Effects of slurry mixing methods and solid loading on 3D printed silica glass parts based on DLP stereolithography

In this work, digital light processing (DLP) 3D printing technology was used to prepare silica glass parts. The effects of slurry mixing methods and solid loading on the rheological properties of the silica slurry were investigated. The viscosity of the multi-step mixing method was less than the one-step mixing method at different solid loadings. When the solid loading of the slurry was 60 wt%, the viscosity by the multi-step mixing method and the one-step mixing method was 2059.7 mPa s and 5461.2 mPa s respectively at a shear rate of 0.1 sec(-1), with a difference of 3401.5 mPa s. The results of heat treatment experiments showed that transparent glass samples could be obtained when the solid loading was >= 40 wt%. The density of the sintered sample remained substantially constant as the solid loading increased, but the linear shrinkage gradually decreased. The heat treatment time could be reduced to less than 16 h by optimizing the debinding and sintering process using a simultaneous thermal analyzer. Glass samples with the relative density of more than 99% and a transmittance of more than 90% in the range of 300-1800 nm were acquired, and the microstructure and physical properties of the sintered glass were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and digital micro-Vickers hardness tester.