Microstructure, conductivity and mechanical properties of calcia stabilized zirconia ceramics obtained from nanosized precursor and reduced graphene oxide doped precursor powders

Kurapova, Olga Yu.; Glumov, O. V.; Lomakin, Ivan; Голубев, С. С.; Pivovarov, M.M.; Krivolapova, Julia V.; Конаков, В. Г.

doi:10.1016/j.ceramint.2018.05.202

Cited by 16 publications

(4 citation statements)

References 40 publications

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“…Crystallite sizes for the Z0-Z2 samples are about 110-120 nm, which is higher than the value for YSZ ceramics sintered at 1150 • C for 3 h in air (35 nm) [29]. A low signal from the carbon phase in the ceramics may indicate either its homogeneous distribution (as it was observed for powder composites in [9,30]) or rGO evaporation/burnout during the sintering process. For more accurate study of the carbon state in the samples, Raman spectroscopy was used.…”

Section: Phase Compositionmentioning

confidence: 73%

Phase Formation and the Electrical Properties of YSZ/rGO Composite Ceramics Sintered Using Silicon Carbide Powder Bed

et al. 2021

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Fully stabilized zirconia/graphene composites are very promising advanced structural materials having mixed ion–electron conductivity for energy storage and energy conversion applications. The existing methods of the composite manufacturing have a number of disadvantages that limit their practical use. Thus, the search for new sintering methods is an actively developing area. In this work, we report for the first time the application of the SiC powder bed sintering technique for fully stabilized zirconia (YSZ) composite fabrication. The reduced graphene oxide (rGO) was used as a graphene derivative. As a result, well-formed ceramics with high density and crystallinity, the maximal microhardness of 13 GPa and the values of the ionic conductivity up to 10−2 S/cm at 650 °C was obtained. The effects of the sintering conditions and rGO concentration on the microstructure and conductivities of ceramics are discussed in detail. The suggested powder bed sintering technique in a layered graphite/SiC/graphite powder bed allowed well-formed dense YSZ/rGO ceramics fabrication and can become a suitable alternative to existing methods for various oxide ceramic matrix composite fabrication: both conventional sintering and non-equilibrium (SPS, flash sintering) approaches.

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Section: Phase Compositionmentioning

confidence: 73%

Phase Formation and the Electrical Properties of YSZ/rGO Composite Ceramics Sintered Using Silicon Carbide Powder Bed

et al. 2021

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“…The presence of a large amount of the amorphous phase plays a negative role in the conductivity. The more accomplished a crystal structure of a solid is, fewer defects are present in the structure, the higher the conductivity [ 48 , 49 , 50 ].…”

Section: Discussionmentioning

confidence: 99%

Mixed Electronic-Ionic Conductivity and Stability of Spark Plasma Sintered Graphene-Augmented Alumina Nanofibres Doped Yttria Stabilized Zirconia GAlN/YSZ Composites

et al. 2023

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Graphene-doped ceramic composites with mixed electronic-ionic conductivity are currently attracting attention for their application in electrochemical devices, in particular membranes for solid electrolyte fuel cells with no necessity to use the current collector. In this work, composites of the Y2O3-ZrO2 matrix with graphene-augmented γ-Al2O3 nanofibres (GAlN) were spark plasma sintered. The conductivity and electrical stability in cyclic experiments were tested using electrical impedance spectroscopy. Composites with 0.5 and 1 wt.% GAlN show high ionic conductivity of 10−2–10−3 S/cm at 773 K. Around 3 wt.% GAlN percolation threshold was achieved and a gradual increase of electronic conductivity from ~10−2 to 4 × 10−2 S/cm with an activation energy of 0.2 eV was observed from 298 to 773 K while ionic conductivity was maintained at elevated temperatures. The investigation of the evolution of conductivity was performed at 298–973 K. Besides, the composites with 1–3 wt.% of GAlN addition show a remarkable hardness of 14.9–15.8 GPa due to ZrC formation on the surfaces of the materials.

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“…Consequently, this results in the development of a microstructure with coarse grain size with a potential risk of degradation in the required properties. 6,7 However, usage of alternative approaches (e.g., utilizing a reducing environment or low oxygen atmosphere) may be beneficial for sintering as it may lower the temperature and dwell time required for sintering. Sintering or annealing of ZrO 2 in a reducing/low oxygen atmosphere has been reported to stabilize the high-temperature phases of ZrO 2 .…”

Section: Introductionmentioning

confidence: 99%

“…Stabilization of the cubic ZrO 2 phase in ceramics through pressure‐less sintering needs elevated sintering temperatures (typically ≥1500°C) with prolonged dwell times (1–3 h). Consequently, this results in the development of a microstructure with coarse grain size with a potential risk of degradation in the required properties 6,7 . However, usage of alternative approaches (e.g., utilizing a reducing environment or low oxygen atmosphere) may be beneficial for sintering as it may lower the temperature and dwell time required for sintering.…”

Section: Introductionmentioning

confidence: 99%

Insights into the issues during hot‐pressing and vacuum sintering of 10 mol.% CaO doped zirconia ceramics

Reddy,

Lakshya,

Chowdhury

2024

J Am Ceram Soc.

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A vacuum environment is usually preferred for reducing the dwell time and sintering temperature for doped zirconia ceramics. However, for the present work with 10 mol.% CaO‐doped ZrO2 (10CaSZ) ceramics, both hot‐pressing and vacuum sintering techniques yielded ceramics with open pores (ρ ∼ 93%) and significant amounts of the deleterious monoclinic phase (50%). This is in stark contrast with the conventionally sintered highly dense (>99%) 10CaSZ ceramics, where only tetragonal and cubic phases were noted. Probing via electron paramagnetic resonance (EPR) depicted the trapping of oxygen vacancies by vacancies generated in vacuum at high temperature. A possible change in the local coordination (of ions) and the subsequent chemical environment was confirmed by the observed asymmetric signal shape and broader linewidth of the EPR signals. Potential loss of oxygen and deviation from stoichiometry (for dopant) was confirmed via EPR analysis along with the support of energy dispersive spectra analysis. Despite no noticeable shift in the XRD pattern for Ca2+ depletion, the observed compositional gradient differences in the calcium elemental mapping suggested dopant segregation at the grain boundaries. The conclusions from the present work point toward specificity of a given materials system for its beneficial densification under hot pressing or vacuum sintering.

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Microstructure, conductivity and mechanical properties of calcia stabilized zirconia ceramics obtained from nanosized precursor and reduced graphene oxide doped precursor powders

Cited by 16 publications

References 40 publications

Phase Formation and the Electrical Properties of YSZ/rGO Composite Ceramics Sintered Using Silicon Carbide Powder Bed

Phase Formation and the Electrical Properties of YSZ/rGO Composite Ceramics Sintered Using Silicon Carbide Powder Bed

Mixed Electronic-Ionic Conductivity and Stability of Spark Plasma Sintered Graphene-Augmented Alumina Nanofibres Doped Yttria Stabilized Zirconia GAlN/YSZ Composites

Insights into the issues during hot‐pressing and vacuum sintering of 10 mol.% CaO doped zirconia ceramics

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