Robocasting of dense yttria-stabilized zirconia structures

Advanced ceramic materials with complex design have become inseparable from the current engineering applications. Due to the limitation of traditional ceramic processing, ceramic additive manufacturing (AM) which allows high degree of fabrication freedom has gained significant research interest. Among these AM techniques, low-cost robocasting technique is often considered to fabricate complex ceramic components. In this work, aqueous ceramic suspension comprising of commercial nano-sized yttria-stabilized zirconia (YSZ) powder has been developed for robocasting purpose. Both fully and partially stabilized YSZ green bodies with complex morphologies were successfully printed in ambient conditions using relatively low-solid-content ceramic suspensions (< 38 vol%). The sintered structures were able to retain the original morphologies with > 94% of the theoretical density despite its high linear shrinkage (up to 33%). The microstructure analysis indicated that dense fully and partially stabilized YSZ with grain size as small as 1.40 +/- 0.53 and 0.38 +/- 0.10 mu m can be obtained, respectively. The sintered partially stabilized YSZ solid and porous mesh samples (porosity of macro-pores > 45%) exhibited hardness up to 13.29 GPa and flexural strengths up to 242.8 +/- 11.4 and 57.3 +/- 5.2 MPa, respectively. The aqueous-based ceramic suspension was also demonstrated to be suitable for the fabrication of large YSZ parts with good repeatability.