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We report a novel approach to fabricate dense zirconia-toughened alumina (ZTA) ceramics with excellent properties via an additive manufacturing process based on stereolithography. The XRD patterns show the ZTA sample consists of α-Al 2 O 3 and t-ZrO 2 with the dominance of α-Al 2 O 3 . The zirconia grain with the average size of 0.35 µm is small enough to trigger the toughening behavior of zirconia in the ZTA. The prepared ceramics showed a density, Vickers hardness, bending strength, and fracture toughness of 4.26 g/cm 3 , 17.76 GPa, 530.25 MPa, and 5.72 MPa m 1/2 , respectively. These properties are comparable to those for ceramics obtained through conventional ceramic processing. [ABSTRACT FROM AUTHOR]

In this study, Al 2 O 3 ceramics were printed by stereolithography from particles with different particle size distributions, which are the micro-sized Al 2 O 3 , nano-sized Al 2 O 3 , and a mixture of both. The influence of the particle size and the debinding method on the density and morphology of the sintered bodies were investigated. The density of the samples containing both micro-sized and nano-sized alumina particles is highest among the three samples. Furthermore, the samples subjected to the vacuum debinding showed a higher density compared with the samples subjected to the traditional thermal debinding. The results suggest that the combination of a powder with a bimodal particle size distribution and the vacuum debinding process offers an effective way to print 3D ceramics with a good performance through stereolithography. [ABSTRACT FROM AUTHOR]

In this study, we report a novel approach, integrating stereolithography and liquid precursor infiltration techniques, to fabricate fine-grained alumina ceramics. The XRD patterns of the sample immersed with Zr 4+ or Zr 4+ (Y 3+ ) show that the sintered body contains Al 2 O 3 and t-ZrO 2 as the major phase and minor phase, respectively. Moreover, the t-ZrO 2 phase in the sample immersed with Zr 4+ (Y 3+ ) shows intense peaks compared to the composite immersed with Zr 4+ . On the other hand, the sample immersed with Mg 2+ contained Al 2 O 3 and MgAl 2 O 4 as the major phase and minor phase, respectively. The microstructure of the sample immersed with Zr 4+ shows that ZrO 2 particles are homogeneously distributed in the Al 2 O 3 matrix, thus inhibiting the grain growth of alumina particles. Moreover, the sample immersed with Mg 2+ shows a more dense and fine-grained structure. Compared to the non-infiltrated sample, the average grain size of the alumina sample immersed with Zr 4+ or Mg 2+ decreased. The sample infiltrated with Zr 4+ (Y 3+ ) had the smallest alumina average grain size of 1.14 µm. The ceramics prepared by infiltration showed a higher hardness (19.54 GPa), but a slightly lower fracture toughness (4.02 MPa m 1/2 ) compared to the samples (17.2 GPa, 4.13 MPa m 1/2 ) without infiltration. [ABSTRACT FROM AUTHOR]

A dense defect-free alumina cutting tool was fabricated via stereolithography process. Different drying processes and debinding profiles were then tested and compared to find the optimal way for the preparation of the sintered body. The experimental results showed that using PEG400 as a liquid desiccant results in a lower deformation of the body compared to the natural drying process. Compared with vacuum debinding or air debinding, a two-step debinding process, which consisted of both a vacuum pyrolysis step and the following air debinding, is allowed to control the pyrolysis rate while suppressing the formation of defects in the alumina body. After optimization of the postprocessing, the relative density of the sample as high as 99.3%, and the Vickers hardness ∼17.5 GPa. These properties are similar to the properties of alumina bodies prepared via the conventional shaping method. [ABSTRACT FROM AUTHOR]