Preparation method of rare earth zirconate nano material

Abstract

The invention discloses a preparation method of a rare earth zirconate nano-material, which comprises the following steps of: mixing zirconium oxychloride serving as a zirconium source, rare earth elements introduced into rare earth chlorate and fructose serving as a reaction chelating agent in proportion, controlling the reaction temperature and the crystal growth speed through a simple water bath reaction to obtain a rare earth zirconate precursor solution, and drying to obtain the rare earth zirconate nano-material. And sintering at high temperature to successfully prepare various rare earth zirconate nano materials. The synthesis process is simple and easy to implement, good in repeatability and suitable for synthesis and preparation of various rare earth zirconates, and the prepared rare earth zirconates are excellent in thermal physical performance and have wide application prospects in the field of thermal barrier coatings.

Description

Technical Field

[0001] The invention belongs to the technical field of inorganic material preparation, and particularly relates to a method for preparing a rare earth zirconate nanomaterial. Background Art

[0002] Thermal barrier coatings (TBCs) are a key protective technology in the aerospace and energy power sectors. By depositing a thermally insulating ceramic coating on a high-temperature alloy surface, they effectively reduce the substrate temperature, ensuring stable operation of hot-end components such as engine turbine blades in extremely high-temperature environments. This high-temperature-resistant, highly insulating ceramic coating system not only significantly extends component service life but also improves engine thrust-to-weight ratio and thermal efficiency, thereby achieving energy conservation and emission reduction goals. As a core component of thermal barrier coatings, the ceramic layer plays a crucial role in resisting high temperatures and corrosion, and its performance directly determines the reliability of the coating system. To meet stringent service conditions, the ceramic layer material must possess a number of specialized properties. Yttrium-stabilized zirconia (YSZ), due to its comprehensive performance advantages, has become the mainstream material for ceramic layers in thermal barrier coatings. However, when the service temperature exceeds 1200°C, the metastable tetragonal phase of YSZ decomposes into a monoclinic phase under thermal cycling, accompanied by a 3%-5% volume expansion, which can easily cause the coating to buckle and fracture. This problem seriously restricts the application of thermal barrier coatings in higher temperature environments.

[0003] Cubic rare earth zirconates (RE2Zr2O7) exhibit exceptional performance due to their unique crystal structure, primarily comprising pyrochlore and defective fluorite. A significant advantage of this material lies in its exceptional high-temperature phase stability, maintaining a single phase structure throughout the entire service temperature range of thermal barrier coatings. This unique crystal structure contributes to their exceptional low thermal conductivity, effectively blocking heat transfer and exhibiting excellent sintering resistance, preventing material performance degradation at high temperatures. Furthermore, their oxygen impermeability further enhances the material's chemical stability, enabling it to maintain structural and performance integrity even in high-temperature, complex environments, making them a promising candidate for ceramic layers in thermal barrier coatings.

[0004] However, in actual preparation, the solid-phase reaction method is prone to compositional deviations after high-temperature sintering. High temperatures also cause abnormal grain growth to the micron level, leading to severe particle agglomeration and difficulty meeting the coating material's requirements for fine particle size and high dispersibility. Mechanical grinding and mixing of raw materials can easily introduce impurities, reducing product purity and affecting material performance and application effectiveness. The co-precipitation method uses demanding precipitation conditions, and the precipitated product is prone to adsorbing impurity ions. Residual impurities can affect phase stability at high temperatures.

[0005] The Chinese patent "A rare earth zirconate ceramic nanopowder material and its preparation method" (CN 118479876 A) discloses a rare earth zirconate ceramic nanopowder material and its preparation method. Rare earth salt and zirconium salt are weighed to prepare a solution, and ammonia water is added to the mixture as a precipitant. After stirring, the mixture is allowed to stand to obtain a complex precipitate. The precipitate is then subjected to cross-flow treatment, repeatedly washed and refined into colloidal particles to obtain a pure alkaline precipitate, which is mixed with a dispersant, distilled and dried under a vacuum environment to obtain a powder. After rolling and grinding with a roller mill, calcination treatment, and air flow pulverization, a nanopowder is obtained. However, this method has complex process steps, high operational difficulty, high requirements for equipment and process parameters, and low production efficiency. It requires multiple treatments and drying and calcination, and the overall production cycle is long, making it difficult to achieve large-scale rapid production.

[0006] The Chinese patent "A Green Preparation Method for Nano-Lanzirconate Powder" (CN 115010171A) discloses a green method for preparing nano-lanthanum zirconate powder. La2O3, ZrO2, and a NaCl-KCl salt mixture are ball-milled to uniformity. The mixture is then sintered at 1000-1200°C to directly obtain nano-La2Zr2O7 powder. After cooling, filtering, and washing, a pure phase powder is obtained. However, the particle sizes of La2O3 and nano-ZrO2 differ significantly in this method, which can lead to uneven dispersion during ball-milling, affecting the phase purity and particle size uniformity of the La2Zr2O7.

[0007] The Chinese patent "Rare Earth Zirconate Particles and Preparation Method Thereof" (CN 115340126 B) discloses rare earth zirconate particles and their preparation method. A water-soluble sulfate, ammonium salt, and zirconium oxychloride are prepared into a mixed aqueous solution. Ammonium bicarbonate solution A is added dropwise for reaction, followed by solid-liquid separation to obtain a first solid. This solid is then mixed with a water-soluble rare earth salt and water to form a liquid. Ammonium bicarbonate solution B is then added dropwise for reaction to obtain a rare earth zirconate precursor. Calcination yields larger rare earth zirconate particles. However, this method produces particles with a wide particle size distribution, with a D50 of 25 to 55 μm. This wide range of particle sizes is also attributed to differences in the conditions of the two precipitation reactions, which can lead to inconsistent growth of the precursor particles and uneven particle size distribution after calcination, affecting the stability of the material's properties. Summary of the Invention

[0008] In response to the problems existing in the prior art, the purpose of the present invention is to provide a universal and simple method for preparing rare earth zirconate nanomaterials by water bath reaction. The preparation process is simple and applicable to the preparation of a variety of rare earth zirconate materials. The obtained rare earth zirconate ceramic powder is non-toxic and harmless, high-purity and ultrafine, and has excellent thermophysical properties.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A method for preparing a rare earth zirconate nanomaterial comprises the following steps:

[0011] Step 1, weighing zirconium oxychloride, rare earth chloride and fructose, placing them in a beaker, adding deionized water, and stirring to obtain a colored solution, which is a rare earth zirconate precursor solution;

[0012] Step 2: The rare earth zirconate precursor solution obtained in step 1 is transferred into a water bath to react in a water bath. After the reaction is complete, the solution is dried in an electric blast drying oven to obtain a rare earth zirconate precursor powder.

[0013] Step 3: Place the rare earth zirconate precursor powder obtained in step 2 in a muffle furnace and calcine it at high temperature in air to obtain rare earth zirconate nanomaterials.

[0014] Furthermore, in step 1, the molar ratio of zirconium oxychloride, rare earth chloride and fructose is 1:1:2.

[0015] Furthermore, the stirring process in step 1 is carried out using a magnetic stirrer, and the stirring time is 30 minutes.

[0016] Furthermore, the specific steps of step 2 are:

[0017] The rare earth zirconate precursor solution obtained in step 1 is transferred to a water bath for water bath reaction. The reaction conditions are as follows: the water bath temperature is set at 70-80°C and the reaction time is 8-10 hours. The solution is then placed in an electric blast drying oven for drying at 120°C for 10-12 hours to obtain rare earth zirconate precursor powder.

[0018] Furthermore, in step 3, the high temperature calcination temperature is 1000-1500° C., and the holding time is 60-120 minutes.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention provides a method for preparing rare earth zirconate nanomaterials. By preparing a rare earth zirconate precursor suspension and reacting it in a low-temperature water bath, the metal ions in the rare earth zirconate precursor are brought into uniform and sufficient contact in the liquid phase, and nucleation and growth are performed to obtain rare earth zirconate seed crystals. At the same time, a lower water bath temperature is conducive to the slow nucleation and growth of the rare earth zirconate precursor seed crystals, thereby obtaining nano-scale seed crystals, which provides a prerequisite for the subsequent preparation of rare earth zirconate nanomaterials.

[0021] 2. The present invention avoids the use of reagents such as ammonia and ammonium bicarbonate in the preparation process, and selects safe and environmentally friendly fructose as a reaction aid. The reaction process is simple to operate, and the method has wide applicability and can realize the preparation of various rare earth zirconates. The hydroxyl O atoms in fructose can react with Zr 4+ and the metal ions La in the four rare earth elements3+ 、Sm 3+ 、Gd 3+ 、Er 3+ A stable complex is formed, which has lower binding energy and more stable structure than a single zirconate, thereby inhibiting the nucleation and growth process of the grains, and ultimately obtaining fine-sized nanoparticles, laying the foundation for the mass production of high-quality, process-stable rare earth zirconate nanomaterials.

[0022] 3. The water bath reaction process used in this preparation method is highly stable, and the reaction conditions of the low-temperature water bath are less affected by environmental fluctuations. Compared with traditional processes such as high-temperature solid-phase synthesis, the energy required is greatly reduced, and the energy consumption of the production process is reduced, which helps to achieve energy conservation and emission reduction and is in line with the trend of green manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A process flow chart of a method for preparing a rare earth zirconate nanomaterial provided by the present invention;

[0024] Figure 2 The XRD pattern, SEM pattern, TEM pattern, and EDS pattern of the lanthanum zirconate nanomaterial prepared in Example 1 of the present invention are shown;

[0025] Figure 3 The XRD pattern, SEM pattern, TEM pattern, and EDS pattern of the samarium zirconate nanomaterial prepared in Example 2 of the present invention are shown;

[0026] Figure 4 The XRD pattern, SEM pattern, TEM pattern, and EDS pattern of the gadolinium zirconate nanomaterial prepared in Example 3 of the present invention are shown;

[0027] Figure 5 The XRD pattern, SEM pattern, TEM pattern, and EDS pattern of the erbium zirconate nanomaterial prepared in Example 4 of the present invention are shown;

[0028] Figure 6 The figure shows a comparison of the thermal expansion coefficients of the rare earth zirconate nanomaterials prepared in Examples 1-4 of the present invention. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] like Figure 1 As shown, a method for preparing rare earth zirconate nanomaterials, the specific steps are as follows:

[0031] Step 1, prepare precursor solution: zirconium oxychloride (ZrOCl2), rare earth chloride (ReCl3), fructose (C6H 12 O6) was weighed in a molar ratio of 1:1:2, placed in a beaker and added with 50 mL of deionized water, and stirred to obtain a colored solution, which is the rare earth zirconate precursor solution. The stirring process was carried out using a magnetic stirrer for 30 min;

[0032] Step 2: Prepare precursor powder by water bath reaction: The rare earth zirconate precursor solution obtained in step 1 is transferred to a water bath. The conditions for the water bath reaction are: the water bath temperature is set at 70-80°C, and the reaction time is continued for 8-10 hours; then, the solution is placed in an electric blast drying oven for drying at 120°C for 10-12 hours to obtain rare earth zirconate precursor powder;

[0033] Step 3, high-temperature sintering to prepare rare earth zirconate nanomaterials: placing the rare earth zirconate precursor powder obtained in step 2 in a muffle furnace and calcining it in air at a high temperature of 1000-1500° C. for 60-120 minutes to obtain rare earth zirconate nanomaterials.

[0034] Example 1

[0035] Step 1: weigh 8.138g ZrOCl2, 9.285g LaCl3·7H2O, 9.009g C6H 12 O6 was placed in a beaker and 50 mL of deionized water was added, and stirred for 30 min using a magnetic stirrer to obtain a lanthanum zirconate precursor solution;

[0036] Step 2: The lanthanum zirconate precursor solution obtained in step 1 is transferred into a water bath, the water bath temperature is set at 80° C., and the reaction time is continued for 8 hours; then, the solution is placed in an electric blast drying oven for drying, the electric blast drying oven temperature is set at 120° C., and dried for 10 hours to obtain a lanthanum zirconate precursor powder;

[0037] Step 3: Place the lanthanum zirconate precursor powder obtained in step 2 in a muffle furnace and perform high-temperature calcination in air at a high-temperature calcination temperature of 1200° C. and a holding time of 60 minutes to obtain a lanthanum zirconate nanomaterial.

[0038] The lanthanum zirconate nanomaterial prepared in Example 1 was subjected to X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) morphology analysis, transmission electron microscopy (TEM) and EDS element distribution analysis. Figure 2 As shown. Figure 2It can be seen from (a) that only the characteristic peaks of lanthanum zirconate appear in the lanthanum zirconate nanomaterials sintered at 1200°C and correspond to its standard card. The prepared lanthanum zirconate particles have good crystallinity and are basically free of impurity phases. Figure 2 (b) and Figure 2 (c) is a SEM image of the lanthanum zirconate nanomaterial obtained in Example 1. It can be seen that the lanthanum zirconate nanomaterial particles obtained by sintering at 1200°C are evenly distributed and have an average particle size of 65 nm. Figure 2 (d) shows the particle morphology, Figure 2 (e) and Figure 2 (f) is HRTEM, where the lattice fringes are clear and the (222) interplanar spacing is 0.3076 nm, corresponding to the XRD results. Figure 2 (g) In region 1, element mapping is performed. Figure 2 (hj) shows that the elements are evenly distributed. Figure 2 (k) The energy spectrum analysis is consistent with the expected elemental composition, proving that the method of the present invention can successfully prepare high-purity, ultrafine, and uniformly controlled lanthanum zirconate nanomaterials.

[0039] Example 2

[0040] Step 1: weigh 8.138g ZrOCl2, 9.119g SmCl3·6H2O, 9.009g C6H 12 O6 was placed in a beaker and 50 mL of deionized water was added, and stirred with a magnetic stirrer for 30 min to obtain a samarium zirconate precursor solution;

[0041] Step 2: The samarium zirconate precursor solution obtained in step 1 is transferred into a water bath, the water bath temperature is set at 70° C., and the reaction time is continued for 10 hours; then, the solution is placed in an electric blast drying oven for drying, the electric blast drying oven temperature is set at 120° C., and dried for 12 hours to obtain a samarium zirconate precursor powder;

[0042] Step 3: Place the samarium zirconate precursor powder obtained in step 2 in a muffle furnace and calcine it at a high temperature in air at a calcination temperature of 1000° C. for 120 minutes to obtain samarium zirconate nanomaterials.

[0043] The samarium zirconate nanomaterial prepared in Example 2 of the present invention was subjected to X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) morphology analysis, transmission electron microscopy (TEM) and EDS element distribution analysis, as shown in FIG. Figure 3 As shown, from Figure 3 It can be seen from (a) that only the characteristic peak of samarium zirconate appears in the samarium zirconate nanomaterial sintered at 1000°C and corresponds to its standard card. The prepared samarium zirconate nanomaterial has good crystallinity and is basically free of impurity phases. Figure 3 (b) and Figure 3(c) is a SEM image of the samarium zirconate nanomaterial obtained in Example 2. It can be seen that the nano-samarium zirconate particles obtained by sintering at 1000°C are evenly distributed and have an average particle size of 60 nm. Figure 3 (d) shows the particle morphology, Figure 3 (e) and Figure 3 (f) is HRTEM, where the lattice fringes are clear and the (222) interplanar spacing is 0.299 nm, corresponding to the XRD results. Figure 3 (g) In region 1, element mapping is performed. Figure 3 (hj) shows that the elements are evenly distributed. Figure 3 (k) The energy spectrum analysis is consistent with the expected elemental composition, proving that the method of the present invention can successfully prepare high-purity, ultrafine, uniformly composed and controllable samarium zirconate nanomaterials.

[0044] Example 3

[0045] Step 1: weigh 8.138g ZrOCl2, 9.291g GdCl3·6H2O, 9.009g C6H 12 O6 was placed in a beaker and 50 mL of deionized water was added, and stirred for 30 min using a magnetic stirrer to obtain a gadolinium zirconate precursor solution;

[0046] Step 2: The gadolinium zirconate precursor solution obtained in step 1 is transferred into a water bath, the water bath temperature is set at 80° C., and the reaction time is continued for 8 hours; the solution is then placed in an electric blast drying oven for drying, the electric blast drying oven temperature is set at 120° C., and dried for 10 hours to obtain a gadolinium zirconate precursor powder;

[0047] Step 3: Place the gadolinium zirconate precursor powder obtained in step 2 in a muffle furnace and calcine it at a high temperature in air at a calcination temperature of 1500° C. for 60 minutes to obtain a gadolinium zirconate nanomaterial.

[0048] The gadolinium zirconate nanomaterial prepared in Example 3 of the present invention was subjected to X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) morphology analysis, transmission electron microscopy (TEM) and EDS element distribution analysis. Figure 4 As shown, from Figure 4 As can be seen in (a), the nano-gadolinium zirconate material sintered at 1500°C only shows characteristic peaks of gadolinium zirconate and corresponds to its standard card. The prepared gadolinium zirconate nanomaterial has good crystallinity and is basically free of impurity phases. Figure 4 (b) and Figure 4 (c) is a SEM image of the gadolinium zirconate nanomaterial obtained in Example 3. It can be seen that the nano-gadolinium zirconate particles sintered at 1500°C are evenly distributed with an average particle size of 150 nm. Figure 4 (d) shows the particle morphology, Figure 4 (e) and Figure 4 (f) is HRTEM, where the lattice fringes are clear and the (111) interplanar spacing is 0.304 nm, corresponding to the XRD results. Figure 4 (g) In region 1, element mapping is performed. Figure 4 (hj) shows that the elements are evenly distributed. Figure 4 (k) The energy spectrum analysis is consistent with the expected elemental composition, proving that the method of the present invention can successfully prepare high-purity, ultrafine, and uniformly controlled gadolinium zirconate nanomaterials.

[0049] Example 4

[0050] Step 1: weigh 8.138g ZrOCl2, 9.541g ErCl3·6H2O, 9.009g C6H 12 O6 was placed in a beaker and 50 mL of deionized water was added, and stirred for 30 min using a magnetic stirrer to obtain an erbium zirconate precursor solution;

[0051] Step 2: The erbium zirconate precursor solution obtained in step 1 is transferred into a water bath, the water bath temperature is set at 80° C., and the reaction time is continued for 8 hours; then, the solution is placed in an electric blast drying oven for drying, the electric blast drying oven temperature is set at 120° C., and dried for 10 hours to obtain an erbium zirconate precursor powder;

[0052] Step 3: placing the erbium zirconate precursor powder obtained in step 2 in a muffle furnace and calcining it at a high temperature in air at a calcination temperature of 1200° C. for 60 minutes to obtain erbium zirconate nanomaterials.

[0053] The erbium zirconate nanomaterial prepared in Example 4 of the present invention was subjected to X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) morphology analysis, transmission electron microscopy (TEM) and EDS element distribution analysis, as shown in FIG. Figure 5 As shown, from Figure 5 It can be seen from (a) that only the characteristic peak of erbium zirconate appears in the erbium zirconate nanomaterial sintered at 1200°C and corresponds to its standard card. The prepared erbium zirconate nanomaterial has good crystallinity and is basically free of impurity phases. Figure 5 (b) and Figure 5 (c) is the SEM image of nano-erbium zirconate obtained in Example 4. It can be seen that the nano-erbium zirconate particles obtained by sintering at 1200°C are evenly distributed and have an average particle size of 75 nm. Figure 5 (d) shows the particle morphology, Figure 5 (e) and Figure 5 (f) is HRTEM, where the lattice fringes are clear and the (111) interplanar spacing is 0.3001 nm, corresponding to the XRD results. Figure 5 (g) In region 1, element mapping is performed. Figure 5(hj) shows that the elements are evenly distributed. Figure 5 (k) The energy spectrum analysis is consistent with the expected elemental composition, proving that the method of the present invention can successfully prepare high-purity, ultrafine, uniform and controllable erbium zirconate nanomaterials.

[0054] The rare earth zirconate nanomaterials prepared in Examples 1-4 were subjected to high temperature thermal expansion coefficient (TEC) tests, and the results were as follows: Figure 6 As shown in the results, the prepared samples have a high thermal expansion coefficient, and the thermal expansion coefficients are 8.81×10 -6 ·K -1 、10.8×10 -6 ·K -1 , 9.04×10 -6 ·K -1 , 9.15×10 -6 ·K -1 (400~800℃).

[0055] The precursor conversion rate of the nano rare earth zirconate prepared in Examples 1-4 was calculated by mass loss before and after calcination, and the grain size of the nano rare earth zirconate in Examples 1-4 was calculated by the Scherrer formula, as shown in Table 1, indicating that the method of the present invention successfully controls the grain growth process and obtains high-purity ultrafine zirconate nanomaterials.

[0056] Table 1

[0057]

[0058] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing rare earth zirconate nanomaterials, characterized in that: The specific steps include: Step 1, weighing zirconium oxychloride, rare earth chloride and fructose, placing them in a beaker, adding deionized water, and stirring to obtain a colored solution, which is a rare earth zirconate precursor solution; Step 2: The rare earth zirconate precursor solution obtained in step 1 is transferred into a water bath to react in a water bath. After the reaction is complete, the solution is dried in an electric blast drying oven to obtain a rare earth zirconate precursor powder. Step 3: Place the rare earth zirconate precursor powder obtained in step 2 in a muffle furnace and calcine it at high temperature in air to obtain rare earth zirconate nanomaterials.

2. The method for preparing a rare earth zirconate nanomaterial according to claim 1, wherein: The molar ratio of zirconium oxychloride, rare earth chloride and fructose in step 1 is 1:1:

2.

3. The method for preparing a rare earth zirconate nanomaterial according to claim 1, wherein: The stirring process in step 1 is carried out using a magnetic stirrer, and the stirring time is 30 min.

4. The method for preparing a rare earth zirconate nanomaterial according to claim 1, wherein: The specific steps for step 2 are: The rare earth zirconate precursor solution obtained in step 1 is transferred to a water bath for water bath reaction. The reaction conditions are as follows: the water bath temperature is set at 70-80°C and the reaction time is 8-10 hours. The solution is then placed in an electric blast drying oven for drying at 120°C for 10-12 hours to obtain rare earth zirconate precursor powder.

5. The method for preparing a rare earth zirconate nanomaterial according to claim 1, characterized in that: In step 3, the high-temperature calcination temperature is 1000-1500° C., and the holding time is 60-120 minutes.

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