei;

[0014] (4) The inhibitor is added to the rare earth zirconate slurry for crystallization reaction, and after solid-liquid separation, washing, drying and high-temperature calcination, rare earth zirconate powder is obtained.

[0015] According to a specific embodiment of the present invention, in the method for preparing rare earth zirconate powder for thermal barrier coating, in step (1), the zirconium source is selected from one or more of zirconium oxycarbonate, zirconium hydroxide, and zirconium oxychloride; and / or, the dispersant is selected from polyethylene glycol, polyvinylpyrrole, or polyvinylpyrrolidone.

[0016] The rare earth raw material is one of the commonly available industrial rare earth carbonates, rare earth oxides, and rare earth hydroxides, with a relative purity of ≥99.99%. For example, rare earth oxide Y2O3 / ∑REO ≥99.99%.

[0017] The rare earth mixture obtained in step (1) contains rare earth nitrate and zirconium oxynitrate.

[0018] According to the specific embodiment of the present invention, the concentration of the rare earth mixture obtained in step (1) is 80-220 g / L.

[0019] According to a specific embodiment of the present invention, in the preparation method of rare earth zirconate powder for thermal barrier coating, in step (2), the concentration of ammonia water is 2-5 mol / L, and / or,

[0020] Carbon dioxide gas is passed through ammonia water to adjust the pH of the solution to 7.5-10.0.

[0021] High-purity ammonium bicarbonate is prepared by reacting carbon dioxide with ammonia water. It is used as a precipitant, and the high-purity ammonium bicarbonate co-precipitates with trace amounts of impurities such as iron, silicon, aluminum, magnesium and chloride ions in the raw materials, thereby removing impurities and improving the purity of rare earth zirconate powder products.

[0022] According to a specific embodiment of the present invention, in the preparation method of rare earth zirconate powder for thermal barrier coating, in step (3), the reactor is one of a stirred reactor, a pipe mixer, or a supergravity reactor;

[0023] In step (3), the rare earth mixture and the precipitant are fed into the supergravity reactor in parallel, and the reaction temperature is 15℃-95℃.

[0024] In this invention, the hypergravity reactor is a device that utilizes a hypergravity environment to enhance mass transfer, mixing, and reaction processes. It generates a centrifugal force field much greater than Earth's gravity (typically tens to thousands of times the acceleration due to gravity) through high-speed rotation. This invention utilizes its hypergravity field to increase the contact area between liquid-liquid and liquid-solid phases, while the centrifugal force accelerates the renewal rate of the phase interfaces, increasing the mass transfer coefficient by tens to hundreds of times.

[0025] The core of the reaction between rare earth mixtures and precipitants is the formation of rare earth precipitates. This process follows the basic principle of "nucleation → growth," but excessively high local concentrations can directly disrupt the balance between the two, inducing agglomeration. This invention introduces the rare earth mixture and precipitant into a hypergravity reactor in a parallel flow, achieving instantaneous and uniform mixing of the reactants. This ensures "uniform concentration → synchronous nucleation → growth → intact grains + uniform spacing," ultimately effectively suppressing grain agglomeration caused by excessively high local concentrations and guaranteeing particle size uniformity.

[0026] Preferably, the stirring speed of the supergravity reactor is 2000-6000 rpm.

[0027] The addition time for the rare earth mixture is 0.5-3.0 h; the addition time for the precipitant is 0.5-3.0 h. The flow rate is set according to the volume of the prepared solution, and the rare earth mixture and precipitant are added simultaneously.

[0028] According to the specific embodiment of the present invention, in the preparation method of rare earth zirconate powder for thermal barrier coating, in step (4), the inhibitor is citric acid or EDTA; the amount added is 0.05-1%.

[0029] After adding the inhibitor to the rare earth zirconate slurry, it is aged for 1-12 hours.

[0030] According to the specific embodiment of the present invention, in the preparation method of rare earth zirconate powder for thermal barrier coating, in step (5), the calcination temperature is 1000℃-1400℃ and the calcination time is 2-5 h.

[0031] The beneficial effects of this invention are:

[0032] (1) The present invention prepares high-purity ammonium bicarbonate by reacting carbon dioxide with ammonia water as a precipitant, which can play a role in removing impurities and purifying the product. It can effectively prevent trace amounts of iron, silicon, aluminum, magnesium and chloride ions in the raw materials from co-precipitating into the product, thereby ensuring the high purity of rare earth zirconate powder.

[0033] (2) The present invention uses a super gravity reactor to achieve instantaneous and uniform mixing of rare earth mixture and precipitant, effectively suppressing the agglomeration of crystals caused by excessive local concentration. At the same time, the addition of inhibitors prevents the crystals from growing in water / salt solution, so as to form uniform nano-sized particles. The resulting powder can be a rare earth zirconate powder product with extremely narrow particle size distribution after calcination without the need for sand milling, grinding or other steps. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a process flow diagram of the method for preparing rare earth zirconate powder for thermal barrier coating of the present invention.

[0036] Figure 2 This is the particle size distribution of gadolinium zirconate prepared in Example 1.

[0037] Figure 3This is the microstructure of gadolinium zirconate prepared in Example 1.

[0038] Figure 4 This is the phase structure of gadolinium zirconate prepared in Example 1.

[0039] Figure 5 This is the particle size distribution of the rare earth zirconate powder prepared in Example 2.

[0040] Figure 6 This is the particle size distribution of the rare earth zirconate powder prepared in Example 3.

[0041] Figure 7 This is the particle size distribution of gadolinium zirconate prepared in Comparative Example 2.

[0042] Figure 8 The image shows the microstructure of the gadolinium zirconate prepared in Comparative Example 2. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0044] This invention provides a rare earth zirconate powder for thermal barrier coatings, the structural formula of which is (RE 1 1-x RE 2 x )2(Zr 1-y Ce y )2O7, where 0≤x≤1, 0≤y≤1, RE 1 and RE 2 Each element is independently selected from one of the rare earth elements, namely lanthanum, cerium, samarium, gadolinium, or ytterbium.

[0045] Preferably, the structural formula of the rare earth zirconate powder is (RE 1 1-x RE 2 x )2(Zr 1-y Ce y )2O7, where 0≤x≤0.3 (x is 0, 0.1, 0.2, or 0.3), 0≤y<0.3 (y is 0, 0.1, 0.2, or 0.3). For example, Yb 0.2 Gd 1.8 Zr2O7, RE 2 It's Yb, RE 1It is Gd, x=0.1, y=0; La2Zr 1.8 Ce 0.2 In O7, RE 1 It is La, x=0, y=0.1.

[0046] The phase structure of the rare earth zirconate powder obtained by this invention is a pyrochlore structure with ordered oxygen vacancies / a fluorite structure with disordered oxygen vacancies.

[0047] The method for preparing rare earth zirconate powder for thermal barrier coating of the present invention includes the following steps:

[0048] (1) Weigh the raw materials (zirconium source and rare earth raw materials) according to the structural formula of rare earth zirconate, dissolve the zirconium source and rare earth raw materials separately with nitric acid, mix them, dilute with water, and add dispersant to obtain rare earth mixture;

[0049] (2) Carbon dioxide gas is passed through ammonia water to adjust the pH of the solution and obtain a precipitant;

[0050] (3) The rare earth mixture and the precipitant are flowed in parallel into the reactor to react and a rare earth zirconate slurry is obtained immediately.

[0051] (4) The inhibitor is added to the rare earth zirconate slurry for crystallization reaction, and after solid-liquid separation, washing, drying and high-temperature calcination, rare earth zirconate powder is obtained.

[0052] A flowchart of the preparation method of rare earth zirconate powder for thermal barrier coating is shown below. Figure 1 The mixture consists of dispersant (Y1), mixture (material A), precipitant (material B), rare earth zirconate slurry (material C), and inhibitor (Y2).

[0053] Preferably, in step (1), the zirconium source is selected from one or more of zirconium oxycarbonate, zirconium hydroxide, and zirconium oxychloride;

[0054] The dispersant is selected from polyethylene glycol, polyvinylpyrrole, or polyvinylpyrrolidone, and the amount of dispersant used is 0.05-1% (by mass percentage of the raw material). Preferably, the amount of dispersant used is 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0%, or any value within the range of 0.05-1%. These values ​​will not be elaborated here.

[0055] In step (1), the raw materials (zirconium source and rare earth raw materials) are used as solutes, and the concentration of the resulting rare earth mixture is 80-220 g / L. Preferably, the concentration of the rare earth mixture is 100-200 g / L, or its concentration is 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, or 200 g / L, or any value within the range of 80-220 g / L. These will not be elaborated here.

[0056] In step (2), the concentration of ammonia is 2-5 mol / L. Preferably, the concentration of ammonia is 2, 2.5, 3.5, 4, 4.5, or 5 mol / L, or any value within the range of 2-5 mol / L. These will not be elaborated here.

[0057] Carbon dioxide gas is passed through ammonia water to adjust the pH of the solution to 7.5-10.0.

[0058] In step (3), the reactor is one of the following: a stirred reactor, a pipe mixer, or a supergravity reactor;

[0059] Preferably, the reactor is a supergravity reactor, in which rare earth mixture and precipitant are introduced into supergravity reactor in parallel, and the reaction temperature is 15℃-95℃.

[0060] The stirring speed of the supergravity reactor is 2000-6000 rpm. Depending on the volume and flow rate of the inflowing liquid, the stirring speed can be adjusted to 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500 or 6000 rpm, or any value within the range of 2000-6000 rpm, which will not be elaborated here.

[0061] The addition time for the rare earth mixture is 0.5-3.0 h; the addition time for the precipitant is 0.5-3.0 h. The addition times for both the rare earth mixture and the precipitant can be adjusted separately. Preferably, the addition times for the rare earth mixture and the precipitant are equal.

[0062] The addition time is the time it takes for the materials (rare earth mixture, precipitant) to be added into the reactor.

[0063] In step (4), the inhibitor is citric acid or EDTA; the amount of inhibitor used is 0.05-1% (by mass percentage of the raw material), preferably 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0%, or the amount of dispersant used is any value within the range of 0.05-1%, which will not be elaborated here.

[0064] After the inhibitor is added to the rare earth zirconate slurry, it is aged for 1-12 hours.

[0065] In step (5), the calcination temperature is 1000℃-1400℃, and the calcination time is 2-5 h. Preferably, the calcination temperature is 1050, 1100, 1150, 1200, 1250, 1300, 1350, or 1400℃, or any value within the range of 1000℃-1400℃, which will not be elaborated here.

[0066] Example 1

[0067] The method for preparing rare earth zirconate powder for thermal barrier coatings in this embodiment includes the following steps:

[0068] According to the chemical formula Yb 0.2 Gd 1.8 To prepare the rare earth mixture, weigh out 5000 g of zirconium oxycarbonate, 324 g of ytterbium oxide, and 2656 g of gadolinium oxide. Dissolve them in 520 g, 4625 g, and 3410 g of nitric acid, respectively. After mixing the three, add 41.6 L of pure water to prepare a concentration of 120 g / L. At the same time, add 5 g of polyethylene glycol 4000 as a dispersant to obtain the rare earth mixture.

[0069] At room temperature, compressed carbon dioxide gas is passed into ammonia water with a concentration of 5 mol / L to lower its pH value to 8.0, thus obtaining a precipitant.

[0070] The rare earth mixture and precipitant were simultaneously introduced into a high-gravity reactor for reaction at a reaction temperature of 60 ℃ and a stirring speed of 2000 rpm to obtain a rare earth zirconate slurry. The rare earth zirconate slurry was a mixture of zirconium hydroxide, gadolinium carbonate, and ytterbium carbonate.

[0071] Add 5 g of the inhibitor citric acid to the rare earth zirconate slurry to crystallize the crystal nuclei for 2 h. After solid-liquid separation, washing and drying, the precursor powder of rare earth zirconate is obtained.

[0072] The obtained dry powder was calcined at a high temperature of 1100 ℃ for 3 h. After calcination, a multi-rare earth zirconate powder with fine particle size and high absolute purity was obtained. The multi-rare earth zirconate powder can be used for thermal barrier coatings.

[0073] like Figure 2 and Figure 3 As shown, the particle size distribution and microstructure of gadolinium zirconate prepared in Example 1 are illustrated. The microstructure consists of uniformly dispersed nanoparticles. 50 The primary particle size is 109 μm. This particle size can be directly granulated after dispersion with a dispersant, without the need for nano-grinding.

[0074] Chloride ions were determined using silver nitrate turbidimetric method; calcium and magnesium ions were determined using flame atomic absorption spectrometry; silicon was determined using inductively coupled plasma atomic emission spectrometry; iron ions were determined using potassium thiocyanate and 1,10-diazaphenanthrene spectrophotometry; and titanium was determined using inductively coupled plasma spectrometry.

[0075] Table 1 shows the component detection data of gadolinium zirconate prepared in Example 1 compared with the national standard.

[0076] Table 1. Component analysis results of gadolinium zirconate prepared in Example 1

[0077]

[0078] As shown in Table 1, the Fe, Si, and Al impurities all meet the national standards, which is particularly crucial for thermal barrier coating materials.

[0079] Figure 4 The image shows the XRD pattern of gadolinium zirconate prepared in Example 1, which conforms to an ordered defective fluorite structure.

[0080] Example 2

[0081] The method for preparing rare earth zirconate powder for thermal barrier coatings in this embodiment includes the following steps:

[0082] According to the chemical formula La2Zr 1.8 Ce 0.2 In the O7 mixture, 795.54 g of zirconium oxycarbonate and 1119.55 g of lanthanum oxide were weighed out and dissolved in 1688.86 g and 2845 g of nitric acid, respectively. In addition, 149.21 g of cerium nitrate crystals were weighed out. After mixing the three, 5.5 L of pure water was added to prepare a concentration of 180 g / L. At the same time, 1 g of polyvinylpyrrolidone was added as a dispersant to obtain a rare earth mixture.

[0083] Compressed carbon dioxide gas was passed into a 3 mol / L ammonia solution at room temperature to lower its pH value to 7.0, thus obtaining a precipitant.

[0084] The rare earth mixture and precipitant were simultaneously fed into a self-made supergravity reactor for reaction at a reaction temperature of 85°C and a stirring speed of 6000 rpm to obtain a rare earth zirconate slurry, which was a mixture of zirconium hydroxide and lanthanum carbonate.

[0085] Citric acid, an inhibitor, was added to a rare earth zirconate slurry to crystallize the crystal nuclei for 5 hours. After solid-liquid separation, washing, and drying, the precursor of rare earth zirconate was obtained.

[0086] The obtained dry powder was calcined at a high temperature of 1200 ℃ for 4 h. After calcination, a multi-rare earth zirconate powder with fine particle size and high absolute purity was obtained. Figure 5 This is the particle size distribution of the rare earth zirconate powder prepared in Example 2.

[0087] Table 2. Detection results of the composition of the polyrare earth zirconate powder prepared in Example 2.

[0088]

[0089] Example 3

[0090] The method for preparing rare earth zirconate powder for thermal barrier coatings in this embodiment includes the following steps:

[0091] According to the chemical formula Sm2Zr 1.5 Ce 0.5 In the O7 formulation, 2340.38 g of zirconium oxychloride and 3376.83 g of samarium oxide were weighed out and dissolved in 3966.02 g and 7932.05 g of nitric acid, respectively. In addition, 1051.19 g of cerium nitrate crystals were weighed out. After mixing the three, 20 L of pure water was added to prepare a concentration of 150 g / L. At the same time, 6 g of polyethylene glycol 10000 dispersant was added to obtain a rare earth mixture.

[0092] Compressed carbon dioxide gas was passed into ammonia water with a concentration of 4.5 mol / L at room temperature to lower its pH value to 8.5, thus obtaining a precipitant.

[0093] The rare earth mixture and precipitant were simultaneously fed into a self-made supergravity reactor for reaction at a reaction temperature of 35°C, and a rare earth zirconate slurry was immediately obtained. The rare earth zirconate slurry was a mixture of zirconium hydroxide and samarium carbonate.

[0094] The inhibitor EDTA was added to the rare earth zirconate slurry to crystallize the crystal nuclei for 4 hours. Then, after solid-liquid separation, washing and drying, the precursor of rare earth zirconate was obtained.

[0095] The obtained dry powder was calcined at a high temperature of 1000 ℃ for 4 h to obtain multi-rare earth zirconate powder with fine particle size and high absolute purity. The obtained multi-rare earth zirconate powder can be used for thermal barrier coatings.

[0096] Figure 6 This is the particle size distribution of the rare earth zirconate powder prepared in Example 3.

[0097] Table 3. Composition detection results of the polyrare earth zirconate powder prepared in Example 3

[0098]

[0099] Comparative Example 1

[0100] The method for preparing rare earth zirconate powder in this embodiment includes the following steps:

[0101] Chemical formula Yb 0.2 Gd 1.8 Zr2O7 was prepared according to the method in Example 1, the only difference being the preparation method of the precipitant:

[0102] At room temperature, food-grade ammonium bicarbonate is prepared into a solution with a concentration of 2.5 mol / L to obtain a precipitant.

[0103] The rare earth zirconate powder was subjected to compositional analysis, and the results are shown in the table below.

[0104] Table 4 shows the compositional results of the rare earth zirconate powder prepared in Comparative Example 1.

[0105]

[0106] The results are shown in Table 4. The content of impurities exceeds the national standard requirements and does not meet the requirements for thermal barrier coatings.

[0107] Comparative Example 2

[0108] The preparation method of the rare earth zirconate powder in this comparative example includes the following steps:

[0109] Chemical formula Yb 0.2 Gd 1.8 Zr2O 7， The preparation was carried out in accordance with the method of Example 1, with the following difference:

[0110] At room temperature, food-grade ammonium bicarbonate is prepared into a solution with a concentration of 2.5 mol / L to obtain a precipitant.

[0111] The rare earth mixture and precipitant were simultaneously introduced into a glass reactor for reaction at a temperature of 60 °C. After both the mixture and the precipitant were added, the reaction was continued for 30 minutes with stirring to obtain a rare earth zirconate slurry.

[0112] The other steps are the same as in Example 1.

[0113] The obtained rare earth zirconate powder was tested by a particle size analyzer.

[0114] The results are as follows Figure 7 and Figure 8 As shown, although the primary particle size of rare earth zirconate powder is also in the nanometer range, it is severely agglomerated and the particles are not distinct. The particle size distribution curve shows two peaks, indicating the presence of excessively large particles that cannot be dispersed.

[0115] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing rare earth zirconate powder for thermal barrier coatings, characterized in that, The preparation method includes the following steps: (1) Weigh the zirconium source and rare earth raw materials according to the structural formula of rare earth zirconate, dissolve the zirconium source and rare earth raw materials separately with nitric acid, mix them, dilute with water, and add dispersant to obtain rare earth mixture; (2) Carbon dioxide gas is passed through ammonia water to adjust the pH of the solution and obtain a precipitant; (3) The rare earth mixture and the precipitant are flowed in parallel into the reactor to react and obtain a rare earth zirconate slurry containing crystal nuclei; (4) Add the inhibitor to the rare earth zirconate slurry for crystallization reaction, and after solid-liquid separation, washing, drying and high-temperature calcination, rare earth zirconate powder is obtained. The inhibitor is citric acid or EDTA. The structural formula of the rare earth zirconate powder is (RE 1 1-x RE 2 x )2(Zr 1-y Ce y )2O7, where 0≤x≤1, 0≤y≤1, RE 1 and RE 2 Each element is independently selected from one of the rare earth elements. The rare earth element is lanthanum, cerium, samarium, gadolinium, or ytterbium; In step (3), the rare earth mixture and the precipitant flow in parallel and are introduced into the hypergravity reactor. The stirring speed of the hypergravity reactor is 2000-6000 rpm. The rare earth mixture is added over a period of 0.5-3.0 hours. The precipitant is added over a period of 0.5-3.0 hours. In step (3), the rare earth mixture and the precipitant are fed into the reactor in parallel, and the reaction temperature is 15℃-95℃.

2. The method for preparing rare earth zirconate powder for thermal barrier coatings according to claim 1, characterized in that, In step (1), the zirconium source is selected from one or more of zirconium oxycarbonate, zirconium hydroxide, and zirconium oxychloride; and / or, the dispersant is selected from polyethylene glycol or polyvinylpyrrole.

3. The method for preparing rare earth zirconate powder for thermal barrier coatings according to claim 1, characterized in that, The concentration of the rare earth mixture obtained in step (1) is 80-220 g / L.

4. The method for preparing rare earth zirconate powder for thermal barrier coatings according to claim 1, characterized in that, In step (2), the concentration of ammonia is 2-5 mol / L, and / or, Carbon dioxide gas is passed through ammonia water to adjust the pH of the solution to 7.5-10.

0.

5. The method for preparing rare earth zirconate powder for thermal barrier coatings according to claim 1, characterized in that, In step (4), the inhibitor is added to the rare earth zirconate slurry and aged for 1-12 hours.

6. The method for preparing rare earth zirconate powder for thermal barrier coatings according to claim 1, characterized in that, In step (5), the roasting temperature is 1000℃-1400℃ and the roasting time is 2-5 h.

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