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Specification section 1.5 Modern and Smart materials 1.5 What do you need to learn? The advantages and disadvantages of each material when manufacturing products Modern and Smart materials 1.5 Shape Memory Alloys (SMA) • This can be easily shaped when cooled and returns to its ‘remembered’ shape when heated above a certain temperature. • An example of this is Nitinol • Product example: if your glasses are made from an SMA then if you bend them you can put them in a bowl of hot water and reshape them. • How does this happen? A change in their crystal structure above their transformation temperature causes them to return to their original shape. Modern and Smart materials 1.5 Shape Memory Alloys (SMA) Modern and Smart materials 1.5 Photochromic paint • Photochromic materials change reversibly colour with changes in light intensity. • Usually, they are colourless in a dark place, and when sunlight or ultraviolet radiation is applied molecular structure of the material changes and it exhibits colour. When the relevant light source is removed the colour disappears. • Changes from one colour to another colour are possible mixing photochromic colours with base colours. They are used in paints, inks, and mixed to mould or casting materials. •http://www.youtube.com/watch?v=a0tYj2hr6L0 Modern and Smart materials 1.5 Photochromic ink Modern and Smart materials 1.5 Thermochromic paint Modern and Smart materials 1.5 Reactive glass Case Study – RavenBrick • This company have use nanotechnology to develop a glass that automatically changes tint according to its temperature. • When the glass gets hot the windows darken to block incoming solar radiation. • When it is cold they are clear to allow the free heat in — all without electricity. • On a hot sunny day, a RavenBrick window will transform to a darkened state, the benefits of this is that it can significantly reduce heating and cooling costs, the greatest energy consumers in commercial buildings. •This can also improve the glare from the sunlight in offices as it dulls it when it is too bright. Modern and Smart materials 1.5 Reactive glass Modern and Smart materials 1.5 Carbon Nanotubes •Carbon nanotubes are molecular-scale tubes of graphitic carbon with outstanding properties. •They are among the stiffest and strongest fibres known, and have remarkable electronic properties and many other unique characteristics. •They are only just starting to be used in industry mainly because of the high production costs of the best quality nanotubes. • They are stronger than the same amount of steel and lighter in weight. Modern and Smart materials 1.5 What are Carbon Nanotubes? Modern and Smart materials 1.5 What are Carbon Nanotubes used for?