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Method for preparing acicular alpha alumina

A technology of alpha alumina and alumina, applied in the field of preparation of needle-shaped alpha alumina

Active Publication Date: 2009-03-25
中铝郑州有色金属研究院有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The most commonly used one is zirconia toughening, which is to add a part of stable zirconia or zirconia compound to alumina. It is a toughening method that absorbs and slows down energy concentration through microcracks, but it increases toughness itself. also very limited

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  • Method for preparing acicular alpha alumina

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preparation example Construction

[0018] A method for preparing needle-shaped alumina, which involves re-dissolving industrial-grade aluminum hydroxide with potassium hydroxide to prepare a potassium aluminate solution, and then adding needle-shaped aluminum hydroxide seeds for decomposition to obtain slender needle-shaped Aluminum hydroxide (pseudo-hexagonal prism), the obtained aluminum hydroxide is calcined at about 900°C to obtain γ-alumina. Add additives to promote crystal development and improve the conversion of aluminum to γ-alumina, mix them evenly, and roast in a high-temperature furnace to obtain α-acicular alumina. (Acicular aluminum hydroxide seed crystals used above are obtained by carbonation and decomposition of potassium aluminate solution, and acicular aluminum hydroxide is prepared, which can be recycled.)

[0019] The above-mentioned potassium hydroxide used for dissolving technical grade aluminum hydroxide is technical grade, and the purity is greater than 99.5%.

[0020] The molar ratio ...

Embodiment 1

[0026] Using industrial-grade aluminum hydroxide (intermediate pilot plant of Zhengzhou Research Institute) as raw material, first add 200g aluminum hydroxide (calculated on a dry basis) and 214 grams of potassium hydroxide to water (1400 grams), stir and heat in the reactor ( Reactor is in water bath, and the set temperature of water bath is 100 ℃), when solution is all clarified, stop stirring, and the temperature of regulating water bath is 80 ℃, adds 6 grams of acicular aluminum hydroxide crystal seeds, stirs and decomposes 1 After hours, the decomposition was stopped, and the precipitated aluminum hydroxide was taken out, washed, dried, calcined in a muffle furnace to 850°C, and kept for 2 hours to obtain γ-alumina. Take 100 grams of γ-alumina and 0.8 grams of boric acid and mix evenly, calcinate in a high-temperature furnace to 1350 ° C, and keep the temperature for 3 hours. Acicular α-alumina was obtained with a conversion rate of 95.1%, a primary crystal aspect ratio o...

Embodiment 2

[0028] Using industrial-grade aluminum hydroxide (intermediate pilot plant of Zhengzhou Research Institute) as raw material, first add 200g aluminum hydroxide (calculated on a dry basis) and 244 grams of potassium hydroxide to water (1400 grams), stir and heat in the reactor ( Reactor is in water bath, and the set temperature of water bath is 100 ℃), when solution is all clarified, stop stirring, and the temperature of regulating water bath is 80 ℃, adds 10 grams of acicular aluminum hydroxide crystal seeds, stirs and decomposes 1 After hours, the decomposition was stopped, and the precipitated aluminum hydroxide was taken out, washed, dried, calcined in a muffle furnace to 900°C, and kept for 2 hours to obtain γ-alumina. Take 100 grams of γ-alumina and 0.8 grams of aluminum fluoride and mix evenly, calcinate in a high-temperature furnace to 1400 ° C, and keep the temperature for 2 hours. Acicular α-alumina was obtained with a conversion rate of 95.5%, an aspect ratio of the o...

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Abstract

The invention discloses a preparation method for needle-shaped Alpha-alumina, comprising the following steps: firstly, industrial grade aluminum hydroxide reacts with potassium hydroxide so as to prepare aluminum potassium solution, later needle-shaped aluminum hydroxide seed is added for carrying out decomposition and obtaining fine long needle-shaped aluminum hydroxide (pseudo hexagonal prism), then the obtained aluminum hydroxide is calcined at 900 DEG C or so for obtaining Gamma-alumina. By adding additive which can promote the crystal growth and improve transformation aluminum into the Gamma-alumina, after evenly mixing, Alpha-needle-shaped alumina is obtained when in the calcination of a high temperature furnace.

Description

technical field [0001] The invention discloses a method for preparing needle-shaped α-alumina, and relates to a method for preparing α-alumina used for preparing ceramic products with high performance and good toughness. Background technique [0002] α-alumina powder is a chemical formula Al 2 o 3 And the compound with α crystal phase is widely used. At present, the α-alumina produced industrially is mainly made of industrial aluminum hydroxide, industrial alumina or a mixture of the two with appropriate amount of additives mixed uniformly, and then calcined in one step in a draft furnace or a tunnel kiln. The morphology of ordinary calcined α-alumina is mainly related to the morphology of the raw materials (the main morphology and structure of industrial alumina and industrial aluminum hydroxide are flakes). The particles calcined in this way are mostly flaky, granular, nearly spherical, powder hammer and irregular. [0003] Due to its high mechanical strength, high har...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/30
Inventor 李晋峰
Owner 中铝郑州有色金属研究院有限公司