Open pore description of mechanical properties of ceramics

Wagh, Arun S.; Poeppel, R.B.; Singh, J. P.

doi:10.1007/bf01184983

Cited by 130 publications

(99 citation statements)

References 28 publications

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“…(32), is a variable calculated from a microscopic model of a frame moving in a fluid and is here taken as ¼. Furthermore, the porosity dependency of the skeletal frame moduli (Young's modulus, , bulk modulus, , and rigidity modulus, ) can be expressed in terms of material volume fraction, ( ), and Young's modulus of the solid material of the frame, , as (Wagh et al 1991) (33-1)…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

Application of Acoustic Bessel Beams for Handling of Hollow Porous Spheres

Azarpeyvand

2014

Ultrasound in Medicine & Biology

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ABSTRACT-Acoustic manipulation of porous spherical shells, widely used as drug delivery carriers and magnetic resonance imaging contrast agents, is investigated analytically. The technique used for this purpose is based on the application of high-order Bessel beams for as a single-beam acoustic manipulation device, using which particles lying on the axis of the beam can be pulled toward the beam source. The exerted acoustic radiation force is calculated using the standard partial-wave series method and the wave propagation within the porous media is modeled using Biot's theory of poroelasticity. Numerical simulations are performed for porous aluminum and silica shells of different thicknesses and porosities.Results have shown that manipulation of low-porosity shells is possible using Bessel beams with large conical angles, over a number of broadband frequency ranges; while that for highly porous shells generally occurs over some narrowband frequency domains at much smaller conical angles.

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Section: Numerical Results and Discussionmentioning

confidence: 99%

Application of Acoustic Bessel Beams for Handling of Hollow Porous Spheres

Azarpeyvand

2014

Ultrasound in Medicine & Biology

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“…18,19 The increasing tortuosity is caused by pore coarsening. [20][21][22][23] Coarsening causes higher standard deviation in tortuosity caused by the variance in the pore size distribution.…”

Section: Electrochemical and Solid-state Letters 10 ͑12͒ B214-b217 ͑mentioning

confidence: 99%

Three-Dimensional Reconstruction of Porous LSCF Cathodes

Gostovic

Smith

Kundinger

et al. 2007

Electrochem. Solid-State Lett.

206

165

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In this initial study the electrochemically active region of a La 0.8 Sr 0.2 Co 0.2 Fe 0.8 O 3−␦ ͑LSCF͒ cathode was reconstructed in three dimensions using a focused ion beam/scanning electron microscope. The reconstructed volume totaled 1065 m 3 from the free air surface to the dense yttria-stabilized zirconia electrolyte interface. Various microstructural properties were measured, including overall porosity, closed porosity, graded porosity, surface area, tortuosity, triple-phase boundary length, and pore size. Electrochemical impedance spectroscopy data was correlated to microstructure. © 2007 The Electrochemical Society. ͓DOI: 10.1149/1.2794672͔ All rights reserved. Solid oxide fuel cells ͑SOFCs͒ are efficient, environmentally friendly, and fuel-flexible electrochemical devices for the generation of electrical power and heat.1 They consist of three basic layers: cathode, electrolyte, and anode. The cathode is a porous, conductive catalyst for the reduction of O 2 and for the oxidation of fuel. Between the cathode and anode is the dense electrolyte. The circuit is completed via cathode and anode contacts to an external load.The basic chemical formula for the cathodic reduction reaction isCurrent SOFC performance is limited by cathode polarization, which increases with decreasing operational temperatures. 2,3 Cathode microstructure and morphology have a strong effect on this polarization. [2][3][4] In this initial study a dual-beam focused ion beam/scanning electron microscope ͑FIB/SEM͒ was utilized to reconstruct an actual three-dimensional ͑3D͒ model of a La 0.8 Sr 0.2 Co 0.2 Fe 0.8 O 3−␦ ͑LSCF͒ cathode and its interface with a dense yttrium-stabilized zirconia ͑YSZ͒ electrolyte. This highresolution, 3D technique advances the understanding of the cathode microstructure's effect on performance. The identification of critical microstructural properties such as surface area, tortuosity, and interfacial porosity may be correlated with the ionic, electronic, and catalytic processes for a better fundamental understanding of electrochemical performance. With this tool, SOFC material and microstructural design can be more effective in reducing cathodic polarization at lower operational temperatures.The semiconductor industry has used the FIB since the 1980s to deposit, etch, micromachine, and image specimens during different stages of circuit processing. 5,6 This technology was brought forward to reconstruct 3D, geometrically complex submicrometer structures. [7][8][9][10][11] With the advent of 3D modeling software, nanotomography utilizing the dual-beam FIB/SEM technique was used to quantify nanoceramic suspended powders. [10][11][12] This technique was applied to SOFC cermet anodes to quantify microstructural properties such as porosity, triple-phase-boundary ͑TPB͒ length, and degree of anisotropy via tortuosity.13 Such a technique has never before been applied to reconstruct a cathode and the cathode/ electrolyte interface. ExperimentalSquare LSCF symmetric cell cathodes ͑8 ϫ 8 mm͒ were screen printed using prem...

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Section: Micromachines 2015 6 1373mentioning

confidence: 87%

“…Here, as an example we will use a conservative value (f = 1.20). Finally, as noted by Wagh et al [65] fittings of experimental data for different materials often give p c = 1 and this is the value we adopt for this example. Indeed, as indicated in Table 1, the values found for the different cases of porosity validate the above discussion of the decreased elastic modulus of the laser-affected zones.…”

Section: Micromachines 2015 6 1373mentioning

confidence: 89%

A Monolithic Micro-Tensile Tester for Investigating Silicon Dioxide Polymorph Micromechanics, Fabricated and Operated Using a Femtosecond Laser

Athanasiou

Bellouard

2015

Micromachines

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Mechanical testing of materials at the microscales is challenging. It requires delicate procedures not only for producing and handling the specimen to be tested, but also for applying an accurate and controlled force. This endeavor is even more challenging when it comes to investigating the behavior of brittle materials such as glass. Here, we present a microtensile tester for investigating silica glass polymorphs. The instrument is entirely made of silica and for which the same femtosecond laser is not only used for fabricating the device, but also for operating it (loading the specimen) as well as for performing in situ measurements. As a proof-of-concept, we present a stress-strain curve of fused silica for unprecedented high tensile stress of 2.4 GPa, as well as preliminary results of the elastic modulus of femtosecond laser-affected zones of fused silica, providing new insights on their microstructures and mechanical behavior.

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Open pore description of mechanical properties of ceramics

Cited by 130 publications

References 28 publications

Application of Acoustic Bessel Beams for Handling of Hollow Porous Spheres

Application of Acoustic Bessel Beams for Handling of Hollow Porous Spheres

Three-Dimensional Reconstruction of Porous LSCF Cathodes

A Monolithic Micro-Tensile Tester for Investigating Silicon Dioxide Polymorph Micromechanics, Fabricated and Operated Using a Femtosecond Laser

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