Fabrication of complex shaped ceramic parts with surface-oxidized Si3N4 powder via digital light processing based stereolithography method

Abstract

Si3N4 ceramic is difficultly fabricated by digital light processing (DLP) based stereolithography method, due to a large refractive index difference between Si3N4 powder and resin. In this paper, a surface oxidation approach of Si3N4 powder for improving cure depth is proposed. The results showed that, the amorphous SiO2 layer was uniformly attached onto the surface of Si3N4 powder by surface oxidation, and the absorbance of Si3N4 powder decreased as increasing oxidation degree. Moreover, the cure depth of the suspension significantly increased because of a smaller absorbance and a refractive index difference at the interface between oxidized Si3N4 powder and resin. At the exposure energy of 500 mJ/cm2, the cure depth of the raw Si3N4 powder was 34 µm. After oxidizing at 1150 °C and 1200 °C for 1 h, the cure depth effectively increased to 42 µm and 51 µm, respectively. Finally, the complex-shaped Si3N4 parts were successfully fabricated using surface-oxidized Si3N4 powder via DLP method.