Corse: Light Metallic Alloys spring 2013

By: Prof. Eng. Nahed El- MahalawyPresentation by: Alia Ahmed Diaa

Production Engineer

Metallic Foams

Metallic Foams

New class of materials with low densities and novel physical, mechanical, thermal,

electrical and acoustic properties.

Foam !!!!!

sea

detergentShampoo Pepsi

some polymers

cappucc

ino

Random Packing Of Bubbles In Another Medium

Solid cellular structure containing a large volume fraction of

gas-filled pores75~95% porous

Ultra- light material Kinds: - closed-cell foam (The pores

are sealed) - open-cell foam (form an

interconnected network).

Metallic Foams

Open-cell metal foam

Closed-cell metal foam

Table of content

Introduction

Production Methods

Production Stages

Applications

Porosity Effect

Characteristics

1

2,3

4

Formation

Growth

Collapse

Heterogeneous nucleation

Inflation

Drainage

Coarsening

Metallic Foam Production Stages

Introduction

Prod. Methods

Prod. Stages

Applications

Characteristics

Porosity Effect

Introduction

Metallic Foam Production Methods:

Production Considerations:

cell size cell type (open or closed) relative densities of each manufacturing methods.

Prod. stages

Characteristics

Applications

Porosity Effect

Prod. Methods

1. Melt gas injection

( closed cell )5. Vapor of chemical

decomposition, on open cell

polymer foam template (open cell)

4. Solidification in open cell mold

( open cell )2. Particle

decomposition in

melt (closed cell)

7. Hollow sphere consolidation

(open/closed cells)

3. Particle decomposition in semi-solid (closed cell)

8. compaction Or Casting Of Materials ( One Of Which Is Leachable)

9. Gas metal

eutectic (closed cell)

6. Entrapped gas expansion

(closed cells)

Relative Densities

Cell

Siz

e (

Cm

)

0.01 0. 1 1

0.01

0.1

10

1

1. Metal Gas Injection [MGI}

Problem: quick drainage to form foam.

Solution: - raise aluminum viscosity

stabilizing the foam.- mixing 10–30% of small, insoluble, or slowly dissolving particles, (AL2O3, SiC ),

Gases:Mostly Air, but CO2, O2, inert gases, may be used

aluminum alloys: low density + do not excessively oxidize when the melt is exposed to air or other gases containing oxygen.

Foam metal are drawn-off the to create large (up to 1 m wide and 0.2 m thick )slabs - closed cell - pores with diameters between 5 and 20 mm.

2. Gas-releasing particle decomposition in the melt

3. Gas-releasing particle decomposition in Semi - solids

4. Casting using an open cell polymer or wax precursor as template

Investment casting technique

Controlled cell size and relative densities

Porosity --- Strength

Behavior of metal foams under compression

Introduction

Prod. Methods

Prod. Stages

Applications

Characteristics

Porosity Effect

Made from Al

Metallic Foam Characteristics

, C,

Cu,

Ti, Si, based Alloys

Introduction

Prod. Methods

Prod. Stages

Applications

Characteristics

Porosity Effect

Metallic Foam Characteristics

75-95% void spacesLow density

Still stiff

Advanced technology of manufacturing

Metallic Foam Properties

High Cost

High Poros

ity

Reduced

conductivity

Similar thermal expansio

n coefficie

nt

Corrosion

Resistance

OTHER • Resistance to harsh environments (high temperatures,

corrosion & humidity depending on metals and ceramics used)

• Good impact energy absorption• Great noise attenuation• Recyclable

Metallic Foam Applications

Introduction

Prod. Methods

Prod. Stages

Applications

Characteristics

Porosity Effect

1. High Absorption Of Impact Energy.

automobile industry

control collapse vibration damping

.

2. Sound Absorption,

3. Electro-magnetic Shielding

Low Magnetic Permeability

4. Load Baring Parts good mechanical properties (strength - stiffness)

+ low weight

5. Metallic Filter Silicon carbide filter for hot gases at rocket nozzle (high temp. strength)

Strength up to 100 kN both in the normal and shear plane cheaper than conventional honeycomb design)

6. Heat Exchanger• interconnected cells + a random orientation + high

surface area make metal foam ideal for

heat exchangers catalysts.

• pore-size of metal foam results in heat removal

effectiveness

7. Aluminium Foam Sandwich panels (AFS)

Advances of foamed metal over dense metal

• much stiffer than sheet at same mass• manufacture of complex shapes (3D) possible• cost• elastic limit• failure mode• damage tolerance• integration into system→ joining technology• other aspects, e.g. mechanical, acoustic electromagneticdamping ...

8. Medical applications

Spongeous bone and metallic foam show similar structures

• Ti (titanium) shows high compatibility with

tissue. • metal foam is used as an

experimental prosthetic (an artificial part) in animals.

• hole is drilled into the bone and the metal foam is inserted into the hole drilled in the bone.

The pores allow the formation of vascular system grow within the area. More recently,

• orthopedic device manufacturers have started producing devices that use either metal foam construction or metal foam coating to achieve the desire level of osseointegration.

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