Preparation method of rare earth zirconate powder for thermal barrier coating

Abstract

The invention belongs to the technical field of thermal barrier coatings, and particularly relates to a preparation method of rare earth zirconate powder for a thermal barrier coating. The preparation method comprises the following steps: respectively dissolving a zirconium source and a rare earth raw material with nitric acid, mixing, adding water for dilution, and adding a dispersing agent to obtain a rare earth mixture; enabling carbon dioxide gas to pass through ammonia water, and adjusting the pH value of the solution to obtain a precipitant; the rare earth mixture and a precipitant are subjected to parallel flow and are introduced into a reactor for a reaction, and rare earth zirconate slurry is obtained; and adding an inhibitor into the rare earth zirconate slurry to carry out crystallization reaction, and carrying out solid-liquid separation, washing, drying and high-temperature roasting to obtain the rare earth zirconate powder. The multi-rare-earth zirconate powder obtained by the method is fine in granularity, high in absolute purity and low in roasting temperature, and can be directly subjected to spray granulation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of thermal barrier coatings, and particularly relates to a preparation method of a rare earth zirconate powder for thermal barrier coatings. BACKGROUND

[0002] A thermal barrier coating (TBC) is a multifunctional ceramic protective system deposited on the surface of a hot end metal component of an aero-engine, a gas turbine (hereinafter referred to as "two machines") and the like. By isolating the heat conduction of the high-temperature gas flow and the metal substrate, the working temperature of the engine is significantly improved (up to 1500℃ or more). Its core function depends on the ultra-low lattice thermal conductivity of the ceramic layer, which inhibits the heat transfer to the substrate, thereby achieving the improvement of the service life of the component, the reduction of pollutant emissions and the breakthrough increase of the thermal efficiency of the heat engine.

[0003] At present, the two machines are evolving towards high thrust-to-weight ratio and high thermal efficiency. The continuous increase of the turbine inlet temperature makes the traditional yttria-stabilized zirconia (YSZ) coating face fundamental limitations. YSZ will undergo phase decomposition when it is used above 1200℃, which will cause the coating to fail. Sintering acceleration and crack propagation will seriously restrict the service life of high-temperature components. Finding a thermal barrier coating material with lower thermal conductivity and higher thermal expansion coefficient has become a key issue to improve the thermal efficiency of the heat engine.

[0004] Rare earth zirconate belongs to the cubic crystal system. According to the radius ratio of Ln 3+ and Zr 4+ , cation and oxygen vacancy arrangement ordered pyrochlore / unordered fluorite structure can be formed, so rare earth zirconate has ultra-low lattice thermal conductivity, high-temperature thermal stability and controllable thermal expansion coefficient, and is the most promising thermal barrier coating material at present.

[0005] Patent (CN 118420358 A) mixes a rare earth salt solution and a zirconium salt solution according to the molar ratio, stirs them uniformly, uses ammonia water as a precipitant to prepare a precipitate, then separates and filters the precipitate through a ceramic membrane, grinds it after slurry preparation with nitric acid, and finally performs heat treatment to obtain a spherical nano-structured high-entropy rare earth zirconate powder. In this method, ammonia water is used as a precipitant, and the slurry obtained is not easy to filter, and after drying, it is clumped. Patent (CN 110563035 A) mixes rare earth oxides, zirconium oxide, molten salt and anhydrous ethanol to obtain a mixture; the mixture is calcined to obtain the rare earth zirconate nano-powder. This method is a molten salt solid-phase sintering method, and sodium chloride, potassium chloride and lithium chloride used in the method will eventually be doped into the product, and it is not easy to be industrialized. Patent (CN 112661511 A) adds nitric acid rare earth or chlorinated rare earth to ammonia water, filters, washes, dries and calcines the hydroxide precipitate for 12 hours, and then grinds and freeze-dries to obtain a rare earth zirconate powder. The powder obtained by this method has a long calcination time, and the calcined product needs to be ground and freeze-dried, which has a high cost. SUMMARY

[0006] The present application provides a kind of multiref ractory zirconate powder for thermal barrier coating and its preparation method, solve the problem that industrial production nanometer powder is difficult to filter, also have the problem that Fe, Si, Al and other impurity elements are not up to standard, can obtain the multiref ractory zirconate powder of fine powder particle size, high absolute purity.

[0007] According to the specific embodiment of the present application, the structure formula of the rare earth zirconate powder for thermal barrier coating is (RE 1 1-x RE 2 x )2(Zr 1-y Ce y )2O7, wherein 0≤x≤1, 0≤y≤1, RE 1 And RE 2 Each is independently selected from one of rare earth elements.

[0008] According to the specific embodiment of the present application, the rare earth element is lanthanum, cerium, samarium, gadolinium or ytterbium.

[0009] The phase structure of the rare earth zirconate powder obtained by the present application is ordered pyrochlore structure with oxygen vacancy arrangement / disordered fluorite structure.

[0010] According to the specific embodiment of the present application, the preparation method of the rare earth zirconate powder for thermal barrier coating comprises the following steps: (1) according to the structure formula of rare earth zirconate, zirconium source and rare earth raw material are weighed, and zirconium source and rare earth raw material are dissolved with nitric acid respectively, mixed, diluted with water, and then a dispersing agent is added to obtain a rare earth mixture; (2) carbon dioxide gas is passed through ammonia water to adjust the pH of the solution to obtain a precipitant; (3) the rare earth mixture and the precipitant are parallel, and are introduced into a reactor to react to obtain a rare earth zirconate slurry containing crystal nucleus; (4) an inhibitor is added to the rare earth zirconate slurry for crystallization reaction, and then solid-liquid separation, washing, drying and high temperature calcination are carried out to obtain the rare earth zirconate powder.

[0011] According to the specific embodiment of the present application, in step (1), the zirconium source is selected from one or more of zirconium carbonate, zirconium hydroxide and zirconium oxychloride; and / or, the dispersing agent is selected from polyethylene glycol, polyvinylpyrrole or polyvinylpyrrolidone.

[0012] The rare earth raw material is one of the common commercially available industrial rare earth carbonate, rare earth oxide and rare earth hydroxide, and the relative purity is greater than or equal to 99.99%, for example, the ratio of Y2O3 to ∑REO in the rare earth oxide is greater than or equal to 99.99%.

[0013] The rare earth mixture obtained in step (1) contains rare earth nitrate and zirconyl nitrate.

[0014] According to the preparation method of the rare earth zirconate powder for thermal barrier coating according to the specific embodiment of the present application, the concentration of the rare earth mixture obtained in step (1) is 80-220 g / L.

[0015] According to the preparation method of the rare earth zirconate powder for thermal barrier coating according to the specific embodiment of the present application, in step (2), the concentration of the ammonia water is 2-5 mol / L, and / or, The carbon dioxide gas is passed through the ammonia water to adjust the pH of the solution to 7.5-10.0.

[0016] The carbon dioxide is reacted with the ammonia water to prepare high-purity ammonium bicarbonate, which is used as a precipitant. The high-purity ammonium bicarbonate co-precipitates with trace amounts of impurities such as iron, silicon, aluminum, magnesium and chloride ions in the raw material, plays a role in impurity removal, and can improve the purity of the rare earth zirconate powder product.

[0017] According to the preparation method of the rare earth zirconate powder for thermal barrier coating according to the specific embodiment of the present application, in step (3), the reactor is one of a stirred reaction kettle, a pipeline mixer and a high gravity reactor. In step (3), the rare earth mixture and the precipitant are passed into the high gravity reactor in parallel flow, and the reaction temperature is 15°C-95°C.

[0018] In the present application, the high gravity reactor is a device that uses a high gravity environment to intensify mass transfer, mixing and reaction processes. It generates a centrifugal force field that is much larger than the gravity of the earth (usually several tens to several thousand times the gravity acceleration). The present application utilizes the high gravity field to increase the contact area between liquid-liquid and liquid-solid phases, while the centrifugal force accelerates the renewal rate of the phase interface, and the mass transfer coefficient is increased by tens to hundreds of times.

[0019] The core of the reaction of the rare earth mixture and the precipitant is to generate rare earth precipitates, which follow the basic law of "nucleation-growth". However, too high local concentration will directly break the balance between the two, inducing agglomeration. In the present application, the rare earth mixture and the precipitant are passed into the high gravity reactor in parallel flow, realizing instantaneous and uniform mixing of the reactants, ensuring "uniform concentration-nucleation-growth synchronization-complete crystal grains + uniform spacing", and finally effectively inhibiting the agglomeration of crystal grains caused by too high local concentration, and ensuring the uniformity of the particle size.

[0020] Preferably, the stirring speed of the high gravity reactor is 2000-6000 rpm.

[0021] The adding time of the rare earth mixture is 0.5-3.0 h; the adding time of the precipitator 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 the precipitator are added at the same time.

[0022] In step (4) of the preparation method of the rare earth zirconate powder for thermal barrier coating according to the embodiment of the present application, the inhibitor is citric acid or EDTA; and the adding amount is 0.05-1%.

[0023] After the inhibitor is added into the rare earth zirconate slurry, aging is performed for 1-12 h.

[0024] In step (5) of the preparation method of the rare earth zirconate powder for thermal barrier coating according to the embodiment of the present application, the calcination temperature is 1000-1400 ℃, and the calcination time is 2-5 h.

[0025] The present application has the following advantages: (1) The present application uses high-purity ammonium bicarbonate prepared by the reaction of carbon dioxide and ammonia water as a precipitator, which can remove impurities and purify, and effectively prevents trace amounts of iron, silicon, aluminum, magnesium and chloride ions and other impurities in the original material from co-precipitating into the product, thereby ensuring the high purity of the rare earth zirconate powder.

[0026] (2) The present application uses a supergravity reactor to realize instantaneous and uniform mixing of the rare earth mixture and the precipitator, effectively inhibits the grain agglomeration caused by excessive local concentration, and cooperates with the addition of the inhibitor to prevent the grain from growing in the water / salt solution, so as to form uniform nano-sized particles, and the obtained powder can be calcined to obtain a rare earth zirconate powder product with extremely narrow particle size distribution without sanding and grinding. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0028] Figure 1 The process flow chart of the preparation method of the rare earth zirconate powder for thermal barrier coating of the present application.

[0029] Figure 2 The particle size distribution of the ytterbium gadolinium zirconate prepared in Example 1.

[0030] Figure 3 The micro-morphology of the ytterbium gadolinium zirconate prepared in Example 1.

[0031] Figure 4is the phase structure of the gadolinium ytterbium zirconate prepared in Example 1.

[0032] Figure 5 is the particle size distribution of the rare earth zirconate powder prepared in Example 2.

[0033] Figure 6 is the particle size distribution of the rare earth zirconate powder prepared in Example 3.

[0034] Figure 7 is the particle size distribution of the gadolinium ytterbium zirconate prepared in Comparative Example 2.

[0035] Figure 8 is the micro-morphology of the gadolinium ytterbium zirconate prepared in Comparative Example 2. DETAILED DESCRIPTION

[0036] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described in detail below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0037] The present application provides a rare earth zirconate powder for thermal barrier coating, which has a structural formula of (RE 1 1-x RE 2 x )2(Zr 1-y Ce y )2O7, wherein 0≤x≤1, 0≤y≤1, RE 1 and RE 2 are each independently selected from one of rare earth elements, and the rare earth elements are lanthanum, cerium, samarium, gadolinium or ytterbium.

[0038] Preferably, the rare earth zirconate powder has a structural formula of (RE 1 1-x RE 2 x )2(Zr 1-y Ce y )2O7, wherein 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, in Yb 0.2 Gd 1.8 Zr2O7, RE 2 is Yb, RE 1 is Gd, x=0.1, y=0; in La2Zr 1.8 Ce 0.2 O7, RE 1La, x=0, y=0.1.

[0039] The phase structure of the rare earth zirconate powder obtained by the method is an ordered oxygen vacancy arrangement pyrochlore structure / unordered fluorite structure.

[0040] The method for preparing the rare earth zirconate powder for thermal barrier coating comprises the following steps: (1) The raw materials (zirconium source and rare earth raw materials) are weighed according to the structure formula of the rare earth zirconate, the zirconium source and the rare earth raw materials are respectively dissolved with nitric acid, mixed, diluted with water, and a dispersing agent is added to obtain a rare earth mixture; (2) Carbon dioxide gas is passed through ammonia water to adjust the pH of the solution to obtain a precipitant; (3) The rare earth mixture and the precipitant are flowed together and introduced into a reactor to react, and the rare earth zirconate slurry is immediately obtained; (4) An inhibitor is added to the rare earth zirconate slurry to perform a crystallization reaction, and the rare earth zirconate powder is obtained through solid-liquid separation, washing, drying and high-temperature calcination.

[0041] The flow chart of the method for preparing the rare earth zirconate powder for thermal barrier coating is shown in the figure Figure 1 wherein, the dispersing agent (Y1), the mixture (material A), the precipitant (material B), the rare earth zirconate slurry (material C), and the inhibitor (Y2).

[0042] Preferably, in step (1), the zirconium source is selected from one or more of zirconium carbonate, zirconium hydroxide and zirconium oxychloride; The dispersing agent is selected from polyethylene glycol, polyvinylpyrrole or polyvinylpyrrolidone, and the amount of the dispersing agent is 0.05-1% (mass percentage of the raw materials). Preferably, the amount of the dispersing agent 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 the amount of the dispersing agent is any value within the range of 0.05-1%.

[0043] In step (1), the concentration of the rare earth mixture obtained with the raw materials (zirconium source and rare earth raw materials) as solutes is 80-220 g / L. Preferably, the concentration of the rare earth mixture is 100-200 g / L, or the concentration is 100, 110, 120, 130, 140, 150, 160, 170, 180, 190 or 200 g / L, or the concentration of the rare earth mixture is any value within the range of 80-220 g / L, which is not listed one by one here.

[0044] In step (2), the concentration of the ammonia water is 2-5 mol / L. Preferably, the concentration of the ammonia water is 2, 2.5, 3.5, 4, 4.5 or 5 mol / L, or the concentration of the ammonia water is any value within the range of 2-5 mol / L, which is not listed one by one here.

[0045] The carbon dioxide gas is passed through the ammonia water, and the pH of the solution is adjusted to 7.5-10.0.

[0046] In step (3), the reactor is one of a stirred tank reactor, a pipe mixer, and a high gravity reactor. Preferably, the reactor is a high gravity reactor, and the rare earth mixture and the precipitant are passed into the high gravity reactor in parallel flow, and the reaction temperature is 15-95℃.

[0047] The stirring speed of the high gravity reactor is 2000-6000 rpm. According to 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 is not listed here.

[0048] The filling time of the rare earth mixture is 0.5-3.0 h, and the filling time of the precipitant is 0.5-3.0 h. The filling time of the rare earth mixture and the precipitant can be adjusted individually, and preferably, the filling time of the rare earth mixture and the precipitant is equal.

[0049] The filling time is the time for the material (rare earth mixture, precipitant) to be added to the reactor.

[0050] In step (4), the inhibitor is citric acid or EDTA, and the amount of the inhibitor is 0.05-1% (mass percentage of the raw material), and preferably, the amount of the inhibitor 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 the amount of the dispersant is any value within the range of 0.05-1%, which is not listed here.

[0051] After the inhibitor is added to the rare earth zirconate slurry, it is aged for 1-12 h.

[0052] 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 is not listed here.

[0053] Example 1 The preparation method of the rare earth zirconate powder for thermal barrier coating in this example comprises the following steps: According to the chemical formula Yb 0.2 Gd 1.8To 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.

[0054] 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.

[0055] 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 rare earth zirconate slurry, which is a mixture of zirconium hydroxide, gadolinium carbonate, and ytterbium carbonate.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] Table 1 shows the component detection data of gadolinium zirconate prepared in Example 1 compared with the national standard.

[0061] Table 1. Component analysis results of gadolinium zirconate prepared in Example 1

[0062] 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.

[0063] Figure 4The XRD pattern of the gadolinium ytterbium zirconate prepared in Example 1 is consistent with the ordered defect-fluorite structure.

[0064] Example 2 The preparation method of the rare earth zirconate powder for thermal barrier coating in this example comprises the following steps: According to the chemical formula La2Zr 1.8 Ce 0.2 O7, 795.54 g of zirconium carbonate, 1119.55 g of lanthanum oxide are weighed according to the proportion, respectively dissolved with 1688.86 g and 2845 g of nitric acid, and 149.21 g of cerium nitrate crystal is additionally weighed. After mixing, 5.5 L of pure water is added to prepare a rare earth mixture with a concentration of 180 g / L. At the same time, 1 g of polyvinylpyrrolidone is added as a dispersant to obtain the rare earth mixture.

[0065] At room temperature, compressed carbon dioxide gas is introduced into ammonia water with a concentration of 3 mol / L to reduce the pH value to 7.0 to obtain a precipitant; The rare earth mixture and the precipitant are introduced into a self-made high gravity reactor at the same time for reaction, the reaction temperature is 85℃, and the stirring speed is 6000 rpm to obtain a rare earth zirconate slurry. The rare earth zirconate slurry is a mixed slurry of zirconium hydroxide and lanthanum carbonate; The inhibitor citric acid is added to the rare earth zirconate slurry to crystallize the crystal nucleus for 5 h, and then the solid-liquid separation, washing and drying steps are carried out to obtain the rare earth zirconate precursor.

[0066] The obtained dry powder is calcined at high temperature, the calcination temperature is 1200℃, and the calcination time is 4 h. After calcination, the multi-rare earth zirconate powder with fine particle size and high absolute purity can be obtained. Figure 5 The particle size distribution of the rare earth zirconate powder prepared in Example 2 is shown in the following table.

[0067] Table 2 shows the composition detection results of the multi-rare earth zirconate powder prepared in Example 2.

[0068] Example 3 The preparation method of the rare earth zirconate powder for thermal barrier coating in this example comprises the following steps: According to the chemical formula Sm2Zr 1.5 Ce 0.5 O7, 795.54 g of zirconium carbonate, 1119.55 g of lanthanum oxide are weighed according to the proportion, respectively dissolved with 1688.86 g and 2845 g of nitric acid, and 149.21 g of cerium nitrate crystal is additionally weighed. After mixing, 5.5 L of pure water is added to prepare a rare earth mixture with a concentration of 180 g / L. At the same time, 1 g of polyvinylpyrrolidone is added as a dispersant to obtain the rare earth mixture. The compressed carbon dioxide gas is introduced into ammonia water with a concentration of 4.5 mol / L at room temperature to reduce the pH value to 8.5 to obtain a precipitant; The rare earth mixture and the precipitant are introduced into a self-made high gravity reactor at the same time to react at a temperature of 35℃ to obtain a rare earth zirconate slurry immediately, which is a mixed slurry of zirconium hydroxide and samarium carbonate; The inhibitor EDTA is added into the rare earth zirconate slurry to crystallize the crystal nucleus for 4 h, and then the rare earth zirconate precursor is obtained through the steps of solid-liquid separation, washing and drying. The obtained dry powder is calcined at a high temperature, and the calcination temperature is 1000℃ and the calcination time is 4 h. After calcination, the multi-rare earth zirconate powder with fine particle size and high absolute purity is obtained. The multi-rare earth zirconate powder can be used for thermal barrier coating.

[0069] Figure 6 The particle size distribution of the rare earth zirconate powder prepared in Example 3 is shown in the following table.

[0070] Table 3 shows the composition detection results of the multi-rare earth zirconate powder prepared in Example 3.

[0071] Comparative Example 1 The preparation method of the rare earth zirconate powder in this example includes the following steps: Chemical formula Yb 0.2 Gd 1.8 Zr2O7, prepared in the manner of Example 1, the only difference being the preparation method of the precipitant: At room temperature, food-grade ammonium bicarbonate is configured into a solution with a concentration of 2.5 mol / L to obtain a precipitant.

[0072] The obtained rare earth zirconate powder is subjected to composition detection, and the results are shown in the following table.

[0073] Table 4 shows the composition detection results of the rare earth zirconate powder prepared in Comparative Example 1.

[0074] The results are shown in Table 4, in which the impurity content exceeds the national standard requirements and does not meet the requirements for thermal barrier coating.

[0075] Comparative Example 2 The preparation method of the rare earth zirconate powder in this example includes the following steps: Chemical formula Yb 0.2 Gd 1.8 Zr2O 7， Prepared in the manner of Example 1, the difference is: Food-grade ammonium bicarbonate is configured into a solution with a concentration of 2.5 mol / L at room temperature to obtain a precipitant.

[0076] The rare earth mixture and the precipitant are simultaneously introduced into a glass reaction kettle for reaction, the reaction temperature is 60 ℃, after the liquid and the precipitant are both added, the stirring is continued for 30 min to obtain a rare earth zirconate slurry.

[0077] The other steps are the same as those in Example 1.

[0078] The rare earth zirconate powder obtained is tested by a particle size tester.

[0079] The results are shown in Figure 7 and Figure 8 Although the primary particle size of the rare earth zirconate powder is also nanoscale, the agglomeration is serious, the particles are not distinct, the particle size distribution curve shows two peak values, and there are oversized particles that cannot be dispersed.

[0080] The above merely describes the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A rare earth zirconate powder for thermal barrier coating, characterized by comprising a rare earth element and zirconium, and having a particle size of 0.1 to 10 μm. The structure formula of the rare earth zirconate powder is (RE 1 1-x RE 2 x )2(Zr 1-y y )2O7, wherein 0≤x≤1, 0≤y≤1, RE 1 and RE 2 are each independently selected from one of the rare earth elements.​ 2. The rare earth zirconate powder for thermal barrier coating according to claim 1, characterized by, The rare earth element is lanthanum, cerium, samarium, gadolinium or ytterbium.

3. The method of producing a rare earth zirconate powder for thermal barrier coating as claimed in any one of claims 1 to 2, characterized by, The preparation method comprises the following steps: (1) according to the structural formula of the rare earth zirconate, zirconium source and rare earth raw materials are weighed, the zirconium source and the rare earth raw materials are dissolved with nitric acid respectively, mixed, diluted with water, and a dispersing agent is added to obtain a rare earth mixture; (2) carbon dioxide gas is passed through ammonia water to adjust the pH of the solution to obtain a precipitant; (3) the rare earth mixture and the precipitant are flowed together and introduced into a reactor to react to obtain a rare earth zirconate slurry containing crystal nuclei; (4) an inhibitor is added to the rare earth zirconate slurry to perform a crystallization reaction, and after solid-liquid separation, washing, drying and high-temperature calcination, a rare earth zirconate powder is obtained.

4. The method for producing a rare earth zirconate powder for thermal barrier coating according to claim 3, characterized by, In step (1), the zirconium source is selected from one or more of zirconium oxycarbonate, zirconium hydroxide and zirconium oxychloride; and / or, the dispersing agent is selected from polyethylene glycol or polyvinylpyrrole.

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

6. The method for producing a rare earth zirconate powder for thermal barrier coating according to claim 3, characterized by, In step (2), the concentration of the ammonia water is 2-5 mol / L, and / or, The carbon dioxide gas is passed through the ammonia water to adjust the pH of the solution to 7.5-10.

0.

7. The method for producing a rare earth zirconate powder for thermal barrier coating according to claim 3, characterized by, In step (3), the rare earth mixture and the precipitant are flowed together and introduced into a high gravity reactor, the stirring speed of the high gravity reactor is 2000-6000 rpm, and / or, The injection time of the rare earth mixture is 0.5-3.0 h, The injection time of the precipitant is 0.5-3.0 h; In step (3), the rare earth mixture and the precipitant are flowed together and introduced into the reactor, and the reaction temperature is 15℃-95℃.

8. The method for producing a rare earth zirconate powder for thermal barrier coating according to claim 3, characterized by, In step (4), the inhibitor is citric acid or EDTA; and / or, After the inhibitor is added to the rare earth zirconate slurry, it is aged for 1-12 h.

9. The method for producing a rare earth zirconate powder for thermal barrier coating according to claim 3, characterized by, In step (5), the calcination temperature is 1000℃-1400℃, and the calcination time is 2-5 h.

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