Micro structural control of stabilized zirconia ceramics (8YSZ)through modified conventional sintering methodologies

摘要

Slip cast Y_2O_3 stabilized Zirconia (8YSZ) ceramics was subjected to Conventional Ramp and Hold (CRH), Rate Controlled (RCS) and Two Stage Sintering (2SS) methodologies. Sintered samples were characterized for their densities and grain size analysis by Scanning Electron Microscopy. The slip cast samples sintered by CRH and 2SS have achieved 98 – 99 % of theoretical densities while RCS samples have exhibited a low density of 97 %. The samples exhibited an average grain size of 2.64 μm by 2SS sintering in comparison to 8.83 μm in case of CRH and 3.45 μm in case of RCS. Controlled pore growth associated with RCS, when compared to CRH methodology is mainly responsible for the relatively smaller grain size observed with RCS. A four fold decrease in grain size i.e. 2.64 μm observed with the two step sintering can be attributed to the fact that the first heating step to high temperature of 1550℃ for a shorter duration closes the porosity without significant grain growth. The second step at 1375℃ for a longer period of time imparts densification with limited grain growth.