Sintering Behavior of 0.8 mol%‐CuO‐Doped 3Y‐TZP Ceramics

Abstract

In recent years, 3 mol% yttria‐stabilized tetragonal zirconia polycrystals (3Y‐TZP) doped with copper oxide has obtained increasing interest due to its enhanced superplastisity and good potential in tribological applications. In this work, the effect of addition of small amounts (0.8 mol%) of copper oxide on the sintering behavior of 3Y‐TZP was studied using a dilatometer and high‐temperature X‐ray diffraction (XRD). A qualitative sintering model was established based on several reactions during sintering as indicated by thermal analysis and XRD. Some of these reactions remarkably retard densification and consequently result in low final density (86%) of the sample sintered at 1400°C in air. The reaction between molten Cu2O and yttria as segregated to the Y‐TZP grain boundaries at around 1180°C leads to the depletion of yttria from Y‐TZP grains, which results in the formation of monoclinic phase during cooling. A relatively higher oxygen partial pressure can inhibit the dissociation of CuO to Cu2O. This inhibition in dissociation is one of the reasons why a dense (>96%) 0.8 mol% CuO‐doped 3Y‐TZP ceramic can be obtained after sintering at 1400°C in flowing oxygen.

Densification kinetics of ZrO2-based ceramics using a master sintering curve

“…Due to these properties, YSZ materials are used in different industrial applications such as cutting tools, valve guide, abrasive tools, solid oxide fuel cells (SOFC), oxygen sensors, etc [1][2][3].…”

Study of pore closure during pressure-less sintering of advanced oxide ceramics

“…From equilibrium phase diagram it follows that for sintering temperatures above 1100 C ZrO 2 doped by 8 mol% Y 2 O 3 is cubic and ZrO 2 doped by 3 mol% Y 2 O 3 is a mixture of tetragonal and cubic phases with fractions depending on annealing temperature [18]. Since the variation in the phase composition due to temperature and also kinetic reasons causes only minor deviations in the theoretical densities (lower than 0.3%) [18], we employ commonly used literature values of theoretical densities: 6.08 g/cm 3 for ZrO 2 doped by 3 mol% Y 2 O 3 [19,20] and 5.99 g/cm 3 for ZrO 2 doped by 8 mol% Y 2 O 3 [21,22].…”

Positronium Probing of Pores in Zirconia Nanopowders

“…One can see from the table that the present experimentally measured mass densities have a range between 2.5 and 3.3 g/cm 3 with a mean value of ≈ 2.9 g/cm 3 . The theoretical densities published so far for the tetragonal and cubic ZrO 2 lattices [10,11] appear to be close to each other, ρ th =6.10 and 6.09 g/cm 3 respectively, while a somewhat lower value of ρ th = 5.85 g/cm 3 has been reported for the monoclinic ZrO 2 lattice [11]. In addition, the mass density of the reference t-YSZ single crystal was measured as 5.98 ± 0.01 g/cm 3 in the present work which is close to the theoretical value.…”