Physical and mechanical properties of ceramic fabricated by additive manufacturing with varying amounts of solid loading in suspension

Abstract

Zirconia is gaining significant attention due to its high mechanical properties, excellent ion conductivity, and outstanding biocompatibility. Recently, it has gained significant research interest in the dental field, especially in combination with Digital Light Processing (DLP) 3D printing. This study investigates the effects of different solid loadings in zirconia slurries on their mechanical and physical properties. Slurries with zirconia loadings of 45 vol %, 50 vol%, and 55 vol% were prepared and compared to a commercial control. Rheological analysis, polymerization analysis, thermal analysis, density, sintering shrinkage, microstructure, hardness, and biaxial flexural strength were evaluated. The results showed that 45 vol% and 50 vol% exhibited suitable viscosities for DLP printing, with values below 3 Pa s at a shear rate of 30 s-1. FT-IR spectroscopy confirmed successful polymerization in all groups. Increasing the solid loading led to lower sintering shrinkage rates, denser grain distribution, and finer grains. Grain size analysis further revealed that the average grain size decreased from 0.54 mu m (45 vol %) to 0.43 mu m (50 vol%) and 0.34 mu m (55 vol%). Higher hardness and reliability in strength were observed with increasing solid loading. The study demonstrates that increasing solid loading in zirconia slurries for DLP printing can lead to improved physical and mechanical properties, including reduced shrinkage, finer microstructure, and enhanced hardness. However, the prepared slurries showed lower flexural strength compared to the commercial control, likely due to the presence of micro-defects and lower dispersion stability. This research establishes a foundation for optimizing zirconia slurries for DLP-based additive manufacturing in dental applications. It highlights the potential for achieving desirable properties through careful control of solid loading.