Analysis of Deformation of Porous Metals

1998 ◽  
Vol 521 ◽  
Author(s):  
Dong Nyung Lee ◽  
Heung Nam Han ◽  
Kyu Hwan Oh ◽  
Hyoung Seop Kim
Keyword(s):  
Yield Criterion ◽  
Porous Metal ◽  
Porous Iron ◽  
Porous Metals ◽  
Metal Rings ◽  
Porous Copper ◽  
Inner Diameter ◽  
The Relationship ◽  
Hardness Values ◽  
Good Agreement

ABSTRACTThe elasto-plastic finite element method using a yield criterion advanced by Lee and Kim was employed to analyze the effect of indenting geometry on the Brinell hardness of sintered porous copper specimens with various densities. The changes in geometry of porous iron rings with various initial relative densities were also calculated for various friction coefficients between the metal rings and compression platens. The calculated hardness values were in very good agreement with the measured data. The friction coefficient could be determined from the relationship between the change in the inner diameter and height reduction of porous metal rings with various initial relative densities.

Experimental Study of Acoustic Performance of Porous Metals at High Temperatures

2018 ◽  
Vol 933 ◽  
pp. 373-379
Author(s):  
Jun Zhe Zhang ◽  
Xiao Peng Wang ◽  
Bo Zhang ◽  
Li Hong Zhang
Keyword(s):  
High Temperatures ◽  
Temperature Stability ◽  
Porous Metal ◽  
Acoustic Properties ◽  
Temperature Fields ◽  
Testing System ◽  
Porous Metals ◽  
Ambient Temperatures ◽  
Acoustic Performance ◽  
Good Agreement

Based on an improved two-microphone transfer function method, a testing system for the exploration of acoustic performance of porous materials under high temperature conditions was developed with porous foam copper as one of research objects. The acoustic performances of some porous metallic materials were studied in the temperature range of 300°C to 700°C under the premise of ensuring the temperature stability that makes the measurement uncertainty be ± 6°C at high temperatures. The sound absorption coefficient and the acoustic impedance ratio of porous coppers at different ambient temperatures were acquired accordingly. And then the influence of the variation of temperature fields on the acoustic properties of porous metals was analyzed. The experimental results are in good agreement with the theoretical analysis, which proves the rationality of design of the device and provides important references and specific guidance for future study of the acoustic properties of porous metal materials.

Porosity Measurement of Porous Copper by Unidirectional Solidification

2012 ◽  
Vol 724 ◽  
pp. 197-200
Author(s):  
Hao Du ◽  
Yuan Xia Lao ◽  
Jian Zhong Qi ◽  
Tian Ying Xiong
Keyword(s):  
Relative Density ◽  
Cross Section ◽  
Density Ratio ◽  
Porous Metal ◽  
Unidirectional Solidification ◽  
Analysis Method ◽  
Porous Metals ◽  
Image Analysis Method ◽  
Density Method ◽  
Porous Copper

Generally, there are two ways available for porosity measurement of porous metals. One is by calculating density ratio of a porous metal and a corresponding non-porous metal, called as relative density method. The other is by counting the percentage of pores on cross section of a porous metal, called as image analysis method. In this work, both methods were employed for lotus-type porous copper on porosity measurement. The effects of several parameters in both methods on porosity values of the porous copper are reported and discussed. The relative density method is recommended as porosity by this method is more reliable for the porous copper.

Effect of Pore Diameter Distribution on Heat Transfer Capacity of Lotus-Type Porous Copper Heat Sink for Air Cooling

2010 ◽  
Vol 658 ◽  
pp. 220-223 ◽  
Author(s):  
Hiroshi Chiba ◽  
T. Ogushi ◽  
Shunkichi Ueno ◽  
Hideo Nakajima
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Pore Diameter ◽  
Small Diameter ◽  
Porous Metal ◽  
Diameter Distribution ◽  
Air Cooling ◽  
Porous Metals ◽  
Porous Copper ◽  
Heat Transfer Capacity

Lotus-type porous metal with many straight pores is attractive as a heat sink because larger heat transfer capacity is obtained due to the small diameter of the pores. The heat transfer capacity of the lotus-type porous copper heat sink was calculated using the model with the pores of uniform diameters. However, actual lotus-type porous metals have a distribution of pore diameter. In the present work, we investigated the lotus-type porous copper fin model by considering size distribution of the lotus-type porous copper fin. Prediction of the heat transfer characteristics for the lotus-type porous copper heat sink shows a good agreement with the experimental data.

scholarly journals Heat Transfer Enhancement Using Unidirectional Porous Media under High Heat Flux Conditions

2021 ◽  
Author(s):  
Kazuhisa Yuki
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Enhancement ◽  
Porous Metal ◽  
High Heat ◽  
High Heat Flux ◽  
Porous Metals ◽  
Transfer Enhancement ◽  
Two Phase ◽  
Porous Copper

In this chapter, new heat transfer enhancement technologies with unidirectional porous metal called “EVAPORON” and “Lotus’ Breathing” are introduced to remove and manage heat from high heat flux equipment. The unidirectional porous metals introduced here can be easily fabricated by unique techniques such as mold casting technique, explosive welding technique, and 3D printing technique. First of all, many kinds of porous media, which have been introduced by the author so far as a heat transfer promoter, are compared each other to clarify what kind of porous metal is more suitable for high heat flux removal and cooling by focusing on the permeability and the effective thermal conductivity. For the practical use of the unidirectional porous copper with high permeability and high thermal conductivity, at first, heat transfer performance of two-phase flow cooling using a heat removal device called “EVAPORON” is reviewed aiming at extremely high heat flux removal beyond 10 MW/m2. We have been proposing this device with the unidirectional porous copper fabricated by 3D printing technique as the heat sink of a nuclear fusion divertor and a continuous casting mold. Second, two-phase immersion cooling technique called “Lotus’ Breathing” utilizing “Breathing Phenomenon” is introduced targeting at thermal management of various electronics such as power electronics and high performance computers. The level of the heat flux is 0.1 MW/m2 to 5 MW/m2. In addition, as the other heat transfer enhancing technology with unidirectional porous metals, unidirectional porous copper pipes fabricated by explosive welding technique are also introduced for heat transfer enhancement of single-phase flow.

scholarly journals Experimental studies on the transformation from firn to ice in the wet-snow zone of temperate glaciers

1997 ◽  
Vol 24 ◽  
pp. 181-185 ◽  
Author(s):  
Katsuhisa Kawashima ◽  
Tomomi Yamada
Keyword(s):  
Experimental Studies ◽  
Ice Formation ◽  
Compression Tests ◽  
Densification Rate ◽  
Overburden Pressure ◽  
Proportionality Constant ◽  
Wet Snow ◽  
Water Saturated ◽  
The Relationship ◽  
Good Agreement

The densification of water-saturated firn, which had formed just above the firn-ice transition in the wet-snow zone of temperate glaciers, was investigated by compression tests under pressures ranging from 0.036 to 0.173 MPa, with special reference to the relationship between densification rate, time and pressure. At each test, the logarithm of the densification rate was proportional to the logarithm of the time, and its proportionality constant increased exponentially with increasing pressure. The time necessary for ice formation in the firn aquifer was calculated using the empirical formula obtained from the tests. Consequently, the necessary time decreased exponentially as the pressure increased, which shows that the transformation from firn in ice can be completed within the period when the firn aquifer exists, if the overburden pressure acting on the water-saturated firn is above 0.12–0.14 MPa. This critical value of pressure was in good agreement with the overburden pressure obtained from depth–density curves of temperate glaciers. It was concluded that the depth of firn–ice transition was self-balanced by the overburden pressure to result in the concentration between 20 and 30 m.

Estimation of Interlayer Thickness in Inorganic Particulate-Filled Polymer Composites

2011 ◽  
Vol 24 (6) ◽  
pp. 777-788 ◽  
Author(s):  
J.Z. Liang
Keyword(s):  
Polymer Composites ◽  
Volume Fraction ◽  
Particle Diameter ◽  
Interfacial Structure ◽  
Interlayer Thickness ◽  
Filled Polymer ◽  
Mechanical And Physical Properties ◽  
The Relationship ◽  
Good Agreement

The structure of the interlayer between matrix and inclusions affect directly the mechanical and physical properties of inorganic particulate-filled polymer composites. The interlayer thickness is an important parameter for characterization of the interfacial structure. The effects of the interlayer between the filler particles and matrix on the mechanical properties of polymer composites were analyzed in this article. On the basis of a simplified model of interlayer, an expression for estimating the interlayer thickness ([Formula: see text]) was proposed. In addition, the relationship between the [Formula: see text] and the particle size and its concentration was discussed. The results showed that the calculations of the [Formula: see text] and thickness/particle diameter ratio ([Formula: see text]) increased nonlinearly with an increase of the volume fraction of the inclusions. Moreover, the predictions of [Formula: see text] and the relevant data reported in literature were compared, and good agreement was found between them.

TCAD Study of the Raised SiGe Source/Drain in 40nm PMOS

2015 ◽  
Vol 645-646 ◽  
pp. 70-74 ◽  
Author(s):  
Min Zhong ◽  
Yu Hang Zhao ◽  
Shou Mian Chen ◽  
Ming Li ◽  
Shao Hai Zeng ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Critical Role ◽  
Sige Layer ◽  
Strain Engineering ◽  
Effect Transistor ◽  
Simulation Results ◽  
Aided Design ◽  
The Relationship ◽  
Growth Experiments ◽  
Good Agreement

An embedded SiGe layer was applied in the source/drain areas (S/D) of a field-effect transistor to boost the performance in the p channels. Raised SiGe S/D plays a critical role in strain engineering. In this study, the relationship between the SiGe overfilling and the enhancement of channel stress was investigated. Systematic technology computer aided design (TCAD) simulations of the SiGe overfill height in a 40 nm PMOS were performed. The simulation results indicate that a moderate SiGe overfilling induces the highest stress in the channel. Corresponding epitaxial growth experiments were done and the obtained experimental data was in good agreement with the simulation results. The effect of the SiGe overfilling is briefly discussed. The results and conclusions presented within this paper might serve as useful references for the optimization of the embedded SiGe stressor for 40 nm logic technology node and beyond.

Hard Materials with Tunable Porosity

MRS Bulletin ◽  
2009 ◽  
Vol 34 (8) ◽  
pp. 561-568 ◽  
Author(s):  
Jonah Erlebacher ◽  
Ram Seshadri
Keyword(s):  
Porous Materials ◽  
Self Assembly ◽  
Porous Metal ◽  
Ceramic Materials ◽  
Equilibrium Temperature ◽  
Length Scale ◽  
Porous Metals ◽  
Hard Materials ◽  
Mesoporous Zeolites ◽  
Pattern Forming

AbstractPorous metals and ceramic materials are of critical importance in catalysis, sensing, and adsorption technologies and exhibit unusual mechanical, magnetic, electrical, and optical properties compared to nonporous bulk materials. Materials with nanoscale porosity often are formed through molecular self-assembly processes that lock in a particular length scale; consider, for instance, the assembly of crystalline mesoporous zeolites with a pore size of 2–50 nm or the evolution of structural domains in block copolymers. Of recent interest has been the identification of general kinetic pattern-forming principles that underlie the formation of mesoporous materials without a locked- in length scale. When materials are kinetically locked out of thermodynamic equilibrium, temperature or chemistry can be used as a “knob” to tune their microstructure and properties. In this issue of the MRS Bulletin, we explore new porous metal and ceramic materials, which we collectively refer to as “hard” materials, formed by pattern-forming instabilities, either in the bulk or at interfaces, and discuss how such nonequilibrium processing can be used to tune porosity and properties. The focus on hard materials here involves thermal, chemical, and electrochemical processing usually not compatible with soft (for example, polymeric) porous materials and generally adds to the rich variety of routes to fabricate porous materials.

Phase stability, Debye temperature and hardness of semiconducting manganese tetraboride MnB4: First-principles investigations

2017 ◽  
Vol 31 (20) ◽  
pp. 1750131 ◽  
Author(s):  
Ming-Min Zhong ◽  
Cheng Huang ◽  
Chun-Ling Tian
Keyword(s):  
Debye Temperature ◽  
Phase Stability ◽  
First Principles ◽  
Formation Enthalpy ◽  
Structural Features ◽  
High Melting Point ◽  
Fundamental Understanding ◽  
New Perspective ◽  
The Relationship ◽  
Good Agreement

First-principles investigations are employed to provide a fundamental understanding of the structural features, phase stability, mechanical properties, Debye temperature, and hardness of manganese tetraboride. Eight candidate structures of known transition-metal tetraborides are chosen to probe. The calculated lattice parameters, elastic properties, Poisson’s ratio, and [Formula: see text] ratio are derived. It is observed that the monoclinic structure with [Formula: see text] symmetry (MnB4–MnB4) is the most stable in energy. The mechanical and thermodynamic stabilities of seven possible phases are confirmed by the calculated elastic constants and formation enthalpy. Moreover, the analysis on density of states demonstrates semiconducting behavior of MnB4–MnB4 and different metallic behaviors of other phases. The estimated hardness of MnB4–MnB4 is 38.3 GPa, which is in good agreement with experimental value. Furthermore, the relationship between hardness and Debye temperature is investigated and verifies that MnB4–MnB4 is a newly potential semiconducting ultrahard material with high melting point. It provides a new perspective of searching for semiconducting superhard materials to be applied in extreme conditions.

Estimating the influence of temperature on the survival of chinook salmon smolts (Oncorhynchus tshawytscha) migrating through the Sacramento – San Joaquin River Delta of California

1995 ◽  
Vol 52 (4) ◽  
pp. 855-863 ◽  
Author(s):  
Peter Fritz Baker ◽  
Franklin K. Ligon ◽  
Terence P. Speed
Keyword(s):  
Water Temperature ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Logistic Function ◽  
Laboratory Findings ◽  
Natural Systems ◽  
San Joaquin River ◽  
Influence Of Temperature On ◽  
The Relationship ◽  
Good Agreement

Data from the U.S. Fish and Wildlife Service are used to investigate the relationship between water temperature and survival of hatchery-raised fall-run chinook salmon (Oncorhynchus tshawytscha) smolts migrating through the Sacramento – San Joaquin Delta of California. A formal statistical model is presented for the release of smolts marked with coded-wire tags (CWTs) in the lower Sacramento River and the subsequent recovery of marked smolts in midwater trawls in the Delta. This model treats survival as a logistic function of water temperature, and the release and recovery of different CWT groups as independent mark–recapture experiments. Iteratively reweighted least squares is used to fit the model to the data, and simulation is used to establish confidence intervals for the fitted parameters. A 95% confidence interval for the upper incipient lethal temperature, inferred from the trawl data by this method, is 23.01 ± 1.08 °C This is in good agreement with published experimental results obtained under controlled conditions (24.3 ± 0.1 and 25.1 ± 0.1 °C for chinook salmon acclimatized to 10 and 20 °C, respectively): this agreement has implications for the applicability of laboratory findings to natural systems.

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