Toughening mechanisms in low-density zirconia-toughened alumina fabricated by binder jetting 3D printing

The toughening behavior of ceramics typically increases with matrix density, yet the market demand for lightweight components drives interest in low-density structures. Understanding the onset of toughening is critical for guiding the structure design. Binder Jetting (BJ) 3D printing enables an efficient fabrication route for complex composite structures, but has struggled to produce zirconia-toughened alumina (ZTA) due to the inherently low density of printed parts. This study demonstrates the feasibility of ZTA fabrication via BJ and investigates the toughening mechanism under low-density structure conditions. ZTA samples with varying zirconia contents, sintering temperatures, and holding times were analyzed. The Skorohod–Olevsky viscous sintering (SOVS) model was employed to model densification process and shrinkage. The results showed that densification improved with higher sintering temperatures and longer holding times, and a clear toughening gain was observed when the relative density exceeded 81 %. With 30 mol% ZrO 2 and sintering at 1650 °C for 5 h, the maximum flexural strength and fracture toughness reached 38.43 MPa and 2.59 MPa m 1/2 , which are 35.6 % and 34.2 % higher than monolithic alumina. A sintering–densification–mechanical property relationship was then established, linking sintering-driven densification to the activation of zirconia toughening mechanisms, thereby enabling the design of the lightweight ZTA components.