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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

CDL May 2015

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

CDL May 2015

Sintering process

https://www.youtube.com/watch?v=-K6_wbBnXmc&feature=player_detailpage

CDL May 2015

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

CDL May 2015

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

CDL May 2015

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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CDL May 2015

CDL May 2015

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

CDL May 2015

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

CDL May 2015

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

CDL May 2015

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