Designing alumina-zirconia composites by DLP-based stereolithography: Microstructural tailoring and mechanical performances

Abstract

Digital Light Processing (DLP) is attracting high interest thanks to the possibility to prepare dense or complex ceramic parts starting from a photosensitive ceramic slurry. ZrO2 and Al2O3 are the most studied ceramic materials for DLP, while few studies deal with their composites in spite their wide range of applications. In this work, three alumina-zirconia composites (at 15, 50 and 85 vol% of ZrO2) were prepared by mixing ready-to-use ZrO2 and Al2O3 slurries. The mechanical and physical properties of the composites prepared via DLP technique were investigated and compared to those of neat alumina and zirconia materials used as a reference. For each composite, the sintering temperature was optimized on the ground of final density and microstructural development, with the aim to achieve a target density (i.e. ρ > 98.5%TD), while keeping a fine microstructure. The composites were characterized by quite homogeneous microstructures, with a good distribution of the two phases, in line with the materials prepared by conventional techniques. Flexural strength, elastic modulus and Vickers hardness of fabricated alumina-zirconia composites ranged between 415 and 843 MPa, 188–318 GPa and 15–21 GPa, respectively. These results show that the well-known microstructure-properties relationship, which dominates the conventionally fabricated materials, also plays an important role in stereolithography processed samples. In fact, once optimized the fired densities and the microstructures, the 3D-printed alumina-zirconia composites reached mechanical properties higher than almost all previous investigations for the same composites fabricated by stereolithography, and in most cases even higher than those of conventional composites of analogous compositions.