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

Abstract

Aiming to obtain 3D-printed ZrO2 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 ZrO2 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 m0.5 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.