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Preparation method and application of alpha-alumina with reduced phase transition temperature

A phase transition temperature and alumina technology, applied in the field of sintered body materials, can solve problems such as complex operation, incomplete removal of solvents and additives, and reduced compactness of α-alumina, and achieve high reaction efficiency

Pending Publication Date: 2021-06-11
SHANDONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

On the one hand, grain agglomeration is easy to occur during high-temperature calcination, resulting in a decrease in the compactness of α-alumina, which in turn affects product performance
On the other hand, sintering at a higher temperature to obtain α-alumina requires a lot of heat, which will cause high energy loss. If sintering at a temperature lower than 1200°C, impure α-alumina will be obtained.
[0005] Although the prior art discloses some methods for preparing α-alumina at low temperatures, the inventors have found that some methods use multi-step hydrolysis, the operation is complicated, and the concentration of the aluminum source is high, and the uniformity of the prepared particles is poor.
There are also some methods that use the oil phase and the water phase to react, the sintering temperature is high, and there are many types of solvents and additives, the reaction system is easy to introduce impurity ions, or the removal of solvents and additives is not complete, affecting the purity and uniformity of α-alumina

Method used

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  • Preparation method and application of alpha-alumina with reduced phase transition temperature
  • Preparation method and application of alpha-alumina with reduced phase transition temperature
  • Preparation method and application of alpha-alumina with reduced phase transition temperature

Examples

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preparation example Construction

[0030] The first aspect of the present invention provides a method for preparing α-alumina with a reduced phase transition temperature, comprising:

[0031] Mix aluminum isopropoxide with a solvent, add ammonium bicarbonate solution to hydrolyze, dry, heat up the dried product, keep it warm, and cool down to obtain the product.

[0032] In one or more embodiments of the present invention, the solvent is selected from ethanol, propanol, n-butanol and isopropanol;

[0033] Further preferably, the solvent is isopropanol. Because the hydrolysis of aluminum isopropoxide will generate isopropanol and AlOOH, it is selected to dissolve aluminum isopropoxide in isopropanol for hydrolysis, which is beneficial to the uniformity of the hydrolysis process and avoids unhydrolyzed aluminum isopropoxide during the hydrolysis process. Being wrapped by hydrolyzed products affects the completeness of hydrolysis. On the other hand, the hydrolysis of aluminum isopropoxide will not introduce unne...

Embodiment 1

[0062] Under magnetic stirring, 5g of aluminum isopropoxide was added to 20mL of isopropanol, stirred at 70°C for 40min until aluminum isopropoxide was completely dissolved, then 15mL of water with a volume ratio of 1:4 was added dropwise. Isopropanol mixed solution, the hydrolysis temperature is 70°C, the hydrolysis time is 2h, the hydrolysis process is continuously stirred, after the hydrolysis is completed, the stirring is continued for 0.5h, the hydrolyzed gel is dried in a 60°C oven for 24h, and then the obtained The samples were heat-treated in a muffle furnace under the following conditions: the furnace temperature was raised to 1150°C within 2 hours, kept at 1150°C for 2 hours, and then cooled in the furnace.

[0063] figure 1 This is the X-ray diffraction pattern of the product obtained in Example 1. It can be seen from the figure that after calcination at 1150°C, the sample obtained by hydrolysis without adding ammonium bicarbonate contains more θ-alumina. From this...

Embodiment 2

[0065] Under magnetic stirring, add 5g of aluminum isopropoxide into 20mL of isopropanol, stir at 70°C for 40min until the aluminum isopropoxide is completely dissolved, then add 15mL of ammonium bicarbonate mixed with 0.005g drop by volume It is a 1:4 mixed solution of water and isopropanol, the hydrolysis temperature is 70°C, and the hydrolysis time is 2h. Stir continuously during the hydrolysis process. After the hydrolysis is completed, continue to stir for 0.5h. The gel obtained after hydrolysis is placed in an oven at 60°C. After drying for 24 hours, the obtained sample was heat-treated in a muffle furnace. The treatment conditions were as follows: the furnace temperature was raised to 1150°C within 2 hours, and kept at 1150°C for 2 hours, and then cooled in the furnace.

[0066] image 3 This is the X-ray diffraction pattern of the product obtained in Example 2. It can be seen from the figure that after calcination at 1150°C, the sample obtained by adding 0.005g of ammo...

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Abstract

The invention belongs to the technical field of sintered body materials, and particularly relates to a preparation method and application of alpha-aluminum oxide with reduced phase transition temperature. The preparation method comprises the steps of mixing aluminum isopropoxide with a solvent, adding an ammonium bicarbonate solution, hydrolyzing, drying, heating the dried product, preserving heat, and cooling to obtain alpha-aluminum oxide. The introduction of ammonium bicarbonate reduces the phase transition temperature of alpha-aluminum oxide, and aluminum isopropoxide and ammonium bicarbonate react in a water phase, so that alpha-aluminum oxide with higher purity can be prepared only through one-step hydrolysis, and the reaction efficiency is higher. The method has a good application prospect in preparation of alpha-aluminum oxide with high purity and low energy consumption.

Description

technical field [0001] The invention belongs to the technical field of sintered body materials, and in particular relates to a preparation method and application of α-alumina with reduced phase transition temperature. Background technique [0002] The information disclosed in this background section is only intended to increase the understanding of the general background of the present invention, and is not necessarily taken as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to those skilled in the art. [0003] α-alumina is one of the most widely used ceramic materials in various industries. It has strong acid and alkali resistance, good formability, relatively stable crystal phase, high hardness, and good dimensional stability. It can be widely used in various Plastics, rubber, ceramics, refractory materials, catalyst carriers and other products. [0004] However, the current domestic α-alumina commonly used prepara...

Claims

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Application Information

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IPC IPC(8): C01F7/30
CPCC01F7/30C01P2002/72C01P2004/03
Inventor 郑昭科马法豪黄柏标王泽岩程合锋王朋刘媛媛张晓阳张倩倩
Owner SHANDONG UNIV
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