The rising crack resistance curve behavior and mechanism of rod-like La2O3 doped zirconia toughened alumina composites prepared via vat photopolymerization based 3D printing

In this study, we combined liquid precursor infiltration of high introduction amounts of bi-additives (20 wt%) and vat photopolymerization-based 3D printing to fabricate zirconia toughened alumina, and the infiltration systems consist of the four following systems Zr 4+ /La 3+ , Zr 4+ /Ce 4+ , Zr 4+ /Gd 3+ , and Zr 4+ /Er 3+ . The sample immersed with Zr 4+ /La 3+ shows intense peaks of m-ZrO 2 phase compared to the other samples while a new phase of rod-like LaAl 11 O 18 grain occurs in the Zr 4+ /La 3+ immersed sample, the existence of which could be confirmed by XRD and EDS. The fracture toughness of the Zr 4+ /Ce 4+ , Zr 4+ /Gd 3+ , and Zr 4+ /Er 3+ samples remained basically unchanged versus the crack size, with the fracture toughness between 4 MPa m 1/2 and 5 MPa m 1/2 ; while the measured fracture toughness values for the Zr 4+ /La 3+ system show a rising crack resistance curve behavior, with the toughness enhanced from 6.37 MPa m 1/2 to 8 MPa m 1/2 . The obvious enhancement of the toughness could be attributed to thermal expansion misfit and rod-like LaAl 11 O 18 in the Zr 4+ /La 3+ system. The toughening mechanism and the effect of residual stresses on the fracture mode are discussed on the basis of theoretical calculation and analysis. The rising crack resistance curve behavior could provide a new toughening strategy in ceramic 3D printing. • Liquid precursor infiltration and 3D printing was combined to fabricate ZTA. • The bi-additives Zr 4+ /La 3+ system shows a rising crack resistance curve behavior. • It could attributed to thermal expansion misfit and rod-like LaAl 11 O 18 . • The toughening mechanism and effects of residual stresses are discussed. • It could provide a new toughening strategy in ceramic 3D printing.