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Prepn. of submicron high-purity transparent alumina ceramic material

A sub-micron technology for alumina ceramics, which is applied in the field of preparation of transparent alumina ceramic materials, and can solve the problems of large crystal grains of transparent alumina ceramics, affecting light transmission performance, and high energy consumption.

Inactive Publication Date: 2003-01-08
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The transparent alumina ceramics obtained by these methods show coarse grains in the microstructure, generally reaching a dozen to tens of microns, which will affect the light transmission performance of the material macroscopically.
At the same time, the high temperature sintering method also has the disadvantage of high energy consumption

Method used

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  • Prepn. of submicron high-purity transparent alumina ceramic material
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  • Prepn. of submicron high-purity transparent alumina ceramic material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] Commercial α-Al with a purity of 99.99% was processed by 50MPa dry pressing and 200MPa cold isostatic pressing 2 o 3 (The same below) Raw material powder molding; Then the molded green body was pre-sintered without pressure at 1200 ° C for 400 minutes; the pre-fired green body was placed in a hot isostatic pressing furnace for post-treatment under an Ar gas atmosphere, and the temperature was 1250°C, pressure 140Mpa, heat preservation and pressure holding time 40 minutes; finally use a surface grinder and diamond abrasive paste to grind and polish the ceramic surface.

[0017] The relative density of the obtained ceramic body was 99.9%, and the average grain size was 0.68 μm. The results of the transmittance test are as follows figure 1 Shown: the transmittance can reach 70% in the visible light region (380nm~760nm), and 80% in the infrared light region (>760nm). At the same time, in the ultraviolet light region (<380nm), the transmittance ratio of the material presen...

Embodiment 2

[0019] Using 50MPa dry pressing plus 200MPa cold isostatic pressing process to shape the raw material powder; then pre-sinter the molded green body at 1250°C for 90 minutes without pressure; put the pre-fired green body into a hot isostatic pressing furnace under Ar The post-treatment is carried out under the air atmosphere, the temperature is 1200°C, the pressure is 140Mpa, and the time of heat preservation and pressure holding is 40 minutes; finally, the ceramic surface is ground and polished with a surface grinder and diamond grinding paste.

[0020] The relative density of the obtained ceramic body was 99.95%, and the average grain size was 0.63 μm. The results of the transmittance test are as follows figure 2 Shown: in the visible light region (380nm~760nm), the transmittance can reach 75%, while in the infrared region (>760nm) it can reach more than 85%. Similarly, in the ultraviolet region (<380nm), the transmittance ratio of the material It shows a straight-line down...

Embodiment 3

[0022] The raw material powder is molded by 50MPa dry pressing plus 200MPa cold isostatic pressing; then the molded green body is pre-sintered without pressure at 1350°C for 30 minutes; the pre-sintered green body is placed in a hot isostatic pressing furnace under Ar The post-treatment is carried out under an air atmosphere, the temperature is 1350°C, the pressure is 140Mpa, and the time of heat preservation and pressure holding is 40 minutes; finally, the ceramic surface is ground and polished with a surface grinder and diamond grinding paste.

[0023] The obtained ceramic body has a relative density of 99.95% and an average grain size of 1 μm. The results of the transmittance test are as follows image 3 As shown: the transmittance can reach 50% in the visible light region (380nm~760nm), and can reach more than 80% in the infrared region (>760nm). Due to the large grain size, the sample prepared by this process is transparent Light performance is lower than the previous tw...

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Abstract

The preparation method of submicron high-purity transparent alumina ceramic material includes the following steps: using static pressure process of dry-pressing and cooling, etc. to mould alpha-Al2O3 powder; then pressure-less presintering these blank bodies, its pressure-less presintering temp. is 1200-1350 deg.C, and time is 30-480 min.; placing these presintered blank bodies into thermal isostatic pressing furnace to make after-treatment, its treatment temp. is 1150-1350 deg.C, pressure is 140-190 Mpa, heat-insulating and pressure-retaining time is 30-60 min.; using Ar gas as protective gas, the relative density of obtained ceramic body is greater than 99.9%, finally grinding surface of sintered ceramic body and polishing. Its grain size is less than 1 micro, it possesses high transparence and mechanical properties, can be suitable for making high-voltage sodium lamp tube, high-temp. furnace window and decorative material.

Description

technical field [0001] The invention relates to a preparation method of a submicron high-purity transparent alumina ceramic material, which relates to the technical field of preparation of transparent alumina ceramic materials. Background technique [0002] At present, the transparent alumina ceramics produced in large quantities must be made of α-Al 2 o 3 Add a certain proportion of additives to the main phase. Since the publication of the patent US3026210, MgO has been used the most. In order to improve the refractive index of the grain boundary, other additives are also used. For example, Y is used in the patent US3792142 2 o 3 , La 2 o 3 etc., the patent CN1141271 adopts Lu 2 o 3 . The sintering methods used are all high temperature sintering methods, whether in a vacuum atmosphere or in N 2 Gas, H 2 The sintering temperature needs to be above 1600°C, and some even reach 1950°C, such as the sintering method adopted in the patent CN1263877, which is at a tempera...

Claims

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Application Information

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IPC IPC(8): C04B35/10C04B35/622C04B35/64
Inventor 司文捷刘大鹏苗赫濯
Owner TSINGHUA UNIV
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