Flash grain welding in yttria stabilized zirconia

Muccillo, R.; Kleitz, M.; Muccillo, E.N.S.

doi:10.1016/j.jeurceramsoc.2011.02.030

Cited by 88 publications

(64 citation statements)

References 16 publications

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“…Self-standing cylinder samples of 8YSZ samples were sintered to , discharge time: 60 s), using a spring loaded system similar to the setup shown in Figure 4(b) [75].…”

Section: Fs Of Ionic Conductorsmentioning

confidence: 99%

Review of flash sintering: materials, mechanisms and modelling

Grasso

McKinnon

et al. 2016

Advances in Applied Ceramics

376

248

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Flash sintering (FS) is an energy efficient sintering technique involving electrical Joule heating, which allows very rapid densification (<60 s) of particulate materials. Since the first publication on flash-sintered zirconia (3YSZ) in 2010, it has been intensively researched and applied to a wide range of materials. Going back more than a century ago, we have found a close similarity between FS of oxides and Nernst glowers developed in 1897. This review provides a comprehensive overview of FS and is based on a literature survey consisting of 88 papers and seven patents. It correlates processing parameters (i.e. electric field magnitude, current density, waveforms (AC, DC) and frequency, furnace temperature, electrode materials/ configuration, externally applied pressure and sintering atmosphere) with microstructures and densification mechanisms. Theorised mechanisms driving the rapid densification are substantiated by modelling work, advanced in situ analysis techniques and by established theories applied to electric current assisted/activated sintering techniques. The possibility of applying FS to a wider range of materials and its implementation in industrial scale processes are discussed.

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“…Self-standing cylinder samples of 8YSZ samples were sintered to , discharge time: 60 s), using a spring loaded system similar to the setup shown in Figure 4(b) [75].…”

Section: Fs Of Ionic Conductorsmentioning

confidence: 99%

Review of flash sintering: materials, mechanisms and modelling

Grasso

McKinnon

et al. 2016

Advances in Applied Ceramics

376

248

View full text Add to dashboard Cite

show abstract

“…It has been reported that the space charge region in yttria-stabilized zirconia consists of a positively charged nucleus with an excess of oxygen vacancy and an accumulation of yttrium, for the electroneutrality (charge compensation) [46,47]. The decrease of the intergranular resistivity is attributed to the welding of the grains [6,8] and the decrease of the intragranular resistivity to the increase in the oxide ion concentration due to the thermal migration to the bulk of the chemical species depleted at the space charge region, enhancing the oxide ion concentration, and consequently Figure 5 shows the impedance diagrams of 3YSZ sintered at 1400 • C, flash sintered, and flash sintered specimens previously sintered at 1400 • C. All diagrams consist of two semicircles, one at high frequencies corresponding to the electrical response of the bulk, and the other at low frequencies, corresponding to the intergranular contribution (interfaces, usually grain boundaries and pores). The total electrical resistivity of the 3YSZ sintered at 1400 • C is 45 kΩ·cm, higher than the value determined for the sintered sample submitted to the flash event.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…The electric field-assisted pressureless sintering technique has mainly been applied to yttria-stabilized zirconia ceramics [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Many other reports were published applying this technique to other materials [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30], studying the dependence on the amplitudes of the electric field and current density [31], on the average particle size [32], on the porosity [33], and searching for an explanation of such events [34][35][36][37][38][39][40].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Electrical Behavior and Microstructural Features of Electric Field-Assisted and Conventionally Sintered 3 mol% Yttria-Stabilized Zirconia

Carvalho¹,

Muccillo²,

Muccillo

2018

Ceramics

Self Cite

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ZrO 2 : 3 mol % Y 2 O 3 (3YSZ) polycrystalline pellets were sintered at 1400 • C and by applying an alternating current (AC) electric field at 1000 • C. An alumina sample holder with platinum wires for connecting the sample to a power supply was designed for the electric field-assisted sintering experiments. The apparent density was evaluated with the Archimedes technique, the grain size distribution by analysis of scanning electron microscopy images, and the electrical behavior by the impedance spectroscopy technique. Sintering with the application of AC electric fields to 3YSZ enhances its ionic conductivity. An explanation is proposed, based on the dissolution back to the bulk of chemical species, which are depleted at the grain boundaries, leading to an increase in the oxygen vacancy concentration. For the enhancement of the grain boundary conductivity, an explanation is given based on the diminution of the concentration of depleted chemical species, which migrate to the bulk. This migration leads to a decrease of the potential barrier of the space charge region, known to be responsible for blocking the oxide ions through the intergranular region. Moreover, the heterogeneity of the distribution of the grain sizes is ascribed to the skin effect, the tendency of the AC current density to be largest near the surface, decreasing towards the bulk.

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“…These mechanisms are usually thermally activated, and are predominant in specific temperature ranges. Among the numerous sintering employed techniques we may cite: Flash Sintering [12], Two Step Sintering [13] and Spark Plasma Sin-tering (SPS) [14][15]. The innovative technique of SPS sintering is quite promising for conductive ceramic production.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of electrical conductivity and density of 8 mol% yttria-stabilized zirconia produced by Spark Plasma Sintering

Polla¹,

Valentini²,

Junior³

et al. 2016

Blucher Chemistry Proceedings

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In this work, 8 mol% yttria-stabilized zirconia (8%YSZ) containing micro or nanoparticles were manufactured by Spark Plasma Sintering technique, in order to improve sample densification and control grain growth. The electrical conductivity of dense 8%YSZ pellets sintered was investigated by electrochemical impedance spectroscopy (EIS). Preliminary results showed for samples produced from both micro and nanoparticle sintered at 1000 °C for 5 min, the relative density is approximately 98 %, while for the others samples sintered at 1200 °C the density is above 99 %. These densities are higher in comparison to the same composite sintered by conventional method. The electrical measurements were carried out at 500 °C in air and the best results were obtained for samples with nano particle size in comparison with micro granulometry. The SPS process allows using lower temperatures and shorter times to produce materials with high density and controlled grain growth.

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Flash grain welding in yttria stabilized zirconia

Cited by 88 publications

References 16 publications

Review of flash sintering: materials, mechanisms and modelling

Review of flash sintering: materials, mechanisms and modelling

Electrical Behavior and Microstructural Features of Electric Field-Assisted and Conventionally Sintered 3 mol% Yttria-Stabilized Zirconia

Evaluation of electrical conductivity and density of 8 mol% yttria-stabilized zirconia produced by Spark Plasma Sintering

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