Fabrication of mechanically robust nanoporous ZrSiO4 ceramics at low temperature with a low doping level of Mn dopant

Zircon (ZrSiO₄) ceramics have been widely used in many fields due to their excellent physical and chemical properties. However, ZrSiO₄ ceramics typically possess moderately low mechanical properties, which hinders their wider application. Meanwhile, elevated temperatures (∼1500°C) are required to obtain high-purity synthetic ZrSiO₄ ceramics, which is time- and energy-consuming. In the present study, we prepared mechanically robust ZrSiO₄ ceramics at low temperature (∼1170°C) with a low doping level of Mn dopant (<2 mol%). The ZrSiO₄ ceramic processed by hot isostatic pressing with .5 mol% Mn dopant achieved the highest flexural strength (512 MPa), elastic modulus (341 GPa), and nanohardness (20.8 GPa). These values are significantly higher than conventional ZrSiO₄ ceramics. The strengthening mechanisms of the prepared ZrSiO₄ ceramics were attributed to the formation of homogeneously-distributed nanopores due to incomplete densification and submicron ZrSiO₄ grains (∼300 nm). The nanopores avoided stress concentration and deflected microcracks during loading, and the submicron ZrSiO₄ grains endowed the ZrSiO₄ ceramics with grain refinement strengthening. The results reported in this study would offer guidance to fabricate mechanically robust ZrSiO₄ ceramics at low temperatures with a low doping level of dopant.