Determination of sintering mechanism and grain growth kinetics of MgO-doped Al2O3

MgO in the form of a solid solution can segregate along the Al2O3 ceramic grain boudary. This will lower the grain boundary mobility and also inhibit the grain growth. This article describes the determination of the sintering mechanism and grain growth kinetics of MgO-doped Al2O3 sintered at 1773K. A linier shrinkage model was used for deterimining the sintering mechanism. Average grain size of ceramic samples was determined from their x-ray diffraction data, by implementing the statistical fluctuation method (SFM). The results showed that the sintering mechanism for samples with 0.1 %wt and 0.3 wt% MgO was dominated by surface diffusion, while for 0.5 wt% and 1.0 %wt MgO dominated by grain boundary diffusion. The average grain size for pure Al2O3 samples, sintered for 2 hours , was 21.1 μm. For the same sintering time, MgO doping of 0.1 wt% to 1.0 wt% reduced the average grain size down to 12 to 10 μm, respectively.