The Influence of Internal Pore Pressure During Roll Forming of Structurally Porous Metals

1998 ◽  
Vol 521 ◽  
Author(s):  
D. M. Elzey ◽  
H. N. G. Wadley
Keyword(s):  
Pore Pressure ◽  
High Pressures ◽  
Hot Isostatic Pressing ◽  
Matrix Material ◽  
Porous Metal ◽  
Roll Forming ◽  
Dense Matrix ◽  
Porous Metals ◽  
Noticeable Effect ◽  
Internal Pore

ABSTRACTStructurally porous metal sandwich panels consisting of dense face sheets and porous cores of controlled relative density can be manufactured by trapping inert gas during hot isostatic pressing and modifying its distribution via subsequent thermo-mechanical forming. At high pressures, the internal gas is expected to influence the forming response. This paper describes a model for the roll forming of a porous metal panel and its use to explore the effects of internal pore pressure upon rolling response. It is shown that for gas pressures below about half the yield strength of the fully dense matrix material, there is essentially no influence on the forming response. Only in the case of very high initial pore pressures or at relative densities approaching full theoretical does a noticeable effect arise. In this case, a limiting upper density is attainable which depends on the specific rolling conditions and geometry.

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.

Experimental investigation of the effect of compliant pores on reservoir rocks under hydrostatic and triaxial compression stress states

2019 ◽  
Vol 56 (7) ◽  
pp. 983-991
Author(s):  
Hua Yu ◽  
Kam Ng ◽  
Dario Grana ◽  
John Kaszuba ◽  
Vladimir Alvarado ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Triaxial Compression ◽  
Matrix Material ◽  
Volumetric Strain ◽  
Confining Pressure ◽  
Differential Pressure ◽  
Sandstone Sample ◽  
Stress States ◽  
Rock Springs ◽  
Stage 1

The presence of compliant pores in rocks is important for understanding the stress–strain behaviors under different stress conditions. This paper describes findings on the effect of compliant pores on the mechanical behavior of a reservoir sandstone under hydrostatic and triaxial compression. Laboratory experiments were conducted at reservoir temperature on Weber Sandstone samples from the Rock Springs Uplift, Wyoming. Each experiment was conducted at three sequential stages: (stage 1) increase in the confining pressure while maintaining the pore pressure, (stage 2) increase in the pore pressure while maintaining the confining pressure, and (stage 3) application of the deviatoric load to failure. The nonlinear pore pressure – volumetric strain relationship governed by compliant pores under low confining pressure changes to a linear behavior governed by stiff pores under higher confining pressure. The estimated compressibilities of the matrix material in sandstone samples are close to the typical compressibility of quartz. Because of the change in pore structures during stage 1 and stage 2 loadings, the estimated bulk compressibilities of the sandstone sample under the lowest confining pressure decrease with increasing differential pressure. The increase in crack initiation stress is limited with increasing differential pressure because of similar total crack length governed by initial compliant porosity in sandstone samples.

scholarly journals Preparation and Characterization of Gradient Compressed Porous Metal for High-Efficiency and Thin-Thickness Acoustic Absorber

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1413 ◽  
Author(s):  
Xiaocui Yang ◽  
Xinmin Shen ◽  
Panfeng Bai ◽  
Xiaohui He ◽  
Xiaonan Zhang ◽  
...  
Keyword(s):  
Sound Absorption ◽  
High Efficiency ◽  
Structural Parameters ◽  
Porous Metal ◽  
Theoretical Models ◽  
Absorption Efficiency ◽  
Total Thickness ◽  
Porous Metals ◽  
Absorption Coefficients ◽  
Optimal Average

Increasing absorption efficiency and decreasing total thickness of the acoustic absorber is favorable to promote its practical application. Four compressed porous metals with compression ratios of 0%, 30%, 60%, and 90% were prepared to assemble the four-layer gradient compressed porous metals, which aimed to develop the acoustic absorber with high-efficiency and thin thickness. Through deriving structural parameters of thickness, porosity, and static flow resistivity for the compressed porous metals, theoretical models of sound absorption coefficients of the gradient compressed porous metals were constructed through transfer matrix method according to the Johnson–Champoux–Allard model. Sound absorption coefficients of four-layer gradient compressed porous metals with the different permutations were theoretically analyzed and experimentally measured, and the optimal average sound absorption coefficient of 60.33% in 100–6000 Hz was obtained with the total thickness of 11 mm. Sound absorption coefficients of the optimal gradient compressed porous metal were further compared with those of the simple superposed compressed porous metal, which proved that the former could obtain higher absorption efficiency with thinner thickness and fewer materials. These phenomena were explored by morphology characterizations. The developed high-efficiency and thin-thickness acoustic absorber of gradient compressed porous metal can be applied in acoustic environmental detection and industrial noise reduction.

scholarly journals Subcellular compartmentalization of maize storage proteins in Xenopus oocytes injected with zein messenger RNAs.

1981 ◽  
Vol 89 (2) ◽  
pp. 292-299 ◽  
Author(s):  
W J Hurkman ◽  
L D Smith ◽  
J Richter ◽  
B A Larkins
Keyword(s):  
Storage Proteins ◽  
Matrix Material ◽  
Membrane Vesicles ◽  
Subcellular Fractionation ◽  
Dense Matrix ◽  
Messenger Rnas ◽  
Material Density ◽  
Optimal Separation ◽  
High Concentrations ◽  
Subcellular Compartmentalization

Maize storage proteins synthesized in oocytes were compartmentalized in membrane vesicles because they were resistant to hydrolysis by protease, unless detergent was present. The site of storage protein deposition within the oocyte was determined by subcellular fractionation. Optimal separation of oocyte membranes and organelles was obtained when EDTA and high concentrations of NaCl were included in the homogenization and gradient buffers. Under these conditions, fractions in sucrose gradients containing a heterogeneous mixture of smooth membranes (presumably endoplasmic reticulum, Golgi apparatus, and plasma membrane, density = 1.10-1.12 g/cm3), mitochondria (densities = 1.14 and 1.16 g/cm3), yolk platelets (density = 1.21 g/cm3), and a dense matrix material (density = 1.22 g/cm3) could be separated. Some zein proteins were recovered in the mixed membrane fraction, but the majority occurred in vesicles sedimenting with yolk platelets and granular material at a density of approximately 1.22 g/cm3. When metrizamide was included in the gradient to increase the density, little of the dense matrix material was isolated, and vesicles containing zein proteins were separated from other oocyte components. These vesicles were similar to protein bodies in maize endosperm because they were of identical density and contained the same group of polypeptides.

scholarly journals Heat-exchange units with porous inserts

2019 ◽  
Vol 140 ◽  
pp. 05006 ◽  
Author(s):  
Oleg Stepanov ◽  
Boris Aksenov ◽  
Natalia Rydalina ◽  
Elena Antonova
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Heat Supply ◽  
Analytical Data ◽  
Porous Metal ◽  
Hot Water ◽  
Porous Metals ◽  
Proposed Model ◽  
Heat Supply Systems ◽  
Supply Systems

Currently, porous metals are not used in heat supply systems. Usage of porous materials in heat exchangers increases the heat transfer intensity and makes the heat exchangers more compact. An experimental setup consisting of two circuits was developed in order to study the influence of porous metals on heat transfer intensity. In the first circuit the hot coolant is water, which flows through narrow tubes inside the porous metal. In the second circuit the cold coolant is freon. The purpose of the study is to obtain experimental confirmation of the hypothesis of an increase in the heat transfer intensity when using porous metals. To achieve this goal, experiments were carried out, which showed the increased heat transfer intensity. The standard methods for calculating heat exchangers cannot be applied in this case as the inner pores’ surface is unknown. A mathematical model was compiled allowing engineering calculations for the heat exchangers of this type. The hot water temperature inside the heat exchanger is determined analytically. The resulting equation allows us to determine the cooling degree of the first coolant, i.e. hot water. The obtained deviations between experimental and analytical data are within the acceptable limits, which indicates the reliability of the proposed model.

scholarly journals Manufacturing And High Temperature Oxidation Properties Of Electro-Sprayed Fe-24.5% Cr-5%Al Powder Porous Metal

2015 ◽  
Vol 60 (2) ◽  
pp. 1169-1173
Author(s):  
Kee-Ahn Lee ◽  
Jae-Sung Oh ◽  
Young-Min Kong ◽  
Byoung-Kee Kim
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Porous Metal ◽  
Porous Metals ◽  
Temperature Oxidation ◽  
Spray Process ◽  
Surface Areas ◽  
Thermal Gravimetry ◽  
Oxidation Properties ◽  
Al Powder

Abstract Fe-Cr-Al based Powder porous metals were manufactured using a new electro-spray process, and the microstructures and high-temperature oxidation properties were examined. The porous materials were obtained at different sintering temperatures (1350°C, 1400°C, 1450°C, and 1500°)C and with different pore sizes (500 μm, 450 μm, and 200 μm). High-temperature oxidation experiments (TGA, Thermal Gravimetry Analysis) were conducted for 24 hours at 1000°C in a 79% N2+ 21% O2, 100 mL/min. atmosphere. The Fe-Cr-Al powder porous metals manufactured through the electro-spray process showed more-excellent oxidation resistance as sintering temperature and pore size increased. In addition, the fact that the densities and surface areas of the abovementioned powder porous metals had the largest effects on the metal’s oxidation properties could be identified.

scholarly journals Effect of HIP Parameters on the Micro-Structural Evolution of a Single Crystal Ni-Based Superalloy

2011 ◽  
Vol 278 ◽  
pp. 72-77 ◽  
Author(s):  
Inmaculada Lopez-Galilea ◽  
Stephan Huth ◽  
Marion Bartsch ◽  
Werner Theisen
Keyword(s):  
Single Crystal ◽  
Atmospheric Pressure ◽  
High Pressures ◽  
Hot Isostatic Pressing ◽  
Structural Evolution ◽  
Local Deformation ◽  
Local Distribution ◽  
Slow Cooling ◽  
Distribution Of Elements ◽  
Hardened State

For reducing the porosity of single crystal (SX) nickel-based superalloys, Hot Isostatic Pressing (HIP) is used. High pressures of about 100-170 MPa lead to local deformation, which close the pores. However, since HIP also requires high temperatures (1000-1200°C) it has a pronounced effect on the microstructure and the local distribution of elements. This contribution analyses the effect of different HIP treatments on both the microstructure and the segregation of the SX superalloy LEK94 in the as-precipitation-hardened state. In addition, the effects of rapid or slow cooling are analyzed. To distinguish the effect of pressure from those of temperature, the HIPed samples are compared with specimens annealed at atmospheric pressure.

Bioactive Void Metal Composites for Orthopedic Implant Devices

1995 ◽  
Vol 414 ◽  
Author(s):  
Allison A. Campbell ◽  
Gordon L. Graff ◽  
Lin Song ◽  
Ken R. Sump
Keyword(s):  
Pore Diameter ◽  
Porous Metal ◽  
Metal Composite ◽  
Porous Metals ◽  
Mineral Phase ◽  
Bioactive Coatings ◽  
Complex Shapes ◽  
Cylindrical Pores ◽  
Implant Coating ◽  
Uniform Diameter

AbstractAlthough significant advances have been made to provide mechanically strong and nontoxic metals and alloys, biological integration of devices into natural tissues remains a problem. The Surface Induced Mineralization (SIM) and Void Metal Composite (VMC) processes produce a bioactive porous metal implant coating/device which may address many of the problems associated with conventional processing methods.The VMC process produces materials which have cylindrical pores of uniform diameter which can completely penetrate the structure of the material. The pore diameter, orientation and interconnectivety are easily controlledThe SIM process uses the idea of nature's template-mediated mineralization by chemically modifying the implant to produce a surface which induces heterogeneous nucleation from aqueous solution. SIM produced bioactive coatings provide 1) control of the thickness and density of the mineral phase, 2) a way to coat porous metals, complex shapes and large objects, 3) the ability to coat a wide variety of materials, 4) potential choice for the phase of the mineral formed.

Fabrication of Lotus-Type Porous Metals by Continuous Zone Melting and Continuous Casting Techniques

2007 ◽  
Vol 539-543 ◽  
pp. 187-192 ◽  
Author(s):  
Hideo Nakajima ◽  
Soong Keun Hyun ◽  
J.S. Park ◽  
Masakazu Tane
Keyword(s):  
Thermal Conductivity ◽  
Continuous Casting ◽  
Mass Production ◽  
Porous Metal ◽  
Zone Melting ◽  
Metal Plate ◽  
Porous Metals ◽  
Low Thermal Conductivity ◽  
Casting Technique ◽  
Melting Technique

Lotus-type porous metals with low thermal conductivity are fabricated by continuous zone melting technique, which possess directional elongated pores. The porous metals have been able to be fabricated through the conventional casting method by utilizing the solubility gap between solid and liquid in pressurized gas atmosphere. However, there is a shortcoming that the pores are coarsened in the part farther from the chill plate in the ingot. In order to overcome such a shortcoming, we developed the continuous zone melting technique and successfully produced the lotus-type porous metals with even low thermal conductivity such as stainless steel and superalloys. Furthermore, from the viewpoint of mass production with low cost, we invented novel ”continuous casting technique”. The molten metals dissolving gas are solidified continuously by passing through the mold cooled with chiller and thus, lotus-type porous metal plate as long as one meter was produced for short time. Sufficient uniformity of the porosity and pore size was obtained in such long porous ingots. This technique is prospective method for commercial mass production.

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.

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