Titanium and its Uses in Aircraft 5 Minute Version

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Titanium
Microsoft ClipArt

• and its uses in aircraft

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http//www.mac-life.de/wallpapers/
Titanium is a metallic element which was
discovered in 1791, although it has only come
into common usage over the past 50 years.It has
various atomic properties which give it useful
macroscopic properties.These properties make
titanium and its alloys effective materials for
use in aircraft.
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Titanium the Facts
http//cfa-www.harvard.edu/scranmer/Gifs/periodic
_table.gif
Chemical symbol TiAtomic Number 22Atomic
Weight 48Standard state SolidDensity 4.54 g
cm-3Melting Point 1933 KBoiling Point 3560
KForms 2, 3 and 3 ionsFirst isolated in
1910.Modern production uses the Kroll method,
where titanium ores are reacted with chlorine and
carbon. Fractional distillation separates the
products, which are then reduced with magnesium.
Titanium is the fourth most common structural
element in the Earths crust, found in minerals
such as menachanite, ilmenite and rutile.
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Atomic Structure
http//people.bath.ac.uk/ma3yp/titanium/whatisit.h
tml
The three main categories of titanium alloys are
alpha, beta and alpha-beta, beta being used for
heavy duty purposes. In the polycrystalline
structure, the atoms can be arranged in two main
forms of lattice alpha, with a close-packed
hexagonal layout, and beta, with a body-centred
cubic arrangement. Unalloyed titanium changes
from the alpha form to the beta form above 880C.
One of the most commonly used alloys, Ti6Al4V is
an alpha-beta alloy, which means that its
structure is a mixture of the two.
Body-centred cubic
Hexagonal close-packed
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Physical Properties
G. Burton et al., Sallters Advanced Chemistry -
Chemical Ideas, Heinemann Educational Publishers,
2000
In these arrangements, the atoms of the different
metals in the alloy are in an ionised form, held
together by a sea of electrons which have been
delocalised from the atoms of the elements. This
non-directional metallic bonding is very strong
in titanium due to the number of electrons
available for delocalisation. The free electrons
also make these materials electrical and thermal
conductors. As the metal ions can slide past each
other one at a time in the sea of electrons,
metallic substances are malleable and ductile.
Sea of delocalised electrons surrounding
positive metal ions.
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Physical Properties
J. Ogborn M. Whitehouse, Advancing Physics AS
2000, Institute of Physics Publishing, 2000
In these arrangements, the atoms of the different
metals in the alloy are in an ionised form, held
together by a sea of electrons which have been
delocalised from the atoms of the elements. This
non-directional metallic bonding is very strong
in titanium due to the number of electrons
available for delocalisation. The free electrons
also make these materials electrical and thermal
conductors. As the metal ions can slide past each
other one at a time in the sea of electrons,
metallic substances are malleable and ductile.
When an atom moves, the dislocation moves.
Dislocation reaches edge of crystal, causing a
step.
DislocationAtoms can move individually.
AtommovesDislocationmoves
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Physical Properties
J. Ogborn M. Whitehouse, Advancing Physics AS
2000, Institute of Physics Publishing, 2000
However, elements such as oxygen, nitrogen and
carbon (sometimes called interstitial alloys)
insert themselves in the lattice and prevent
relative sliding of the molecules, giving the
titanium a greater tensile strength. The presence
of atoms other than titanium in the alloys also
makes them more resistant to creep, as the
sliding of the atoms is reduced. Finally,
titanium and many of its alloys, like most other
metals, are resistant to cracking. Due to their
ductility, small cracks do not propagate they
only get broader.
In titanium alloy, the dislocation is pinned by
the interstitial atoms, reducing its ductility.
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Physical Properties
J. Ogborn M. Whitehouse, Advancing Physics AS
2000, Institute of Physics Publishing, 2000
However, elements such as oxygen, nitrogen and
carbon (sometimes called interstitial alloys)
insert themselves in the lattice and prevent
relative sliding of the molecules, giving the
titanium a greater tensile strength. The presence
of atoms other than titanium in the alloys also
makes them more resistant to creep, as the
sliding of the atoms is reduced. Finally,
titanium and many of its alloys, like most other
metals, are resistant to cracking. Due to their
ductility, small cracks do not propagate they
only get broader.
Stress
Stress
Stress
Stress
High Stress
Reduced Stress
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Macroscopic Properties
The effect of these microscopic properties which
make titanium so useful can be seen through its
macroscopic properties
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Uses in Aircraft
Out of these properties, several make titanium
and titanium alloys very useful in the
construction of aircraft. They can be cast,
forged or moulded to make various parts.Most
notable is their low density although not as
light as aluminium, they are much less dense than
steel.Titanium and its alloys strong atomic
lattice gives them better characteristics when
heated than other metals, shown by its low
coefficient of linear expansion. At high
supersonic speed, aluminium alloys would expand
too much and fail, whereas titanium expands
comparatively little.Finally, its reasonable
tensile strength and Youngs Modulus, mean that
it can support the varying loads which aircraft
are subject to whilst in flight.
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http//www.boeing.com/defense-space/military/f4/im
ages/titanium.gif
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The Materials Information Society, Introduction
to Selection of Titanium Alloys, ASM
International, 2002
In the Lockheed-Martin F-22 Raptor Advanced
Tactical Fighter, 42 of the structural weight
consists of titanium.
http//www.deneba.com/community/artgallery/images/
cv9/aircraft.jpg
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Titanium Aircraft
The majority of aircraft constructed since around
1960 have used small amounts of titanium to some
extent, such as the previous examples. However,
some aircraft have been constructed virtually
entirely from titanium alloys.The 1962 A-12
(later SR-71 Blackbird) designed to over-fly
Soviet Russia was capable of altitudes over
85,000 feet at speeds of 2,000 mph, Mach 3.2. In
order to be light enough to reach this speed and
at the same time withstand high temperatures of
500 C it was made mostly of titanium alloy,
which expands by 15 cm in flight.
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http//www.dfrc.nasa.gov/Gallery/Photo/SR-71/Mediu
m/EC97-43933-4.jpg
The SR-71 Blackbird
When the aircraft is not in operation, the
titanium alloy panels are not a perfect fit to
compensate for the expansion at high speed
flight. This results in fuel leaking from the
seams!
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Before Titanium
Before aircraft began to use titanium around 50
years ago, many other materials were used.The
first aircraft used stressed canvas over their
wings with simple wooden frames. These are light,
but not very strong, so in the first aircraft
structural failures were common.Later, metals
and alloys began to be used in aeroplanes. Steel
skins were used for a short time, but these were
heavy and limited the performance of
aircraft.Aluminium based alloys such as
duralumin were then used, which are reasonably
strong and light.
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http//www.warbirdsovernewzealand.com
On many aircraft of the First World War such as
this Nieuport 24 biplane the wings were prone to
breaking off when the aircraft went into a dive!
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Modern Aircraft
Improvements in metallurgy allowed for lighter
and stronger alloys to be made which could be
more heat-resistant or cheaper than other
materials. Today, aircraft are mostly
constructed from steel and aluminium alloys, with
titanium alloys for purposes which other
materials cannot match, especially where high
temperatures are involved.In the future,
aircraft may be made from a new generation of
very strong titanium-based ceramic materials.
Perhaps they will not be constructed out of
metals at all, but advanced plastics and
composite materials. Although titanium is very
much a material of the moment, it might not be
long until scientists make a successor to it
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http//www.dfrc.nasa.gov/Gallery/Photo/X-29/Medium
/EC87-0182-14.jpg
Are there already aircraft made from exotic
materials flying at secret testing sites such as
Area 51 in the US or Zhukovski in Russia?
The NASA prototype forward-swept wing X-29 was
constructed mainly out of carbon fibre, which is
less likely to warp in flight than metal alloys.
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Summary
http//www.taiwan.co.jp/exhibition/exh-2/titanium/
titan03.jpg
In the space of less than 100 years, titanium has
gone from being just another element to one of
the more commonly used metals today, particularly
in aircraft, but also in medicine, jewellery and
even as a white pigment. Although its crystalline
structure gives it great strength and it has a
relatively low density, its main advantage is its
fantastic performance at high temperatures. When
alloyed with aluminium and vanadium it can become
more versatile. You only have to look around
you to see how much we utilise this fantastic
material and the extent to which it contributes
to modern life.
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Selected Bibliography
Introduction to Selection of Titanium Alloys by
The Materials Information SocietyOnboard the
A380 by Airbus UKAlchemy of a Supermetal by
Steven Ashley, Scientific American magazine,
October 2003Sticky Fingers by Barry Fox, New
Scientist magazine, October 2002BAe Systems,
http//www.baesystems.comA to Z of Metals,
http//www.azom.comProperties of Titanium,
http//www.roymech.co.uk/Useful_Tables/Matter/Tita
nium.htmlThis presentation can be accessed at
http//www.freewebs.com/basicsoftware/titanium.ppt

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Thanks for watching!
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Titanium the Facts
Pure titanium is rarely used in aircraft, as it
is extremely expensive and can be difficult to
weld, although it is only about two-thirds the
density of steel. More often, commercially pure
(CP) grades of titanium are used, though their
tensile strength is much lower than that of other
alloys. Usually, it is alloyed with other
metals such as aluminium, manganese and vanadium,
to produce strong, lightweight materials, that
are capable of operating at a wide range of
temperatures. Titanium alloys are very durable,
although they can be more susceptible to
frictional wear damage than other materials of
similar hardness.These properties result from
the titanium and its alloys polycrystalline
structure.
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http//www.baesystems.com/gallery/air/images/Airbu
s_A380hires.jpg
The new Airbus A380 uses a wide range of
materials, including titanium, for different
purposes.
Although it does not have to withstand such high
temperatures as military aircraft, it must still
be light so that it can be fuel efficient.