Flash Sintering of YSZ/Al2O3 Composites: Effect of Processing and Testing Conditions

Biesuz, Mattia; Ometto, Andrea

doi:10.3390/ma14041031

Cited by 11 publications

(4 citation statements)

References 52 publications

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“…3 This "catalytic" effect of YSZ of `100 V cm -1 `100 V cm -1 `100 V cm -1 CHR:10 o C min - [2] [1] [3] present work F I G U R E 1 Arrhenius plots showing the flash onset for single phase 3YSZ, 8YSZ, and alumina, as well for 50/50 vol% particulate composites and bilayers. [1] and [2] are from Cologna et al, [3], for 50/50 particulate YSZ/alumina, from Naik et al, and the bilayer results are present work reported later in this article flash sintering of alumina has been further corroborated in recent papers [4][5][6] . The influence of the green microstructure has been rationalized in terms of the percolation of current through the composite.…”

Section: Introductionsupporting

confidence: 76%

“…Interestingly, the onset of flash depends not only on the volume fraction of YSZ but also on the homogeneity of the green microstructure 6 . A similar result was obtained in reactive flash sintering of alumina, magnesia, and 8YSZ to form a composite of magnesium aluminate spinel and YSZ, where agglomerated powders were easier to flash than more homogeneously milled powders 7 .…”

Section: Introductionsupporting

confidence: 62%

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On the catalytic effect of zirconia on flash sintering of alumina

2022

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Flash sintering of alumina is more difficult than of yttria-stabilized zirconia (YSZ). Whereas (MgO doped) alumina requires fields greater than 1 kVcm -1 and temperatures often significantly higher than 1000 • C, YSZ can be flashed sintered at ∼100 Vcm -1 at temperatures below 800 • C. Mixed powders of such bi-phasic ceramics, on the other hand, can be flashed under conditions below those for alumina. This effect is usually subscribed to the influence of YSZ on the overall electrical conductivity of the composite. However, such rationalization leaves open the mechanism by which YSZ catalyzes the flash event in alumina. Here, we present results for the onset of flash in a layered structure of YSZ and alumina where both constituents extend from one electrode to the other. We find that the flash initiates, at first, exclusively in the YSZ layer, under conditions identical to those in usual voltage-to-current experiments in single phase YSZ, and then, after a brief incubation period, spreads transversely through the thickness of the alumina layer at a speed of ∼3.3 mm s -1 , while the power supply is held at constant current. This observation opens a new question as to how flash once initiated in an "easy" phase can migrate normal to itself into a second ceramic, which is nominally more-difficult-to flash. (In the present experiments, the alumina layer sintered to full density with all the shrinkage being accommodated in the thickness direction, consistent with an earlier study that articulated that flash obviates constrained sintering.) It is noteworthy that the catalytic effect depends not only on the volume fraction of YSZ, but also on the architecture of the green state (for example a two-phase powder mixture vs. layered structure), which may affect the initiation of the flash in YSZ but, likely, not its migration behavior into the second phase.

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Section: Introductionsupporting

confidence: 76%

Section: Introductionsupporting

confidence: 62%

On the catalytic effect of zirconia on flash sintering of alumina

2022

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“…Despite its simplicity, FS is an extremely powerful sintering method that can be successfully used for most ceramic materials, from dielectrics (BaTiO 3 [41][42][43][44][45][46][47] or (Bi 0.2 Na 0.2 K 0.2 Ba 0.2 Ca 0.2 )TiO 3 [48]) to ionic (Zirconia, YSZ [2,[49][50][51][52], CeO 2 or doped-CeO 2 [53][54][55][56][57][58]) or electronic (TiO 2 [19,22,[59][60][61][62], BiFeO 3 or substituted-BiFeO 3 [24,27]) conductors. Interestingly, it can be also applied for processing ceramic composites of complex stoichiometry, metastable phases, or materials constituted by volatile species at the temperatures required for their sintering such as YSZ-Al 2 O 3 composites [63][64][65], different types of solid state electrolytes [25,66,67], BiFeO 3 [68,69], or K 0.5 Na 0.5 NbO 3 [26,[70][71][72][73]. Moreover, ceramics prepared by FS present very interesting properties rarely reported for materials obtained by convectional procedures.…”

Section: Resultsmentioning

confidence: 99%

Flash Sintering Research Perspective: A Bibliometric Analysis

2022

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Flash Sintering (FS), a relatively new Field-Assisted Sintering Technique (FAST) for ceramic processing, was proposed for the first time in 2010 by Prof. Rishi Raj’s group from the University of Colorado at Boulder. It quickly grabbed the attention of the scientific community and since then, the field has rapidly evolved, constituting a true milestone in materials processing with the number of publications growing year by year. Moreover, nowadays, there is already a scientific community devoted to FS. In this work, a general picture of the scientific landscape of FS is drawn by bibliometric analysis. The target sources, the most relevant documents, hot and trending topics as well as the social networking of FS are unveiled. A separate bibliometric analysis is also provided for Reaction or Reactive Flash Sintering (RFS), where not only the sintering, but also the synthesis is merged into a single step. To the best of our knowledge, this is the first study of this nature carried out in this field of research and it can constitute a useful tool for researchers to be quickly updated with FS as well as to strategize future research and publishing approaches.

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“…The lowest temperature of 850°C with a 120 V cm –1 DC electric field resulted in a fully densified sample within 5 seconds [8]. The flash sintering behaviour of the yttria-stabilised zirconia/alumina composites was investigated to understand the role of the fundamental processing and testing parameters (electric field intensity, electric current limit, thermal insulation, homogeneity and dispersion of the two phases) on densification [9]. Gadolinia-doped ceria, strontium titanate, MgO-doped alumina, undoped yttria and silicon carbide were also consolidated successfully by flash sintering at relatively lower temperatures than conventional sintering [10].…”

Section: Introductionmentioning

confidence: 99%

Abrupt high grain growth in hydroxyapatite during flash sintering

Kim

Bajpai

Jeon

et al. 2022

Advances in Applied Ceramics

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The electric flash generated by an electric field aided the sintering of hydroxyapatite (HA) in relatively less time and at lower furnace temperatures than the conventional sintering method. The current work has reported a comparative study to explain thermodynamically the effects of the increasing DC electric field strength at 1000°C and 1100°C sintering furnace temperatures during flash sintering in terms of the grain growth and densification of the HA in air. The abrupt change in current density and conductivity of HA during the flash peak correlates the high grain growth and rapid densification with increasing electric field strength. The increased electric field strength reduced the power dissipation from the HA. The abrupt high-rise grain growth phenomenon during flash sintering might consist of the thermal effect and enhancement in ionic conductivity due to the application of an electric field.

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Flash Sintering of YSZ/Al2O3 Composites: Effect of Processing and Testing Conditions

Cited by 11 publications

References 52 publications

On the catalytic effect of zirconia on flash sintering of alumina

On the catalytic effect of zirconia on flash sintering of alumina

Flash Sintering Research Perspective: A Bibliometric Analysis

Abrupt high grain growth in hydroxyapatite during flash sintering

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