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Improvement of translucency in Al2O3 ceramics by two-step sintering technique

Translucent polycrystalline Al2O3 ceramics are used in high-pressure sodium lamp envelopes. Pure, 140, 500, and 2500 ppm MgO-doped Al2O3 specimens were sintered at 1700 C in vacuum with and without pre-sintering heat treatment at 800 C for 50 h in air. Pre-sintering heat treatment improved the trans...

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Bibliographic Details
Published in:Journal of the European Ceramic Society 2007, Vol.27 (13-15), p.3629-3632
Main Authors: KIM, Dong-Suk, LEE, Jong-Heun, RAK JOO SUNG, SANG WOO KIM, HYUNG SOO KIM, JEONG SHIK PAR
Format: Article
Language:English
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Summary:Translucent polycrystalline Al2O3 ceramics are used in high-pressure sodium lamp envelopes. Pure, 140, 500, and 2500 ppm MgO-doped Al2O3 specimens were sintered at 1700 C in vacuum with and without pre-sintering heat treatment at 800 C for 50 h in air. Pre-sintering heat treatment improved the transmittance in the visible (400-700 nm) range significantly. This enhanced transmittance was explained in terms of the removal of residual pores and the homogenisation of the microstructure due to the lowering of the boundary mobility as a result of MgO addition and the suppression of local densification through a pre-coarsening step. 11 refs.
ISSN:0955-2219
1873-619X
DOI:10.1016/j.jeurceramsoc.2007.02.002