High-pressure sintered yttria stabilized zirconia ceramics

This study aims at comparing hot pressing (HP) and the electric field-assisted sintering technique (FAST) of 8 mol% yttriastabilized zirconia (8YSZ). Three different ionic conductive nano-and submicron powders were investigated, with a median particle size of 20-30, 51-65, and 150 nm, respectively. Processing parameters were kept identical for both sintering methods: sample geometry, heating schedule, applied pressure, and atmosphere. Investigations of densification and microstructural characterization reveal that under the same conditions FAST and HP sintered samples behave similarly. The analysis of the sintering curves shows that the densification mechanism is the same for both sintering methods (grain-boundary diffusion). An increase of the heating rate up to 150 K/min does not modify the densification mechanism. The sintering trajectory reveals that grain size depends only on density and not on the sintering method and grains have no preferential orientation. Secondary ion mass spectroscopy shows that both types of specimens are contaminated with carbon only superficially. Measurements of the electrical conductivity at high temperature show no significant difference between HP and FAST samples. II. Experimental Procedure(1) FAST and HP Experiments All experiments were made with HP (model HPW 150/200-2200-100-LA) and FAST (FCT HP D 25/1) equipments were D. Clarke-contributing editor This work was financially supported by the Deutsche Forschungsgemeinschaft (Emmy Noether Program GU993-1/1).

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“…Jaiwen et al 48 . and Li et al 33 . reported a total conductivity of ∼0.01 S/cm at 800°C for fully dense samples sintered by SPS.…”

Section: Resultssupporting

confidence: 56%

“…This shows that grain growth is more pronounced for the finer powders and that the sintering of the NA50 powder leads to the largest final grains. Only the use of very high pressure seems to efficiently limiting grain growth 32,33 . The sintering trajectory of the HP and FAST sintered TO150 samples is shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Electric Field-Assisted Sintering in Comparison with the Hot Pressing of Yttria-Stabilized Zirconia

Langer

Hoffmann²,

Guillon

2010

Journal of the American Ceramic Society

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“…Zirconia (ZrO 2 ) is one of the materials well known for multifunctional applications [1][2][3][4][5][6][7][8]. Commonly employed application domains of ZrO 2 are refractories [9], oxygen sensors [10], and fuel cell membranes [11] due to the high O 2 diffusivity, structural [12], and biomedical applications [13] due to its high strength and toughness.…”

Section: Introductionmentioning

confidence: 99%

Nanostructured Pure and Doped Zirconia: Synthesis and Sintering for SOFC and Optical Applications

Prakasam¹,

Valsan²,

Lu³

et al. 2018

Sintering Technology - Method and Application

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Zirconia is a multifunctional material with potential applications in wide domains. Rareearth doped zirconia and stabilized zirconia yield interesting properties based on the phase transitions induced by the sintering conditions. Zirconia nanopowders were prepared by hydrothermal technique. Synthesis methods of zirconia with various rare earths are discussed here. An overview of the sintering of zirconia-based ceramics is presented in particular for SOFC and sensors and optical applications.

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“…The YSZ phases are poorly studied as a function of pressure and temperature compared to the parent ZrO 2 compound, and the reported results are sometimes contradictory. Namely, static compression experiments on the YSZ phases with Y 3+ concentration <10 at.% suggested the existence of tetragonal–cubic (8 at.% Y and T > 1000°C 7 ), irreversible monoclinic–tetragonal (3–4 at.% Y) or reversible tetragonal–disordered tetragonal (5‐at.% Y) 8 transformations at P < 5 GPa (for the sake of simplicity further in the text samples from the YSZ series will be denoted as NYSZ where N is an at.% content of Y atoms). At higher pressures, a 2YSZ biphasic sample containing both tetragonal and monoclinic phases was found to feature monoclinic‐to‐ortho‐I transformation at T > 400°C 9 .…”

Section: Introductionmentioning

confidence: 99%

Stability of doped zirconia under extreme conditions: Toward long‐term and secure storage of radioactive waste

2022

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Extreme temperatures and pressures were applied to systems based on stabilized zirconia, ZrO 2 , doped with Ce 4+ ions as surrogate for tetravalent Actinides in order to conclude on their long-term stability in deep geological underground. Both tetragonal and cubic yttrium-stabilized ZrO 2 (YSZ) exhibit excellent phase and structural stabilities up to 1150 K. In addition, incorporated guest Ce 4+ did not show any increase in their mobility at elevated temperatures. Application of external pressure did not induce any structural or phase changes in cubic YSZ doped with 5 at.% Ce as well. However, a corresponding tetragonal analog with lower yttrium content exhibits a second-order phase transition toward higher cubic symmetry around 9 GPa. Remarkably, no discharge of the guest Ce 4+ ions was observed throughout the transition and further upon increase in pressure. This together with T-dependent data indicates excellent affinity of guest Ce atoms with the host YSZ matrices. The parent YSZ phases are, therefore, promising candidates as host materials for long-term underground immobilization for radiotoxic tetravalent elements like U, Th, or Pu.

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High-pressure sintered yttria stabilized zirconia ceramics

Cited by 17 publications

References 13 publications

Electric Field-Assisted Sintering in Comparison with the Hot Pressing of Yttria-Stabilized Zirconia

Electric Field-Assisted Sintering in Comparison with the Hot Pressing of Yttria-Stabilized Zirconia

Nanostructured Pure and Doped Zirconia: Synthesis and Sintering for SOFC and Optical Applications

Stability of doped zirconia under extreme conditions: Toward long‐term and secure storage of radioactive waste

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