Surface modification of alumina powder particles through stearic acid for the fabrication of translucent alumina ceramics by injection molding

Abstract

In this paper, we present an improved injection molding technique for the fabrication of translucent high-quality alumina ceramics. In contrast to the traditional approach, the stearic acid (SA) was already introduced during a ball milling of the ceramic powders, prior to the blending process, to modify the surface of the alumina powders. According to the analysis based on an alumina-paraffin oil model system, contact angle measurements using polar solvents, as well as high-resolution transmission electron microscopy investigations, 2wt% of SA was determined as the optimal amount of SA to be added to the powder. Furthermore, the surface modification mechanism was found to be based on an esterification reaction. The results demonstrate that the surface modification could effectively inhibit the agglomeration of the particles during the injection molding process, allowing for the fabrication of dense translucent pore-free alumina ceramics. The surface modification through SA has found its way into bio-medical applications and ceramic crafts.