Gelcasting and vacuum sintering of translucent alumina ceramics with high transparency

Translucent alumina ceramics with high transparency were successfully prepared via gelcasting and vacuum sintering. Effects of powder properties and copolymer content on solids loading of the slurry and then on the porosity, microstructures of both green bodies and sintered ceramics, as well as optical transmittance of the final ceramics were extensively investigated. Fine and de-agglomerated alumina powder was effective to prepare slurries with higher solids loading. They resulted in lower porosity (higher relative density) and smaller pore size in green bodies. After sintered at 1860 degrees C for 6 h in vacuum, the resultant ceramics from higher solids loading had less residual pores. In-line transmittance of the ceramic (1 mm thick) from 55 vol% solids loading reached as high as 53.6% at 600 nm, much higher than previously reported data (<30%). (C) 2015 Elsevier B.V. All rights reserved.