AS D&T Modern Materials and Products Thermo- Ceramics Tinted Glass Photochromic Glass Solar Panels Liquid Crystal Displays Electroluminescent Lighting CDL May 2015

Thermo- Ceramics Extremely hard materials https://www.youtube.com/watch?feature=player_detailpage&v=fI6jCh3IEt0 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 https://www.youtube.com/watch?v=RJzyB_qEWyU&feature=player_detailpage#t=86 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 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 CDL May 2015

Tinted Glass example CDL May 2015

Photochromic Glass 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 CDL May 2015

Reactive glass Unlike Photochromic glass, reactive glass relies on an external stimulus to make them go dark Examples include welding masks and privacy windows https://www.youtube.com/watch?feature=player_detailpage&v=SuLNAGpCVtU CDL May 2015

Solar Panels 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 CDL May 2015

CDL May 2015

CDL May 2015

Liquid Crystal Displays 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 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

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 https://www.youtube.com/watch?feature=player_detailpage&v=WREwKx0qF7o CDL May 2015

Photochromic paint 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 CDL May 2015