Effect of Y2O3 stabilizer content and sintering regime on the microstructure and properties of DLP-printed porous ZrO2 ceramics

The performance of ceramic cores directly affects the dimensional accuracy and casting quality of the internal cavities of hollow turbine blades. Silica- and alumina-based ceramic cores suffer from high-temperature interfacial reactions and difficult core removal, respectively. Therefore, ZrO 2 was selected as the ceramic-core matrix in this study, and its properties were regulated through Y 2 O 3 addition and sintering-temperature control. Ceramic slurries containing 1, 3, 5, 7, and 9 mol% Y 2 O 3 were prepared and shaped by digital light processing. The results showed that increasing the sintering temperature enhanced the flexural strength, linear shrinkage, and bulk density of the ZrO 2 ceramics while reducing their open porosity. With increasing Y 2 O 3 content, the flexural strength initially increased and subsequently decreased. SEM observations showed that higher sintering temperatures reduced surface cracks and interconnected pores and promoted particle bonding and sintering-neck development. XRD analysis indicated that the samples containing 3 mol% Y 2 O 3 consisted predominantly of tetragonal ZrO 2 with a small amount of monoclinic ZrO 2 . Finite element simulation of the three-point bending test reproduced the characteristic stress, strain, and displacement distributions of the specimens. The maximum displacement occurred at the midspan, while pronounced stress concentration developed in the central loading region. Among all investigated conditions, the sample containing 3 mol% Y 2 O 3 and sintered at 1600 °C exhibited the best overall performance, with a flexural strength of 34.5 ± 2.68 MPa, linear shrinkage of 26.38 ± 1.66 %, bulk density of 4.43 ± 0.21 g cm −3 , and open porosity of 30.76 ± 2.89 vol%.