Numerical model for sparking and plasma formation during spark plasma sintering of ceramic compacts

Marder, Rachel; Estournès, Claude; Chevallier, Geoffroy; Chaim, R.

doi:10.1007/s10853-015-9015-z

Cited by 16 publications

(9 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This plasma at the sub-micrometer and nanometer separations (i.e., pore size) is explained by the edge-type breakdown, where the sparks select an energetically favorable distance, due to the electrode (particle) shape and curvature (radius) [ 31 ], with the dominant effect of field emission of the electrons [ 32 ]. A previous analytical model, which was developed for the plasma formation during the spark plasma sintering [ 33 ], and was verified experimentally to cause particle surface melting [ 34 , 35 ], may be applicable for the flash sintering. Numerical simulations of the local field strength during the early stage of field assisted sintering in dielectric materials exhibited the buildup of high local fields at the particle contacts, which may explain the propensity for plasma formation at these loci [ 36 ].…”

Section: Analysis and Discussionmentioning

confidence: 99%

Particle Surface Softening as Universal Behaviour during Flash Sintering of Oxide Nano-Powders

Chaim

2017

Materials

View full text Add to dashboard Cite

The dissipated electric power in oxide powder compacts, subjected to flash sintering, is several hundreds of W·cm−3. This power is analyzed considering local softening/melting and transient plasma/liquid formation at the particle contacts due to thermal runaway. The sudden increase in compact electric conductivity and dissipated power referred to current percolation through the softening/liquid formed at the particle contacts, at the percolation threshold. The energy-balance and heat transfer considerations during the transient flash event are consistent with the local heating of the nanoparticle contacts to the ceramic melting temperature, or above it. The formation of the plasma by field emission of electrons is also considered.

show abstract

Section: Analysis and Discussionmentioning

confidence: 99%

Particle Surface Softening as Universal Behaviour during Flash Sintering of Oxide Nano-Powders

Chaim

2017

Materials

View full text Add to dashboard Cite

show abstract

“…For this purpose, by numerically integrating over time Eq. 5 with the use of relations (4) and (6)- (10), and by taking for the experimental green density ( ≈ 0.61-0.63), densification curves for 20°C/min and 100°C/min heating rates have been calculated.…”

Section: Analytical Calculation Of Densification Curves For Differentmentioning

confidence: 99%

“…Local overheating by formation of arcs and plasmas between the particles has been postulated [3,4], and experimentally observed by optical microscopy [5] and by insitu atomic emission spectroscopy [6]. Given these sparking mechanisms, local melting phenomena occurring at the contact zones of powder particles in various materials have been observed [6][7][8], theoretically analyzed [9] and simulated [10]. Another localized electric effect put forward is that of an intensifying electric current density at the necks between the powder particles, which may cause these zones to melt [11,12].…”

Section: Introductionmentioning

confidence: 99%

Comparison of densification kinetics of a TiAl powder by spark plasma sintering and hot pressing

et al. 2017

View full text Add to dashboard Cite

Densification kinetics by spark plasma sintering (SPS) and hot pressing (HP) have been compared, under isothermal conditions and with heating rates of 20°C/min. Careful calibration of sample temperature has been carried out to obtain comparable results. In all cases, densification kinetics did not exhibit significant differences, ruling out any influence of the SPS current. The stress exponent n and the activation energy Q of the Norton law describing deformation at high temperature of the powder particles have been determined by isothermal experiments at different stresses and temperatures, respectively. The values obtained, n = 1.9 ± 0.3 and Q = 308 ± 20 kJ/mol for SPS, n = 1.5 ± 0.3 and Q = 276 ± 40 kJ/mol for HP, come close in both techniques. Using these values, anisothermal densification kinetics at heating rates of 20°C/ min and 100°C/min, typical of the SPS, could be analytically reproduced, using literature models. The activation parameters suggest that *Text only Click here to download Text only: monchoux_article_version2.docx Click here to view linked References 2 SPS densification kinetics occurs by dislocation climb controlled by Al bulk diffusion, that is, by classical metallurgical mechanisms.

show abstract

“…The capacitors represent the gaps between the non-contacting particles, by which their capacitance also varies with the particle size and gap distance in this percolative system. In a previous work, 14 this model was used for evaluation of the spark and plasma formation at the particle gaps during spark plasma sintering, hence the significance of the capacitor for surface charging and discharging. The loose powder compact (relative density, RD < 50%) in SPS conditions subjected to an applied pressure and to low electric fields (few VÁcm À1 ).…”

Section: The Percolation Modelmentioning

confidence: 99%

Flash sintering of dielectric nanoparticles as a percolation phenomenon through a softened film

Chaim

Chevallier

Weibel

et al. 2017

Journal of Applied Physics

View full text Add to dashboard Cite

Recent work [Biesuz et al., J. Appl. Phys. 120, 145107 (2016)] showed analogies between the flash sintering and dielectric breakdown in a-aluminas pre-sintered to different densities. Here, we show that flash sintering of dielectric nanoparticles can be described as a universal behavior by the percolation model. The electrical system is composed of particles and their contact point resistances, the latter softened first due to preferred local Joule heating and thermal runaway during the flash. Local softening has a hierarchical and invasive nature and propagates between the electrodes. The flash event signals the percolation threshold by invasive nature of the softened layer at the particle surfaces. Rapid densification is associated with local particle rearrangements due to attractive capillary forces induced by the softened film at the particle contacts. Flash sintering is a critical phenomenon with a self-organizing character. The experimental electric conductivity results from flash sintering are in full agreement with those calculated from the percolation model.

show abstract

Numerical model for sparking and plasma formation during spark plasma sintering of ceramic compacts

Abstract: OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.

Cited by 16 publications

References 24 publications

Particle Surface Softening as Universal Behaviour during Flash Sintering of Oxide Nano-Powders

Particle Surface Softening as Universal Behaviour during Flash Sintering of Oxide Nano-Powders

Comparison of densification kinetics of a TiAl powder by spark plasma sintering and hot pressing

Flash sintering of dielectric nanoparticles as a percolation phenomenon through a softened film

Contact Info

Product

Resources

About