Nanometer zirconium oxide powder and preparation method thereof

Abstract

The application discloses a kind of nano zirconium oxide powder and its preparation method, the preparation method includes the following steps: step 1: preparation zirconium salt solution and alkali solution, zirconium salt solution and alkali solution are injected into the center of spiral platform of high-speed rotation, reaction liquid is mixed in platform center, flows along spiral channel until is thrown off platform, and zirconium oxide precursor solution is collected;Step 2: the zirconium oxide precursor solution obtained in step 1 is centrifuged, then washed with water, and finally the precursor is obtained;Step 3: after centrifugation, again add deionized water to be configured into the mixed solution containing solid content 1%-15% for spray drying;Step 4: the powder collected by spray drying is sintered;Step 5: after sintering, deionized water is added to the powder, and the mixed solution containing solid content 8%-20% is configured into the sand mill for sanding, after completion, centrifugation is used again, then washed with anhydrous ethanol, and finally dried to obtain the final product.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of nano zirconium oxide material, and particularly relates to a nano zirconium oxide powder and a preparation method thereof. BACKGROUND

[0002] Nano zirconium oxide has excellent physical and chemical stability, such as being an insulator at room temperature and having the characteristics of solid electrolyte at high temperature. Due to the particularity of its molecular structure, it has a certain catalytic effect, and is an inorganic non-metallic material with good optical, thermal, electrical and mechanical properties, and is resistant to high temperature, wear and corrosion. Nano zirconium oxide particles have high specific surface area and good stability, and are widely used in ceramics, rubber, paint, daily chemical industry, catalysis and the like.

[0003] Due to excellent physical and chemical properties, nano zirconium oxide has always been a highly concerned substance by researchers. It is generally considered that an excellent nano zirconium oxide powder should have the characteristics of complete crystal form, stable structure, uniform particle distribution, large specific surface area and no agglomeration. Traditional methods for preparing nano zirconium oxide include solid phase method and chemical method. The solid phase method is simple to operate, and the preparation conditions are easy to control, and industrial production is easy to carry out, but the energy consumption is large, the prepared product has large particles, the particle morphology is difficult to control, and the product batch repeatability is poor. The chemical method is to mix soluble raw materials and then react, and can prepare a uniform and consistent product with controllable particle size. The chemical method has always been an important method for preparing nano particles, and in the doping process, the doping atoms can be uniformly distributed in the crystal structure to obtain a uniform and high-performance zirconium oxide powder material. In addition, the general preparation method has a long production cycle, which is not conducive to industrial production. SUMMARY

[0004] In view of the problems of high energy consumption, long time efficiency, serious agglomeration and uneven particle size of the prepared nano zirconium oxide, a method for efficiently preparing nano zirconium oxide particles with good dispersion and uniform particle size is needed to meet the needs of the market. The present application provides a new preparation technology of nano zirconium oxide, which is simple and suitable for industrial production. The technical scheme of the present application is as follows:

[0005] A preparation method of nano zirconium oxide powder, comprising the following steps:

[0006] Step 1: prepare a zirconium salt solution with a concentration of 1:3-10 molar ratio and an alkali solution, and inject the zirconium salt solution and the alkali solution into the center of a high-speed rotating spiral platform at a speed of 20-200 ml / min through a feeding pump, the zirconium salt solution and the alkali solution are pulled into a micro-thin film by the high-speed rotating platform in the center of the platform and fully mixed and reacted, the reaction is completed instantaneously (within 5 seconds), then the micro-thin film flows along the spiral channel until it is thrown off the platform, and a zirconium oxide precursor solution is collected;

[0007] Step 2: Centrifugal separation of the zirconium oxide precursor solution obtained in step 1, followed by water washing to remove excess base, to obtain the precursor;

[0008] Step 3: After centrifugation, add deionized water to configure a mixed solution with a solid content of 1%-15% for spray drying;

[0009] Step 4: The spray-dried powder is transferred to a rotary furnace for sintering at a sintering temperature of 400-700°C for 2-6 hours;

[0010] Step 5: Add deionized water to the sintered powder to configure a mixed solution with a solid content of 3%-20% and inject it into a sand mill for sand milling, using 0.1-0.3mm zirconia balls, grinding time is 0.5-4h, then centrifugal separation, followed by removal of water using anhydrous ethanol, and finally drying to obtain the final product. Preferably, the drying temperature is 70°C.

[0011] The zirconium salt in step 1 is zirconium chloride or / and zirconium oxychloride; the base is sodium hydroxide, potassium hydroxide or ammonia.

[0012] The spiral platform rotation speed in step 1 is 500-2000r / min.

[0013] The spiral platform in step 1 includes an outer cylinder, a spiral rotating platform, a support rod and a sealing cover, and the rotating platform is disclosed in Chinese patent CN212882378U.

[0014] The spray drying temperature in step 3 is 150-280°C.

[0015] A kind of nano zirconia powder, zirconia powder particle dispersion is good, particle size is relatively uniform.

[0016] The zirconia powder particle size is 30-70nm, and the crystal structure is monoclinic.

[0017] The application of the aforementioned nano zirconia powder is used as a coating material for various high molecular films, ceramic membranes or surfaces, to improve the hydrophilicity of the membrane or surface.

[0018] The process is simple, continuous and efficient, and the energy consumption is reduced compared with traditional hydrothermal method and solid phase method; the zirconium oxide precursor synthesized by the process has ultrafine and uniform original particle size, the agglomerates are dispersed by sand milling to restore the original particle size, and the zirconium oxide nanoparticles obtained have narrow particle size distribution. The process can greatly reduce the time required for particle diffusion by centrifugal force to pull the two reaction liquids into a thin film and efficiently mix them, on the one hand, accelerate the nucleation and growth process of nanoparticles, on the other hand, make different nanoparticles in similar growth environment, thereby improving the uniformity of the final nanoparticles. In addition, compared with the flat disc, the platform of the spiral channel prolongs the reaction residence time by tens to hundreds of times, so that the reaction is fully completed, overcoming the problem of short reaction residence time of the previous rotating disc.

[0019] Specifically, in step 1 of the preparation method, the zirconium salt solution and the alkali solution are injected into the high-speed rotating spiral disc platform, the two reaction liquids are pulled into a thin film by centrifugal force at the center of the spiral disc, and then mixed with each other and form original crystal nuclei. Then the reaction liquid is thrown away from the center into the spiral channel of the spiral disc, and due to the action of centrifugal force, the reaction liquid forms a longitudinal thin film on the inner wall of the spiral disc and flows along the spiral channel to the outer edge of the spiral disc. When the reaction liquid just enters the spiral channel, the concentration of the growing particles in the reaction liquid is high but uniformly distributed in the longitudinal direction; and the thickness of the thin film formed by the reaction liquid is less than 1mm, so the concentration gradient in the thickness direction of the thin film is also very small. Therefore, different original crystal nuclei are in a very uniform environment of growing particles and start to grow respectively. As the reaction liquid continues to flow along the spiral channel to the outer edge, the growing particles are gradually consumed by growing on the crystal nuclei, and the concentration begins to decrease, until all the growing particles are consumed before the reaction liquid is thrown off the spiral disc, and the growth of the nanoparticles is completed. In this process, the rotation speed of the spiral disc, the reaction temperature and the injection speed of the reaction liquid will affect the reaction time and the film thickness of the reaction liquid, thereby affecting the performance of the zirconium oxide nanoparticle precursor. After the zirconium oxide nanoparticle precursor is thrown off the spiral disc, it enters the flow outlet at the bottom of the reaction chamber and is collected, and then enters the next process. The present application first synthesizes the precursor by using the spiral platform, and then obtains the agglomerates with uniform original particle size after drying and sintering, and then the agglomerates are dispersed by sand milling to restore the original small particles.

[0020] The beneficial technical effects of the present application are: 1) the present application uses an alkali solution and a zirconium salt solution to form a reactant, and then performs spray drying, sintering and sand milling to obtain nano zirconia, which abandons the long preparation time, high temperature and high pressure conditions of traditional zirconia, greatly improves the efficiency, and significantly reduces the energy consumption. 2) the present application uses a nano zirconia reaction device: the alkali solution and the zirconium salt solution are reacted on a high-speed rotating spiral channel platform, so that the particle size is more uniform. 3) the present application can continuously react without interruption, and can control the original particle size of zirconia. 4) the present application can restore the zirconia agglomerates to the original particle size through sand milling and water removal drying. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Figure 1 is a SEM photo of zirconia agglomerates before sand milling in step 4 of Example 1 of the present application;

[0022] Figure 2 Figure 2 is a SEM photo of nano zirconia prepared in Example 1 of the present application;

[0023] Figure 3 Figure 3 is an XRD test result picture of nano zirconia prepared in Example 1 of the present application;

[0024] Figure 4 Figure 4 is a SEM photo of nano zirconia prepared in Example 2 of the present application. DETAILED DESCRIPTION

[0025] Example 1

[0026] At room temperature, the solution was prepared according to the molar ratio of zirconium salt to alkali of 1:3. 1000ml of 32.225g zirconium oxychloride (0.1mol) aqueous solution and 1000ml of 12g sodium hydroxide (0.3mol) aqueous solution were simultaneously added by a feeding pump at a speed of 100ml / min onto a high-speed rotating spiral platform, the platform rotating speed was 1000r / min, after the reaction was completed, the obtained zirconia precursor was transferred to a tubular centrifuge for centrifugation, after the centrifugation was completed, it was configured into a 20% solid content aqueous solution for spray drying, after the drying was completed, the obtained zirconia powder was observed by scanning electron microscope, the spray dried powder was transferred into a rotary furnace to sinter at a sintering temperature of 600℃ for 4 hours, the sintered powder was as shown in Figure 2, which could be seen as a spherical agglomerate composed of uniform small particles, then deionized water was added into the sintered powder, a mixed solution with a solid content of 8% was configured and injected into a sand mill for sand milling, 0.2mm zirconia balls were used for grinding, the grinding time was 1h, then centrifugation was performed again, then anhydrous ethanol was used to remove water, finally the final product was obtained by drying at 70℃. Figure 1 Figure 1 ​​

[0027] The obtained zirconium oxide powder was observed by scanning electron microscopy, as shown in Figure 2 From the figure, it can be seen that the prepared zirconium oxide powder has a uniform particle size, and the particle size D50 is 32 nm. Figure 2 From the figure, it can be seen that the prepared zirconium oxide has a main monoclinic phase. Figure 3

[0028] Example 2

[0029] At room temperature, a solution was prepared according to a molar ratio of zirconium salt to alkali of 1:3. 1000 ml of an aqueous solution containing 64.45 g of zirconium oxychloride (0.2 mol) and 1000 ml of an aqueous solution containing 24 g of sodium hydroxide (0.6 mol) were simultaneously added at a speed of 60 ml / min through a feeding pump to a high-speed rotating spiral platform, and the platform rotated at a speed of 800 r / min. After the reaction was completed, the obtained zirconium oxide precursor was transferred to a tubular centrifuge for centrifugation. After centrifugation, a water solution with a solid content of 20% was prepared and spray dried. After drying, the spray-dried powder was placed in a grinding machine for grinding. After 1 h of grinding, the powder was transferred to a rotary furnace and sintered at a sintering temperature of 600°C for 4 hours. Deionized water was added to the sintered powder to prepare a mixed solution with a solid content of 8%, which was then injected into a sand mill for sand milling. The sand milling used 0.2 mm zirconia balls, and the grinding time was 30-60 min. After sand milling, the powder was centrifuged again, and then anhydrous ethanol was used to remove water. Finally, the powder was dried at 70°C to obtain the final product. After taking out, 24.6 g of zirconium oxide was obtained.

[0030] The obtained zirconium oxide powder was observed by scanning electron microscopy, as shown in Figure 4 From the figure, it can be seen that the prepared zirconium oxide powder has a uniform particle size, and the particle size D50 is 32 nm. Figure 4

[0031] Example 3

[0032] ​​The zirconium chloride aqueous solution with a concentration of 0.2 moL and the potassium hydroxide aqueous solution with a concentration of 0.8 moL prepared according to the raw material zirconium salt and alkali molar ratio of 1:4 are simultaneously dropped onto the spiral platform rotating at a high speed at a speed of 80 ml / min under room temperature conditions, the rotating speed of the platform is 1500 r / min, after the reaction is completed, the obtained zirconia precursor is transferred to a tubular centrifuge for centrifugation, after the centrifugation is completed, the zirconia precursor is configured into an aqueous solution with a solid content of 20% for spray drying, after the spray drying is completed, the spray-dried powder is placed in a grinding machine for grinding, after the grinding for 1 h, the powder is transferred into a rotary furnace for sintering at a sintering temperature of 500°C for 6 h, the sintered powder is mixed with deionized water to prepare a mixed solution with a solid content of 8%-20% and then injected into a sand mill for sand grinding, 0.2 mm zirconia balls are used for sand grinding, after the grinding for 30-60 min, the powder is centrifuged again, then anhydrous ethanol is used to remove the water, and finally the final product is obtained by drying at 70°C.

[0033] Example 4

[0034] The zirconium chloride aqueous solution with a concentration of 0.2 moL and the potassium hydroxide aqueous solution with a concentration of 0.8 moL prepared according to the raw material zirconium salt and alkali molar ratio of 1:4 are simultaneously dropped onto the spiral platform rotating at a high speed at a speed of 80 ml / min under room temperature conditions, the rotating speed of the platform is 1500 r / min, after the reaction is completed, the obtained zirconia precursor is transferred to a tubular centrifuge for centrifugation, after the centrifugation is completed, the zirconia precursor is configured into an aqueous solution with a solid content of 20% for spray drying, after the spray drying is completed, the spray-dried powder is placed in a grinding machine for grinding, after the grinding for 1 h, the powder is transferred into a rotary furnace for sintering at a sintering temperature of 500°C for 6 h, the sintered powder is mixed with deionized water to prepare a mixed solution with a solid content of 8%-20% and then injected into a sand mill for sand grinding, 0.2 mm zirconia balls are used for sand grinding, after the grinding for 30-60 min, the powder is centrifuged again, then anhydrous ethanol is used to remove the water, and finally the final product is obtained by drying at 70°C.

Claims

1. A method for preparing nano-sized zirconia powder, characterized in that The method comprises the following steps: Step 1: preparing a zirconium salt solution and an alkali solution with a molar ratio of 1:3-10, and injecting the zirconium salt solution and the alkali solution into the center of a high-speed rotating spiral platform at a speed of 20-200 ml / min through a feeding pump, and mixing and reacting the zirconium salt solution and the alkali solution in the center of the platform, and flowing along the spiral channel until being thrown off the platform after the reaction is completed, and collecting a zirconia precursor solution; Step 2: centrifuging the zirconia precursor solution obtained in step 1, and washing with water to remove excess alkali, and obtaining a precursor; Step 3: after centrifugation, adding deionized water to prepare a mixed solution with a solid content of 1%-15% for spray drying; Step 4: transferring the spray-dried powder into a rotary furnace to sinter at a sintering temperature of 400-700 ℃ for 2-6 hours; Step 5: adding deionized water to the sintered powder to prepare a mixed solution with a solid content of 3%-20% for sand milling, using 0.1-0.3 mm zirconia balls for sand milling, and grinding for 0.5-4 hours, and then centrifuging again, and then removing water using anhydrous ethanol, and finally drying to obtain the final product.

2. The method of claim 1, wherein the zirconium oxide nanoparticles are prepared by the process of claim 1. The zirconium salt in step 1 is zirconium chloride or / and zirconium oxychloride; and the alkali is sodium hydroxide, potassium hydroxide or ammonia water.

3. The method of claim 1, wherein the zirconium oxide nanoparticles are prepared by the process of claim 1. The rotating speed of the spiral platform in step 1 is 500-2000 r / min.

4. The method of claim 1, wherein the zirconium oxide nano-powder is prepared by the process of claim 1. The spiral platform in step 1 comprises an outer cylinder, a spiral rotating platform, a support rod and a sealing cover.

5. The method of claim 1, wherein the zirconium oxide nano-powder is prepared by the process of claim 1. The temperature for spray drying in step 3 is 150-280 ℃.

6. The nano-sized zirconium oxide powder prepared by the method according to any one of claims 1-5, characterized in that The zirconia powder has good particle dispersion and uniform particle size.

7. The nano zirconium oxide powder according to claim 6, characterized in that The zirconia powder has a particle size of 30-70 nm and a monoclinic crystal structure.

8. The nano zirconia powder according to claim 6 or 7 is used as a coating material for various polymer membranes, ceramic membranes or surfaces to improve the hydrophilicity of the membranes or surfaces.

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