Degree Of Densification Research Articles

Selective removal of aluminum ions from rare earth solutions by using ion-imprinted polymers

Remove of trace Al3+ from rare earth solutions is a challenging task. In the present study, an aluminum ion imprinted polymer (Al (III)-IIP) has been fabricated by surface-imprinting method. Al (III)-IIP was obtained by grafting silica gel with aminopropyl triethoxysilane and acrylic acid (AA). The structure and morphology of the polymer were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and thermogravimetric analysis (TG). The densification degree and the number of grafted functional groups were regulated by changing the synthesis conditions, and the optimal synthesis conditions are obtained as template ion: functional monomer: crosslinker = 1:8:8, and the optimal synthesis temperature is 333.15 K. The adsorption performance and selectivity properties of Al (III)-IIP were also investigated. The results show that at 298.15 K, the optimal pH for Al3+ adsorption is 4. The maximum adsorption capacity is 106.0 mg·g−1 at an Al3+ ion concentration of 1000 mg·L−1, which is 50% higher than that of reported recently. In addition, the adsorption process reaches equilibrium within 180 min. Furthermore, among many adsorption models and isothermal models, pseudo-second-order (PSO) adsorption model and Langmuir isothermal model are more suitable for the adsorption process. The selectivity coefficient of the Al3+ ion in binary mixtures of Nd3+, Ca2+ or Mg2+ are 17.76, 16.72 and 11.09, respectively. In addition, the adsorption mechanism of Al3+ is most probably caused by the formation of ionic bond between the Al3+ ions and the carboxyl functional groups on Al (III)-IIP and template effect. Results show that Al (III)-IIP has a great potential for a selective separation of aluminum ions from rare earth solutions.

Accessing the role of Joule heating on densification during flash sintering of YSZ

Flash sintering is a novel electric field and current assisted sintering technique which densify ceramics at moderate furnace temperature and in short time (few seconds) as compared to the conventional sintering techniques. The onset of flash encompasses three unique characteristics, (i) non-linear rise in conductivity, (ii) luminescence and (iii) rapid densification. the mechanism behind the flash phenomena is not fully understood yet. The present work experimentally demonstrated that the densification in flash sintering is primarily dominated by Joule heating. Herein, we distinguished the onset of flash and the degree of densification of cubic zirconia in sintering atmospheres with different oxygen partial pressures. In this study, we demonstrate that the flash onset temperature and densification are independently influenced by the sintering atmosphere during flash sintering. Furthermore, the extent of densification is not directly influenced by the current density rather, by the power dissipated in the sample.

Geochemical characteristics of diagenetic fluid and densification model of tight gas sandstone reservoirs in Linxing area, eastern margin of Ordos Basin, China

Quasi-continuous tight gas sandstone reservoirs have been discovered widely in the eastern margin of Ordos Basin (Linxing area) within the marine-continent transitional strata in the upper Paleozoic. Differences in formation water chemical properties, water-rock reactions, and diagenetic evolutions between the Taiyuan Formation and the Lower and Upper Shihezi Formations are attributed to various degrees of densification of sandstones, which significantly restrain the exploration and development of tight gas reservoirs. This study utilizes the petrographic features, electron probe, X-ray diffraction, and chemical properties of formation water to establish the diagenetic sequence of tight sandstone reservoirs and finds that the diagenetic systems of the Taiyuan Fm. were more closed than those of the Shihezi Fms., with enrichments in Ca2+and depletions in Mg2+ and Fe2+. Here, we suggest that the dissolution of feldspars and rock fragments, the siliceous cementation, and the transformation of clay minerals are controlled by the K+/H+ ratios of the formation water. In the Taiyuan Fm., the low K+/H+ ratios resulted in a complete illitization reaction in the closed CaCl2 type formation water, and the migration rate of K+ controlled the proportion of the illite contents in the open NaHCO3 type formation water. In the Lower Shihezi Fm., the rapid consumption of H+ caused the elevation of the K+/H+ ratios, leading to the cease of illitization reaction and preservation of kaolinites and K-feldspars. In the Upper Shihezi Fm., the illitization reaction was inefficient, and smectites were transformed to chlorites. Hence, differentiated sandstone densification models are established to characterize different water-rock reaction systems. Typically, clay minerals and ferrous carbonate cements could form seepage barriers around the thick sandstone layers and promote the formation of independent closed high-pressure micro-diagenetic systems. Consequently, the overpressured reservoirs that underwent relatively weak compaction, dissolution, and cementation (Type Ⅰ) and the chlorite-enriched overpressured reservoirs (Type Ⅱ) tend to preserve partially primary pores and form secondary pores, which should be treated as the “sweet spot” target area for the further exploration of tight gas.

Influence of pyrolysis and melt infiltration temperatures on the mechanical properties of SiCf/SiC composites

In order to improve the degree of matrix densification of SiC f /SiC composites based on liquid silicon infiltration (LSI) process, the microstructure and mechanical properties of composites according to various pyrolysis temperatures and melt infiltration temperatures were investigated. Comparing the microstructures of SiC f /C carbon preform by a one-step pyrolysis process at 600 °C and two-step pyrolysis process at 600 and 1600 °C, the width of the crack and microcrack formation between the fibers and matrix in the fiber bundle increased during the two-step pyrolysis process. For each pyrolysis process, the density, porosity, and flexural strength of the SiC f /SiC composites manufactured by the LSI process at 1450–1550 °C were measured to evaluate the degree of matrix densification and mechanical properties. As a result, the SiC f /SiC composite that was fabricated by the two-step pyrolysis process and LSI process showed an 18% increase in density, 16%p decrease in porosity, and 150% increase in flexural strength on average compared to the composite fabricated by the one-step pyrolysis process. In addition, among the SiC f /SiC specimens fabricated by the LSI process after the same two-step pyrolysis process, the specimen that underwent the LSI process at 1500 °C showed 30% higher flexural strength on average than those at 1450 or 1550 °C. Furthermore, under the same pyrolysis temperature, the mechanical strength of SiC f /SiC specimens in which the LSI process was performed at 1500 °C was higher than that of the 1550 °C although both porosity and density were almost similar. This is because the mechanical properties of the Tyranno-S grade SiC fibers degraded rapidly with increasing LSI process temperature.

Electrical and Ferroelectric Properties of Undoped and Er-Doped PZT52/48 Electroceramics Synthesized by a Polymeric Precursor Method

The effect of Er on the structural and electrical properties of doped PZT 52/48 ceramics has been studied in this work. The ferroelectric properties (permittivity, ferro-paraelectric phase transition and hysteresis) of such materials are thus found to be strongly dependent on the degree of densification and structural phase development during sintering at high temperatures. In particular, the nature of the ferroelectric to paraelectric phase transition is in these materials that can be represented through the Curie-Weiss Law equation modified, appropriate for the characterization diffuse transitions. The substitution of Er3+ for (Zr,Ti)4+ is found to induce strong diffuse phase transition in these materials. The electrical properties reported in this work are in magnitude comparable to those exhibited by PZT52/48 materials.

Geochemical characteristics and mechanisms of densification of pre-Jurassic crude oil in the Tainan Sag, Turpan-Hami Basin, China

Large volumes of heavy oil were distributed in the pre-Jurassic strata of Tainan sag, Turpan Hami Basin, China. The geochemical characteristics and origins of heavy oil are of great significance to future exploration in the region. In this study, we classified crude oil using data on its physical properties, group composition, and biomarker compounds. Further, the distribution characteristics of different types of crude oil in horizontal and vertical directions are clarified. We also summarize the mechanism of densification of crude oil in the study area. Our results indicate that there are four categories of crude oil with different densities in the Tainan Sag, which are distributed across the areas of (from west to east) Tuyuke, Lukeqin, and Yingyeer: light oil (<0.9/cm3), heavy oil (0.9–0.93 g/cm3), extra-heavy oil (0.93–0.98 g/cm3), and ultra-heavy oil (>0.98 g/cm3). Notable differences were observed in the composition of these distinct crude oil types. As the densification degree of crude oil increases, the content of saturated hydrocarbon and aromatic hydrocarbon decreases gradually, and the content of asphaltene increases gradually. The light oil in the Tuyuke area of the Tainan Sag has undergone severe water washing and slight-to-moderate biodegradation. The extra-heavy oil in the Lukeqin area has undergone severe water washing but moderate-to-severe biodegradation. The ultra-heavy oil in the Yingyeer area has not undergone notable water washing but has been subjected to severe biodegradation. Biodegradation damages saturated hydrocarbons and aromatic hydrocarbons in crude oil to varying degrees, increasing the relative content of non-hydrocarbon constituents and asphaltenes and causing the oil to thicken gradually. This occurrence is highly common in areas of severe strata erosion. Water washing, usually occurring in the interlayers where oil and water are in contact with each other over a large area, causes densification of the oil by destroying the low-carbon aromatics in it. This study determined the geochemical characteristics, as well as the reservoir geology of crude oil under various causes of densification and, can serve as a scientific reference for research on the mechanisms of densification of crude oil in other locations.

Additive manufacturing of aluminum nitride ceramics with high thermal conductivity via digital light processing

Aluminum nitride (AlN) powder systems for additive manufacturing (AM) via digital light processing (DLP) were successfully developed, shaped by a DLP-based manufacturing technique, and sintered at 1700 °C. Properties of the AM parts were compared to reference samples consolidated via cold-isostatic pressing. AlN powders from two different manufacturers were used in the powder mixtures, underlining the flexibility of the process. Thorough process control was crucial for obtaining materials with a high degree of densification, exhibiting microstructural, thermal, and mechanical properties comparable to conventionally processed reference materials. Thermal conductivity of AM samples exceeded 160 W m−1 K−1, while flexural strength of AM samples varied between 320 and 498 MPa, depending on the orientation of specimens with respect to the building direction. The feasibility of this approach to generate complex-shaped parts was successfully shown by fabrication of crack-free demonstrator parts, highlighting prospective novel use cases in advanced heat management applications.

Fabrication and characterization of Cu reinforced with Y-enriched particles following a novel powder metallurgy route

• DS Cu-Y has been obtained by a powder metallurgical route from Cu and yttrium acetate. • TEM measurements reveal the presence of Y 2 O 3 nanometric particles. • The cavities are formed from volatile compounds. • The EBSD analysis indicate that the average grain size is below one micrometer. • The DS Cu-Y yield strength is greater than that of Cu below 473 K. Dispersion strengthened copper alloys have been produced following an innovative powder metallurgy route. Copper and yttrium acetate powders have been mechanically alloyed and posteriorly thermal treated at 923 K for 3 h and 15 h under a hydrogen atmosphere in order to transform the yttrium acetate into Y 2 O 3 . Subsequently, the powders were consolidated by hot isostatic pressing. It has been concluded that the duration of the thermal treatment of the powder is a determining factor in the degree of densification of the alloy. The study of the microstructure by Scanning Electron Microscopy and Electron Backscatter Diffraction has revealed the presence of micrometer and submicrometer grains and nanometric Y-O enriched Cu particles embedded in the copper matrix, the mean grain size being smaller for the sample produced from the powder thermal treated for 15 h. Transmission Electron Microscopy investigations concluded that the nanoparticles exhibit a spherical shape with a size up to 25 nm and correspond to monoclinic Y 2 O 3 . Annealing twins have been also observed, especially in the material produced from thermal treated powder for longer. The mechanical properties have been inferred from Vickers microhardness measurements and compression tests. Below 473 K the yield strengths of the produced materials are greater than that of pure copper and above 473 K are close to them. From the study of the thermal properties of the densest material it has been found that its thermal conductivity remains nearly constant in the temperature range 300–773 K, and its value is around 85% the thermal conductivity of CuCrZr, the reference material for ITER.

A novel ultra-low loss ceramic Li5ZnSnNbO8 with a rock salt structure

In this contribution, we synthesized a novel Li5ZnSnNbO8 ceramics with the traditional solid-state reaction. The correlations between microwave performance and crystal structures were systematically studied. According to the XRD result, the Li5ZnSnNbO8 formed a rock salt structure, belongs to Fm-3m (225) space group, which can be further confirmed by the Rietveld refinement method. By observing the SEM photograph and measuring the density, it is found that the sample has the highest degree of densification. Typically, the Li5ZnSnNbO8 ceramic sintered at 1250 °C for 4 h exhibited the excellent microwave dielectric performance of εr = 17.17, Q×f = 51519 GHz and τf = −28.2 ppm/°C.

Hardened wood as a renewable alternative to steel and plastic

Hardened wood as a renewable alternative to steel and plastic

Progress and Opportunities in the Application of Cold Sintering to Solid-State, Electrochemical, and Ceramic Devices

The high temperature conventional sintering process has been practiced by humans for thousands of years, but only in recent decades has there been significant progress in modifying the sintering process to achieve lower temperatures or shorter dwell times.In this talk, we focus on the newest addition to the family of alternative sintering techniques; cold sintering. Cold sintering is characterized by the addition of a small amount of a transient sintering aid, such as an alkali hydroxide, to the parent ceramic powder. The mixture is then subjected to low temperatures (Tsinter < 400°C) and moderate uniaxial pressure (100 - 300 MPa) which results in a remarkable degree of densification for a wide range of ceramics. Broadly speaking, cold sintering is able to densify even the most refractory technical ceramics at around 30% of the melting temperature, whereas conventional wisdom asserts that the solid-state sintering process requires temperatures near 70% of the melting temperature.To illustrate the benefits of this dramatic reduction in sintering temperature, we will present recent examples of cold sintering applied to conductive ceramics for high temperature electrochemical devices. These examples include sodium ion electrolytes for solid-state batteries (e.g. Na3Zr2Si2PO12, β’’-Al2O3) and oxygen-ion electrolytes for solid oxide fuel cells (e.g. CeO2). For these electrolytes, we illustrate how the density and conductivity of the cold sintered electrolytes is comparable to the conventionally fired ceramics. In doing so, we also discuss the opportunities and open questions surrounding these ceramic materials which have been densified at low temperatures.These examples show how the elimination of elemental volatilization and grain size control can be easily achieved with lower temperature processing. We will conclude with a forward-looking assessment of some of the opportunities that low temperature sintering may enable, such as co-firing device layers and the inclusion of thermally fragile additives into the sintered ceramics. The low temperatures afforded by cold sintering presents new opportunities for the processing of many ceramic-dominated solid-state electrochemical devices.Figure Caption: The relative density is plotted as a function of sintering temperature for the prototypical refractory solid electrolyte, sodium-ion conducting β’’-Al2O3. Conventional sintering methods include hot pressing, spark plasma sintering, liquid phase sintering, and solid-state sintering. Cold sintering achieves high densities at exceedingly low temperatures for this refractory material. Figure 1

Fabrication of magnetically controllable glass ceramics with completely dense microstructure by hot pressing

AbstractCompletely dense magnetite‐based aluminosilicate glass ceramics with adjustable magnetic properties were successfully synthesized by method of hot pressing. The influences of sintering conditions and magnetite contents on magnetic properties and microstructure of samples were analyzed. It was found that increases in sintering temperature and time could improve the densification degree of samples. However, precipitation of crystalline phases from glass would worsen the densification of samples. The optimum parameters of hot pressing were 950°C for 1 h, under which condition, the glass ceramics containing 10–65 wt.% magnetite showed a fully dense microstructure. As the magnetite content increased from 10 to 65 wt.%, magnetization and area of hysteresis loops of glass ceramics increased, while coercivity showed an opposite trend. However, when the magnetite content increased to 70 wt.%, pores appeared and the degree of densification decreased.

Properties of wood-based composites manufactured from densified beech wood in viscoelastic and plastic region of the force-deflection diagram (FDD)

Abstract It is still little or no knowledge about the properties of layered wood-based composites and nonwood components in the viscoelastic and plastic region of the force-deflection diagram (FDD). The properties of composites in this area are influenced by several factors such as the composition of the layered composite, the method of modification of the individual layers, the type of adhesive used, etc. This paper focuses on the analysis of the effect of the thickness of individual layers (5 and 9 mm) of beech wood (Fagus sylvatica L.), modification of these layers with different degrees of densification (10, 20, 30, and 40%) and the type of the nonwood component (carbon and high-strength glass fibers) used to reinforce the layered composite on the properties of materials in the plastic region of the FDD. The paper describes the impact of selected factors and those interactions behavior of the tangent modulus in the whole FDD. This is the first study that describes the development of layered wood-based composites and nonwood components in the viscoelastic and plastic region and analyzes the impact of most imported types of modifications on the characteristics in the viscoelastic and plastic regions.

Additive manufacturing of TiB2-containing CoCrFeMnNi high-entropy alloy matrix composites with high density and enhanced mechanical properties

Near-fully dense CoCrFeMnNi high-entropy alloy (HEA) matrix composites reinforced with 5 wt% TiB2 nanoparticles were successfully additively manufactured via the laser-engineered net shaping technique. Compared to the monolithic CoCrFeMnNi printing process, a higher energy density input is shown to produce a synergic combination of Marangoni flow and capillary force in the laser-generated melt pool. It facilitates the enhancement of wettability, and hence a more uniform distribution of the reinforcement material and a high degree of densification of 99.72%, which are able to delay the early fracture of the material. The as-deposited composites exhibit improved yield strength, surpassing that of the monolithic HEA by 42%. The enhanced strength is mainly ascribed to dispersion strengthening. Besides, the refined grain size, the increased dislocation density, and the additional load transfer effect also contribute to the strength enhancement. Furthermore, the wear resistance properties of the CoCrFeMnNi/TiB2 composite are also shown to be superior to those of the CoCrFeMnNi, indicating a decrease in friction coefficient by 22.4%. The enhanced tribological properties are attributed to the synergic effect of high-hardness and self-lubrication of TiB2 nanoparticles. The findings provide guidelines for achieving high-performance HEA-matrix composites.

Preparation and characterization of Cf/Pollucite composites through geopolymer precursors

Continuous carbon-fibre-reinforced Cs-geopolymer composite (Cf/CsGP) were prepared, and its in-situ conversion was investigated during high-temperature treatments. The effect of treatment temperature on the thermal evolution process and mechanical properties of the resulting products were systematically evaluated. The results indicated that the crystallization temperature of Cf/CsGP composite was considerably delayed because the amorphous structure of carbon fibres was not conducive as a nucleation substrate for pollucite derived from the CsGP matrix. Moreover, the integrity of the corresponding resulting products derived from the Cf/CsGP composite were damaged due to thermal shrinkage that occurred during the high-temperature treatment process. When treatment temperature was ≤1200oC, the mechanical properties of the corresponding products exhibited an upward trend, which was ascribed to the improvement of the densification degree of the resulting composite and well interface-bonding state between carbon fibres and pollucite. However, the mechanical properties of the resulting composites decreased with the treatment temperature continued increased from 1200 to 1400oC. This phenomenon was attributed to the impairment of fibre properties caused by interfacial reactions.

Effect of compression ratio and original wood density on pressing characteristics and physical and mechanical properties of thermally compressed coconut wood

This experimental study aims to improve the engineering properties of coconut wood by using a thermal compression method (TM). The effects of original wood density and compression ratio on the pressing characteristic as well as physical and mechanical properties of thermally densified coconut wood were evaluated. Coconut wood boards obtained from the plantation located in Nakhon Si Thammarat province, Thailand, were sorted into low-density (359 ± 36 kg/m3) and medium-density (532 ± 35 kg/m3) groups. They were compressed by 25%, 40%, 55%, and 70% of their original thicknesses under a clamping pressure of 19.6 MPa (pressure gauge), at a temperature of 140 °C for 15 min. The physical and mechanical properties of the densified specimens were measured and compared with the control group specimens. Low-density specimens could be compressed with a higher degree of densification without shape distortion. Thermal compression improved bending strength, modulus of elasticity, compressive strength parallel to grain, and perpendicular-to-grain shear strength up to 125%, 54%, 112%, and 129%, respectively, for low-density wood and 47%, 13%, 41%, and 58%, respectively, for medium density wood. However, the densification did not improve parallel-to-grain shear strength. When the low-density and medium-density wood were compressed to the same density, the densified specimens manufactured from the medium-density group showed more improved dimensional stability, shear strength, and bending properties than those manufactured from the low-density group, while their parallel-to-grain compressive strength properties were not significantly different. However, at the same density level, the natural wood mechanically outperformed the densified wood except for the perpendicular-to-grain shear strength, parallel-to-grain compressive strength, and bending strength perspectives. Thus, the experimental results indicate that the densified coconut wood can be used for structural applications where parallel-to-grain compressive strength or perpendicular-to-grain shear strength is critical.

High‐Temperature Ultrafast Sintering: Exploiting a New Kinetic Region to Fabricate Porous Solid‐State Electrolyte Scaffolds

AbstractSolid‐state batteries (SSBs) promise better safety and potentially higher energy density than the conventional liquid‐ or gel‐based ones. In practice, the implementation of SSBs often necessitates 3D porous scaffolds made by ceramic solid‐state electrolytes (SSEs). Herein, a general and facile method to sinter 3D porous scaffolds with a range of ceramic SSEs on various substrates at high temperature in seconds is reported. The high temperature enables rapid reactive sintering toward the desired crystalline phase and expedites the surface diffusion of grains for neck growth; meanwhile, the short sintering duration limits the coarsening, thus accurately controlling the degree of densification to preserve desired porous structures, as well as reducing the loss of volatile elements. As a proof‐of‐concept, a composite SSE with a good ionic conductivity (i.e., ≈1.9 × 10−4 S cm−1 at room temperature) is demonstrated by integrating poly(ethylene oxide) with the 3D porous Li6.5La3Zr1.5Ta0.5O12 scaffold sintered by this method. This method opens a new door toward sintering a variety of ceramic‐SSE‐based 3D scaffolds for all‐solid‐state battery applications.

Flash sintering of alumina/reduced graphene oxide composites

The flash sintering behavior of Al2O3/reduced graphene oxide (rGO) composites was investigated. rGO was used as a composite component and a conductive additive. Under the electric fields of 250–400 V cm−1, the flash event occurred at extremely low temperatures of 236–249 °C. The current density limit played a significant role in the degree of densification. A larger current density resulted in a higher density of the sample. However, current densities larger than 33.33 A cm−2 resulted in broken samples because of the localization of high current density coupled with the formation of hot spots. Flash sintering at a furnace temperature of 800 °C, electric field of 300 V cm−1 and current density limit of 33.33 A cm−2 produced nearly completely dense Al2O3/rGO composites. In addition to the current limit, the furnace temperature is also a key parameter that controls the degree of densification to achieve “safe” flash sintering.

Optimization of thermo-mechanical densification of bamboo

Due to its reliability, strength, and ease of access, bamboo has become an attractive material for engineering applications. However, heterogeneous properties and durability issues still hinder the widespread use of bamboo as a building material. Thermo-mechanical treatment is a method to decrease the heterogeneity of bamboo culms and enhance mechanical properties and durability, but it may negatively impact dimensional stability. The objective of this study was to achieve the minimum spring back, water absorption, and thickness swelling for densified bamboo. Accordingly, the behavior of bamboo samples subjected to different thermo-mechanical (TM) treatments using a two-step analysis was investigated. In the first step, the optimum TM treatment for achieving the highest critical densification degree (DD) without shear failure was determined. In the second step, the three key elements of dimensional stability were studied for this optimum case. According to the first step results, the maximum achievable DD in which no shear failure happens and the texture is not disturbed is about 43.6%, and it can be obtained at 200 °C with a compression rate of 2 mm/min. X-ray densitometry analysis confirmed that DD of around 50% achieved the highest value of density, 1.30 g.cm−3. The results of step 2 revealed that the lowest values of spring back, water absorption, and thickness swelling, 4.72%, 23.80%, and 17.70% respectively, for densified bamboo occur when the densification process is conducted at 200 °C and adopting a compression rate of 6.7 mm/min. In conclusion, by manipulating and optimizing process parameters, the dimensional stability and final quality of densified bamboo can be improved, opening new opportunities for this class of material.

Development of a processing map for safe flash sintering of gadolinium‐doped ceria

AbstractFlash sintering was discovered in 2010, where a dog‐bone‐shaped zirconia sample was sintered at a furnace temperature of 850°C in &lt;5 s by applying electric fields of ~100 V cm−1 directly to the specimen. Since its discovery, it has been successfully applied to several if not all oxides and even ceramics of complex compositions. Among several processing parameters in flash sintering, the electrical parameters, i.e., electric field and electric current, were found to influence the onset temperature for flash and the degree of densification respectively. In this work, we have systematically investigated the influence of the electrical parameters on the onset temperature, densification behavior, and microstructure of the flash sintered samples. In particular, we focus on the development of a processing map that delineates the safe and fail regions for flash sintering over a wide range of applied current densities and electric fields. As a proof of concept, gadolinium‐doped ceria (GDC) is shown as an example for developing of such a processing map for flash sintering, which can also be transferred to different materials systems. Localization of current coupled with hot spot formation and crack formation is identified as two distinct failure modes in flash sintering. The grain size distribution across the current localized and nominal regions of the specimen was analyzed. The specimens show exaggerated grain growth near the positive electrode (anode). The region adjacent to the negative electrodes (cathode) showed retarded densification with large concentration of isolated pores. The electrical conductivity of the flash sintered and conventional sintered samples shows identical electrical conductivity. This quantitative analysis indicates that similar sintering quality of the GDC can be achieved by flash sintering at temperature as low as 680°C.