Particle size effects in flash sintering

Francis, John S. C.; Cologna, Marco; Raj, Rishi

doi:10.1016/j.jeurceramsoc.2012.04.028

Cited by 113 publications

(95 citation statements)

References 16 publications

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“…A similar effect has been reported for the flash sintering of zirconia, where the onset of flash was significantly delayed in low aspect ratio samples (Bichaud et al, 2015). To verify that the absence of flash sintering is a result of the thermal sink effect of the electrode configuration in our apparatus, a single sample was pressed from the same powder in the shape of a dog bone using method taught by Francis et al (2012) and an attempt was made to sinter the sample using the flash sintering technique. The sample flashed immediately upon application of 300 V/cm DC field at a comparatively low temperature of 400°C proving that the material is indeed amenable to flash if allowed to experience thermal runaway.…”

Section: Resultssupporting

confidence: 68%

Improving NASICON Sinterability through Crystallization under High-Frequency Electrical Fields

Lisenker

Stoldt

2016

Front. Energy Res.

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The effect of high-frequency (HF) electric fields on the crystallization and sintering rates of a lithium aluminum germanium phosphate (LAGP) ion conducting ceramic was investigated. LAGP with the nominal composition Li1.5Al0.5Ge1.5(PO4)3 was crystallized and sintered, both conventionally and under effect of electrical field. Electrical field application, of 300 V/cm at 1 MHz, produced up to a 40% improvement in sintering rate of LAGP that was crystallized and sintered under the HF field. Heat sink effect of the electrodes appears to arrest thermal runaway and subsequent flash behavior. Sintered pellets were characterized using X-ray diffraction, scanning electron microscope, TEM, and electrochemical impedance spectroscopy to compare conventionally and field-sintered processes. The as-sintered structure appears largely unaffected by the field as the sintering curves tend to converge beyond initial stages of sintering. Differences in densities and microstructure after 1 h of sintering were minor with measured sintering strains of 31 vs. 26% with and without field, respectively. Ionic conductivity of the sintered pellets was evaluated, and no deterioration due to the use of HF field was noted, though capacitance of grain boundaries due to secondary phases was significantly increased.

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Section: Resultssupporting

confidence: 68%

Improving NASICON Sinterability through Crystallization under High-Frequency Electrical Fields

Lisenker

Stoldt

2016

Front. Energy Res.

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“…Larger particle sizes induce a higher resistance to sintering. Moreover, it has been found recently that sintered density decreases with increasing particle size [35]; an effect that has been observed for a number of materials [33,34]. Density is an important parameter of a bone tissue scaffold and a well-designed scaffold should have a density and compressive strength similar to that of bone [30].…”

Section: The Role Of Powder Bedmentioning

confidence: 87%

Powder bed generation in integrated modelling of additive layer manufacturing of orthopaedic implants

Krzyżanowski

Svyetlichnyy

Stevenson

et al. 2016

Int J Adv Manuf Technol

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This paper presents an original model of powder bed generation developed within the frame of an integrated modelling approach for studying the interaction of physical mechanisms in additive layer manufacturing (ALM) of orthopaedic implants. The model is based on cellular automata (CA) approach and describes the relationship between moving particles of different sizes during deposition on a surface in three dimensions. The surface is defined by the horizontal two-dimensional CA on which particles fall and irreversibly stick to a growing deposit. The model allows for consideration of different restructuring cases when particles are allowed to rotate as often as necessary until achievement of a local minimum position. Changes in the packing density of the powder bed have been investigated numerically depending on technological parameters, such as particle size distribution, deposition rate and sequence of powder deposition. The model has been developed with the aim of merging to the finite element (FE)-based integrated model and is applicable to a different ranges of materials including metals and also non-metals.

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“…Samples have been flash sintered in dogbone [8,20,22,23,39,41,[71][72][73] and pellet form [26,31,36,37]. The apparatus used includes a vertical tube furnace with camera to detect shrinkage in dogbone samples [20,22,39,41,71,72], a box furnace with front window for use of a camera [8], a commercial spark plasma sintering machine used without the usual graphite mould [31], a vertical furnace adapted to hold pellets by the use of alumina supporting bars with [26,37] or without [36] significant applied load, and a modified system holding suspended dogbones designed for in situ X-ray diffraction studies [23,73].…”

Section: Zirconiamentioning

confidence: 99%

“…It was shown that the stress reduced the onset Most of the 3Y-TZP flash sintering papers in the literature use nanocrystalline powders with little difference in quoted particle size. The effect of varying the particle size have been systematically investigated by Francis and Raj [72]. Flash sintering was observed at 920 o C for 1m average particle size powder at 100V/cm, with 955 o C for 2m, 990 o C for 5m, and 1040 o C for 10m.…”

Section: Zirconiamentioning

confidence: 99%

Flash sintering of ceramic materials

Dancer¹

2016

Mater. Res. Express

159

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During flash sintering, ceramic materials can sinter to high density in a matter of seconds while subjected to electric field and elevated temperature. This process, which occurs at lower furnace temperatures and in shorter times than both conventional ceramic sintering and field-assisted methods such as spark plasma sintering, has the potential to radically reduce the power consumption required for the densification of ceramic materials. This paper reviews the experimental work on flash sintering methods carried out to date, and compares the properties of the materials obtained to those produced by conventional sintering. The flash sintering process is described for oxides of zirconium, yttrium, aluminium, tin, zinc, and titanium; silicon and boron carbide, zirconium diboride, materials for solid oxide fuel applications, ferroelectric materials, and composite materials. While experimental observations have been made on a wide range of materials, understanding of the underlying mechanisms responsible for the onset and latter stages of flash sintering is still elusive. Elements of the proposed theories to explain the observed behaviour include extensive Joule heating throughout the material causing thermal runaway, arrested by the current limitation in the power supply, and the formation of defect avalanches which rapidly and dramatically increase the sample conductivity.Undoubtedly, the flash sintering process is affected by the electric field strength, furnace temperature and current density limit, but also by microstructural features such as the presence of second phase particles or dopants and the particle size in the starting material. While further experimental work and modelling is still required to attain a full understanding capable of predicting the success of the flash sintering process in different materials, the technique nonetheless holds great potential for exceptional control of the ceramic sintering process.

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Particle size effects in flash sintering

Cited by 113 publications

References 16 publications

Improving NASICON Sinterability through Crystallization under High-Frequency Electrical Fields

Improving NASICON Sinterability through Crystallization under High-Frequency Electrical Fields

Powder bed generation in integrated modelling of additive layer manufacturing of orthopaedic implants

Flash sintering of ceramic materials

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