1 materials and proccesses- smart materials Flashcards
smart materials
smart materials are materials whose physical properties change due to changes in the environment or input and then return to their original state afterwards.
examples of smart materials
thermo- ceramics
shape memory alloys
reactive glass
liquid crystal display
photochromic materials
thermo- chromic materials
quantum tunnelling composites
Thermo ceramics
They have an internal structure that
makes them extremely hard and they are very stable at very high temperatures. These
materials are used in places where there is a need for stability and strength at high
temperatures, for example, they are being used for the turbine blades in jet engines.
There are some disadvantages to thermo-ceramics. They can be brittle and
can break if dropped and if there are imperfections in the ceramic material it can crack or
break.
shape memory alloys
shape-memory alloy (SMA) is bent out of shape, when it is heated above a certain temperature it will
return to its original shape.
SMAs are used as triggers to start
the sprinklers in fire alarm systems, controllers for hot water valves in showers or coffee machines and
for spectacle frames.
Reactive glass
reactive glass requires an external stimulus to
make it turn from clear to dark.
One application of reactive glass is in masks for electric
arc welding. These have clear glass that remains clear until an arc is struck.
Other applications include
glass panels that can replace curtains or blinds and give privacy at the touch of a button.
Liquid crystal display
Liquid crystals are organic, carbon-based compounds that can exhibit both liquid and solid
crystal characteristics.
crystal. In the case of a digital clock or wristwatch, a liquid crystal display
(LCD) has a pattern of conducting electrodes that is capable of displaying numbers via a
seven-segment display.
With the rapid advance of LCD technology came the full-colour LCD display commonly used in laptops.
Photocromic materials
Photochromic materials change colour according to different lighting conditions. They are used for security markers that can only be seen in ultraviolet light.
Thermochromic materials
Thermochromic materials change colour as the temperature changes. These are used on
contact thermometers made from plastic strips and test strips on the side of batteries
(where the heat comes from a resistor under the thermochromic film). They are also used as
food packaging materials that show you when the product they contain is cooked to the
right temperature.
quantum tunnelling composite
When QTC is in its relaxed state, it is a near-perfect electrical insulator but when it is stretched,
compressed or twisted it becomes an electrical conductor and allows, in some instances, very high currents to pass-through
it.
QTC in Medicine – QTC sensors can be incorporated into the cuffs of blood pressure machines to ensure that they are
tightened correctly to reduce inaccurate readings.
