Translucent Alumina Produced by Slip-Casting Using a Gypsum Mold

Abstract

Translucent Al₂O₃ ceramics could be successfully produced by slip casting using a gypsum mold, provided that CaSO₄ impurities, which had penetrated into the green compacts from the gypsum mold, were removed by the wash of calcined compacts with HCl aqueous solution. Al₂O₃ ceramic samples were sintered at 1350°C for 2h under vacuum. The relative densities of the sintered Al₂O₃ ceramic compacts with the HCl treatment were slightly higher than those of the untreated samples. Grains in the HCl-treated samples grew homogeneously with about 1μm in diameter. The sintered Al₂O₃ ceramics with the HCl treatment were translucent. Transmittance values were measured by spectroscopy. Transmittance values in the HCl-treated samples increased from 0 to 12% as the wavelength increased from 300 to 900nm.