Phase Transformation Behavior, Mechanical Properties Under Thermal Stress, and Slag-Induced Erosion of 2–4 mol% CeO2-Doped CaO-Stabilized Zirconia

We investigated the phase transitions, mechanical properties, and chemical durability of a composition of 9 mol% CaO-stabilized zirconia (9CSZ) doped with 2-4 mol% CeO₂ under thermal stress against molten slag. The monoclinic phase fraction of 9CSZ was 7.14% at room temperature, and CSZ doped with 2-4 mol% CeO₂ showed a slightly lower value of 5.55-3.72%, with only a minor difference between them. The microstructure of 9CSZ doped with 2-3 mol% CeO₂ was similar to that of undoped 9CSZ, whereas the microstructure of 9CSZ doped with 4 mol% CeO₂ exhibited noticeable grain refinement. The mechanical properties of CSZ at room temperature tended to improve as the CeO₂ doping concentration increased. The Vickers hardness increased from 1088.4 HV to 1497.6 HV when the CeO₂ doping amount was 4 mol%, and the specific wear amount decreased from 1.5941 to 1.1320 × 10⁵ mm³/Nm. This tendency remained similar even after applying thermal stress. The monoclinic phase fraction of 9CSZ increased from 7.14% to 67.71% after the erosion experiment with the CaF₂-based slag. CeO₂-doped CSZ had a lower monoclinic phase fraction than CSZ after the erosion experiment, but as CeO₂ content increased from 2 to 4 mol%, the fraction rose to 4.07%, 30.85%, and 77.11%.