Strength properties of zirconium ceramics with silica additives hardened with alumina

The effect of Al$_{2}$O$_{3}$ and SiO$_{2}$ admixtures on strength properties of calcia-stabilized zirconia ceramics is studied. Optimal ratios of the components of CaO–ZrO$_{2}$+Al$_{2}$O$_{3}$+SiO$_{2}$ are determined; at these ratios, high flexural and compressive strength limits ($\sigma_f$ and $\sigma_c$, respectively) are observed. Their values are the following: $\sigma_f$ = 980–70 MPa (at $C_{\mathrm{Al}_2\mathrm{O}_3}$ = 5 wt.% and $C_{\mathrm{SiO}_2}$ = 0 mol.%) and $\sigma_c$= 2.44–0.15 GPa (at $C_{\mathrm{Al}_2\mathrm{O}_3}$ of 5 wt.% and $C_{\mathrm{SiO}_2}$ of 5 mol.%). Signs of plasticity (appearance of a yield line on $\sigma$–$\varepsilon$ diagrams) are observed at the introduction of 4–5% SiO$_2$ in the CaO-ZrO$_{2}$+Al$_{2}$O$_{3}$ ceramics.