New and Smart Materials
Mr P Mulholland
St Joseph’s High School Crossmaglen
New and Smart Materials
• Engineers are constantly developing new materials to meet
specific requirements. Smart materials are one of these new
materials.
• A smart material is defined as a material that reacts to an
outside stimulus, and once the stimulus has been removed,
changes back to its original state.
• The stimulus is usually electricity or heat.
• Smart materials are being used in products such as food
processors and electric drills.
Shape Memory Alloys
• A shape memory alloy is a material that can be deformed
having been given an outside stimulus and then once it is
removed it will return to its original state.
• Some react to heat while others react to light.
• The most common smart material is Nitinol, an alloy of nickel
and titanium.
• Nitinol is programmed to maintain a particular length or
shape at a certain temperature. If the temperature is raised
the material will contract or bend and will remain in that state
until the heat is removed and will then return to its original
shape.
• This cycle can be repeated millions of times.
Shape Memory Alloys
• A use for Nitinol includes spectacle frames. The alloy is soft,
so the frames are comfortable to wear. But if they get
accidentally bent, you can heat the frames using hot water,
and they will spring back to their original shape.
• http://www.grand-illusions.com/acatalog/Hot_Wire.html
• There are some disadvantages. They are relatively expensive
to manufacture and are difficult to machine. They are also not
as strong as traditional materials such as steel.
Reactive Glass
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Reactive glass is a smart glass.
One application of reactive glass is in welding masks.
These have clear glass that remains clear until an arc is struck.
When light from the arc is sensed, the glass turns dark
instantly. The welding shield contains electronics and batteries
to allow them to operate.
• Another application is glass panels that can replace curtains or
blinds and give privacy at the touch of a button.
• Reactive Glass Video
Photochromic Paint
• Photochromic paints contain pigments that change
colour according to light conditions.
• In one situation they might be one colour, but when
sunlight or ultraviolet light falls onto the pigment,
there is an immediate change in colour.
• When the light source or ultraviolet light is removed
the paint returns to its original state.
• Examples include security markers or ultraviolet light
warning sensors.
Photochromic Paint
• Photochromism - colour change caused by light.
• Photochromic Paint Video
Quantum Tunnelling Composites
• QTC Video
• QTC is a new smart material which has a number of
applications.
• When QTC is in its relaxed state, it is a near perfect electrical
insulator but when it is stretched, compressed and twisted it
becomes an electrical conductor and allows in some cases,
very high currents to pass through it.
• The greater the stress that is applied to the material the more
it will conduct electricity.
• It is being used in products such as power tool switches and
robots. It also has potential applications in the textiles
industry linking clothes to electronic devices.
Quantum Tunnelling Composites
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QTC can be used as a switch, a speed control, or a sensor. Some applications can
include:
• Controlling speed of a drill by using this in the finger trigger
• Embedding QTC in fabrics to make textiles that respond to touch
• Long flexible tubes of QTC can be used in the door jam of
automobiles to monitor impacts
• How QTC works is quite technical as it utilizes a principle of physics
called quantum tunneling. The benefit of QTC over other conductive
rubbers is that it can carry significantly more current and also there is
a more dramatic change in resistance with even a slight change in
pressure. This is because its conductivity does not depend on
conductive particles in the material actually touching. It can carry up
to 10 amps of electricity.
Quantum Tunnelling Composites
An example of where QTC
fabrics can be woven into
clothing. The jacket sleeve
features a control panel for the
operation of a personal stereo
Proposed Use: Inside fabric as a
soft switch. A ski jacket has music
controls on the sleeve.
Proposed Use: Tubing around the frame of
doors to sense if the doors are shut. When the
door is shut, it will pinch on the QTC cable.
Also use a sheet along the inside of body
panels to detect impact at any point and
activate air bags.