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CN-121974382-A - Preparation method of nano alpha alumina

CN121974382ACN 121974382 ACN121974382 ACN 121974382ACN-121974382-A

Abstract

The application relates to a preparation method of nano alpha alumina, belonging to the technical field of nano material preparation. The method comprises the steps of sequentially carrying out gradient acid etching treatment and silane coupling agent surface protection treatment on industrial aluminum powder, carrying out low-temperature ball milling treatment on the industrial aluminum powder subjected to surface protection treatment under the protection of inert atmosphere to obtain superfine activated aluminum powder, mixing the superfine activated aluminum powder, polyaluminium chloride solution and trisodium citrate to obtain aluminum source mixed solution, sequentially carrying out first-stage hydrolysis reaction and second-stage hydrolysis reaction on the aluminum source mixed solution under the protection of inert atmosphere to obtain aluminum hydroxide sol, adding absolute ethyl alcohol into the aluminum hydroxide sol to carry out solvent replacement treatment, adding polyethylene glycol into the aluminum hydroxide sol subjected to solvent replacement treatment to carry out stabilization treatment to obtain stable mixed sol, and sequentially carrying out spray drying treatment and calcination treatment on the stable mixed sol to obtain nano alpha alumina.

Inventors

  • ZHOU SHAN
  • WANG JIANLI
  • WANG JIN
  • YANG FENGHAO
  • CHEN XIANG
  • LI XIAOXING
  • REN XINLIN
  • WANG YI
  • GUO DONGFENG

Assignees

  • 中铝郑州有色金属研究院有限公司

Dates

Publication Date
20260505
Application Date
20260205

Claims (10)

  1. 1. A method for preparing nano alpha alumina, which is characterized by comprising the following steps: sequentially carrying out gradient acid etching treatment and surface protection treatment of a silane coupling agent on industrial aluminum powder; under the protection of inert atmosphere, carrying out low-temperature ball milling treatment on the industrial aluminum powder subjected to surface protection treatment to obtain superfine activated aluminum powder; mixing the superfine activated aluminum powder, the polyaluminum chloride solution and the trisodium citrate to obtain an aluminum source mixed solution; under the protection of inert atmosphere, carrying out a first-stage hydrolysis reaction and a second-stage hydrolysis reaction on the aluminum source mixed solution in sequence to obtain aluminum hydroxide sol; adding absolute ethyl alcohol into the aluminum hydroxide sol for solvent replacement treatment; adding polyethylene glycol into the aluminum hydroxide sol subjected to solvent replacement treatment for stabilization treatment to obtain a stable mixed sol; and sequentially carrying out spray drying treatment and calcination treatment on the stable mixed sol to obtain the nano alpha alumina.
  2. 2. The method according to claim 1, wherein the step of sequentially performing a first-stage hydrolysis reaction and a second-stage hydrolysis reaction on the aluminum source mixed solution under the protection of an inert atmosphere to obtain an aluminum hydroxide sol comprises: Under the protection of inert atmosphere, carrying out a first-stage hydrolysis reaction of 30-40 min on the aluminum source mixed solution; Adjusting the pH value of the aluminum source mixed solution after the first-stage hydrolysis reaction to 4.5-6.0 by using a pH adjusting solution, and then performing a second-stage hydrolysis reaction for 60-90 min to obtain aluminum hydroxide sol, The temperature of the first-stage hydrolysis reaction is 45-50 ℃, and the temperature of the second-stage hydrolysis reaction is 60-65 ℃.
  3. 3. The method according to claim 1, characterized in that the gradient acid etching treatment is specifically: Placing the industrial aluminum powder into a hydrochloric acid solution with a first concentration for first acid etching treatment to remove a loose oxide layer on the surface of the industrial aluminum powder; placing the industrial aluminum powder subjected to the first acid etching treatment into a hydrochloric acid solution with a second concentration for performing the second acid etching treatment so as to remove a compact oxide layer on the surface of the industrial aluminum powder, wherein the second concentration is higher than the first concentration.
  4. 4. The method of claim 3, wherein the first concentration is 5-8 wt%, the first acid etching treatment is performed at a temperature of 30-40 ℃, the first acid etching treatment is performed for 10-15 min, the second concentration is 10-12 wt%, the second acid etching treatment is performed at a temperature of 45-50 ℃, and the second acid etching treatment is performed for 5-8 min.
  5. 5. The method according to claim 1, wherein the ball milling temperature of the low-temperature ball milling treatment is 5-30 ℃, the low-temperature ball milling treatment is performed in a step-variable speed mode, and the particle size D50 of the superfine activated aluminum powder obtained through the low-temperature ball milling treatment is 0.5-5 μm.
  6. 6. The method according to claim 1, wherein the molar concentration of the polyaluminum chloride solution is 0.8 mol/L-1.2 mol/L, the mass ratio of the superfine activated aluminum powder to the polyaluminum chloride solution is 1:4-1:7, and the mass of the trisodium citrate is 0.5% -0.8% of the total mass of the superfine activated aluminum powder and the polyaluminum chloride solution.
  7. 7. The method according to claim 1, wherein the addition volume of the absolute ethyl alcohol is 2-3 times the volume of the aluminum hydroxide sol, and the temperature of the solvent replacement treatment is 50-55 ℃.
  8. 8. The method according to claim 1, wherein the polyethylene glycol is polyethylene glycol 400, the polyethylene glycol is added in an amount of 0.2% -0.3% of the total mass of the system before the stabilization treatment, and/or, The silane coupling agent used for the surface protection treatment is KH-550, KH-560 or KH-570.
  9. 9. The method of claim 1, wherein the feed rate of the spray drying process is 0.5 mL to 0.8 mL/min, the inlet temperature of the spray drying process is 80 to 150 ℃, and/or, The temperature rising rate of the calcination treatment is 2-5 ℃ per minute, the target calcination temperature of the calcination treatment is 900-1200 ℃, and the heat preservation time of the calcination treatment is 0.5-3 h.
  10. 10. The method according to claim 1, wherein the grain size of the nano alpha alumina is 30 nm to 100 nm.

Description

Preparation method of nano alpha alumina Technical Field The application relates to the technical field of nano material preparation, in particular to a preparation method of nano alpha alumina. Background The nano alpha alumina is used as a key base material in the fields of high-performance structural ceramics, precision polishing, catalyst carriers and the like, and can show extremely high sintering activity, excellent mechanical property and stable chemical property when the primary crystal size is reduced to below 100 nanometers. However, the industrialized preparation thereof has long faced outstanding contradiction that the cost, the performance and the environmental protection are difficult to be cooperated and considered. The existing mainstream preparation technology has the remarkable limitations that gas phase methods (such as laser-induced chemical vapor deposition) are expensive in equipment, low in yield and difficult to scale, solid phase methods (such as high-temperature pyrolysis) are wide in product particle size distribution and easy to agglomerate and are easy to pollute the process, liquid phase methods (such as sol-gel methods) are beneficial to amplification, but generally depend on expensive raw materials such as metal alkoxide and the like, are high in cost, have insufficient control precision on hydrolysis-nucleation-growth processes, and are difficult to stably obtain the nano alpha alumina with high dispersion and narrow particle size distribution. Disclosure of Invention The application provides a preparation method of nano alpha alumina, which aims to solve the technical problem of how to provide a preparation method of nano alpha alumina with low cost and strong process controllability. The embodiment of the application provides a preparation method of nano alpha alumina, which comprises the following steps: sequentially carrying out gradient acid etching treatment and surface protection treatment of a silane coupling agent on industrial aluminum powder; under the protection of inert atmosphere, carrying out low-temperature ball milling treatment on the industrial aluminum powder subjected to surface protection treatment to obtain superfine activated aluminum powder; mixing the superfine activated aluminum powder, the polyaluminum chloride solution and the trisodium citrate to obtain an aluminum source mixed solution; under the protection of inert atmosphere, carrying out a first-stage hydrolysis reaction and a second-stage hydrolysis reaction on the aluminum source mixed solution in sequence to obtain aluminum hydroxide sol; adding absolute ethyl alcohol into the aluminum hydroxide sol for solvent replacement treatment; adding polyethylene glycol into the aluminum hydroxide sol subjected to solvent replacement treatment for stabilization treatment to obtain a stable mixed sol; and sequentially carrying out spray drying treatment and calcination treatment on the stable mixed sol to obtain the nano alpha alumina. Optionally, under the protection of inert atmosphere, the aluminum source mixed solution is subjected to a first-stage hydrolysis reaction and a second-stage hydrolysis reaction in sequence to obtain aluminum hydroxide sol, which comprises the following steps: Under the protection of inert atmosphere, carrying out a first-stage hydrolysis reaction of 30-40 min on the aluminum source mixed solution; Adjusting the pH value of the aluminum source mixed solution after the first-stage hydrolysis reaction to 4.5-6.0 by using a pH adjusting solution, and then performing a second-stage hydrolysis reaction for 60-90 min to obtain aluminum hydroxide sol, The temperature of the first-stage hydrolysis reaction is 45-50 ℃, and the temperature of the second-stage hydrolysis reaction is 60-65 ℃. Optionally, the gradient acid etching treatment specifically includes: Placing the industrial aluminum powder into a hydrochloric acid solution with a first concentration for first acid etching treatment to remove a loose oxide layer on the surface of the industrial aluminum powder; placing the industrial aluminum powder subjected to the first acid etching treatment into a hydrochloric acid solution with a second concentration for performing the second acid etching treatment so as to remove a compact oxide layer on the surface of the industrial aluminum powder, wherein the second concentration is higher than the first concentration. Optionally, the first concentration is 5-8wt%, the temperature of the first acid etching treatment is 30-40deg.C, the time of the first acid etching treatment is 10-15 min, the second concentration is 10-12wt%, the temperature of the second acid etching treatment is 45-50deg.C, and the time of the second acid etching treatment is 5-8 min. Optionally, the ball milling temperature of the low-temperature ball milling treatment is 5-30 ℃, the low-temperature ball milling treatment is carried out in a step speed changing mode, and the particle size D50 of the superfin