Fabrication and characterisation of Al2O3–ZrO2 functionally graded ceramics via DLP-based additive manufacturing

Al 2 O 3 –ZrO 2 functionally graded ceramics (FGMs) were successfully fabricated using a digital light processing (DLP)-based additive manufacturing approach. An 11-step compositional gradient, ranging from 100 % Al 2 O 3 to 100 % ZrO 2 , was precisely achieved through an optimised film-fed slurry system, minimising thermal and residual stresses between dissimilar ceramics. Sintering analysis revealed that the shrinkage onset temperature progressively decreased with increasing ZrO 2 content, attributed to accelerated diffusion in ZrO 2 -rich regions and grain-boundary pinning in Al 2 O 3 -rich regions. Scanning electron microscopy with energy-dispersive X-ray spectroscopy confirmed uniform layer stacking, a continuous compositional gradient, and defect-free interfaces across the entire gradient. The FGM exhibited a high interfacial shear strength of 447.9 ± 76.0 MPa, comparable to that of conventional zirconia toughened alumina (ZTA) composites, indicating effective mitigation of residual stresses during co-sintering. These findings demonstrate that compositional gradient design can serve as an intrinsic parameter to control densification mismatch and stress distribution in multi-material ceramics. The developed DLP-based process offers a practical and scalable approach for fabricating dense, thermally stable, and geometrically complex 3-dimensional FGM structures with tailored mechanical and thermal properties.