Curing behaviors and mechanical properties of SiC-whisker-reinforced alumina ceramics fabricated with digital light processing

Abstract

Silicon carbide whiskers (SiCw) have presented great potential to improve the mechanical properties of Al2O3 ceramic. However, effective curing of SiCw/Al2O3 ceramic slurry during digital light processing (DLP) is still challenged due to the high refractive index of SiCw. This paper aims to investigate the effect of SiCw content on rheological properties and associated curing behaviors of ceramic slurry. A modified Beer-Lambert model is proposed to evaluate the curing depth as functions of SiCw content and exposure parameters. The SiCw/Al2O3 ceramic slurries with the whiskers content of 0 to 16 vol.% are prepared and characterized. The results indicate that the curing depth decreased from 158 to 19 μm at the given exposure energy of 100 mJ/cm2 with the increase of SiCw content. The scattering and absorbance of light result in the decrease of curing depth and the geometrical overgrowth. The rheological properties of ceramic slurry are affected by the agglomerated whiskers. Furthermore, SiCw/Al2O3 ceramics are fabricated by DLP method, based on which the relationships among mechanical properties, microstructures and whiskers contents are determined. Significant effect of reinforcement is obtained in SiCw/Al2O3 ceramic due to whiskers pullout consuming the external loading energy. The microhardness and flexural strength of the SiCw/Al2O3 ceramics with 8 vol.% SiCw are 16.72 GPa and 208.5 MPa, respectively.