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AS D&TModern Materials and Products
• Thermo- Ceramics• Tinted Glass• Photochromic Glass• Solar Panels• Liquid Crystal Displays• Electroluminescent Lighting
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Extremely hard materials Very stable shape at high temperatures Expensive Uses: jet engine turbine blades, car brake
discs, spacecraft heat protection Made by a process called sintering using
powdered metals
Thermo- Ceramics
https://www.youtube.com/watch?v=RJzyB_qEWyU&feature=player_detailpage#t=86
https://www.youtube.com/watch?feature=player_detailpage&v=fI6jCh3IEt0
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Sintering• A process used to make new materials by
compressing heated powders of metal and ceramics
• The particles are not chemically joined like in alloys, but simply stuck together under pressure
• Sintered metals have tiny spaces between the particles, which can absorb oil to make bearings that need no maintenance
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Sintering process
https://www.youtube.com/watch?v=-K6_wbBnXmc&feature=player_detailpage
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Tinted glass is simply glass that has been given a tint, or colour
Normally used to provide shade and protection from bright light
Examples include welding goggles, sunglasses and tinted car windows
The tint is permanent and cannot be reversed
Tinted Glass
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Tinted Glass example
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Similar to tinted glass, but the tint is reversible Glass automatically darkens when exposed to
ultraviolet light Reverts to clear glass when the light is reduced Works by mixing tiny particles of Silver Halide
into the glass Silver halide reacts to light and is used in
photographic paper (permanent change) In photochromic glass the reaction is reversible
Photochromic Glass
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Unlike Photochromic glass, reactive glass relies on an external stimulus to make them go dark
Examples include welding masks and privacy windows
Reactive glass
https://www.youtube.com/watch?feature=player_detailpage&v=SuLNAGpCVtU
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Originally developed for space exploration Now becoming viable on earth as an alternative to burning
fossil fuels Solar panels contain Photovoltaic, or Solar cells Photovoltaic cells are made from layers of silicon; the sun
cause an imbalance of electrons between the layers, causing a flow of electricity
The voltages produced are small and the panels require a lot of sunlight to work efficiently
Government subsidies have recently encouraged more householders in the UK to install the panels
Solar Panels
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Made from organic, carbon based compounds Work by passing an electric current across the liquid
crystal, which causes the crystals to align and block light from passing through
Use very small amounts of electricity LCD TV’s have colour LCD displays, but the picture
is not as good as some old cathode ray TV’s, and the viewing angle is not as good
LED TV’s are similar to LCD, but give a better picture and allow the TV to be thinner
Liquid Crystal Displays
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Electroluminescent Lighting
• EL lighting are made of an organic phosphor sandwiched between two electrodes
• The phosphor emits radiation in the form of visible light
• Extremely low power consumption
• Used in wristwatches and in advertising
• Very thin sheets can be made, which are waterproof so they are good for bill boards and the sides of bus shelters
• They have a limited life span
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https://www.youtube.com/watch?feature=player_detailpage&v=WREwKx0qF7o
Shape Memory Alloys• Nitinol (Nickel Titanium Alloy) is the best known SMA• Distorted SMA’s change back to their original shape when heated to
an exact temperature• The transition temperature is about 650c for Nitinol• Heating can be by passing an electric current through the wire, or by
heating directly• This process can be repeated indefinitely
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Photochromic paint contains pigments that change colour according to light conditions
When the light it removed, the paint reverts back to its original colour
Uses include: UV light warning signs or advertising
Photochromic paint