| Summary: | This study experimentally investigates the mechanical behavior of additively manufactured (AM) alumina ceramics by stereolithography technique. The AM alumina specimens with two different printing orientations (POs) are tested under quasi-static and dynamic loading rates. The material shows a quasi-static (i.e., a strain rate of 10−3 s−1) compressive strength of 1640.54 ± 99.33 MPa and 1494.25 ± 260.08 MPa for the PO1 and PO2, respectively, and a dynamic (i.e., a strain rate of 640–730 s−1) compressive strength of 3077.25 ± 174.07 MPa and 3107.33 ± 97.03 MPa for the PO1 and PO2, respectively, which are among the highest reported values for AM alumina due to the higher density and finer grain size. The strain-rate-dependent compressive strength of the material is slightly affected by the PO which is alleviated with the increase in strain rate from quasi-static to dynamic loading conditions. In contrast, the PO noticeably affects the macro-scale failure pattern. The fractography analysis shows the dominant contribution of the intergranular failure mechanism and a combination of intergranular and transgranular mechanisms under quasi-static and dynamic loading, respectively. The crack speed propagation is found to be 785 ± 174 m/s on average which is ∼68% less than that of conventional ones in the literature. The current AM alumina shows a hardness of 24.45 ± 0.88 GPa which is higher than that of the majority of other AM alumina. Overall, this study discusses the potentiality of using AM ceramics in engineering fields replacing the conventionally-made counterparts, and provides implications for designing better-performing AM ceramics.
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