Sintering mechanisms of ZrO 2·MgO with addition of TiO 2 and CuO

Abstract

Substitutions of Ti and Cu in ZrO 2·MgO (Z), cause transformation from monoclinic (m) to cubic (c) and tetragonal (t). According to the vacancy model and solid solution formation models, neither CuO nor TiO 2 cause zirconia stabilization, which derives from other phenomena. Data analysis by TMA using the CRH (constant rate of heating) method shows a solid state reaction of ZrO 2·MgO·TiO 2 (Z·TiO 2) demonstrating a dominant mechanism of volume diffusion ( n=1). However, the sintering of ZrO 2·MgO·CuO (Z·CuO) shows a viscous flow mechanism ( n=0), a similar phenomena to that of by sintering of glass. Transformations, such as: CuO to Cu 2O at 1000 °C, ZrO 2 (m) to ZrO 2 (t) at 1100 °C and Cu 2O (s) to Cu 2O (l) at 1230 °C cause successive rearrangements of microstructure inside of region I (sintering process) and lead to interpretation errors when the Bannister equation is used.