METAL FOAM
INTRODUCTION
• A metal foam is a cellular structure consisting of a solid metal, For ex.
aluminium, containing a large volume fraction of gas-filled pores.
• The pores can be sealed (closed-cell foam), or they can form an
interconnected network (open-cell foam).
• The defining characteristic of metal foams is a very high porosity: typically
75-95% of the volume consists of void spaces.
• The strength of foamed metal possesses a power law relationship to its
density; i.e., a 20% dense material is more than twice as strong as a 10%
dense material.
• Metallic foams typically retain some physical properties of their base
material. Foam made from non-flammable metal will remain nonflammable and the foam is generally recyclable back to its base
material. Coefficient of thermal expansion will also remain similar
while thermal conductivity will likely be reduced.
STRUCTURE OF METAL FOAM
• In metal foams cells are divided into
distinct cells. the boundaries of
these materials are made of solid
material, the interior are voids.
TYPES OF METAL FOAM
OPEN CELL METAL FOAM
Open cell Ni -foam
CLOSED CELL METAL FOAM
Closed cell Al foam
OPEN CELL METAL FOAM
1.Heat exchangers
Compact electronics cooling
Cryogen tanks
PCM heat exchangers
2.Energy absorption
3.Flow diffusion and lightweight optics
4.Extremely fine-scale metal foam are
used as high-temperature filters in the
chemical industry.
Due to the high cost of the material it is
most typically used in advanced
technology aerospace and
manufacturing.
CLOSED CELL METAL FOAM
1. Closed-cell metal foams are primarily used
as an impact-absorbing material,
2. They are light (typically 10–25% of the
density of the metal they are made of,
which is usually aluminium) and stiff, and
are frequently proposed as a lightweight
structural material. However, they have not
yet been widely used for this purpose.
3. Closed-cell foams retain the fire resistant
and recycling capability of other metallic
foams but add an ability to float in water.
4. Light weight Al foam has a density of from
300 to 1,000 kg/m³, that is, 30 to 100% that
of water. Components made of the material
can therefore be expected to float.
5. Foam metal has also begun to be used as
an experimental prosthetic in animals
MANUFACTURING
1. Foaming of Melts by Gas Injection
2. Foaming of Melts with Blowing agents
3. Powder processing method
SIMULATION OF THE CRUSHING OF A METAL FOAM
CHARACTERISTICS OF AL FOAM
• Are very stiff at a very low weight
• Are very effective in terms of acoustical absorption
• Are very effective in terms of electromagnetic
shielding and structural damping
• Absorb impact energy regardless of impact direction
• Are much more stable than organic materials like
wood or plastics
• Are decorative are completely recyclables and hence
do not cause any harm to our environment
PROPERTIES
1. STIFFNESS
2. SOUND ABSORPTION
3. IMPACT ENERGY ABSORPTION
4. Thermal conductivity
• Thermal conductivity λ, defined according
Fourier’s law
• Depends strongly on the cross sectional area S
enabling the thermal flow rate Q’ through the
specimen (dT/dx is a temperature gradient).
• In a foamed aluminium only a small part of the
cross section (pore walls) is metallic with the
thermal conductivity given by the base alloy. The
rest are the pores filled with gas which has a
much lower thermal conductivity than an
aluminium alloy
APPLICATION OF AL FOAM
1.Crash box
Photographs of crushed crash box
2.Acoustic noise reduction
-Sound absorption in difficult condition
-Sound absorption in commercial buildings, hotels, roads
3.Electromagnetic shielding
-Cover boxes for electronic devices
-Wall and ceiling plates for protection of rooms against
entering or releasing of electromagnetic waves
4.Self-supporting, stiff and super light weight panels for
building and transport
5.Compressor casings
6.Heat exchangers, filters, catalysts
7.Instrument housing
8.Loudspeaker enclosures
9.Gearbox housings
10.Structural parts for spacecraft
ADVANTAGES
1. Metal foams provide excellent energy absorption
features at a higher strength level as compared to
foamed polymers
2. Metal foams are easily processed by sawing, drilling,
milling, etc,
3. Metal Foams can be joined by adhesive bonding,
brazing, and TIG and laser welding techniques.
4. It does not erode, even under the effects of air flow or
vibration.
5. It is easily recyclable.
6. Provides sound absorption at low frequencies at a
smaller material thickness in comparison with other
absorption materials such as glass or mineral wool
fibers or polymer foams.
DISADVANTAGES
1. They are difficult to manufacture as precision
manufacturing is required.
2. Cost is a major factor
3. Difficultly in manufacturing high temperature
metal
4. Knowledge about the metal foam is still not
wide spread
5. Once damaged it can not be repaired ,the
whole metal foam has to replaced by new
one.
CONCLUSION
1.There is considerable interest in the applications
of metallic foams from a wide range of
industries.
2.Impact and energy absorption are key
applications, particularly within the
transport industries.
3.Thermal management properties can
be exploited by the electronics industry
in particular.
SUGGESTIONS
Metal foam are yet to widely used the metal
foams can be used in the following fields
which are yet to tapped in the market.
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1. In commercial light weight doors
2. In the impact absorbing in cars
3. In lift safety system
4. In road medians and dividers
5. In construction industry as light weight material
6.In Shipping industries
7. In helmets
THANK YOU