Flash sintering of ionic conductors: The need of a reversible electrochemical reaction

Caliman, Lorena Batista; Bouchet, Renaud; Gouvêa, Douglas; Soudant, Priscillia; Steil, M.C.

doi:10.1016/j.jeurceramsoc.2015.12.005

Cited by 49 publications

(41 citation statements)

References 25 publications

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“…Two studies where different electrode materials were used in the same study give some insight. Caliman et al [43] used both silver and platinum ink applied over the surfaces of disc samples of -alumina (MgNa2Al10O17). In this material, no flash sintered occurred when using the platinum, due to the incompatibility between the sodium-ion conducting -alumina and the platinum metal.…”

Section: Electrical Contactmentioning

confidence: 99%

“…As the methods of electrode attachment are generally dictated by the sample geometry and the apparatus configuration there is little systematic comparison of the different approaches within the literature other than the study of Caliman et al [43] and Biesuz and Sglavo [44] described above, which only considered changes to the electrode materials. As there are simultaneously other significant variations between the flash sintering apparatus used by different groups, such an analysis is difficult to establish from reviewing the literature.…”

Section: Electrical Contactmentioning

confidence: 99%

“…The somewhat confusingly-named -alumina, which is actually sodium-aluminate e.g. MgNa2Al10O17, a strongly ionic material used in applications such as solid oxide fuel cells, was flash sintered by Caliman et al [43] using silver electrodes with electric fields of 120V/cm, furnace temperature of 550 o C, and maximum critical current of 10A/cm 2 . These samples had relative densities of 88%, the highest achieved in the study.…”

Section: Aluminamentioning

confidence: 99%

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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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Section: Electrical Contactmentioning

confidence: 99%

Section: Electrical Contactmentioning

confidence: 99%

Section: Aluminamentioning

confidence: 99%

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Flash sintering of ceramic materials

Dancer¹

2016

Mater. Res. Express

159

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“…The two techniques differ by the set-up, the ranges of the applied voltage and the electric current density; however, the physical and chemical processes, and the electric field effects with the ionic/semiconducting ceramics are very similar. In this respect, different densification mechanisms suggested for the enhanced densification kinetics, where the processes at the particle surfaces and interfaces play the dominating role [1,2,3,4,5,6,7,8,9,10,11,12]. Recently, local melting of ceramic particle surfaces further supported the formation of spark and plasma during SPS [13,14,15,16,17].…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the local nature of melting/reaction was confirmed by the islands in the partially reacted microstructure [9]. Several works also reported the formation of local liquid as well as heterogeneous microstructure during flash sintering [9,25]. Therefore, in this paper I will evaluate the formation of liquid at the particle contacts during FS and its consequences upon densification kinetics and microstructure via capillary forces.…”

Section: Introductionmentioning

confidence: 99%

Liquid Film Capillary Mechanism for Densification of Ceramic Powders during Flash Sintering

Chaim

2016

Materials

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Recently, local melting of the particle surfaces confirmed the formation of spark and plasma during spark plasma sintering, which explains the rapid densification mechanism via liquid. A model for rapid densification of flash sintered ceramics by liquid film capillary was presented, where liquid film forms by local melting at the particle contacts, due to Joule heating followed by thermal runaway. Local densification is by particle rearrangement led by spreading of the liquid, due to local attractive capillary forces. Electrowetting may assist this process. The asymmetric nature of the powder compact represents an invasive percolating system.

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Recent Advances in Mechanism Research and Methods for Electric‐Field‐Assisted Sintering of Ceramics

2018

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Electric-field-assisted sintering of ceramic materials is under considerable attention during recent years. The current research is reviewed with a focus on mechanism research. Research of the mass transfer mechanisms in flash sintering (FS) is under debate during recent years. The research yields three main proposed mechanisms: nucleation due to movement of charged defects, Joule heating runaway, and electrochemical reactions. These are critically presented and discussed. Unlike FS, the mechanism of field-assisted sintering technologies (FAST) of ceramics is well agreed upon. However, recent studies challenge even this perception with new approaches, which are presented here. New technological and methodological developments in both FS and FAST/spark plasma sintering are also presented.

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Flash sintering of ionic conductors: The need of a reversible electrochemical reaction

Cited by 49 publications

References 25 publications

Flash sintering of ceramic materials

Flash sintering of ceramic materials

Liquid Film Capillary Mechanism for Densification of Ceramic Powders during Flash Sintering

Recent Advances in Mechanism Research and Methods for Electric‐Field‐Assisted Sintering of Ceramics

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