scholarly journals Microstructural and corrosion study of aluminum foams obtained by space holder process using low-cost removable preforms

2021 ◽  
Vol 19 (3) ◽  
pp. 202-216
Author(s):  
P. Fernández Morales ◽  
L. Marulanda Zapata ◽  
M. Vásquez Rendón
Keyword(s):  
Aluminum Foam ◽  
Low Cost ◽  
Morphological Structure ◽  
Metal Foams ◽  
Aluminum Foams ◽  
Space Holder ◽  
Common Technique ◽  
A356 Aluminum ◽  
Metal Microstructure

The space holder process (SHP) is a useful and common technique to obtain metal foams. However, an important question remains unsolved: Would the quality of the salt affect the properties of the aluminum foam obtained? In this paper, removable preforms of two types of salt (refined and unrefined) were infiltrated with A356 aluminum alloy to obtain metal foams with different pore sizes. The interaction preform-metal was studied from analyzing the morphological structure of the foams, the metal microstructure, and the corrosion resistance of the Al356 alloy. It was observed that, although the two types of salt exhibited some differences, they did not show variations in relation to the porous structure and metal microstructure in the aluminum foams obtained. Additionally, the electrochemical analyses did not show significant effects on the corrosion behavior of aluminum foams caused by the interaction with the salt preforms.

Application of Superplastic Flow to Manufacturing of Microcellular Aluminum Foams

2005 ◽  
Vol 475-479 ◽  
pp. 3021-3024 ◽  
Author(s):  
Shinya Kamimura ◽  
Koichi Kitazono ◽  
Eiichi Sato ◽  
Kazuhiko Kuribayashi
Keyword(s):  
Thermal Conductivity ◽  
Cell Shape ◽  
Aluminum Foam ◽  
Oblate Spheroid ◽  
Metal Foams ◽  
Aluminum Foams ◽  
Roll Bonding ◽  
Heat Insulator ◽  
5083 Aluminum Alloy ◽  
Superplastic Condition

A new application of superplasticity was proposed in the manufacturing process of metal foams. Preform sheets were manufactured using superplastic 5083 aluminum alloy sheets through accumulative roll-bonding (ARB) process. Microcellular aluminum foam plates with 50% porosity were produced through solid-state foaming under the superplastic condition. The cell shape was oblate spheroid, which is effective to reduce the thermal conductivity. The present aluminum foam plates have a potential as an excellent heat insulator.

Structure and Deformation of Gradient Metal Foams Produced by Machining

2019 ◽  
Author(s):  
H. Qiao ◽  
T. G. Murthy ◽  
C. Saldana
Keyword(s):  
Aluminum Foam ◽  
Mechanical Performance ◽  
Metal Foams ◽  
Aluminum Foams ◽  
Open Cell ◽  
Computed Tomographic ◽  
Surface Gradient ◽  
Structure Changes

Abstract The effects of surface structure on mechanical performance for open-cell aluminum foam specimens was investigated in the present study. A surface gradient for pore structure and diameter was introduced into open cell aluminum foams by machining-based processing. The structure changes in the strut and pore network were evaluated by computed tomography characterization. The role of structure gradients in affecting mechanical performance was determined using digital volume correlation and in situ compression within the computed tomographic scanner. These preliminary results show that the strength of these materials may be enhanced through surface structural gradients.

Structure and Deformation of Gradient Metal Foams Produced by Machining

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Haipeng Qiao ◽  
Tejas G. Murthy ◽  
Christopher Saldana
Keyword(s):  
Aluminum Foam ◽  
Mechanical Performance ◽  
Metal Foams ◽  
Aluminum Foams ◽  
Open Cell ◽  
Computed Tomographic ◽  
Surface Gradient ◽  
Structure Changes

The effects of surface structure on mechanical performance for open-cell aluminum foam specimens were investigated in the present study. A surface gradient for pore structure and diameter was introduced into open-cell aluminum foams by machining-based processing. The structure changes in the strut and pore network were evaluated by computed tomography characterization. The role of structure gradients in affecting mechanical performance was determined using digital volume correlation and in situ compression within the computed tomographic scanner. These preliminary results show that the strength of these materials may be enhanced through surface structural gradients.

Dissolution Method of Aluminum Foams Containing Mg Using Carbamide Space Holder

2017 ◽  
Vol 888 ◽  
pp. 373-376
Author(s):  
Amirah Ahmad Hamdi ◽  
Nurul Akmal Mohd Sharif ◽  
Anasyida Abu Seman
Keyword(s):  
Energy Absorption ◽  
Aluminum Foam ◽  
Aluminium Foam ◽  
Aluminum Foams ◽  
Dissolution Method ◽  
Space Holder

This study investigated the properties of aluminium foam containing Mg with various amount of space holder. Aluminum foam was fabricated using dissolution method with various amount of carbamide (20, 40 and 60 wt. %). Aluminum foam with 60 wt. % carbamide has the lowest density (0.68 g/cm3) and exhibited the highest porosity (74.97%). However, the results indicates that aluminum foam with 40 wt. % of carbamide have good compressive and energy absorption with acceptable density and porosity value.

scholarly journals Sustainable Production of Powder Metallurgy Aluminum Foams Sintered by Concentrated Solar Energy

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1544
Author(s):  
Antonio Cañadilla ◽  
Ana Romero ◽  
Gloria P. Rodríguez
Keyword(s):  
Compressive Strength ◽  
Powder Metallurgy ◽  
Solar Energy ◽  
Energy Absorption ◽  
Impact Energy ◽  
Low Cost ◽  
Powder Metallurgy Method ◽  
Aluminum Foams ◽  
Space Holder ◽  
Concentrated Solar Energy

Porous aluminum foams were successfully fabricated following the space-holder powder metallurgy method with a solar sintering stage. Al foams with porosities of 50, 60, and 70 vol.% were sintered in a low-cost Fresnel lens. Green parts were prepared using aluminum powder as the main metallic material and saccharose as a soluble space-holder. The dissolution stage was designed for each foam and required longer periods of time, between 8 and 32 h, as the design porosity increased. Brown parts were fully sintered by concentrated solar energy at a lower temperature (500 °C) and for shorter times (12–20 min) than those required by conventional sintering techniques (640 °C, ~9 h). The evaluation of density and the characterization of pore size and distribution in the sintered foams was carried out. All obtained foams were stable and presented a homogeneously distributed porosity, very close to the design porosity, with differences lower than 2.1 vol.%, and with approximately half being characterized as open porosity. Moreover, the solar sintered foams presented a high quality, and similar or even greater mechanical properties (such as compressive strength and impact energy absorption) than those achieved by conventional techniques. Foams with 50 vol.% of porosity exhibited the best mechanical behavior, in terms of impact-energy absorption (24.42 MJ/m3) and compressive strength (27.4 MPa).

Production of Open Cell Aluminum Foams by Using the Dissolution and Sintering Process (DSP)

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
M. Barletta ◽  
A. Gisario ◽  
S. Guarino ◽  
G. Rubino
Keyword(s):  
Neural Network ◽  
Compaction Pressure ◽  
Metal Foams ◽  
Sintering Process ◽  
Back Propagation Algorithm ◽  
Aluminum Foams ◽  
Open Cell ◽  
Aluminum Powders ◽  
Space Holder ◽  
Rbf Network

The manufacture of open cell metal foams by dissolution and sintering process (DSP) is the matter of the present work. Aluminum foams were produced by mixing together carbamide particles with different mesh sizes (i.e., space-holder) and very fine aluminum powders. Attention was first paid at understanding the leading phenomena of the different stages the manufacturing process gets through: Compaction of the main constituents, space-holder dissolution, and aluminum powders sintering. Then, experimental tests were performed to analyze the influence of several process parameters, namely, carbamide grain size, carbamide wt %, compaction pressure, and compaction speed on the overall mechanical performance of the aluminum foams. Meaningfulness of each operational parameter was assessed by analysis of variance. Metal foams were found to be particularly sensitive to changes in compaction pressure, exhibiting their best performances for values not higher than 400 MPa. Neural network solutions were used to model the DSP. Radial basis function (RBF) neural network trained with back propagation algorithm was found to be the fittest model. Genetic algorithm (GA) was developed to improve the capability of the RBF network in modeling the available experimental data, leading to very low overall errors. Accordingly, RBF network with GA forms the basis for the development of an accurate and versatile prediction model of the DSP, hence becoming a useful support tool for the purposes of process automation and control.

Effects of Extrusion Methods and Powder Carriers on Powder Forming and Precursor Foaming Behavior in the Preparation Process of Aluminum Foam

2013 ◽  
Vol 634-638 ◽  
pp. 1734-1739 ◽  
Author(s):  
Zhi Qiang Guo ◽  
Xiang Li ◽  
Xiao Guang Yuan ◽  
Hong Jun Huang
Keyword(s):  
Aluminum Foam ◽  
Whole Body ◽  
Preparation Process ◽  
Aluminum Foams ◽  
Minimum Density ◽  
Pore Structures ◽  
Foaming Behavior ◽  
New Type ◽  
Powder Forming

Aluminum foam is a new type of material that can be used in many fields. Compaction conditions are the most important parameters that have influence on foam preparation process. So in this paper, detailed researches about extrusion methods and powder carriers are conducted. The results show that: compare with direct extrusion, pre-pressing can effectively eliminate the influences of hydrogen, obtain high density precursors. However, when the flank of the precursor is wrapped with copper, H2 can escape from the combination parts of Al and Cu, in early foaming stage. The minimum density is only 0.75g/cm3, pore structures are almost round and nearly no plateau borders exist, so the quality of aluminum foam is still poor. When there is no copper wrapped, an oxide layer can be formed in the whole body of the precursor and limit the escaping of H2. The minimum density can reach 0.45g/cm3, pore structures are polygonal with thin cell walls about 0.08mm. Thus high quality aluminum foams can be obtained by using pre-pressing and then extruding method and precursor sheet powder carrier.

Effect of Computerized Auditory Training on Speech Perception of Adults With Hearing Impairment

2013 ◽  
Vol 20 (3) ◽  
pp. 91-106 ◽  
Author(s):  
Rachel Pizarek ◽  
Valeriy Shafiro ◽  
Patricia McCarthy
Keyword(s):  
Hearing Loss ◽  
Speech Perception ◽  
Literature Review ◽  
Low Cost ◽  
Experimental Designs ◽  
Auditory Training ◽  
Hearing Impairments ◽  
Communicative Disorders ◽  
And Training

Computerized auditory training (CAT) is a convenient, low-cost approach to improving communication of individuals with hearing loss or other communicative disorders. A number of CAT programs are being marketed to patients and audiologists. The present literature review is an examination of evidence for the effectiveness of CAT in improving speech perception in adults with hearing impairments. Six current CAT programs, used in 9 published studies, were reviewed. In all 9 studies, some benefit of CAT for speech perception was demonstrated. Although these results are encouraging, the overall quality of available evidence remains low, and many programs currently on the market have not yet been evaluated. Thus, caution is needed when selecting CAT programs for specific patients. It is hoped that future researchers will (a) examine a greater number of CAT programs using more rigorous experimental designs, (b) determine which program features and training regimens are most effective, and (c) indicate which patients may benefit from CAT the most.

The system of indicators of the quality of the carbon-carbon composite materials and technologies of their production

2018 ◽  
pp. 127-132
Author(s):  
T. N. Antipova ◽  
D. S. Shiroyan
Keyword(s):  
Composite Material ◽  
Low Cost ◽  
Experimental Studies ◽  
Carbon Matrix ◽  
Carbon Composite ◽  
Optimal Number ◽  
Laboratory Equipment ◽  
Carbon Composite Material ◽  
Carbon Composite Materials

The system of indicators of quality of carbon-carbon composite material and technological operations of its production is proved in the work. As a result of the experimental studies, with respect to the existing laboratory equipment, the optimal number of cycles of saturation of the reinforcing frame with a carbon matrix is determined. It was found that to obtain a carbon-carbon composite material with a low cost and the required quality indicators, it is necessary to introduce additional parameters of the pitch melt at the impregnation stage.

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