Enhanced photocuring and reaction assisted densification of stereolithography printed colored ZrO2-ZrSiO4 composites through SiO2 substitution

Colored zirconia suspensions are difficult to process by stereolithography because coloring species absorb ultraviolet light and the ceramic particles introduce additional scattering. Here, pink, green, and blue 3Y-ZrO 2 suspensions were modified by replacing 0-20 vol% of the ceramic phase with SiO 2 while maintaining a constant total solids loading of 45 vol%. Increasing the SiO 2 content reduced the apparent optical attenuation near 355 nm, increased the cure depth and depth-sensitivity parameter, and lowered the critical exposure energy. Suspensions containing 15-20 vol% SiO 2 showed the most favorable photocuring response within the investigated range and enabled stable printing. The same compositional modification also influenced subsequent thermal evolution: SiO 2 reacted with ZrO 2 to form ZrSiO 4 , and the selected composites reached relative densities above 97%. The sintered specimens retained characteristic pink, green, and blue coloration, with only limited color differences between the 15 and 20 vol% compositions. Flexural strengths of 200-370 MPa and Vickers hardness values of 10-14 GPa were obtained. These results show that SiO 2 substitution can improve the printability of strongly attenuating colored zirconia suspensions while supporting densification during sintering, although ZrSiO 4 formation introduces a trade-off in mechanical performance.