Mechanical properties and microstructure evolution of in-situ formation whiskers reinforced 3D-printed ZrO2 ceramics using material extrusion

Aiming to obtain 3D-printed ZrO 2 ceramics with high strength-toughness, this work developed zirconia/tourmaline ceramic inks suitable for material extrusion, and proposed a novel strategy of in-situ formation whiskers to improve the interlayer bonding and intralayer microstructure of 3D printed ZrO 2 ceramics. Effect of tourmaline contents on the ceramic inks printability, the mechanical properties and microstructure formation of in-situ whiskers reinforced zirconia ceramics were systematically investigated. When the addition of tourmaline was 4 vol%, printed different 3D structures presented a good retention, owing to the zirconia/tourmaline ceramic inks with good rheological behavior. Compared to the pure zirconia ceramics, incorporated tourmaline particle significantly increased the relative density of 3D-printed zirconia ceramics from 97.52 % to 98.92 %, the optimal flexural strength of 612 ± 32 MPa and fracture toughness of 5.98 ± 0.20 MPa m 0.5 were obtained for 3D-printed zirconia composite ceramics. The strengthening mechanism is attributed to the higher densification of zirconia ceramics and the in-situ formation mullite whiskers in interlayer and intralayer microstructure, which is demonstrated via systematical characterizations. This interlayer strengthening method based on in-situ formation whisker provides an effective and convenient approach to fabricating 3D-printed zirconia ceramics with high strength and toughness.