Modern Materials and Products Mr P Mulholland St Joseph’s High School Crossmaglen

Thermo-Ceramics Thermo-ceramics are advanced ceramic materials that have properties that make them useful in specialist situations. They have an internal structure that makes them extremely hard and very stable at high temperatures. They are used in places where there is need for stability and strength at high temperatures, e.g. turbine blades in jet engines and turbo chargers of cars. They are produced by combining ceramic and metallic powders by sintering (method for creating objects from powders, including metal and ceramic powders). The powders are heated, placed in a die (mould) and put under high pressure until particles bond.

Thermo-Ceramics Disadvantages Brittle and can break if dropped Imperfections in ceramic material when being made can cause it to crack or break Cost of thermo ceramics is very high

Photochromic Glass Photochromic glass is a glass that automatically darkens when exposed to ultraviolet (UV) light. Once the light source is removed it changes back to clear glass again. Most commonly seen in spectacles that change from clear to dark in bright sunlight and then become clear when the sun goes away. Glass is impregnated (filled throughout) with silver halide. Silver halide reacts to light . As the silver halide is sealed within the glass the process can be reversed. Light to dark Dark to light

Photochromic Glass

Solar Panels Photovoltaic or solar cells are used to generate electricity. Photovoltaic cells are made from thin layers of silicon with impurities added. When exposed to sunlight, one layer becomes electron rich and the other becomes electron deficient. As a result electrons will flow. A voltage is set up between the two layers. If contacts are attached the electricity can be tapped off. Voltage produced is small and many cells are needed. Photovoltaic cells are generally used where electricity is not available, e.g. marine buoys at sea, school crossing signs They are being used to produce renewable energy at home and in business.

Solar Panels

Liquid Crystal Display Liquid crystals are organic, carbon based compounds that exhibit both liquid and solid crystal characteristics When a cell containing liquid crystal has a voltage applied to it, and when light falls on it appears to go dark. In the example of a digital clock a LCD has a pattern of conducting electrodes that is capable of displaying numbers through a seven segment display. LCD uses very little energy and as a result can be powered by a battery. Useful for electrical products as battery life is good.

Liquid Crystal Display

Liquid Crystal Display Advances in LCD technology has led to a full colour LCD screen/display. They are used in television, computer screens and phones. Sometimes the picture produces is not as good as cathode ray screens. The viewing angle can be narrow.

Electroluminescent Lighting EL converts electrical energy to light. By applying a voltage across electrodes. An organic phosphor is sandwiched between two conductors. As the electric current is applied it rapidly charges the phosphor crystals which emit radiation in the form of visible light. EL has extremely low power consumption which makes it ideal for the backlight on LCD displays. EL panels are being used instead of advertising posters at bus shelters, on the sides of buildings and on busses. They are waterproof, highly visible and extremely reliable and use very small amounts of energy.

Electroluminescent Lighting