Abstract
This study investigated how minor additions of copper oxide (CuO), manganese oxide (MnO₂), and stainless steel (SS) influence the densification and mechanical performance of alumina-toughened zirconia (ATZ) composites consisting of 3Y-TZP and 20 wt% Al₂O₃. The doped compositions were compared with undoped ATZ, and all samples were consolidated by microwave sintering at 1250, 1350, and 1500 °C, with a heating rate of 30 °C/min and a dwell time of 5 min. Regardless of dopant type, relative density and mechanical properties rose steadily as the sintering temperature increased. Additions of 0.2 wt% CuO, 0.5 wt% MnO₂, and 0.2 wt% SS promoted densification and strengthened the composites without causing noticeable grain growth. The samples were characterized in terms of relative density, stability of the tetragonal phase, microstructural development, Vickers hardness, and fracture toughness. Among the additives, 0.2 wt% CuO proved the most effective at the lowest temperature (1250 °C), yielding a relative density of 97%, a hardness of 13.2 GPa, and a fracture toughness of 6.5 MPa·m¹ᐟ². By contrast, undoped ATZ reached similar values only at considerably higher sintering temperatures. ANOVA results confirmed that CuO doping had the most significant positive effect on both hardness (H) and fracture toughness (K_IC) at every temperature examined. The findings further indicate that microwave sintering is more effective than conventional sintering in enhancing the densification and mechanical properties of ceramic composites.