Preparation method of zirconium oxide powder with negative thermal expansion material film layer

Abstract

The invention provides a preparation method of zirconium oxide powder with a negative thermal expansion material film layer. According to the specific technical thought, a fluidization technology is utilized, working gas is preheated, the preheated working gas serves as carrier gas, the carrier gas and zirconium oxide powder form gas-solid two-phase flow, and the gas-solid two-phase flow is introduced into a fluidized bed reactor in a plasma device; and introducing the gasified negative thermal expansion material and working gas into the fluidized bed reactor from the bottom of the fluidized bed reactor at the same time, so that the gasified negative thermal expansion material is deposited on the surface of the fluidized zirconium oxide powder, the gas phase and the solid phase are in complete contact, and the negative thermal expansion material is uniformly coated on the surfaces of the zirconium oxide powder particles to form a uniform and compact film. And finally, introducing a gas-solid phase mixture generated by the reaction into a gas-solid separation device, and treating to obtain the zirconium oxide powder with the negative thermal expansion material film layer. The method is simple in process, short in production period, stable in product structure, small in particle size and uniform in particle size distribution.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of advanced functional ceramic materials, and in particular relates to a method for preparing zirconium oxide powder with a negative thermal expansion material film layer. Background Art

[0002] Zirconia powder and product materials have a wide range of applications in various fields. However, zirconia undergoes phase transformation at high temperatures, and when faced with large temperature changes, it will crack and fail due to its own thermal expansion. To solve this problem, researchers compounded negative thermal expansion materials with zirconia powder materials to prepare zirconia composite powder materials with low thermal expansion coefficients. At present, there are many methods for preparing composite powder materials of low thermal expansion materials and zirconia, mainly including coprecipitation method, sol-gel method, solid phase method, hydrothermal method, etc. Among them, the solid phase method has a simple process and convenient operation, but the product particles are easy to agglomerate and the product purity is low; the sol-gel method has simple experimental conditions, convenient operation, and the product composition is easy to control and the chemical uniformity is good, but the required raw materials are expensive, the reaction cycle is long, the hydrolysis conditions are difficult to control, and the gel shrinks greatly when drying, and the product is easy to agglomerate; the hydrothermal method is a common method for preparing composite powder materials of low expansion materials and zirconia, but the equipment investment is large and the technical requirements are high. Manufacturers often choose precipitation method to produce composite powders of low expansion materials and zirconium oxide. In order to avoid powder agglomeration caused by impurity ions and hydrogen bonds during drying and heat treatment, multiple water washing and alcohol washing processes are required, which will produce a large amount of wastewater and pollute the environment. In summary, existing preparation technologies such as sol-gel and co-precipitation methods are difficult to achieve industrial large-scale production.

[0003] Compared with the existing preparation technology, plasma chemical vapor deposition technology is a chemical vapor deposition technology that uses plasma to activate chemical reactions. It can achieve high-quality, uniform and controllable thin film deposition by introducing plasma in the chemical vapor deposition process, activating gas molecules and enhancing the reaction rate. This technology is widely used in the field of thin film coating, such as: material surface modification, biomedical materials, solar cells, etc. For example, patent CN118256869A provides a film-forming method and device for powder deposition using plasma, in which the oxide powder is blown with a carrier gas until an aerosol is generated. In the plasma device, the carrier gas and the aerosol are sprayed onto the surface of the parent substrate along the central axis of the magnetic flux line, and an oxide film is deposited on the surface of the parent substrate. This method is beneficial to the formation of a dense and uniform oxide film. In addition, plasma technology as a new technology has also been applied to technical fields such as powder preparation, powder surface modification, and film coating. For example, patent CN115838919A provides an inorganic non-metallic particle coating material and its control method. By combining plasma chemical vapor deposition and fluidized bed technology, an oxide film is deposited on the surface of non-metallic particles, so that the target film layer grows uniformly along the surface of the inorganic non-metallic particles, and the coating is complete and uniform, so that the metal compound can uniformly and completely coat the inorganic non-metallic particles. This method combines plasma vapor deposition with fluidized bed technology, in which the fluidized bed has high heat and mass transfer efficiency and is widely used in the field of powder preparation technology. Plasma technology can greatly improve the reactivity of gas, and is a surface treatment technology with good deposition effect, controllable film growth, and high efficiency. However, the target film layer precursor in this method is relatively expensive, which increases the cost, and the inorganic non-metallic particles and the reaction gas in the fluidized bed reactor pass through the bed in the form of bubbles, which reduces the contact opportunity between the gas-solid phase and reduces the reaction conversion rate.

[0004] In view of the shortcomings in the existing technical methods for preparing composite powder materials of low-expansion materials and zirconium oxide, researchers need to improve the existing technical processes and provide a low-expansion zirconium oxide and zirconium tungstate powder composite material with simple process, uniform particle distribution and excellent performance. Summary of the invention

[0005] The present invention aims to provide a method for preparing zirconium oxide powder with a negative thermal expansion material film layer. The method combines the advantages of existing plasma chemical vapor deposition and fluidized bed technology, and improves on the basis of existing technology to design and develop a zirconium oxide powder with a negative thermal expansion material film layer with simple process, short production cycle, stable powder structure, small particle size, and uniform particle size distribution. The specific technical idea is: using fluidization technology, by preheating the working gas, using the preheated working gas as a carrier gas, and forming a gas-solid two-phase flow with the zirconium oxide powder and introducing it into the fluidized bed reactor in the plasma device, at the same time, the gasified negative thermal expansion material and the working gas are simultaneously introduced into the fluidized bed reactor from the bottom of the fluidized bed reactor, so that the gasified negative thermal expansion material is deposited on the surface of the fluidized zirconium oxide powder, and the gas and solid two-phase contact is complete, so that the negative thermal expansion material is evenly coated on the surface of the zirconium oxide powder particles to form a uniform and dense film. The gas-solid phase mixture generated by the reaction is passed into a gas-solid separation device for treatment to obtain a zirconium oxide powder with a negative thermal expansion material film layer.

[0006] The present invention forms a gas-solid two-phase flow with the preheated working gas and the zirconium oxide powder to flow at high speed in a suspended state in a fluidized bed reactor, and fully contacts with the upward negative thermal expansion material gas flow in a fluidized state. At the same time, the temperature in the fluidized bed is uniform, and the gas-solid contact area is large, which is conducive to the deposition of the negative thermal expansion material film layer on the surface of the zirconium oxide powder to form a complete and uniform film layer. In addition, the present invention adds a metal aluminum salt to the precursor solution of the negative expansion material, and a small amount of liquid phase product is generated during the sintering process, forming a solid-liquid interface on the grain boundary. The movement speed of the grain boundary is reduced so that the pores are always kept on the grain boundary and discharged during the sintering process, while ensuring that the low expansion material forms a stable structure, the powder material is promoted to be densified. The present invention solves the problems existing in the prior art. The preparation method of the present invention has a simple process, high reaction efficiency, short production cycle, and low raw material cost, which is conducive to industrial application.

[0007] To achieve the above object, the technical solution of the present invention is as follows: A method for preparing zirconium oxide powder having a negative thermal expansion material film layer, characterized in that it comprises the following steps: (1) introducing the preheated working gas into a zirconia powder feeding device to form a gas-solid two-phase flow consisting of zirconia powder and the working gas, and introducing the formed zirconia powder gas-solid two-phase flow into a fluidized bed reactor in a plasma device; (2) introducing a negative thermal expansion material precursor solution into a gasification device, and simultaneously raising the temperature of the gasification device and the gas pipeline, and after the negative thermal expansion material precursor solution is gasified, it is introduced into the fluidized bed reactor simultaneously with the working gas from the bottom of the fluidized bed reactor; (3) turning on the power of the plasma device and setting the working parameters so that the gas after the negative thermal expansion material precursor solution is vaporized undergoes a chemical vapor deposition reaction on the surface of the zirconium oxide particles to obtain a gas-solid phase zirconium oxide powder mixture having a negative thermal expansion material film layer; (4) Turn on the separation device to perform gas-solid separation on the gas-solid mixture obtained in step 3 to obtain zirconium oxide powder having a negative thermal expansion material film layer.

[0008] Specifically, the average particle size of the zirconium oxide powder in step (1) is 100-500 nm, the working gas is argon, and the preheating temperature is 800-1000° C. In the present invention, the preheated working gas is used as a carrier gas to form a gas-solid two-phase flow with the nano zirconium oxide powder and flow at a high speed in a suspended state in a fluidized bed reactor, so that the nano zirconium oxide powder is fully in contact with the upward negative thermal expansion material gas flow, and the gas-solid contact area is large, which is conducive to the deposition of the negative thermal expansion material film layer on the surface of the zirconium oxide powder to form a complete and uniform film layer.

[0009] Specifically, the negative thermal expansion material precursor solution described in step (2) is composed of a mixture of metal zirconium salt, tungstate, metal aluminum salt and water, wherein the metal zirconium salt is zirconium tetrachloride or zirconium nitrate; the metal aluminum salt is aluminum tetrachloride or aluminum nitrate; and the tungstate is ammonium tungstate. The present invention adds metal aluminum salt to the negative thermal expansion material precursor solution, which is beneficial to the low expansion powder material while ensuring the formation of a stable structure and promoting the densification of the powder material. In addition, the present invention vaporizes the negative thermal expansion material precursor solution, and then deposits the nano zirconium oxide powder into a film on the surface of the fluidized nano zirconium oxide powder by chemical vapor deposition. The two have a high bonding strength and are not easy to decompose.

[0010] Furthermore, the mass ratio of the metal zirconium salt, tungstate, metal aluminum salt and water is 1: (1.5 ~ 2.5): (0.15 ~ 0.35): (20 ~ 50).

[0011] Specifically, the temperature of the gasification device and the gas pipeline in step (2) is 120-200°C, and the flow rate of the negative thermal expansion material precursor solution after gasification is 0.15-0.5 mL / min.

[0012] Specifically, the working gas in step (2) is a mixture of argon and oxygen, and the flow rate is 50 to 200 mL / min.

[0013] Specifically, the operating parameters of the plasma device described in step (3) are set to microwave power of 500-1000W and pressure of 1-10 kPa; and the chemical vapor deposition time is 0.5-1 h.

[0014] Specifically, the gas-solid separation device described in step (4) is a gas-solid separation ceramic membrane.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention has simple process, high reaction efficiency, short production cycle, high product purity, uniform particle distribution and good performance.

[0016] (2) The present invention utilizes fluidization technology to form a gas-solid two-phase flow with the preheated working gas and the zirconium oxide powder, and introduces the flow into the fluidized bed reactor in the plasma device, so that the gasified negative thermal expansion material is deposited on the surface of the fluidized zirconium oxide powder, and the gas-solid two-phase contact area is large. The gasified negative thermal expansion material is evenly coated on the surface of the zirconium oxide powder particles to form a uniform and dense film. The prepared zirconium oxide powder with a negative thermal expansion material film layer has uniform particle distribution, high structural stability, and is not easy to decompose.

[0017] (3) The present invention introduces a metal aluminum salt into the negative thermal expansion material precursor solution, and during the sintering process of the zirconium oxide powder having the negative thermal expansion material film layer, ensures that the low expansion material forms a stable structure while promoting the densification of the powder material. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The process flow chart for preparing zirconium oxide powder with a negative thermal expansion material film layer.

[0019] In the figure: working gas device (1), flow valve (2), preheating device (3), feeding device (4), gasification device (5), plasma device (6), fluidized bed device (7), separation device (8), and gas pipeline (9).

[0020] Figure 2 This is the surface SEM image of the powder sample in Example 1.

[0021] Figure 3 This is the surface SEM of the powder product material in Example 1.

[0022] Figure 4 Surface SEM image of the powder sample of Comparative Example 1. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with specific examples, but the present invention is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry.

[0024] Example 1 (1) introducing argon gas preheated at 950° C. into a zirconia powder feeding device (wherein the average particle size of the zirconia powder is 100 nm) to form a gas-solid two-phase flow consisting of zirconia powder and argon gas, and introducing the formed zirconia powder gas-solid two-phase flow into a fluidized bed reactor in a plasma device; (2) zirconium tetrachloride, ammonium tungstate, aluminum tetrachloride and water are mixed in a mass ratio of 1:1.5:0.15:30 to obtain a negative thermal expansion material precursor solution, and then the negative thermal expansion material precursor solution is input into a gasification device, and the gasification device and the gas pipeline are heated to 200° C. After the negative thermal expansion material precursor solution is gasified, a working gas with a flow rate of 0.15 mL / min and a flow rate of 150 mL / min are simultaneously introduced into the fluidized bed reactor from the bottom of the fluidized bed reactor; (3) Turning on the power of the plasma device, setting the working parameters to a microwave power of 900 W and a pressure of 8 kPa; the chemical vapor deposition time is 0.8 h, so that the gas after the negative thermal expansion material precursor solution is vaporized undergoes a chemical vapor deposition reaction on the surface of the zirconium oxide particles to obtain a gas-solid phase zirconium oxide powder mixture having a negative thermal expansion material film layer; (4) Turn on the separation device to perform gas-solid separation on the gas-solid mixture obtained in step 3 to obtain zirconium oxide powder having a negative thermal expansion material film layer.

[0025] Example 2 (1) introducing argon gas preheated at 900° C. into a zirconia powder feeding device (wherein the average particle size of the zirconia powder is 200 nm) to form a gas-solid two-phase flow consisting of the zirconia powder and argon gas, and introducing the formed zirconia powder gas-solid two-phase flow into a fluidized bed reactor in a plasma device; (2) zirconium tetrachloride, ammonium tungstate, aluminum tetrachloride and water are mixed in a mass ratio of 1:1.8:0.2:20 to obtain a negative thermal expansion material precursor solution, and then the negative thermal expansion material precursor solution is input into a gasification device, and the gasification device and the gas pipeline are heated to 150° C. After the negative thermal expansion material precursor solution is gasified, a working gas at a flow rate of 0.35 mL / min and a flow rate of 50 mL / min are simultaneously introduced into the fluidized bed reactor from the bottom of the fluidized bed reactor; (3) Turning on the power of the plasma device, setting the working parameters to a microwave power of 850 W and a pressure of 5 kPa; the chemical vapor deposition time is 0.6 h, so that the gas after the negative thermal expansion material precursor solution is vaporized undergoes a chemical vapor deposition reaction on the surface of the zirconium oxide particles to obtain a gas-solid phase zirconium oxide powder mixture having a negative thermal expansion material film layer; (4) Turn on the separation device to perform gas-solid separation on the gas-solid mixture obtained in step 3 to obtain zirconium oxide powder having a negative thermal expansion material film layer.

[0026] Example 3 (1) introducing argon gas preheated at 800° C. into a zirconia powder feeding device (wherein the average particle size of the zirconia powder is 300 nm) to form a gas-solid two-phase flow consisting of the zirconia powder and argon gas, and introducing the formed zirconia powder gas-solid two-phase flow into a fluidized bed reactor in a plasma device; (2) zirconium nitrate, ammonium tungstate, aluminum nitrate and water are mixed in a mass ratio of 1:2:0.25:35 to obtain a negative thermal expansion material precursor solution, and then the negative thermal expansion material precursor solution is input into a gasification device, and the gasification device and the gas pipeline are heated to 120° C. After the negative thermal expansion material precursor solution is gasified, a working gas with a flow rate of 0.5 mL / min and a flow rate of 100 mL / min are simultaneously introduced into the fluidized bed reactor from the bottom of the fluidized bed reactor; (3) Turning on the power of the plasma device, setting the working parameters to a microwave power of 1000 W and a pressure of 1 kPa; the chemical vapor deposition time is 0.5 h, so that the gas after the negative thermal expansion material precursor solution is vaporized undergoes a chemical vapor deposition reaction on the surface of the zirconium oxide particles to obtain a gas-solid phase zirconium oxide powder mixture having a negative thermal expansion material film layer; (4) Turn on the separation device to perform gas-solid separation on the gas-solid mixture obtained in step 3 to obtain zirconium oxide powder having a negative thermal expansion material film layer.

[0027] Example 4 (1) introducing argon gas preheated at 1000° C. into a zirconia powder feeding device (wherein the average particle size of the zirconia powder is 500 nm) to form a gas-solid two-phase flow consisting of the zirconia powder and argon gas, and introducing the formed zirconia powder gas-solid two-phase flow into a fluidized bed reactor in a plasma device; (2) zirconium nitrate, ammonium tungstate, aluminum nitrate and water are mixed in a mass ratio of 1:2.5:0.35:50 to obtain a negative thermal expansion material precursor solution, and then the negative thermal expansion material precursor solution is input into a gasification device, and the gasification device and the gas pipeline are heated to 180° C. After the negative thermal expansion material precursor solution is gasified, a working gas with a flow rate of 0.25 mL / min and a flow rate of 200 mL / min are simultaneously introduced into the fluidized bed reactor from the bottom of the fluidized bed reactor; (3) Turning on the power of the plasma device, setting the working parameters to a microwave power of 500 W and a pressure of 10 kPa; the chemical vapor deposition time is 1 hour, so that the gas after the negative thermal expansion material precursor solution is vaporized undergoes a chemical vapor deposition reaction on the surface of the zirconium oxide particles to obtain a gas-solid phase zirconium oxide powder mixture having a negative thermal expansion material film layer; (4) Turn on the separation device to perform gas-solid separation on the gas-solid mixture obtained in step 3 to obtain zirconium oxide powder having a negative thermal expansion material film layer.

[0028] Comparative Example 1 The present comparative example provides a method for preparing a zirconium oxide / zirconium tungstate composite powder. Zirconium oxide, zirconium tungstate, and aluminum oxide powders are mixed in a mass ratio of 1:1.5:0.15, the mixed powders are mixed with water to form a mixed slurry with a mass fraction of 50%, the mixed slurry is put into a ball mill for 50 minutes, the mixture is sieved and dried at 80°C, and then sintered in a muffle furnace at 1170°C to obtain the zirconium oxide / zirconium tungstate composite powder.

[0029] The present invention conducts microscopic morphology analysis, powder product sintering density test, XRD phase analysis, and thermal expansion performance analysis on the powder properties prepared in the above Examples 1 to 4 and Comparative Example 1. The test results are shown in Table 1. The specific test methods are as follows: 1. Powder micromorphology analysis: Use a scanning electron microscope to observe the specific surface morphology of the powder; 2. Sintering density test of powder products: (1) Preparation of powder products: 5 g of the prepared powder was placed in a mold with a diameter of 30 mm, pressurized at 4 MPa, and maintained at pressure for 30 seconds. After demolding, a sample body with a diameter of 30 mm and a thickness of 2.5 mm was obtained. The sample body was placed in a muffle furnace and sintered at 1300 °C to obtain a powder product material; (2) Apparent porosity test: The apparent porosity of powder products is low, indicating that the sintered density of the products is high. The apparent porosity is calculated according to formula (a): P= ·100%; where: P—apparent porosity; m1—dry mass of the sample, in grams; m2—suspended mass of the saturated sample in the immersion liquid, in grams; m3—mass of the saturated sample in the air, in grams; 3. XRD phase analysis: The prepared powder is quantitatively analyzed by XRD to detect the decomposition rate; 4. Thermal expansion performance analysis: Thermal expansion coefficient is tested by thermal expansion analyzer.

[0030] Table 1 is a summary of the performance test results of the powders and powder product materials prepared in Examples 1 to 4 and Comparative Example 1.

[0031] Serial number Apparent porosity P (%) Decomposition rate (%) Coefficient of thermal expansion (K) Example 1 1.76 3.1 <![CDATA[0.6·10 -6 ]]> Example 2 1.63 2.8 <![CDATA[0.83·10 -6 ]]> Example 3 1.35 2.7 <![CDATA[0.91·10 -6 ]]> Example 4 1.17 3.0 <![CDATA[0.95·10 -6 ]]> Comparative Example 1 2.54 8.5 <![CDATA[0.53·10 -6 ]]> By comparing the test results of the samples of Examples 1 to 4 and Comparative Example 1, it can be seen that the zirconium oxide powder with a negative thermal expansion material film layer prepared by combining plasma chemical vapor deposition technology, fluidization technology, and gas-solid separation membrane technology has high structural stability, is not easy to decompose, and has high density of powder products, with an apparent porosity of 1.17-1.76%. However, the zirconium oxide / zirconium tungstate composite powder prepared in Comparative Example 1 is easy to agglomerate, has poor dispersibility, poor structural stability, is easy to decompose, and has low sintering density of the powder.

[0032] According to the test results of the samples of Examples 1 to 4 and Comparative Example 1, the following conclusions are obtained: (1) The present invention combines the advantages of plasma chemical vapor deposition and fluidized bed technology to uniformly deposit and coat the gasified negative thermal expansion material on the surface of fluidized zirconia powder to form a uniform and dense film, thereby preparing zirconia powder with a negative thermal expansion material film layer having uniform particle distribution and high structural stability.

[0033] (2) The present invention introduces a metal aluminum salt into the negative thermal expansion material precursor solution, thereby ensuring that the low thermal expansion material forms a stable structure and effectively promoting the densification of the powder material during the sintering process of the zirconium oxide powder having a negative thermal expansion material film layer.

[0034] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing zirconium oxide powder having a negative thermal expansion material film layer, characterized in that: The following steps are involved: (1) introducing the preheated working gas into a zirconia powder feeding device to form a gas-solid two-phase flow consisting of zirconia powder and the working gas, and introducing the formed zirconia powder gas-solid two-phase flow into a fluidized bed reactor in a plasma device; (2) introducing a negative thermal expansion material precursor solution into a gasification device, and simultaneously raising the temperature of the gasification device and the gas pipeline, and after the negative thermal expansion material precursor solution is gasified, it is introduced into the fluidized bed reactor simultaneously with the working gas from the bottom of the fluidized bed reactor; (3) turning on the power of the plasma device and setting the working parameters so that the gas after the negative thermal expansion material precursor solution is vaporized undergoes a chemical vapor deposition reaction on the surface of the zirconium oxide particles to obtain a gas-solid phase zirconium oxide powder mixture having a negative thermal expansion material film layer; (4) Turn on the separation device to perform gas-solid separation on the gas-solid mixture obtained in step 3 to obtain zirconium oxide powder having a negative thermal expansion material film layer.

2. The method for preparing zirconium oxide powder having a negative thermal expansion material film layer according to claim 1, characterized in that: The average particle size of the zirconium oxide powder in step (1) is 100-500 nm, the working gas is argon, and the preheating temperature is 800-1000°C.

3. The method for preparing zirconium oxide powder having a negative thermal expansion material film layer according to claim 1, characterized in that: The negative thermal expansion material precursor solution described in step (2) is composed of a mixture of metal zirconium salt, tungstate, metal aluminum salt and water, wherein the metal zirconium salt is zirconium tetrachloride or zirconium nitrate; the metal aluminum salt is aluminum tetrachloride or aluminum nitrate; the tungstate is ammonium tungstate; and the mass ratio of the metal zirconium salt, tungstate, metal aluminum salt and water is 1: (1.5 ~ 2.5): (0.15 ~ 0.35): (20 ~ 50).

4. The method for preparing zirconium oxide powder having a negative thermal expansion material film layer according to claim 1, characterized in that: The temperature of the gasification device and the gas pipeline in step (2) is increased to 120-200°C, and the flow rate of the negative thermal expansion material precursor solution after gasification is 0.15-0.5 mL / min.

5. The method for preparing zirconium oxide powder having a negative thermal expansion material film layer according to claim 1, characterized in that: The working gas in step (2) is a mixture of argon and oxygen, and the flow rate is 50 ~ 200 mL / min.

6. The method for preparing zirconium oxide powder having a negative thermal expansion material film layer according to claim 1, characterized in that: The operating parameters of the plasma device described in step (3) are set to microwave power of 500 to 1000 W and pressure of 1 to 10 kPa; the chemical vapor deposition time is 0.5 to 1 h.

7. The method for preparing zirconium oxide powder having a negative thermal expansion material film layer according to claim 1, characterized in that: The gas-solid separation device described in step (4) is a gas-solid separation ceramic membrane.

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