scholarly journals Al-Based Foams as Permanent Cores in Al Castings: Effect of Surface Skin Thickness and Composition on Infiltration and Core-Shell Bonding

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1715
Author(s):  
Sara Ferraris ◽  
Antonio Santostefano ◽  
Antonio Barbato ◽  
Roberto Molina ◽  
Graziano Ubertalli
Keyword(s):  
Skin Thickness ◽  
Al Alloy ◽  
Strength Increase ◽  
Aluminum Foams ◽  
Gravity Casting ◽  
Acoustic Insulation ◽  
Metallurgical Bonding ◽  
Compression Resistance ◽  
Effect Of Surface ◽  
Al Foams

An emerging and still poorly explored application of aluminum foams is their potential use as permanent cores (inserts) in the casting of aluminum alloys. In this context, Al-based foams can introduce a weight reduction, the obtainment of cavities, a strength increase, the ability to absorb impact energy and vibration, acoustic insulation ability, the possibility to simplify the technological processes (no removal/recycling of traditional sand cores), and finally, they can be fully recyclable. Cymat-type Al foams with thin outer skin were used as permanent cores in Al-alloy gravity casting in the present research. Al-foams were characterized in terms of porosity, density, cell wall and skin thickness, surface chemical composition and morphology, and compression resistance. Cast objects with foam inserts were characterized by means of optical microscopy. The preservation of up to 50% of the initial porosity was observed for foam inserts with higher density. Metallurgical bonding between the foam core and the cast metal was observed in some regions.

Formability of Open-Cell Aluminum Foams by Laser

2010 ◽  
Author(s):  
Loredana Santo ◽  
Alessandro Guglielmotti ◽  
Fabrizio Quadrini
Keyword(s):  
Element Model ◽  
Laser Forming ◽  
Process Conditions ◽  
Al Alloy ◽  
Aluminum Foams ◽  
Bending Tests ◽  
Open Cell ◽  
Laser Velocity ◽  
Material Interaction ◽  
Al Foams

A new forming method for open-cell aluminum (Al) foams by laser was introduced. Laser forming is generally applied to sheet metals but a good formability was observed also for Al alloy cellular structures. In this study, laser bending tests were performed on rectangular samples made of open-cell Al alloy foams by means of a diode laser. Laser scan velocity and power were changed in the experimentation so as to identify the best process conditions for three different Al foams. A finite element model was implemented to simulate the laser-material interaction during forming in dependence of the foam structure. At fixed values of laser velocity and power, higher bending angles were obtained for foams with smaller pores but, changing the process parameters, a better formability was observed for the foams with bigger pores.

Effect of Surface Modification on the Sound Absorption Behavior of Open Celled Aluminum Foams

2014 ◽  
Vol 783-786 ◽  
pp. 1509-1512 ◽  
Author(s):  
Yun Jie Li ◽  
Yue Lu Ren ◽  
Zhen Dong Li ◽  
Fu Sheng Han
Keyword(s):  
Phase Composition ◽  
Cell Walls ◽  
Sound Absorption ◽  
Flow Resistance ◽  
Aluminum Foams ◽  
Absorption Properties ◽  
Low Frequencies ◽  
Al Foam ◽  
Effect Of Surface ◽  
Al Foams

In the present study, needle like micro-Co3O4 rods were synthesized on the cell walls of open celled Al foam. The microstructure and phase composition of micro-rods and sound absorption properties of resultant samples were characterized. Compared with original Al foams, the modified ones showed enhanced sound absorption capacities, particularly at low frequencies, which were more obvious as the length of Co3O4 rods increased. The improvement is related to increased air flow resistance owing to increased roughness of the cell walls.

Microstructure and Properties of Fe-Based Composite Coating by Plasma Jet Surface Metallurgy

2011 ◽  
Vol 179-180 ◽  
pp. 253-256
Author(s):  
Hao Chen ◽  
Jian Gao Yang ◽  
Mi Song Chen
Keyword(s):  
Steel Substrate ◽  
Composite Coatings ◽  
Low Carbon Steel ◽  
Plasma Jet ◽  
Optical Microscope ◽  
Al Alloy ◽  
Low Carbon ◽  
X Ray Diffraction ◽  
Metallurgical Bonding

The Fe-based composite coatings were formed by plasma jet surface metallurgy using Fe, C, W, Cr and Al alloy powders on the low carbon steel. The morphology, microstructure, interface structure and the distribution of the in situ particles in the coatings were observed with optical microscope, scanning electron microscope and x-ray diffraction analysis. The results show that metallurgical bonding is obtained between coating and substrate, and the microstructure of coatings is mainly composed of γ-Fe, (Fe,Cr,W,Nb)7C3 and AlFe particles which are synthesized in stiu, are dispersivly distributed in the coatings. The micro-hardness gradually increased from bottom to the top of the coating, the maximum is 986 Hv0.1, about 4 times larger than that of the steel substrate.

Vacuum Foaming of Aluminum Scrap

2012 ◽  
Vol 1481 ◽  
pp. 83-88
Author(s):  
J. A. Garabito ◽  
H. Granados ◽  
V. H. López ◽  
A. R. Kennedy ◽  
J. E. Bedolla
Keyword(s):  
Automotive Industry ◽  
Vacuum Chamber ◽  
Low Cost ◽  
Porous Structures ◽  
Aluminum Foams ◽  
Casting And Solidification ◽  
Different Temperatures ◽  
Different Levels ◽  
Al Foams

ABSTRACTIn this study, scrap from the automotive industry was used to produce aluminium foams under vacuum. Chips of an aluminium alloy LM26 were melted and 1wt. % of Mg was added for creating a viscous casting with uniform distribution of oxides. An ingot was obtained of this alloy after casting and solidification. Trials for foaming this alloy were performed by re-melting pieces under vacuum at different temperatures. A window in the vacuum chamber allowed observation of the foaming and collapse of the porous structures was observed during cooling. Characterization of the aluminum foams revealed different levels of expansion, porous structures and degrees of drainage. The best foams were obtained at 680 °C with a density of 0.78 g/cm3. This technique appears to be a feasible low cost route for producing Al foams based on scrap material.

Solid State Bonding of Al Alloy/SUS304 by Metal Salt Generation Bonding Technique with Acetic Acid

2014 ◽  
Vol 922 ◽  
pp. 491-496 ◽  
Author(s):  
Kota Matsubara ◽  
Shinji Koyama ◽  
Hideo Nagata ◽  
Yoshiyuki Suda ◽  
Ikuo Shohji
Keyword(s):  
Acetic Acid ◽  
Surface Modification ◽  
Metal Salt ◽  
Bonding Temperature ◽  
Maximum Load ◽  
Al Alloy ◽  
Bonded Joints ◽  
Modified Surfaces ◽  
Aluminum Surfaces ◽  
Effect Of Surface

The effect of surface modification on the tensile strength of the bonded interface of Al alloy and SUS304 stainless steel was investigated by SEM observations of interfacial microstructures and fractured surfaces. Aluminum surfaces were modified by boiling in 5% aqueous solution of NaOH for 20 s and 99.7% Acetic acid for 60 s. Bonding was performed at bonding temperature of 753 ~ 813 K under a pressure of 6 MPa (bonding time of 1.8 ks). As a result of surface modification, bonded joints were obtained at a bonding temperature 20 K lower than that required for non-modified surfaces, and the bonded strength was comparable to that of the maximum load.

Morphology and Tensile Behavior of 2024 Al Alloy Objects Fabricated by Uniform Droplet Spraying Deposition

2012 ◽  
Vol 472-475 ◽  
pp. 787-790
Author(s):  
Peng Yun Wang ◽  
He Jun Li ◽  
Le Hua Qi ◽  
Hai Liang Deng ◽  
Han Song Zuo
Keyword(s):  
Shear Fracture ◽  
Tensile Behavior ◽  
Al Alloy ◽  
Drop On Demand ◽  
Metallurgical Bonding ◽  
Smooth Region ◽  
Molten Droplets ◽  
Rough Region ◽  
Uniform Droplet ◽  
Moving Substrate

A metal rapid prototyping technique, uniform droplet spraying, is utilized to fabricate 2024 Al alloy objects. Molten droplets are generated by drop-on-demand mode and deposited onto a zigzag moving substrate, which produces objects with different side surfaces. The tensile strength of the deposited specimen is 180.5 MPa, with elongation to fracture of ~8.2%. The fracture surface of deposited specimen presents two regions, namely, rough region and smooth region. The smooth region initially cracks under tension load, and the rough region presents many elongated dimples, indicating a ductile shear fracture. This unique tensile behavior could be attributed to weak metallurgical bonding between droplets and the special movement of substrate.

Effect of surface treatments on natural cork: surface energy, adhesion, and acoustic insulation

2013 ◽  
Vol 48 (1) ◽  
pp. 207-224 ◽  
Author(s):  
J. Abenojar ◽  
A. Q. Barbosa ◽  
Y. Ballesteros ◽  
J. C. del Real ◽  
L. F. M. da Silva ◽  
...  
Keyword(s):  
Surface Energy ◽  
Surface Treatments ◽  
Acoustic Insulation ◽  
Natural Cork ◽  
Effect Of Surface

Effect of Foaming Temperature on Pore Morphology of Al/AlN Composite Foam Fabricated by Melt Foaming Method

2010 ◽  
Vol 658 ◽  
pp. 189-192 ◽  
Author(s):  
Yeong Hwan Song ◽  
Masakazu Tane ◽  
Takuya Ide ◽  
Yoshihiro Seimiya ◽  
Bo Young Hur ◽  
...  
Keyword(s):  
Nitrogen Atmosphere ◽  
Al Alloy ◽  
Pore Morphology ◽  
Composite Foam ◽  
Blowing Agents ◽  
Composite Foams ◽  
Foaming Behavior ◽  
Foaming Temperature ◽  
Powder Compacts ◽  
Al Foams

Al foams whose matrix contains dispersed AlN particles (Al/AlN composite foams) were prepared by a melt foaming method, and the effect of foaming temperature on the pore morphology of the prepared foams was investigated. First, Al/AlN composites were prepared by non-compressive infiltration of Al powder compacts with molten Al alloy in nitrogen atmosphere. Next, the prepared composites were melted by induction heating and foamed at various temperatures using TiH2 powders as blowing agents. The porosity of prepared Al/AlN composite foams slightly decreases with increasing foaming temperature, and the pore morphology of the foam becomes homogeneous simultaneously. When the foaming temperature is 1123 K, homogeneous pores are formed in all over the ingot. This pore homogeneity is probably achieved by the stabilization of the foaming behavior due to the formation of Al3Ti particles in the melt and dispersion of AlN particles.

Study on Fabrication, Defects and Compression Properties of Al Foams at Different Foaming Temperatures

2011 ◽  
Vol 214 ◽  
pp. 70-74 ◽  
Author(s):  
Wei Min Zhao ◽  
Hui Zhang ◽  
Hai Peng Li ◽  
Zhi Feng Wang ◽  
Yang Zhao ◽  
...  
Keyword(s):  
Pore Structure ◽  
Aluminum Foams ◽  
Foaming Agent ◽  
Compression Properties ◽  
Al Powder ◽  
Fabrication Defects ◽  
Lower Temperature ◽  
Foaming Temperature ◽  
Better Than ◽  
Al Foams

Using Al powder as thickening agent and CaCO3 powder as foaming agent, Al foams with above 85% porosity, pore sizes between 1mm and 4mm and relatively uniform pore structure have been fabricated by melt foaming method at different foaming temperatures. Meanwhile, the paper researched the effect of foaming temperature on foaming effect and analyzed the defects in Al foams. At last, compression test were taken in order to investigate the mechanical properties of aluminum foams. The results showed that pore structure, pore distribution and compression properties of Al foams fabricated at 720°C were much better than that fabricated at lower temperature.

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