Synthesis of Porous Noble Metal Films With Tunable Porosity by Timed Dealloying

2018 ◽  
Author(s):  
Stanislau Niauzorau ◽  
Placid Ferreira ◽  
Bruno Azeredo
Keyword(s):  
Thin Films ◽  
Pore Size ◽  
Pore Volume ◽  
Volume Fraction ◽  
Chemical Catalysis ◽  
Nanoporous Films ◽  
Simple Strategy ◽  
Pore Volume Fraction ◽  
Nanoporous Metal ◽  
High Degree

Nanoporous metal foams have an increasing importance in applications such as chemical catalysis, energy storage, and nanomedicine. This paper examines a simple strategy for controlling the pore volume fraction and pore size of nanoporous films synthesized by dealloying thin-films. By means of controlling the temperature and concentration of nitric acid in dealloying of AgAu thin-films, partially dealloyed AgAu nanoporous films are produced with a high degree of control over the pore size and pore volume fraction. Such capability enables the design of nanoporous metal catalysts materials with desired morphology.

Instrumented Microindentation of Nanoporous Alumina Films

2005 ◽  
Vol 128 (2) ◽  
pp. 225-233 ◽  
Author(s):  
Ken Gall ◽  
Yiping Liu ◽  
Dmitri Routkevitch ◽  
Dudley S. Finch
Keyword(s):  
Thin Films ◽  
Pore Volume ◽  
Volume Fraction ◽  
Hertzian Contact ◽  
Porous Solids ◽  
Nanoporous Structure ◽  
Nanoporous Films ◽  
Pore Volume Fraction ◽  
Spherical Ball ◽  
Depth Response

We examine the mechanical behavior of anodic alumina thin films with organized nanometer-scale porosity. The cylindrical pores in the alumina film are arranged perpendicular to the film thickness in a near-perfect triangular lattice. The films used in this work had pore diameters ranging from 35 to 75nm, and volume fractions ranging from 10% to 45%. Films with both amorphous and crystalline structures were considered. Mechanical properties of the thin films were studied using an instrumented indentor to measure the force-depth response of the films during indentation or the force-deflection response of micromachined beams in bending. The films showed increasing hardness/modulus with a decrease in pore volume fraction or transformation from amorphous to a polycrystalline alpha-alumina phase. The asymmetric films show higher hardness and modulus on their barrier side (with closed pores) relative to their open pore side. The force-depth response, measured with a spherical ball indentor, demonstrates fairly good agreement with an elastic Hertzian contact solution. The force-depth response, measured with a sharp Vickers indentor, shows an elastoplastic response. Microcracking at the corners of sharp indentations was not observed in amorphous nanoporous films, and rarely in harder, crystalline nanoporous films. High-resolution scanning electron microscopy revealed a collapse of the nanoporous structure beneath the indentor tip during sharp indentation. The results are discussed in light of continuum-based models for the elastic properties of porous solids. In general, the models are not capable of predicting the change in modulus of the films, given pore volume fraction and the properties of bulk crystalline alumina.

Microstructural Tailoring of Open-Pore Microcellular Aluminium by Replication Processing

2006 ◽  
Vol 512 ◽  
pp. 281-288 ◽  
Author(s):  
Jean-François Despois ◽  
Ariane Marmottant ◽  
Yves Conde ◽  
Russell Goodall ◽  
Luc Salvo ◽  
...  
Keyword(s):  
Pore Size ◽  
Pore Volume ◽  
Volume Fraction ◽  
Pore Shape ◽  
Replication Process ◽  
Microstructural Parameters ◽  
Pore Volume Fraction

The replication process is presented and discussed with emphasis on methods for microstructural tailoring of open-pore microcellular aluminium-based foams, highlighting methods it offers for control of principal foam mesostructural and microstructural parameters: pore volume fraction, pore shape, pore size(s), as well as the composition and microstructure of the metal making the foam.

Estimation of porosity, fluid bulk modulus, and stiff-pore volume fraction using a multi-trace Bayesian AVO petrophysics inversion in multi-porosity reservoirs

Geophysics ◽  
2021 ◽  
pp. 1-101
Author(s):  
Kun Li ◽  
Xingyao Yin ◽  
Zhaoyun Zong ◽  
Dario Grana
Keyword(s):  
Bulk Modulus ◽  
Pore Volume ◽  
Elastic Moduli ◽  
Wave Reflection ◽  
Volume Fraction ◽  
Inversion Method ◽  
Reservoir Properties ◽  
Pore Volume Fraction ◽  
Pp Wave ◽  
Matrix Shear

The estimation of petrophysical and fluid-filling properties of subsurface reservoirs from seismic data is a crucial component of reservoir characterization. Seismic amplitude variation with offset (AVO) inversion driven by rock physics is an effective approach to characterize reservoir properties. Generally, PP-wave reflection coefficients, elastic moduli and petrophysical parameters are nonlinearly coupled, especially in the multiple type pore-space reservoirs, which makes seismic AVO petrophysics inversion ill-posed. We propose a new approach that combines Biot-Gassmann’s poro-elasticity theory with Russell’s linear AVO approximation, to estimate the reservoir properties including elastic moduli and petrophysical parameters based on multi-trace probabilistic AVO inversion algorithm. We first derive a novel PP-wave reflection coefficient formulation in terms of porosity, stiff-pore volume fraction, rock matrix shear modulus, and fluid bulk modulus to incorporate the effect of pore structures on elastic moduli by considering the soft and stiff pores with different aspect ratios in sandstone reservoirs. Through the analysis of the four types of PP-wave reflection coefficients, the approximation accuracy and inversion feasibility of the derived formulation are verified. The proposed stochastic inversion method aims to predict the posterior probability density function in a Bayesian setting according to a prior Laplace distribution with vertical correlation and prior Gaussian distribution with lateral correlation of model parameters. A Metropolis-Hastings stochastic sampling algorithm with multiple Markov chains is developed to simulate the posterior models of porosity, stiff-pore volume fraction, rock-matrix shear modulus, and fluid bulk modulus from seismic AVO gathers. The applicability and validity of the proposed inversion method is illustrated with synthetic examples and a real data application.

Electrical, Mechanical, and Structural Properties of Fluoro-Containing Poly(silsesquioxanes) Based Porous Low k Thin Films

2003 ◽  
Vol 766 ◽  
Author(s):  
Jingyu Hyeon-Lee ◽  
Jihoon Rhee ◽  
Jungbae Kim ◽  
Jin-Heong Yim ◽  
Seok Chang
Keyword(s):  
Thin Films ◽  
Pore Size ◽  
Dielectric Constants ◽  
Commercial Application ◽  
Porous Films ◽  
Low Dielectric ◽  
Nanoporous Films ◽  
Positronium Annihilation ◽  
Positronium Annihilation Lifetime Spectroscopy ◽  
Low K

AbstractLow dielectric fluoro-containing poly(silsesquioxanes) (PSSQs) have been synthesized using trifluoropropyl trimethoxysilane (TFPTMS), methyl trimethoxysilane (MTMS), and 2, 4, 6, 8-tetramethyl-2, 4, 6, 8-tetra(trimethoxysilylethyl) cyclotetrasiloxane. The properties of fluorocontaining PSSQs based thin films were studied by electrical, mechanical, and structural characterization. Film was spun on a silicon substrate, baked at 150°C and 250°C for 1 minute, respectively, and cured in the furnace at 420°C for 1 hour under vacuum condition. Thermally decomposable trifluoropropyl groups of the fluoro-containing PSSQ were served as a pore generator and partially contributed to lower a dielectric constant. â-cyclodextrin (CD) was also employed as a pore generator. The concentration of the pore generator in the film was varied from 0 to 30 %. The dielectric constants of the porous PSSQ films were found to be in the range of 2.7 – 1.9 (at 100 kHz). Hardness and Young's modulus of the films were measured by nano-indentation. The elastic modulus and hardness of the porous films were well correlated with the concentration of the pore generators. Positronium Annihilation Lifetime Spectroscopy (PALS) was employed to characterize a pore size of the porous fluoro-containing PSSQ film. The pore size of the film was less than 2.2 nm. The nanoporous films showed quite promising properties for commercial application.

Effect of the pore volume fraction on the thermal conductivity and mechanical properties of kaolin-based foams

2013 ◽  
Vol 33 (9) ◽  
pp. 1487-1495 ◽  
Author(s):  
J. Bourret ◽  
N. Tessier-Doyen ◽  
B. Naït-Ali ◽  
F. Pennec ◽  
A. Alzina ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Pore Volume ◽  
Volume Fraction ◽  
Pore Volume Fraction

Effect of the Pore Formation on the Solution Flow through Acrylamide Gel

1999 ◽  
Vol 600 ◽  
Author(s):  
H. Tamagawa ◽  
S. Popovic ◽  
M. Taya
Keyword(s):  
Flow Rate ◽  
Pore Volume ◽  
Pore Formation ◽  
Volume Fraction ◽  
Synthesis Method ◽  
Solution Flow Rate ◽  
Gelation Temperature ◽  
Solution Flow ◽  
Pore Volume Fraction ◽  
Flow Through

AbstractA simple synthesis method of porous acrylamide gel is proposed. Pore formation in gel body is dominated by the amount of polymerization initiator, accelerator and gelation temperature. We investigated the influence of these factors on the number and the size of pores. Gelation temperature control is the easiest and the most effective way to create a number of large pores in a gel body. We also investigated the pore volume fraction dependence of solution flow through the gels. Solution flow rate was found to be promoted with the increase of pore volume fraction.

scholarly journals Effect of Pip Cycles on Fracture Behaviour in Unidirectional SiC Fibre-Reinforced SiC Matrix Composite

1999 ◽  
Vol 8 (3) ◽  
pp. 096369359900800 ◽  
Author(s):  
H. Kakisawa ◽  
Y. Kagawa ◽  
M. Takeda ◽  
Y. Imai ◽  
H. Ichikawa
Keyword(s):  
Tensile Strength ◽  
Matrix Composite ◽  
Fracture Mode ◽  
Pore Volume ◽  
Volume Fraction ◽  
Fracture Behaviour ◽  
Shear Fracture ◽  
Pore Volume Fraction ◽  
Point Bend ◽  
Polymer Infiltration

The effect of pore volume fraction in unidirectional SiC fibre (Nicalon™)-reinforced SiC matrix composite fabricated by polymer infiltration pyrolysis (PIP) process on three-point bend fracture behaviour has been studied. The pore volume fraction, f u, is varied by changing the number of PIP cycles, N. Results shows that the shear fracture mode is dominant at f u ≥ 0.36 and the strength increased with the decrease of f u. On the other hand, the tensile mode was dominant at f u ≤ 0.17 and the tensile strength was independent of fu. Transition of the fracture mode occurred when the ratio of shear strength to constant tensile strength was reached ≈ 1/30.

scholarly journals Cortical Bone Water Concentration: Dependence of MR Imaging Measures on Age and Pore Volume Fraction

Radiology ◽  
2014 ◽  
Vol 272 (3) ◽  
pp. 796-806 ◽  
Author(s):  
Cheng Li ◽  
Alan C. Seifert ◽  
Hamidreza Saligheh Rad ◽  
Yusuf A. Bhagat ◽  
Chamith S. Rajapakse ◽  
...  
Keyword(s):  
Mr Imaging ◽  
Cortical Bone ◽  
Concentration Dependence ◽  
Pore Volume ◽  
Volume Fraction ◽  
Water Concentration ◽  
Pore Volume Fraction ◽  
Bone Water
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