Influence of Raw Powder on Transparency of SPS-synthesized Aluminas

概要

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Transparent aluminas were synthesized by SPS from a commercial alumina powder (AA-02, average grain size; 230 nm, Sumitomo Chemical Co. Ltd., Japan) under the conditions of 100 MPa and 200°C/min in order to examine the influence of raw powder on the transparency. Comparing with the aluminas SPSed using another commercial powder (TMDAR, average grain size; 100 nm, Taimei Chemicals Co. Ltd., Japan), relatively lower transparency was observed for AA-02 SPSed aluminas in the temperature range between 1150°C and 1250°C. On the other hand, a fairly high transparency was obtained for the AA-02 alumina SPSed at 1300°C. The findings are attributed to the larger grain size of AA-02 alumina powder and show the importance of the characters of raw powder for high transparency. In addition, it is suggested that somewhat higher densification temperature in AA-02 alumina leaves fair amount of micropores remained, resulting in the low transparency of AA-02 SPSed aluminas.