3D printer fabrication of the metal oxide doped Al2O3 bioceramicsand investigation of structural, mechanical and biological

Bioceramics are widely used in orthopedic and dental applications due to their high mechanical strength, wear resistance, and biocompatibility. While conventional fabrication techniques present limitations in terms of porosity control and microstructural homogeneity, additive manufacturing technologies—particularly Digital Light Processing (DLP)—offer effective solutions to these challenges. In this study, Al₂O₃-based ceramic composites were fabricated via DLP 3D printing by incorporating Y₂O₃, CaSiO₃, and BaO at 1%, 3%, 5%, and 10% weight ratios. The produced samples were evaluated in terms of density, shrinkage, phase composition, microstructural characteristics, mechanical performance (hardness, fracture toughness, flexural and compressive strength), and biological behavior. The results demonstrated that the additives significantly influenced densification. The highest relative densities were obtained at 3% Y₂O₃ (95.12%, 3.80 g/cm³), 5% CaSiO₃ (95.35%, 3.75 g/cm³), and 3% BaO (94.95%, 3.82 g/cm³). Shrinkage analysis confirmed the anisotropic sintering behavior inherent to the DLP process, with greater shrinkage consistently observed along the Z-axis. Maximum volumetric shrinkages were recorded at 5% CaSiO₃ (61.31%), 3% BaO (57.62%), and 3% Y₂O₃ (53.68%). X-ray diffraction (XRD) analysis revealed the formation of secondary phases depending on the additive: YAG and YAP with Y₂O₃; CaAl₂Si₂O₈ and CaAl₂O₄ with CaSiO₃; and BaAl₁₂O₁₉ and BaAl₂O₄ with BaO. Microstructural analysis indicated that Y₂O₃ and CaSiO₃ promoted fine grain structures, while BaO led to secondary phase agglomeration. The highest hardness values were obtained at 3% Y₂O₃ (17.43 GPa), 5% CaSiO₃ (17.59 GPa), and 3% BaO (16.79 GPa). Similarly, maximum fracture toughness was measured at 6.04 MPa·m¹/² (3% Y₂O₃), 6.71 MPa·m¹/² (5% CaSiO₃), and 6.41 MPa·m¹/² (3% BaO). Compressive strength reached its peak at 3% CaSiO₃ (1319.81 MPa), followed by 3% Y₂O₃ (1241.79 MPa) and 3% BaO (1192.31 MPa), while higher additive levels resulted in mechanical degradation. Biological analyses showed that CaSiO₃-doped samples exhibited superior bioactivity due to their ability to form bioactive calcium phosphate layers, while Y₂O₃- and BaO-doped samples demonstrated moderate biocompatibility. This study confirms that DLP 3D printing enables the production of bioceramic materials with excellent mechanical strength and biological compatibility. The developed materials hold significant potential for applications in bone grafts, orthopedic implants, and biomedical engineering. These findings not only contribute to the development of high-strength, bioactive ceramic composites but also highlight DLP 3D printing as an efficient fabrication route for advanced bioceramics