Study on post-processing of 3D printed alumina ceramics: effects of different metal oxide impregnations

Abstract To enhance the mechanical properties and density of alumina ceramics, this study used metal oxide powders including alumina, zirconia, silica, yttria, and titania as impregnation agents to modify alumina ceramics via impregnation-sintering. The study systematically investigated the effects of different oxide impregnation agents on the flexural strength and density of the samples: alumina- and silica-impregnated groups showed no significant difference compared to the untreated control group. Titania, due to its interfacial compatibility with the alumina matrix and dispersion strengthening effect, became the optimal impregnation agent for enhancing the flexural strength of alumina ceramics. Although yttria can efficiently promote ceramic densification, the large difference in thermal expansion coefficients between yttria and alumina resulted in surface cracks in the sintered ceramic samples and failed to generate an effective secondary phase, thus not improving its mechanical properties. scanning electron microscope results indicate that alumina ceramics impregnated and sintered with titania possess a more uniform and smoother microstructure, exhibiting the best performance, with a flexural strength of 148 ± 3 MPa, an increase of about 20% compared to the control group, relative density of 80.9% ± 1.8%, and open porosity of 14.49 ± 2.85 vol%. This study provides an experimental basis and reference for the optimization of the impregnation modification process of alumina ceramics.