Effect of co-doping manganese oxide and titania on sintering behaviour and mechanical properties of alumina

The effect of co-doping of titania and manganese oxide at different weight percentages (0.5–5 wt%) on sintering behaviour and mechanical properties of alumina were evaluated. The undoped and doped alumina were prepared through pressureless sintering which was carried out at different temperatures (1000 °C–1500 °C) and were characterized through XRD and SEM. XRD revealed presence of R–TiO ₂ and α-alumina at low sintering temperature which further reacted to form Al ₂TiO ₅ at sintering temperature above 1350 °C. Manganese oxide (MnO ₂) was not reactive with alumina due to atomic radii mismatch. SEM indicated abnormal grain growth with increase in sintering temperature and dopant composition. The addition of doping led to reduction in the sintering temperature with high relative density (∼98%) and enhanced mechanical properties (E = 370 GPa and HV = 14.8 GPa) which was only achievable by undoped alumina by sintering at higher temperature regime.