## 2 Materials and Methods  
In this study, 9 mol\(\%\) CSZ was synthesized using ZrO\({}_{2}\) (99\(\%\), \(\leq\) 45 \(\upmu\)m, Daejung Chemicals & Metals Co., Siheung-si, Republic of Korea) and CaO (98\(\%\), Junsei Chemical Co., Tokyo, Japan) as starting materials through a solid-state method, and the synthesized 9-CSZ was subsequently mixed with MnO\({}_{2}\) (90\(\%\), \(\leq\) 500 nm, Junsei Chemical Co., Tokyo, Japan), as shown in Table 1. The mixture was subjected to ball milling using zirconia balls and ethanol for 24 h, dried at 90 \({}^{\circ}\)C for 24 h, and then calcined at 1200 \({}^{\circ}\)C for 2 h with a heating rate of 5 \({}^{\circ}\)C/min.  
The specimens utilized in this research were fabricated by uniaxially compacting the synthesized raw powders at a pressure of 10 tons. This process resulted in cylindrical samples with a diameter of 20 mm and rod-shaped compact samples measuring 5 mm in width and 35 mm in length. These green bodies were subsequently sintered in a box-type electric furnace, where the temperature was increased at a rate of 5 \({}^{\circ}\)C/min, held at 1600 \({}^{\circ}\)  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{2}{c}{**Composition**} & \multicolumn{2}{c}{**Fabrication Conditions**} \\ \cline{2-5}
**Name** & **Raw** & **MnO\({}_{2}\)** & **Calcination** & **Holding** \\  & **Material** & **Addition (mol\(\%\))** & **Temp (\({}^{\circ}\)C)** & **Time (h)** \\ \hline
9-CSZ & & - & & \\
9-CSZ\_2 MnO\({}_{2}\) & 9 mol\(\%\) & 2 & & \\
9-CSZ\_3 MnO\({}_{2}\) & CSZ & 3 & & \\
9-CSZ\_4 MnO\({}_{2}\) & & 4 & & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Compositions and fabrication conditions of 9-CSZ specimens with varying MnO\({}_{2}\) content.  
for 6 h, and then cooled in the furnace. For the thermal shock evaluation, the sintered samples were heated in air to 1300 \({}^{\circ}\)C at a rate of 5 \({}^{\circ}\)C/min, maintained at this temperature for 5 min, and then cooled naturally to 900 \({}^{\circ}\)C. This heating and cooling process was repeated 40 times to induce thermal shock conditions.  
Phase analysis of the specimens before and after thermal shock was performed using X-ray diffraction (XRD; Rigaku, Ultima-IV, Hitachi, Japan). Measurements were taken from 20\({}^{\circ}\) to 80\({}^{\circ}\) with a step size of 0.02\({}^{\circ}\) (20) and a scanning rate of 2\({}^{\circ}\)/min. The resulting diffraction patterns and phase fractions were interpreted using the Rietveld refinement technique in Highscore Plus software (version 3.0c), referencing the ICSD patterns for monoclinic ZrO\({}_{2}\) (m-ZrO\({}_{2}\), ICSD 98-006-0900), tetragonal ZrO\({}_{2}\) (t-ZrO\({}_{2}\), ICSD 98-007-0014), cubic ZrO\({}_{2}\) (c-ZrO\({}_{2}\), ICSD 98-064-7689), and MnO\({}_{2}\) (ICSD 98-000-0393). Surface microstructural features were examined using high-resolution scanning electron microscopy (HR-SEM; SU8230, Hitachi, Japan). High-resolution transmission electron microscopy (JEOL JEM-ARM 200F, 200 kV accelerating voltage) was employed to obtain detailed TEM images. Mechanical properties were assessed using a micro-Vickers hardness tester ([PERSON], VH1102, Lake Bluff, IL, USA) with a 20 N load and a 15 s dwell time. Each sample was measured ten times, and the average value was reported as the Vickers hardness.  
Wear resistance was evaluated using a ball-on-disk operating method, following the ISO 20808 standard [17], with a sliding distance of 1000 m, an applied load of 9.6 N, and a sliding speed of 0.1 m/s, to determine the specific wear rate (mm\({}^{3}\)/N\(\cdot\)m). Flexural strength was determined by conducting three-point bending tests on a universal testing machine from the United States, using a support span of 20 mm and a crosshead speed of 0.5 mm/min.