| Transparent ceramic material, compared with glass and single crystal, characteristic with high strength, high hardness, low preparation temperature, excellent performance and shorter production cycle. The size and structure are easier to control, and mechanical performance is also better than glass and crystal. Alumina is the first production of transparent ceramic material with high thermal conductivity, large temperature strength, good thermal stability and corrosion resistance. widely used in the lighting technology and high temperature insulation, etc.In order to reduce the birefringence ,this article introduce the spinel as template, using tape-casting, to make the spinel grains aligned in the green body, prepared the polycrystalline ceramics with different proportion of spinel templates by vacuum sintering .And then the samples were tested and analyzed by X-ray diffraction ,Scanning Electron Microscopy, micro-hardness and the IR spectrum.we made sphericalα-Al2O3 by AACH, 70100nm. KCl-NaCl as the molten salt, generated hexagonal MgAl2O4, diameter of 35μm. After tape-casting, 200MPa cold isostatic pressing, 1200℃aerobic and 1800℃vacuum sintering, we got the polycrystalline transparent ceramic with template of 0wt%, 2wt%, 5wt%, 10wt%. Compared to the alumina ceramics without template, the infrared transmittance of the sample increased from 1.7 to 1.9 times.With the increase of the template, (110) plane of the diffraction peaks gradually increase, indicating extension direction of preferred orientation, textured appeared. When the template content was 10wt%, the anisotropy of polycrystalline ceramics was from 0.15 of 2wt% up to 0.39.As the same time, ceramic fracture mode was from the intergranular fracture to both intergranular fracture and transgranular fracture, micro-hardness results show that it can improve the hardness of ceramics.
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