Method for preparing needle-like yttrium oxide by soft template method

Abstract

The invention discloses a method for preparing needle-like yttrium oxide by a soft template method, which comprises the following steps: dropwise adding an alkaline solution into a soluble yttrium salt solution containing a template agent, stirring and mixing until the pH value of the mixed solution reaches 7-10; carrying out thermal insulation reaction on the mixed solution, separating, drying, grinding, and carrying out primary ball milling to obtain precursor powder; the precursor powder is subjected to pre-calcination, secondary ball milling and re-calcination, and the needle-like yttrium oxide is obtained. According to the invention, preparation of large-particle needle-like yttrium oxide can be realized at low temperature and normal pressure.

Description

Technical Field

[0001] This invention relates to the field of yttrium oxide preparation technology, and particularly to a method for preparing needle-shaped yttrium oxide using a soft template method. Background Technology

[0002] Needle-shaped yttrium oxide is a high-performance inorganic fiber material with many remarkable properties, such as high temperature resistance, wear resistance, oxidation resistance, low thermal conductivity, low coefficient of thermal expansion, good shock resistance, high modulus, high plasticity, high toughness, high strength, high insulation, and high dielectric constant. These properties make needle-shaped yttrium oxide widely used in many fields.

[0003] Large-particle needle-shaped yttrium oxide (with a diameter of not less than 0.4 μm and a length of not less than 4 μm) has more significant advantages in terms of mechanical properties and can be applied to fields such as insulating materials, fiber protection, reinforcing materials, and electronic devices.

[0004] However, most current preparation processes for needle-shaped yttrium oxide involve small fibrous yttrium oxide particles, while there is a lack of reports on preparation processes for large needle-shaped yttrium oxide particles. Summary of the Invention

[0005] Based on this, the purpose of this invention is to provide a method for preparing needle-shaped yttrium oxide using a soft template method, so as to achieve the preparation of large-particle needle-shaped yttrium oxide at low temperature and ambient pressure.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for preparing needle-shaped yttrium oxide using a soft template method, comprising the following steps: Add an alkaline solution dropwise to a soluble yttrium salt solution containing a template agent, and stir until the pH of the mixture reaches 7-10. The mixture is kept at a certain temperature for reaction, then separated, dried, ground, and ball-milled once to obtain precursor powder; The precursor powder was pre-calcined, ball-milled twice, and then calcined again to obtain needle-shaped yttrium oxide.

[0007] In this invention, the soluble yttrium salt solution is formed by dissolving a soluble yttrium salt in deionized water, and a certain amount of template agent is added to the solution. The soluble yttrium salt mainly refers to an inorganic salt of metallic yttrium that has a certain degree of solubility in deionized water. As a further improvement to the above-mentioned scheme of this invention, the soluble yttrium salt is at least one of yttrium chloride, yttrium nitrate, and yttrium sulfate, but is not limited thereto.

[0008] The template agent refers to a surfactant. Needle-shaped yttrium oxide is prepared by utilizing the ordered aggregates formed by weak intermolecular interactions of the surfactant as a soft template. These template agents can guide the distribution of yttrium oxide through specific structural interfaces, thereby obtaining yttrium oxide with a needle-like structure. Specifically, different surfactants have different functional groups, and molecules with the same functional groups are arranged neatly in solution. Surfactants generally have two different types of functional groups: one hydrophilic and one non-hydrophilic. They can change the morphology of the precursor by affecting the equilibrium of the aqueous solution. In a suitable solution system, the soft template becomes micelles and forms micellar complexes through interactions with the precursor (e.g., hydrogen bonding, hydrophilic-hydrophobic interactions, electrostatic interactions, etc.), and then the final product is prepared through subsequent processing. As a further improvement to the above scheme of the present invention, the template agent is hexadecyltrimethylammonium bromide, PEG2000, or P123, but is not limited to these.

[0009] As a further improvement to the above-described scheme of the present invention, the concentration of the soluble yttrium salt solution is 0.2~2 mol / L, for example, it can be any concentration among 0.2 mol / L, 0.5 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.5 mol / L, 1.7 mol / L, and 2 mol / L.

[0010] In the soluble yttrium salt solution, the amount of template agent added can be adjusted according to the amount of soluble yttrium salt. When the amount of soluble yttrium salt is low, the amount of template agent added is reduced accordingly; when the amount of soluble yttrium salt is high, the amount of template agent added is increased accordingly. As a further improvement of the above-mentioned scheme of the present invention, the content of the template agent in the soluble yttrium salt solution is 0.5wt%~3wt%, for example, it can be any value among 0.5wt%, 0.8wt%, 1wt%, 1.2wt%, 1.5wt%, 1.8wt%, 2wt%, 2.4wt%, 2.6wt%, 2.8wt%, and 3wt%.

[0011] The alkaline solution is a solution capable of reacting with soluble yttrium salts to form yttrium hydroxide. As a further improvement of the above-described scheme of the present invention, the pH of the alkaline solution is 11-12, and the dropping rate of the alkaline solution should not be too fast, because excessively fast dropping rates can easily lead to uneven precipitation. Therefore, preferably, the dropping rate of the alkaline solution does not exceed 5 mL / min.

[0012] To further improve the above-mentioned solution of the present invention, the alkaline solution is an ammonia solution, and the concentration of the ammonia solution is adjusted according to the concentration of the soluble yttrium salt. Specifically, the concentration of the ammonia solution is 1-5 mol / L, for example, it can be any value among 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, or 5 mol / L. A precipitation reaction occurs by adding the soluble yttrium salt and ammonia solution: Y 3+ +3NH3·H2O=Y(OH)3↓+3NH 4+ This generates a yttrium hydroxide precursor. In this invention, adjusting the pH of the mixed solution to 7-10 ensures that the precipitation is significant while forming needle-like yttrium oxide with a regular morphology.

[0013] As a further improvement to the above-described scheme of the present invention, the temperature of the heat preservation reaction is 70~90℃, and after the reaction is completed, it is cooled to room temperature. The precursor is obtained by precipitation through the heat preservation reaction at this temperature. The specific heat preservation reaction time can be adjusted as needed. Preferably, in some specific embodiments of the present invention, the heat preservation reaction time is 3~4 hours.

[0014] Separation and drying after the heat preservation reaction refer to: centrifuging the reaction mixture at least once with deionized water and once with ethanol, preferably three times with deionized water and then three times with ethanol, thereby achieving solid-liquid separation; and drying and grinding the precipitate at the bottom after centrifugation to obtain the precursor. Centrifugation and drying are operations well known to those skilled in the art. In some specific embodiments of the present invention, the centrifugation speed is 6000~8000 rpm for 3~6 min; the drying temperature is 70~90℃ for 10~14 h.

[0015] In this invention, the precursor is ball-milled once to achieve stress relief and dimensional control. Specifically, the ball milling used in this invention is wet ball milling. The dried precursor is added to a ball milling jar for ball milling. The preferred ball-to-material ratio is (8~12):1. The ball milling medium is anhydrous ethanol, the rotation speed is 400~600 rpm, and the time is 6~12 hours. Finally, the ball-milled precursor is passed through a 200-mesh sieve to facilitate uniform heating during the subsequent calcination process and improve the quality of the product.

[0016] As a further improvement to the above-mentioned scheme of the present invention, the pre-calcination is carried out at 400~600℃ for 2~4 hours, and the re-calcination is carried out at 1200~1600℃ for 2~4 hours.

[0017] As a further improvement to the above-mentioned solution of the present invention, the secondary ball milling process is the same as the primary ball milling process.

[0018] By combining pre-calcination with secondary ball milling, stress is further reduced while porosity is decreased, so as to control the production of large-particle needle-shaped yttrium oxide. The obtained needle-shaped yttrium oxide has a particle size of 0.4~1μm and a length of 4~10μm.

[0019] Compared with the prior art, the present invention has the following beneficial effects: This invention optimizes the raw material formulation and process, particularly by using ball milling to release stress and control the size of the precursor. At the same time, a pre-calcination process combined with secondary ball milling before calcination reduces stress and the generation of pores, thereby enabling the preparation of large-particle needle-shaped yttrium oxide under low temperature and normal pressure. Attached Figure Description

[0020] Figure 1 Here is a SEM image of the needle-shaped yttrium oxide obtained in Example 1; Figure 2 This is a SEM image of the needle-shaped yttrium oxide prepared in Example 1. Detailed Implementation

[0021] To facilitate understanding of the present invention, a more comprehensive description will be given below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0023] Example 1 This embodiment proposes a method for preparing needle-shaped yttrium oxide using a soft template method, the specific steps of which are as follows: (1) Preparation of solution: Weigh 34.46g of yttrium nitrate hexahydrate and add it to 300ml of deionized water. Stir magnetically at 330r / min for 1h. After it is completely dissolved, add 0.6g of cetyltrimethylammonium bromide (CTAB) and stir until it is completely dissolved to obtain a yttrium nitrate solution containing template agent. At the same time, prepare 400mL of ammonia solution with a concentration of 1mol / L.

[0024] (2) Under stirring conditions, the prepared ammonia solution is added dropwise to the prepared yttrium nitrate solution at a rate not exceeding 5 mL / min. At the same time, the pH of the mixture is monitored in real time using a pH meter until the pH of the mixture is maintained at 7.0~10.0 for a long time. Stirring is then stopped until the mixture is evenly distributed.

[0025] (3) Transfer the mixture to a three-necked flask and keep it at 70°C for 4 hours. After the reaction is complete, cool it to room temperature.

[0026] (4) The mixture after reaction is put into a centrifuge tube, centrifuged at 8000 rpm for 5 min, centrifuged three times with deionized water, sonicated for 30 min, and then centrifuged three times with ethanol. The precipitate at the bottom after centrifugation is dried, the oven temperature is adjusted to 80℃, dried for 12 h, and then ground to obtain the precursor.

[0027] (5) Place the precursor into a ball mill jar for one ball milling. Add the precursor and the milling balls. The mass ratio of the precursor to the milling balls is 1:10. Add anhydrous ethanol. After milling at 500 rpm for 6 hours, pass the precursor powder through a 200-mesh sieve.

[0028] (6) The precursor powder after the first ball milling is placed in an alumina crucible and pre-calcined in a muffle furnace at 500°C for 2 hours. Then, the powder is ball milled again according to step (5). The milled powder is calcined at 1200°C for 2 hours to obtain needle-shaped yttrium oxide crystals.

[0029] Figure 1 , Figure 2 The SEM characterization results of yttrium oxide in this embodiment are shown. It can be seen that the prepared yttrium oxide is needle-shaped, with a length of about 6 μm and a diameter of about 0.5 μm, which is large-particle needle-shaped yttrium oxide.

[0030] Example 2 This embodiment provides a method for preparing needle-shaped yttrium oxide using a soft template method, the specific steps of which are as follows: (1) Preparation of solution: Weigh 54.88g of yttrium sulfate octahydrate and add it to 300ml of deionized water. Stir magnetically at 330r / min for 1h. After it is completely dissolved, add 0.6g of soft template P123 and stir until it is completely dissolved to obtain a yttrium sulfate solution containing template agent. At the same time, prepare 200mL of ammonia solution with a concentration of 2mol / L.

[0031] (2) Under stirring conditions, the prepared ammonia solution is added dropwise to the prepared yttrium sulfate solution at a rate not exceeding 5 ml / min. At the same time, the pH change of the mixed solution is monitored in real time using a pH meter until the pH of the mixed solution is maintained at 7.0~10.0 for a long time. Stirring is then stopped to obtain a uniformly distributed mixed solution.

[0032] (3) Transfer the mixture to a three-necked flask and keep it at 70°C for 4 hours. After the reaction is complete, cool it to room temperature.

[0033] (4) The solution after reaction is put into a centrifuge tube, centrifuged at 8000 rpm for 5 min, centrifuged three times with deionized water, sonicated for 30 min, centrifuged three times with ethanol, and then the precipitate at the bottom after centrifugation is dried. The oven temperature is adjusted to 80℃ and dried for 12 h. The precursor is then ground.

[0034] (5) Place the precursor in a ball mill jar and ball mill. Add the precursor and the ball milling balls. The mass ratio of the precursor to the ball milling balls is 1:10. Add anhydrous ethanol and ball mill at 400 rpm for 8 hours. Then dry the precursor powder and pass it through a 200-mesh sieve.

[0035] (6) The ball-milled precursor is placed in a yttrium oxide crucible and pre-calcined in a muffle furnace at 400°C for 4 hours. Then, it is ball-milled again according to step (5). The milled powder is calcined at 1400°C for 4 hours to obtain needle-shaped yttrium oxide crystals.

[0036] In this embodiment, the diameter of the prepared needle-shaped yttrium oxide is about 0.4 μm and the length is about 10 μm.

[0037] Example 3 This embodiment provides a method for preparing needle-shaped yttrium oxide using a soft template method, the specific steps of which are as follows: (1) Preparation of solution: Weigh 27.29g of yttrium chloride hexahydrate and add it to 300mL of deionized water. Stir magnetically at 330r / min for 1h. After it is completely dissolved, add 0.07g of PEG2000 and stir until it is completely dissolved to obtain a yttrium chloride solution containing template agent. At the same time, prepare 400ml of ammonia solution with a concentration of 1mol / L.

[0038] (2) Under stirring conditions, the prepared ammonia solution is added dropwise to the prepared yttrium chloride solution at a rate not exceeding 5 mL / min. At the same time, the pH change of the mixed solution is monitored in real time using a pH meter until the pH of the mixed solution is maintained at 7.0~10.0 for a long time. Stir until the solution is clear.

[0039] (3) Transfer the mixed solution to a three-necked flask and keep it at 80°C for 3.5 h. After the reaction is complete, cool it to room temperature.

[0040] (4) The solution after reaction is put into a centrifuge tube, centrifuged at 6000 rpm for 4 min, centrifuged three times with deionized water, sonicated for 30 min, centrifuged three times with ethanol, and then dried the precipitate at the bottom after centrifugation. The oven temperature was adjusted to 80℃ and dried for 12 h. The precursor was then ground.

[0041] (5) Place the precursor in a ball mill jar and ball mill. Add the precursor and the ball milling balls. The mass ratio of the precursor to the ball milling balls is 1:10. Add anhydrous ethanol and ball mill at 600 rpm for 10 hours. Then pass the precursor powder through a 200-mesh sieve.

[0042] (6) The ball-milled precursor is placed in a yttrium oxide crucible and pre-calcined in a muffle furnace at 600°C for 3 hours. Then, it is ball-milled again according to step (5). The milled powder is calcined at 1600°C for 3 hours to obtain needle-shaped yttrium oxide crystals.

[0043] In this embodiment, the diameter of the prepared needle-shaped yttrium oxide is about 0.6 μm and the length is about 8 μm.

[0044] Example 4 This embodiment provides a method for preparing needle-shaped yttrium oxide using a soft template method, the specific steps of which are as follows: (1) Preparation of solution: Weigh 54.88g of yttrium sulfate octahydrate and add it to 300mL of deionized water. Stir magnetically at 330r / min for 1h. After it is completely dissolved, add 4.27g of cetyltrimethylammonium bromide and stir until it is completely dissolved to obtain a yttrium sulfate solution containing template agent. At the same time, prepare 400mL of ammonia solution with a concentration of 5mol / L.

[0045] (2) Under stirring conditions, the prepared ammonia solution is added dropwise to the prepared yttrium sulfate solution at a rate not exceeding 5 mL / min. At the same time, the pH change of the mixed solution is monitored in real time using a pH meter until the pH of the mixed solution is maintained at 7.0~10.0 for a long time. Stir until the solution is clear.

[0046] (3) Transfer the mixed solution to a three-necked flask and keep it at 80°C for 3.5 h. After the reaction is complete, cool it to room temperature.

[0047] (4) The solution after reaction is put into a centrifuge tube, centrifuged at 7000 rpm for 4 min, centrifuged three times with deionized water, sonicated for 30 min, centrifuged three times with ethanol, and then the precipitate at the bottom after centrifugation is dried. The oven temperature is adjusted to 80℃ and dried for 12 h. The precursor is then ground.

[0048] (5) Place the precursor in a ball mill jar and ball mill. Add the precursor and the ball milling balls. The mass ratio of the precursor to the ball milling balls is 1:10. Add anhydrous ethanol and ball mill at 500 rpm for 12 hours. Then, pass the precursor powder through a 200-mesh sieve.

[0049] (6) Place the ball-milled precursor into a yttrium oxide crucible, pre-calcine it at 500°C for 2 hours in a muffle furnace, and then perform a second ball milling as per step (5). Calcine the milled powder at 1600°C for 3 hours to obtain needle-shaped yttrium oxide crystals.

[0050] In this embodiment, the obtained needle-shaped yttrium oxide has a diameter of 0.5 μm and a length of 8 μm.

[0051] Comparative Example 1 The only difference between this comparative example and Example 1 is that the precursor was not ball-milled in this comparative example. The yttrium oxide obtained in this comparative example is needle-shaped, but its diameter and length are both in the nanometer range, not in the micrometer range.

[0052] Comparative Example 2 The only difference between this comparative example and Example 1 is that this comparative example did not undergo pre-calcination and secondary ball milling; instead, the precursor powder after one ball milling was directly calcined at 1100°C for 2 hours.

[0053] The yttrium oxide prepared in this comparative example is needle-shaped, but its diameter and length are both in the nanometer range, not in the micrometer range, and there are a small number of pores in the crystal.

[0054] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0055] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing needle-shaped yttrium oxide using a soft template method, characterized in that, It includes the following steps: Add an alkaline solution dropwise to a soluble yttrium salt solution containing a template agent, and stir until the pH of the mixture reaches 7-10. The mixture is kept at a certain temperature for reaction, then separated, dried, ground, and ball-milled once to obtain precursor powder; The precursor powder was pre-calcined, ball-milled twice, and then calcined again to obtain needle-shaped yttrium oxide.

2. The method for preparing needle-shaped yttrium oxide using the soft template method according to claim 1, characterized in that, The template agent is hexadecyltrimethylammonium bromide, PEG2000, or P123.

3. The method for preparing needle-shaped yttrium oxide using the soft template method according to claim 1, characterized in that, The concentration of the soluble yttrium salt solution is 0.2~2 mol / L, and the content of the template agent in the soluble yttrium salt solution is 0.5wt%~3wt%.

4. The method for preparing needle-shaped yttrium oxide using the soft template method according to claim 1, characterized in that, The soluble yttrium salt is at least one of yttrium chloride, yttrium nitrate, and yttrium sulfate.

5. The method for preparing needle-shaped yttrium oxide using the soft template method according to claim 1, characterized in that, The pH of the alkaline solution is 11-12, and the dropping rate of the alkaline solution does not exceed 5 mL / min.

6. The method for preparing needle-shaped yttrium oxide using the soft template method according to claim 1, characterized in that, The alkaline solution is an ammonia solution with a concentration of 1-5 mol / L.

7. The method for preparing needle-shaped yttrium oxide using the soft template method according to claim 1, characterized in that, The temperature of the heat preservation reaction is 70~90℃.

8. The method for preparing needle-shaped yttrium oxide using the soft template method according to claim 1, characterized in that, The ball-to-material ratio for both the primary and secondary ball milling processes is (8~12):1, the ball milling speed is 400~600 rpm, and the ball milling time is 6~12 h.

9. The method for preparing needle-shaped yttrium oxide using the soft template method according to claim 1, characterized in that, The precursor powder has a particle size of no more than 200 mesh, and the needle-shaped yttrium oxide has a particle size of 0.4~1μm and a length of 4~10μm.

10. The method for preparing needle-shaped yttrium oxide using the soft template method according to claim 1, characterized in that, The pre-calcination temperature is 400~600℃, and the re-calcination temperature is 1200~1600℃.

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