Ultrafine y2o3-mgO nanocomposite powder, and preparation method and application thereof

Abstract

The project provides a method for preparing superfine Y2O3-MgO nano composite powder and application. Yttrium nitrate hexahydrate and magnesium nitrate hexahydrate with purity not less than 99% are dissolved in deionized water to prepare a solution, and the solution is magnetically stirred and heated to a viscous oligomer. The oligomer is placed in a muffle furnace and calcined. Firstly, it is rapidly heated to the decomposition temperature of yttrium nitrate and kept at the temperature until the yttrium nitrate is completely decomposed into an intermediate product. Then, it is rapidly heated to the Y2O3 nucleation temperature while an atmosphere is introduced to inhibit the growth of MgO grains. After reaching the Y2O3 nucleation temperature, the heating rate is reduced. Y2O3 and MgO nucleate and grow simultaneously, maximizing the pinning effect and achieving mutual inhibition of the growth of the two phases. Continue to heat and calcine to ensure complete decomposition of the nitrate. Through powder nucleation control thermal decomposition, composite nano powder is obtained. After ball milling, screening and calcination, Y2O3-MgO nano composite powder with a grain size of not more than 20 nm is obtained. The reduction of grain size can simultaneously improve the bending strength of Y2O3-MgO nano composite ceramic and its transmittance in the near-infrared band.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials technology, and more specifically, to a method for preparing and applying ultrafine Y2O3-MgO nanocomposite powder. Background Technology

[0002] Precision guidance based on infrared imaging has become a key focus of precision guidance technology development for major powers. As infrared-guided aircraft evolve from low to high Mach numbers, new challenges arise for infrared window materials. Y₂O₃-MgO nanocomposite ceramics exhibit excellent transmittance in the 3-7 micrometer wavelength range. Compared to existing infrared window materials (such as sapphire, spinel, and ALON), they offer significant advantages in high-temperature emissivity and possess superior mechanical properties and thermal shock resistance comparable to sapphire. Therefore, they are expected to become the best candidate material for infrared windows / radomes of future high-Mach number missiles.

[0003] The prior art, CN110342907A, discloses a method for preparing Y2O3-MgO nanocomposite infrared ceramics. Y2O3-MgO composite nanopowder is prepared via nitrate thermal decomposition. A solution is prepared by dissolving yttrium nitrate hexahydrate and magnesium nitrate hexahydrate (purity not less than 99%) in deionized water. The solution is magnetically stirred and heated to evaporate to a viscous oligomer. During magnetic stirring, the magnetic stirrer speed is 1-5 Mot, and the heating temperature is 60-200℃. The oligomer is then directly calcined in a muffle furnace at 500-1000℃ for 0.5-6 hours to obtain the Y2O3-MgO composite nanopowder. However, yttrium nitrate and magnesium nitrate have different decomposition temperatures. Direct calcination in a high-temperature muffle furnace causes magnesium nitrate to decompose at a lower temperature, leading to magnesium oxide nucleation and aggregation or agglomeration. This results in abnormally large magnesium oxide grains after sintering into the ceramic, affecting the optical properties of the ceramic. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for preparing ultrafine Y₂O₃-MgO nano-composite powder and its application. This method effectively controls the growth of yttrium oxide and magnesium oxide grains. By staged heating, the time difference between MgO nucleation and Y₂O₃ nucleation is shortened. Furthermore, during the decomposition of magnesium nitrate, an atmosphere is introduced to inhibit MgO nucleation, further reducing the temperature difference between MgO and Y₂O₃ nucleation. After MgO nucleation, Y₂O₃ nucleation is rapidly promoted, maximizing the pinning effect. The two phase grains mutually inhibit each other's growth, reducing agglomeration and resulting in a powder with a grain size of less than 20 nm.

[0005] This invention uses yttrium nitrate hexahydrate and magnesium nitrate hexahydrate with a purity of not less than 99% dissolved in deionized water to prepare a solution. The solution is then magnetically stirred and heated to evaporate to a viscous oligomer. The oligomer is then placed in a muffle furnace for calcination. First, the temperature is rapidly increased to the decomposition temperature of yttrium nitrate and held until the yttrium nitrate is completely decomposed into an intermediate product. Then, the temperature is rapidly increased to the nucleation temperature of Y₂O₃. While heating, an atmosphere is introduced to inhibit the growth of magnesium oxide grains. After reaching the nucleation temperature of Y₂O₃, the heating rate is reduced. Both yttrium oxide and magnesium oxide nucleate and grow simultaneously, which can maximize the pinning effect and achieve mutual inhibition of the growth of the two phase grains. Continuing to heat and calcinate ensures the complete decomposition of nitrates. Composite nanoparticles are obtained by controlling thermal decomposition through powder nucleation. After ball milling, sieving, and calcination, Y₂O₃-MgO nanocomposite powder with a grain size of less than 20 nm is obtained.

[0006] A method for preparing ultrafine Y2O3-MgO nanocomposite powder, the specific steps of which are as follows:

[0007] Step 1: Prepare a solution by dissolving yttrium nitrate hexahydrate and magnesium nitrate hexahydrate with a purity of not less than 99% in deionized water, stir magnetically and heat until completely dissolved, and then continue heating to evaporate to a viscous oligomer.

[0008] Step 2: The oligomer is placed in a muffle furnace for calcination, and nano-composite powder is obtained by controlled thermal decomposition through powder nucleation.

[0009] 2.1 Rapidly heat to 370℃-420℃ and hold at this temperature until the thermal decomposition of yttrium nitrate is complete;

[0010] 2.2 Rapidly heat to 450℃-500℃, while simultaneously introducing an atmosphere to inhibit magnesium oxide grain growth until Y2O3 nucleation is complete;

[0011] 2.3 Slowly raise the temperature to 600℃-800℃ and hold until the nitrates are completely decomposed to obtain Y2O3-MgO nano-composite powder;

[0012] Step 3: The Y2O3-MgO nanocomposite powder is ball-milled, sieved, and calcined to obtain ultrafine Y2O3-MgO nanocomposite powder.

[0013] Furthermore, the molar ratio of yttrium nitrate hexahydrate and magnesium nitrate hexahydrate in step 1 is 1:2 to 1:8.

[0014] Furthermore, the magnetic stirring and heating described in step 1 specifically involves heating at a speed of 250-1250 r / min to 60-100℃, and then continuing to heat at a temperature of 150℃-200℃.

[0015] Furthermore, the heating rate described in step 2.1 is 10-15℃ / min, and the holding time is 0.5-2h.

[0016] Furthermore, the heating rate described in step 2.2 is 10-15℃ / min, and the atmosphere is an inert atmosphere such as argon or nitrogen.

[0017] Furthermore, the heating rate described in step 2.3 is 0.5-2℃ / min, and the holding time is 1-4h.

[0018] Furthermore, the ball milling, sieving, and calcination described in step 3 specifically involve using alcohol compounds as the ball milling medium, a ball milling time of 48-72 hours, a drying temperature of 60-80°C, a drying time of 24-48 hours, a sieve mesh size of 100-300 mesh, and a calcination temperature of 600-800°C for 4-6 hours.

[0019] Furthermore, a zirconia ball mill jar and grinding balls with a diameter of 2 mm were used, the mass ratio of powder to grinding balls was 1:12, the grinding medium was anhydrous ethanol, and the mass ratio of powder to anhydrous ethanol was 1 g: 2 ml.

[0020] The present invention also provides an ultrafine nano-composite powder with a grain size of no more than 20 nm, which is prepared by the above method.

[0021] This invention also provides an application of ultrafine nano-multiphase powder in nano-multiphase ceramics. The nano-multiphase ceramics prepared from the above-mentioned ultrafine Y2O3-MgO nano-multiphase powder have higher transmittance, better optical uniformity, and stronger bending strength because the smaller the particle size and the more uniform the distribution of the ultrafine Y2O3-MgO nano-multiphase powder, the better the transmittance, the better the optical uniformity, and the stronger the bending strength.

[0022] The present invention has the following beneficial effects:

[0023] 1. The present invention provides a method for preparing ultrafine Y2O3-MgO nanocomposite powder. The operation steps are simple. Through innovative thermal decomposition process and powder nucleation control mechanism, the problems of powder agglomeration and abnormal grain growth in the preparation process of nitrate thermal decomposition are effectively suppressed. The generated Y2O3-MgO nanocomposite powder has small grain size, relatively uniform distribution, and no agglomeration. The Y2O3-MgO nanocomposite ceramic prepared by sintering Y2O3-MgO nanocomposite powder has high transmittance, high mechanical strength, and excellent optical uniformity.

[0024] 2. In the thermal decomposition process of this method, by changing the heating rate, sintering temperature and sintering atmosphere, the simultaneous nucleation of Y2O3 and MgO phases is controlled, avoiding the problems of agglomeration and uneven distribution caused by the inconsistent nucleation time of Y2O3 and MgO phases in other powder preparation methods;

[0025] 3. This method shortens the time gap between MgO nucleation and Y2O3 nucleation, maximizes the pinning effect between the two phases, achieves mutual inhibition of grain growth between the two phases, and obtains powder grain size not exceeding 20nm;

[0026] 4. This method does not introduce carbon pollution during the sintering process, has a low sintering temperature, a simple sintering process, can be used for mass production, requires simple sintering equipment, has low production costs, is suitable for the preparation of samples of any shape, and is convenient for industrial production. Attached Figure Description

[0027] Figure 1 The image shows the XRD pattern of the ultrafine Y2O3-MgO nanocomposite powder prepared in Example 1.

[0028] Figure 2 The image shows the TEM morphology of the ultrafine Y2O3-MgO nanocomposite powder prepared in Example 1.

[0029] Figure 3 The transmission spectrum of Y2O3-MgO nanocomposite ceramic prepared from ultrafine Y2O3-MgO nanocomposite powder in Example 1 is shown.

[0030] Figure 4 The image shows the TEM morphology of the ultrafine Y2O3-MgO nanocomposite powder prepared in Example 2. Detailed Implementation

[0031] The present invention will be further described below with reference to embodiments and accompanying drawings. These examples are for illustrative purposes only and should not be construed as limiting the scope of protection of the invention. Unless otherwise specified, specific conditions in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0032] Example 1

[0033] Weigh 60g of yttrium nitrate hexahydrate and 80g of magnesium nitrate hexahydrate (purity not less than 99.99%) into a quartz beaker, add 200ml of deionized water, stir magnetically, and heat at 80℃ until completely dissolved; then continue heating at 150℃ to evaporate to a viscous oligomer; place the oligomer in a muffle furnace for calcination, and obtain nano-multiphase powder through controlled thermal decomposition via powder nucleation. First, heat to 400℃ at 10℃ / min and hold for 1 hour until yttrium nitrate is completely decomposed into an intermediate product; then heat to 400℃ at 15℃ / min. Nitrogen gas was introduced simultaneously with the temperature rise to 50℃ to inhibit magnesium oxide grain growth. The temperature was then increased to 600℃ at a rate of 1℃ / min and held for 2 hours. The obtained Y₂O₃-MgO nanocomposite powder was placed in a zirconia ball mill jar with zirconia grinding balls and anhydrous ethanol, and ball-milled for 72 hours in a planetary ball mill. Afterward, it was dried in a 60℃ oven, sieved through a 200-mesh screen, and then calcined in a muffle furnace at 600℃ for 5 hours to obtain ultrafine Y₂O₃-MgO nanocomposite powder. The obtained powder was cold isostatically pressed at 200MPa and sintered in a vacuum furnace at 1350℃ for 5 hours to obtain high-transmittance Y₂O₃-MgO nanocomposite ceramic.

[0034] Figure 1 The image shows the XRD pattern of the ultrafine Y2O3-MgO nanocomposite powder prepared in Example 1; it can be seen from the image that the nitrate has been completely decomposed. Figure 2 The image shows the SEM morphology of the ultrafine Y2O3-MgO nanocomposite powder prepared in Example 1; the powder has a uniform grain distribution and a size of 15 nm. Figure 3 The image shows the transmission spectrum of the Y2O3-MgO nanocomposite ceramic prepared in Example 1; it can be seen from the figure that the transmittance reaches a maximum of 86.2% in the 3-5 μm range.

[0035] Example 2

[0036] Weigh 30g of yttrium nitrate hexahydrate and 80g of magnesium nitrate hexahydrate (purity not less than 99.99%) into a quartz beaker, add 200ml of deionized water, stir magnetically, and heat at 60℃ until completely dissolved; then continue heating at 175℃ to evaporate to a viscous oligomer; place the oligomer in a muffle furnace for calcination, and obtain nano-multiphase powder through controlled thermal decomposition via powder nucleation. First, heat to 370℃ at 13℃ / min and hold for 0.5 hours until yttrium nitrate is completely decomposed into an intermediate product; then heat at 13℃ / min to... At 475℃, argon gas was introduced to inhibit the growth of magnesium oxide grains during heating; then the temperature was increased to 800℃ at a rate of 2℃ / min and held for 1 hour; the obtained Y2O3-MgO nano-composite powder was placed in a zirconia ball mill jar with zirconia grinding balls and anhydrous ethanol, and ball-milled on a planetary ball mill for 60 hours, then dried in a 70℃ oven, sieved with a 200-mesh sieve, and then calcined in a muffle furnace at 700℃ for 5 hours to obtain ultrafine Y2O3-MgO nano-composite powder. Figure 4 The image shows the SEM morphology of the ultrafine Y2O3-MgO nanocomposite powder prepared in Example 2. The powder has a uniform grain distribution and a size of 15 nm.

[0037] Example 3

[0038] Weigh 60g of yttrium nitrate hexahydrate and 40g of magnesium nitrate hexahydrate (purity not less than 99.99%) into a quartz beaker, add 200ml of deionized water, stir magnetically, and heat at 100℃ until completely dissolved; then continue heating at 200℃ to evaporate to a viscous oligomer; place the oligomer in a muffle furnace for calcination, and obtain nano-multiphase powder through controlled thermal decomposition via powder nucleation. First, heat to 420℃ at 15℃ / min and hold for 2 hours until yttrium nitrate is completely decomposed into an intermediate product; then heat to 50℃ at 15℃ / min. At 0℃, nitrogen gas was introduced to inhibit the growth of magnesium oxide grains while heating. Then, the temperature was increased to 700℃ at a rate of 0.5℃ / min and held for 4 hours. The obtained Y2O3-MgO nano-composite powder was placed in a zirconia ball mill jar with zirconia grinding balls and anhydrous ethanol, and ball milled on a planetary ball mill for 48 hours. After that, it was dried in an 80℃ oven, then sieved with a 200-mesh sieve, and then calcined in a muffle furnace at 800℃ for 5 hours to obtain ultrafine Y2O3-MgO nano-composite powder.

Claims

1. A method for preparing ultrafine Y₂O₃-MgO nanocomposite powder, characterized in that, The specific steps of this preparation method are as follows: Step 1: Prepare a solution by dissolving yttrium nitrate hexahydrate and magnesium nitrate hexahydrate with a purity of not less than 99% in deionized water, stir magnetically and heat until completely dissolved, and then continue heating to evaporate to a viscous oligomer. Step 2: The oligomer is placed in a muffle furnace for calcination, and nano-composite powder is obtained by controlled thermal decomposition through powder nucleation. 2.1 Rapidly heat to 370℃-420℃ and hold at this temperature until the thermal decomposition of yttrium nitrate is complete; 2.2 Rapidly heat to 450℃-500℃, while simultaneously introducing an atmosphere to inhibit magnesium oxide grain growth until Y2O3 nucleation is complete; 2.3 Slowly raise the temperature to 600℃-800℃ and hold until the nitrates are completely decomposed to obtain Y2O3-MgO nano-composite powder; Step 3: The Y2O3-MgO nanocomposite powder is ball-milled, sieved, and calcined to obtain ultrafine Y2O3-MgO nanocomposite powder.

2. The method for preparing ultrafine Y₂O₃-MgO nano-composite powder according to claim 1, characterized in that, The molar ratio of yttrium nitrate hexahydrate and magnesium nitrate hexahydrate mentioned in step 1 is 1:2-1:

8.

3. The method for preparing ultrafine Y₂O₃-MgO nano-composite powder according to claim 1, characterized in that, The magnetic stirring and heating described in step 1 specifically involves heating to 60-100℃ at a speed of 250-1250 r / min, and then continuing to heat to 150℃-200℃.

4. The method for preparing ultrafine Y₂O₃-MgO nano-composite powder according to claim 1, characterized in that, The heating rate described in step 2.1 is 10-15℃ / min, and the holding time is 0.5-2h.

5. The method for preparing ultrafine Y₂O₃-MgO nano-composite powder according to claim 1, characterized in that, The heating rate described in step 2.2 is 10-15℃ / min, and the atmosphere is an inert atmosphere such as argon or nitrogen.

6. The method for preparing ultrafine Y₂O₃-MgO nano-composite powder according to claim 1, characterized in that, The heating rate described in step 2.3 is 0.5-2℃ / min, and the holding time is 1-4h.

7. The method for preparing ultrafine Y₂O₃-MgO nano-composite powder according to claim 1, characterized in that, The ball milling, sieving, and calcination described in step 3 are as follows: the ball milling medium is an alcohol compound, the ball milling time is 48-72 h; the drying temperature is 60-80℃, the drying time is 24-48 h; the sieve mesh size is 100-300 mesh; the calcination temperature is 600-800℃, and the calcination time is 4-6 h.

8. The method for preparing ultrafine Y₂O₃-MgO nano-composite powder according to claim 7, characterized in that, Zirconia ball mill jar and grinding balls with a diameter of 2 mm were used. The mass ratio of powder to grinding balls was 1:

12. Anhydrous ethanol was used as the grinding medium, and the mass ratio of powder to anhydrous ethanol was 1 g:2 ml.

9. An ultrafine Y₂O₃-MgO nanocomposite powder, characterized in that, The ultrafine Y2O3-MgO nanocomposite powder is prepared by any one of claims 1-8, wherein the nanocomposite powder has a grain size of no more than 20 nm.

10. A Y₂O₃-MgO nanocomposite ceramic, characterized in that, It is prepared from the ultrafine Y2O3-MgO nanocomposite powder as described in claim 9.

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