Preparation method for microcrystal alpha-Al2O3 aggregation

A technology of aggregates and microcrystals, applied in the preparation of alumina/hydroxide, etc., can solve the problems of high impurity content, complicated process, low reactivity, etc.

Active Publication Date: 2014-01-08
SHANDONG UNIV
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Problems solved by technology

[0010] Currently commercially available aluminum hydroxide products have poor particle size uniformity, coarse particle size, low reactivity, and high impurity content
The sintering precursor is difficult to peptize, and the dispersion of sintering aids is uneven
Usually prepared by high temperature, high pressure or special sintering process, the process is complicated, requires high equipment and consumes a lot of energy, see J.Eur.Ceram.Soc.2010,30,1351; USP6395214; J.Am.Ceram.Soc.2002 ,85,1921

Method used

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  • Preparation method for microcrystal alpha-Al2O3 aggregation
  • Preparation method for microcrystal alpha-Al2O3 aggregation
  • Preparation method for microcrystal alpha-Al2O3 aggregation

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Embodiment Construction

[0014] An aluminum hydroxide gel, wherein the aluminum hydroxide is amorphous, used to prepare microcrystalline α-Al 2 o 3 Aggregates; are prepared in the following steps:

[0015] (1) NH with a concentration of 25-28wt% 3 ·H 2 O added to water and Al(NO 3 ) 3 9H 2 In the mixed solution of O, Al(NO 3 ) 3 9H 2 O:H 2 O: NH 3 ·H 2 The molar ratio of O is 1:(3-8):(4.5-12), and the suspension is obtained after stirring evenly; centrifuged or suction filtered, and the precipitate is washed 2 to 3 times with deionized water to obtain aluminum hydroxide; the filtrate Used to recover by-product ammonium nitrate.

[0016] (2) adding water to the aluminum hydroxide prepared in step (1) is mixed with a suspension with a solid content of 5 to 15wt%, and adding concentrated nitric acid with a concentration of 65 to 69wt%; the mol ratio of the aluminum hydroxide to the concentrated nitric acid (5 -12): 1. Stir for 2 to 5 hours, add alumina ball milling medium to the suspension, ...

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Abstract

A preparation method for microcrystal alpha-Al2O3 aggregation comprises: reacting aluminium nitrate hydrate with ammonia water to obtain aluminium hydroxide, adding an additive into a fluid suspension subjected to ball milling to obtain aluminium hydroxide gel, drying to obtain aluminium hydroxide xerogel, and performing crushing and calcining on the aluminium hydroxide xerogel to obtain the microcrystal alpha-Al2O3 aggregation. The method is applicable to large-scale production of the microcrystal alpha-Al2O3 aggregation, the technological conditions are easy to control, and the obtained microcrystal alpha-Al2O3 aggregation has a primary crystal grain size of 50-400 nm, a secondary aggregation grain size of 75-600 mu m, a compact structure, the density of 3.90-3.98 g / cm<3> and the hardness of 19-24 GPa. The obtained microcrystal alpha-Al2O3 aggregation can be used as an abrasive, a heat-resistant material, an electronic device material, a high-frequency insulating material, a spaceflight material, an information material and the like.

Description

[0001] This application is a divisional application of 201210285200.7. technical field [0002] The invention relates to an aluminum hydroxide gel and the preparation of microcrystalline α-Al by using the aluminum hydroxide gel as a raw material 2 o 3 The method for aggregate materials belongs to the field of inorganic non-metallic materials. Background technique [0003] Microcrystalline α-Al 2 o 3 Aggregate materials can be used in many basic industries and fields such as chemical engineering, insulating materials, catalyst carriers, ceramics, aerospace, electronics, etc., especially as ceramic materials. Microcrystalline α-Al 2 o 3 Aggregate, as an important ceramic material, has always been a research hotspot at home and abroad, especially the research and application of microcrystalline corundum abrasives, electronic ceramics and transparent ceramics, which have developed rapidly in recent years, are the most typical. [0004] Since the 1980s, α-Al 2 o 3 The pre...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/30
Inventor 陈代荣张建焦秀玲张立
Owner SHANDONG UNIV
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