Effect of mold materials on transparent Y2O3 ceramics during spark plasma sintering

摘要

In the spark plasma sintering (SPS) system, densification can be enhanced by the application of electric field. The electric field enhances the densification by accelerating diffusion, suppressing grain growth and/or softening particle surfaces. Though the exact mechanism is not known, the effect of electric field on densification was proven experimentally [1-3]. The enhanced densification in SPS lowers sintering temperatures. Low sintering temperature is indispensable for fine microstructure to improve optical and mechanical properties of transparent ceramics. The application of mechanical pressure during SPS further lowers the sintering temperature and improves the transparency remarkably [4]. In conventional SPS system, graphite molding set has been used widely. However, due to the high electrical conductivities (> 106 S/m), the electric field around powder is weakened. Kim et al. [1] reported enhanced densification by using SiC molding set. In this study, the effects of mold materials with various electrical conductivities are examined on densification, uniformity, microstructure and transparency of Y2O3 ceramics.