Monoclinic phase-free, low temperature spark plasma sintering of CeO2-doped ZrO2 ceramics and its associated benefits on mechanical properties

Abstract

Consolidating a CeO2-doped ZrO2 ceramics, free from monoclinic phase using spark plasma sintering (SPS) is a major challenge faced by previous researchers; Ce+4 → Ce+3 conversion under reducing environments was assigned as the prime factor. We report dense (> 95 % of theoretical density) 20 mol. % CeO2-doped ZrO2 ceramics, free from monoclinic phase and any of micro/ macro-cracks via SPS. The sintering temperature (1175 ℃) used for the present work was the lowest compared to previous reports on the same system. Phase analysis revealed a mixture of tetragonal (major phase) and cubic phase (minor). No depletion of cerium (Ce) from the ZrO2 matrix and no additional/impurity phases were noted after SPS; a common issue that has been observed in most of the previous works. Sintered ceramics showed appreciably high hardness (>11 GPa); the obtained toughness was in-between of tetragonal and cubic CeO2-ZrO2 ceramics.