Measurement of Thermal Expansion and Volume Changes in Partially Stabilized Zirconia

Abstract

One of the most promising applications of partially stabilized zirconia is in the metal extrusion industry in which CaO or MgO stabilized ZrO₂ dies have outperformed the conventional metal dies. The secret of this success lies in the polyphase nature of PSZ and its high toughness, low expansion and excellent thermal shock resistance which are linked to volume changes associated with phase transformation during heating and cooling.

In this paper we report the thermal expansion data for three different versions of MgO stabilized zirconia in the temperature range 25–1300°C. The densification associated with monoclinic to tetragonal transformation during heating and expansion due to reversion of the phases during cooling can be estimated from expansion curves as can the transformation temperature. The volume change data thus obtained are a function of the monoclinic content and firing conditions and are in good agreement with literature values. The expansion coefficient and volume changes show appreciable difference during remeasurement due to microcracking associated with phase changes. The changes in Young’s Modulus with temperature are also found to be consistent with density changes during heating.