Stabilization of a Zirconia System and Evaluation of Its Electrolyte Characteristics for a Fuel Cell: Based on Electrical and Mechanical Considerations

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Akihiko Yamaji ◽  
Takao Koshikawa ◽  
Wakako Araki ◽  
Tadaharu Adachi
Keyword(s):  
Phase Transformation ◽  
Fuel Cell ◽  
Ionic Conductivity ◽  
Mechanical Strength ◽  
Bending Strength ◽  
Testing Machine ◽  
High Conductivity ◽  
Cubic Phase ◽  
The Relationship ◽  
Zro2 System

The purpose of this study is to clarify the relationship between ionic conductivity and phase transformation of zirconia system codoped with scandium oxide Sc2O3 and ytterbium oxide Yb2O3. Aiming to achieve high ionic conductivity as well as high mechanical strength, the authors have also investigated the relationship between phase transformation and mechanical strength. The results have been discussed with respect to both the conductivity and the mechanical strength. The Sc- and Yb-codoped zirconia (ZrO2) used as samples in this study were prepared by a standard solid-state reaction. X-ray powder diffraction (XRD) method was used to determine the crystal structures of the sintered samples. To detect any phase change between room temperature and 1273K, thermal mechanical analysis (TMA) was conducted. To determine oxygen-ion conductivity in a temperature range from 873to1273K in air, impedance measurements were performed with alternating current (ac). Single-cell performance was confirmed under the condition of 26.2Pa partial hydrogen pressure. Finally, to measure bending strength, three-point bending tests were performed with a universal testing machine. The results of XRD and TMA showed that codoping of Sc2O3 and Yb2O3 into ZrO2 successfully stabilized the cubic phase when the average radius ratio of these two dopants in total was close to the ideal one for the eight-coordinate. The ac impedance measurement demonstrated that the cubic-phase stabilization achieved a high conductivity. Adequate amounts of dopants produced oxygen vacancies for high conductivity without complex defects: ZrO2 system doped with 1mol% of Yb2O3 and 8mol% of Sc2O3 showed the highest conductivity at 1273K and 0.30S∕cm. The bending strength decreased with increasing the content of doped Sc2O3 from 7mol%to11mol%, depending on the amount of the tetragonal phase, which contributes to strengthen materials. In the performance test, the ZrO2 system stabilized with doping 1mol%Yb2O3 and 8mol%Sc2O3 with thickness of 2.16mm showed maximum power density at 1273K, that is, 210mW∕cm2. From all the above tests, we recommend that, based on electrical and mechanical considerations, 1Yb8ScSZ is the present best option for an electrolyte material for a solid oxide fuel cell.

Effect of Al2O3 Addition on Microstructure, Thermal Expansion and Mechanical Properties of Ta2O5 Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 631-634 ◽  
Author(s):  
Jian Er Zhou ◽  
Jing Zhang ◽  
Xiao Zhen Zhang ◽  
Xue Bing Hu
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Phase Transformation ◽  
Mechanical Strength ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Bending Strength ◽  
Minor Phase ◽  
Α Phase ◽  
Dry Pressing

The Ta2O5-based ceramics were prepared by dry pressing/sintering technique using Ta2O5and Al2O3as the starting materials. The present work investigated the effect of alumina (Al2O3) additions on the composition, microstructure, thermal expansion coefficient (TEC) and bending strength of Ta2O5ceramics. The thermal expansion of the samples was measured by the dilatometry method. It was found that Al2O3additions can effectively inhibit the β to α phase transformation in Ta2O5ceramics. Orthorhombic AlTaO4as the minor phase formed when 2.5 and 7.0 wt% Al2O3was added. The addition of Al2O3results in obvious change of TEC and an increase of bending strength. This work demonstrated that the addition of Al2O3is an effective way to modify the TEC and mechanical strength of Ta2O5ceramics.

scholarly journals Kekuatan Mekanis Antibacterial Resin Campuran Titanium Dioksida

2021 ◽  
Vol 12 (1) ◽  
pp. 227
Author(s):  
Azamataufiq Budiprasojo ◽  
Feby Erawantini
Keyword(s):  
Impact Strength ◽  
Mechanical Strength ◽  
Tio2 Nanoparticles ◽  
Bending Strength ◽  
Testing Machine ◽  
Acrylic Resin ◽  
Impact Testing ◽  
Universal Testing ◽  
The Impact ◽  
Pendulum Impact

<p class="Abstract">The aim of this research is to analyze the effect of Titanium Dioxide (TiO2) nanoparticles as resin concentrate on mechanical strength. The tested mechanical strength is Bending strength, Impact Strength, and Microhardenest Strength. The types of resin used in this study were acrylic resin without conventional modification and acrylic resin with an additional 0.01 gr and 0.06 gr of TiO2. Specimen dimensions are made revered to ISO 20795-1 (2008) standard specifications. Mechanical strength was determined by using the universal testing machine, Izod pendulum impact testing machine, and also Vickers microhardness tester. From the analysis, the researcher found that the bending strength of resin acrylic was greatly decreased by increasing the TiO2 concentration. It happens in both TiO2 0.01gr and 0.06gr of acrylic resin compared to the non TiO2 resin. The impact strength of 0.01gr TiO2 acrylic resin was significantly increased compared to non TiO2 acrylic resin. But on the other hand for 0.06gr acrylic resin, impact strength was decreased and recorded the lowest impact strength. The highest Micro hardness strength was found in 0.06gr TiO2, It is significantly increased compared to 0.01gr TiO2 and 0gr TiO2. The general conclusion is, adding 0.01gr TiO2 nanoparticles as concentrated into acrylic resin can significantly increase the bending strength, bending strength, and microhardness strength. Meanwhile, adding 0.06gr Tio2 nanoparticles as concentrated into acrylic resin can only increase the bending strength and the microhardness strength, but not for its impact strength.</p>

Ferroelectric Domain Structure of Pb(Zr.52Ti.48)03

1980 ◽  
Vol 38 ◽  
pp. 214-215
Author(s):  
E.K. Goo ◽  
R.K. Mishra
Keyword(s):  
Phase Transformation ◽  
Domain Structure ◽  
Tetragonal Phase ◽  
Ferroelectric Domain ◽  
Cubic Phase ◽  
Ion Milling ◽  
Thin Foils ◽  
Ferroelectric Domain Structure ◽  
Ferroelectric Domains

Ferroelectric domains are twins that are formed when PZT undergoes a phase transformation from a non-ferroelectric cubic phase to a ferroelectric tetragonal phase upon cooling below ∼375°C.,1 The tetragonal phase is spontaneously polarized in the direction of c-axis, making each twin a ferroelectric domain. Thin foils of polycrystalline Pb (Zr.52Ti.48)03 were made by ion milling and observed in the Philips EM301 with a double tilt stage.

scholarly journals Morphological effect of side chain on H3O+ transfer inside polymer electrolyte membranes across polymeric chain via molecular dynamics simulation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
JinHyeok Cha
Keyword(s):  
Fuel Cell ◽  
Ionic Conductivity ◽  
Polymer Electrolyte ◽  
Polymer Electrolyte Membrane ◽  
Dynamics Simulation ◽  
Polymeric Chain ◽  
Side Chains ◽  
Dynamic Simulations ◽  
Morphological Effect ◽  
Electrolyte Membrane

AbstractPerformance and durability of polymer electrolyte membrane are critical to fuel cell quality. As fuel cell vehicles become increasingly popular, membrane fundamentals must be understood in detail. Here, this study used molecular dynamic simulations to explore the morphological effects of perfluorosulfonic acid (PFSA)-based membranes on ionic conductivity. In particular, I developed an intuitive quantitative approach focusing principally on hydronium adsorbing to, and desorbing from, negatively charged sulfonate groups, while conventional ionic conductivity calculations featured the use of mean square displacements that included natural atomic vibrations. The results revealed that shorter side-chains caused more hydroniums to enter the conductive state, associated with higher ion conductivity. In addition, the hydronium path tracking showed that shorter side-chains allowed hydroniums to move among host groups, facilitating chain adsorption, in agreement with a mechanism suggested in earlier studies.

scholarly journals Influence of Preaging Temperature on the Indentation Strength of 3Y-TZP Aged in Ambient Atmosphere

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2767
Author(s):  
Ki-Won Jeong ◽  
Jung-Suk Han ◽  
Gi-Uk Yang ◽  
Dae-Joon Kim
Keyword(s):  
Residual Stress ◽  
Phase Transformation ◽  
Low Temperature ◽  
Compressive Residual Stress ◽  
Yttria Stabilized Zirconia ◽  
Ambient Atmosphere ◽  
Aged Specimen ◽  
Stabilized Zirconia ◽  
M Phase ◽  
The Relationship

Yttria-stabilized zirconia (3Y-TZP) containing 0.25% Al2O3, which is resistant to low temperature degradation (LTD), was aged for 10 h at 130–220 °C in air. The aged specimens were subsequently indented at loads ranging from 9.8 to 490 N using a Vickers indenter. The influence of preaging temperature on the biaxial strength of the specimens was investigated to elucidate the relationship between the extent of LTD and the strength of zirconia restorations that underwent LTD. The indented strength of the specimens increased as the preaging temperature was increased higher than 160 °C, which was accompanied by extensive t-ZrO2 (t) to m-ZrO2 (m) and c-ZrO2 (c) to r-ZrO2 (r) phase transformations. The influence of preaging temperature on the indented strength was rationalized by the residual stresses raised by the t→m transformation and the reversal of tensile residual stress on the aged specimen surface due to the indentation. The results suggested that the longevity of restorations would not be deteriorated if the aged restorations retain compressive residual stress on the surface, which corresponds to the extent of t→m phase transformation less than 52% in ambient environment.

Observation of Pressure Drop Behavior in an Operating Fuel Cell Stack

2005 ◽  
Author(s):  
Frano Barbir ◽  
Haluk Gorgun ◽  
Xinting Wang
Keyword(s):  
Fuel Cell ◽  
Pressure Drop ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Cathode Side ◽  
Fuel Cell Stack ◽  
Flow Through ◽  
Drying Conditions ◽  
Exchange Membrane ◽  
The Relationship

Pressure drop on the cathode side of a PEM (Proton Exchange Membrane) fuel cell stack has been studied and used as a diagnostic tool. Since the Reynolds number at the beginning of the flow field channel was <250, the flow through the channel is laminar, and the relationship between the pressure drop and the flow rate is linear. Some departure from linearity was observed when water was either introduced in the stack or produced inside the stack in the electrochemical reaction. By monitoring the pressure drop in conjunction with the cell resistance in an operational fuel cell stack, it was possible to diagnose either flooding or drying conditions inside the stack.

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