PhD of Industrial Engineering

Research Activity on Advanced Materials

Metal Foams: Production, Characterization and

Applications

R. Montanari, M.E. Tata, G. Costanza, G. Lapi – Department of Industrial Engineering

University of Rome “Tor Vergata”

G. Barbieri, F. Cognini – ENEA Casaccia Research Centre

S. Kaciulis, S.K. Balijepalli, Mezzi – ISMN - CNR

Metal foams can be used for filtration andseparation processes. For exaple the particulateemissions generated from a side-mounted 2.4 Lgasoline direct injection engime were evaluatedusing a metal foam-type gasoline particulate filterand the number of sub-23 nm particles formed wasreduced with 97% efficiency.

Kim et. al., Journal of Aerosol Science, vol. 57 p.1, 2013.

They can be used in thermal energy storage devicein thermal energy applications in areas such asenergy afficients buildings and solar thermal powerplants. In the solid/liquid phase change process theparaffin wax RT58 is used as phase change materialand the addiction of metal-foam can increase theoverall heat transfer rate by 3 to 10 times,depending on the metal foam structures andmaterials. Lu et.al., Solar Energy, vol.84 p.1402, 2010.

Metal Foams Applications

Thermal transport in metal foams has received growingattention in both academic research and industrialapplications. High porosity, open-celled metal foamshave emerged as one of the most promising materialsfor thermal management applications where a largeamount of heat needs to be transported over a smallvolume. The motivation is attributed to the highsurface area to volume ratio as well as enhanced flowmixing due to the tortuosity of metal foams.

Metal Foams Applications

Regarding their promising mechanical propertiesthe aluminium foams can be used in car/vehicleindustry. The breakthrough happened already in2006: for a structural item of Audi Q7 carfeatured by energy absorption. In the Ferrari F430To offset the loss of the roof, the Spider's chassishas been significantly reinforced. The sillmembers have been strengthened with extremelylight, rigid aluminium foam inserts where theyconnect to the rear B-pillar chassis members.

Teupen (Gronau, Germay) hasdeveloped a novel concept for thesupport structure of a telescope armlifting a working platform. Using AFSthe goal was to increase the currentworking height of 20m to 25m whilekeeping the total weight below 3500Kg.

AFS Applications

Aluminium Foam Production

This manufacturing method using metal powders isespecially suited for the production of net-shape parts. Itstarts from mixing metal powders with a blowing agent,after which the mix is compacted to a dense pre-product.The resulting compacts are foamed by melting, thustriggering the release of gas from the blowing agent andthe corresponding formation of bubbles.

Powder Metallurgy Method

Effects of Powder mix composition

The effect of mix composition on foam morphology has been examinated by imageanalysis carried out on metallographic sections of Al foams prepared by powdermetallurgy. Samples have been prepared by using SiC particles with different mean sizeand different amounts of TiH2. SiC particles distribution on the internal walls of thebubbles has been investigated by SEM observations, whichevidenced also the presence of particles of another phase, identifiedas Ti3Al by EDS.

“Effect of Powder mix composition on Al foam morphology”

R. Montanari, M.E. Tata, G. Costanza, et. al.

Aluminium Foams, particularly Aluminium Foam Sandwiches(AFS), offer a great potential for applications in the automotiveindustry. AFS are light weight, energy absorbing andincombustible and have good sound absorbing properties.

Aluminium Foam Sandwiches are composites comprising an aluminium alloy foam coreand two dense metallic sheets firmly attached to the core.

Aluminium Foam Sandwiches

AFS Properties

• Light weight

• Energy absorbing

• Incombustible

• Sound absorbing

AFS ProductionOne way to manufacture AFS was developed at the Fraunhofer-Institute. A threelayer composite, comprising a foamable aluminium alloy sheet as a core layer andtwo face sheets on both sedes, is made by extrusion or powder rolling and various

subsequent rolling operations, afterwhich the core layer of the panel isexpanded by heating to the foamingtemperature. A pure metallic bondingis maintained that is less heatsensitive than an adhesive and can beused to manufacture heat resistantnon-inflammable structures.

Hot pressing and extrusion.

Manufacturing Facility

MiSE – ENEA - Ricerca di Sistema Elettrico - “Risparmio di energia nel settore dei trasporti”

Automatic Foaming Oven.

Manufacturing Facility

TiH2 Oxidation treatments

Effect of oxidation parameters (Temperature and Time) on the H2 release during thermaldecomposition of TiH2 powders.

OxidationTreatment (°C - min)

Wt% H2 after treatment

Onset Decomposition(°C)

Peak Temperature (°C)

nothing - 410 572

520 - 15 3,28 460 594

520 - 30 3,14 468 597

520 - 60 2,96 490 620

520 - 90 2,85 506 633

Oxidation Treatment (°C - min)

Wt% H2 after treatment

Onset Decomposition (°C)

Peak Temperature (°C)

nothing - 410 572

460 - 90 3,78 425 574

480 - 90 3,31 455 589

500 - 90 3,13 478 599

520 - 90 2,85 506 633

0 100 200 300 400 500 600 700 800 900 10001100

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

TiH2_45um_Forno_Particle 1

Ti-Oxides (O1s)

Ti2p3 TiH2

Ti2p3 TiMet

Ti2p3 TiO2

Etch Level (Secs)

Ato

mic

pe

rce

tag

e %

TiH2 Oxidation treatments

XPS Analysis on the oxide layer.

Sheet/Core metallic bonding

Has been studied the possibility of establishing a metallurgical bond between steel sheetsand Al alloy core. The EDS analysis show the interdiffusion of Al and Fe through an interfaceof about 40 microns.

AlCr Fe

Al Foam Steel

SEM – EDS Analysis

P6

P5

P4

P3

P2

P1

XPS Analysis

P1

P3

P6

Sheet/Core metallic bonding

Extruded profilein AA6060

AlSi10 Foam

Has been studied the possibility to reinforceextruded AA6060 with AlSi10 foam. Theresults show a good metallurgical bond and alack of homogeneity in the foam due to anincorrect calibration of the temperature in theoven.

AA 6082

Extruded

20 X 30 X

400 mm

PSR

2

PSR

1

PSR

2

RX

Sheet/Core metallic bonding

Finite Element Model (FEM)

The numerical simulation of the compression behavior of open-cell aluminium foams is away to extract material prperty information. A bilinear isotropic model was implementedfor the alloy base material whereas a parametric approach was used to build the finiteelement model of the foam structure. Compression tests were performed on commercialfoams with different pore size and density, and the results of lower density foam were usedfor the model validation. Numerical results show a goodagreement withexperimental data in terms of foamdeformationunder compression and required loads.

“Numerical Simulation of Open-Cell Aluminium Foams Under Compression”

F. Quadrini, D. Bellisario, D. Ferrari, L. Santo, A. Santarsiero

Lead – foams could be used as electrodes in batteries instead of Pb bulk. Two techniqueshave been used to manufacturing Pb foams: replication process (RP) and sintering anddissolution process (SDP). The electrodes were immersed in sulfuric acid 31% andsubjected to charge. After four hours the accumulator had a voltage of 2.2 V. A 3W-lamp,powered by the electrodes during discharge, remained alight for 30 minutes. The goal ofthis work is to produce microporous electrodes that can replace the standard ones, withimproved performance and a weight reduction.

“Experiences of Lead-Foam Production by Several Processing Routes”

“Development of lead-foam electrodes for high-efficient batteries recycling scraps”

M.E. Tata, G. Costanza

Lead – Foams Electrodes

Grazie per l’attenzione