A novel sintering method to obtain fully dense gadolinia doped ceria by applying a direct current

Hao, Xiaoming; Liu, Huan; Wang, Zhenhua; Qiao, Jinshuo; Sun, Kening

doi:10.1016/j.jpowsour.2012.03.006

Cited by 127 publications

(67 citation statements)

References 41 publications

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“…Rare earthdoped ceria or RE-DC of various compositions has been the subject of several flash sintering studies, as it has good properties for SOFCs which are hampered by high (1700-1800 o C) densification temperatures. Building on earlier work [48], Jiang et al [96] showed that under 90V/cm and ~86mA/mm 2 current density, Ce0.9Gd0.1O1.95, Ce0.8Gd0.2O1.9 and C0.8Sm0.2O1. under electric field of 70V/cm, with a current limit of 0.5A (corresponding to a current density limit of approximately 0.4A/mm 2 calculated with the given sample dimensions before binder burnout) [42].…”

Section: Materials For Use In Solid Oxide Fuel Cellsmentioning

confidence: 86%

“…The electrodes used for pellets are usually platinum discs placed against the top and bottom surfaces [47] with wires to the power supply attached. Alternative approaches are to attach the wires to meshes of platinum wire placed in the same position as the discs [24], to paint the top and bottom surfaces of the discs with conductive paint/paste (often platinum [48], but silver has also been used [49,50]), or to sputter coat each side of the discs with platinum [51]. Finally, Saunders et al [52] have described a flash sintering approach which used arc plasma electrodes rather than any additional material to realise a contactless setup, and successfully fully densified B4C and SiC/B4C composite materials.…”

Section: Electrical Contactmentioning

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: Materials For Use In Solid Oxide Fuel Cellsmentioning

confidence: 86%

Section: Electrical Contactmentioning

confidence: 99%

Flash sintering of ceramic materials

Dancer¹

2016

Mater. Res. Express

159

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show abstract

“…Excessive grain growth is unavoidable during densification of 10GDC electrolyte by conventional sintering. However, to overcome this drawback of 10GDC, alternative processes such as adding sintering aids [42] or field assisted or flash sintering techniques has been reported [1,4,43]. Evaluating fracture surface of both transverse and casting direction of sintered tapes in high magnification shows that most of the pores left after organic burn off lying parallel with tape plan which are difficult to remove by sintering.…”

Section: Mechanical Properties Of Green Tapesmentioning

confidence: 99%

“…Nevertheless, densification of GDC electrolyte requires high sintering temperatures above 1,500°C for conventional sintering which results in large grain size and as a consequence mechanically unstable at the operating conditions [4]. Using nanosized 10GDC powder prepared by combustion synthesis, co-precipitation, sol-gel, and hydrothermal solution has been offered as a way to overcome this issue [5][6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties of Gd‐CeO₂ Electrolyte for SOFC Prepared by Aqueous Tape Casting

et al. 2013

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Mechanical properties of gadolinium‐doped ceria (Ce0.9Gd0.1O1.95, 10GDC) green tape prepared by aqueous‐based tape casting process were characterized by tensile test and shear punch test (SPT). SPT was found to be a useful method for characterizing mechanical properties of green tapes. Microstructures and mechanical properties such as flexural modulus, bending strength, and microhardness of tapes sintered at 1,300–1,500 °C have been evaluated. Indentation fracture toughness was also determined by the method of Palmqvist cracks at different applied loads for tapes sintered at 1,500 °C. Grain size measurements showed that excessive grain growth occurred during sintering despite using 10GDC nanopowders as the starting material. However, mechanical properties of sintered tapes improved by increasing sintering temperature and the results are comparable with those reported for 10GDC in literature.

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“…The conventional sintering process is not only time consuming, but also oppressively required of energy and equipment. Recently, some novel techniques in applying electrical fields in densification of ceramics termed flash sintering have obvious improvement in terms of reducing the sintering temperature and the sintering time [30][31][32][33][34][35][36][37][38]. These electrical techniques for densification provides us with an opportunity to prepare bulk ZrO 2 ceramics at low temperature in short time.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and electrical field-assisted sintering behaviour of yttria-stabilized tetragonal ZrO2 nanopowders by polyacrylamide gel method

Wang

Zhou

et al. 2016

Bull Mater Sci

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The tetragonal ZrO 2 nanopowders stabilized with 3 mol% Y 2 O 3 (3YSZ) were synthesized using a polyacrylamide gel method. The mean particle size of the 3YSZ nanopowders was found to decrease with increasing molecular ratio of monomer to the precursor salt. The 3YSZ nanopowders with mean particle size of 12 nm can be densified in 1 h at 800 • C, by the application of a d.c. electrical field. Under a constant d.c. electrical field, the current density through the specimen of 3YSZ rose rapidly when the temperature increased to a certain value. In the sintering process, the current density was restricted when the sharp increase occurred. By limiting current density to different values for one hour, it was found that current density was the most important factor in electrical fieldassisted sintering process. The grain size of 3YSZ bulk increased with the enhanced current density. The stable stage of electrical field-assisted sintering process can be explained by Joule heating. Corresponding real temperature of specimens is estimated by applying black body radiation theory.

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A novel sintering method to obtain fully dense gadolinia doped ceria by applying a direct current

Cited by 127 publications

References 41 publications

Flash sintering of ceramic materials

Flash sintering of ceramic materials

Mechanical Properties of Gd‐CeO₂ Electrolyte for SOFC Prepared by Aqueous Tape Casting

Synthesis and electrical field-assisted sintering behaviour of yttria-stabilized tetragonal ZrO2 nanopowders by polyacrylamide gel method

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A novel sintering method to obtain fully dense gadolinia doped ceria by applying a direct current

Cited by 127 publications

References 41 publications

Flash sintering of ceramic materials

Flash sintering of ceramic materials

Mechanical Properties of Gd‐CeO2 Electrolyte for SOFC Prepared by Aqueous Tape Casting

Synthesis and electrical field-assisted sintering behaviour of yttria-stabilized tetragonal ZrO2 nanopowders by polyacrylamide gel method

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Product

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Mechanical Properties of Gd‐CeO₂ Electrolyte for SOFC Prepared by Aqueous Tape Casting