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Where is toughened glass used?

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Storyboard Where is toughened glass used? Toughened glass can have various uses, mainly for when all the properties of normal glass are required, but also the stronger properties that toughened glass has. It is used in situations that glass would just not be strong enough for, such as in frameless shower screens or office partitions inside buildings, or on the exterior of buildings where large spans of glass are required, such as office buildings where the exterior is mainly glass. It is also used a great deal in all forms of transport for windows and windscreens, as regular glass could not stand up to the conditions that many vehicles face. The main use of toughened glass being focussed focused on today is in car windscreens. Toughened glass must be used for these, and in most countries there are regulations in place regarding the thickness and strength to ensure that safety is always at a high standard. It is necessary to use toughened glass in this situation due to the fact that regular glass could prove very dangerous to the occupants of the car if it were to break. ...read more.


is carried out before the toughening process starts. Otherwise, if these are attempted on the treated glass, it will just shatter due to the incredibly high tension and compression within the glass. This extra stage is a heat treatment process which, when performed correctly, should make the surface be in compression while the centre is in tension. Basically, the glass is heated to a very high temperature (approx. 620?C) until it begins to soften. It is then cooled very rapidly using cold jets of water or air. This brings the temperature of the surface of the glass down to room temperature quickly, so quickly that the centre of the glass is still very hot. This means that the surface molecules settle as they are, as they do not have time to move around from being heated to cooled. However, the particles in the center of the glass cool down much more slowly, meaning that they move closer together causing the center of the glass to shrink while the surface is already solid, therefore cannot shrink. This causes the surface of the glass to be forced into compression and the center is put into tension. ...read more.


Other properties The way that toughened glass breaks is not the only difference from normal glass. Some of its other properties are also different. For example, the toughening process involved in making toughened glass can slightly reduce the optical quality. Slight distortion of the surface can be seen when light reflects off the glass at certain angles, but not greatly enough to affect the vision of drivers when it is used in car windscreens. The resistance of the surface of the toughened glass to scratches is not changed by the heating and cooling from that of regular glass. Generally, toughened glass is never any thinner than 6mm with a density of about 2.5kg/m squared. It also has a high compressive strength value of 1000Mpa. This means that 10 tonnes would be required to shatter 1cm cubed of toughened glass. The Young's Modulus of toughened glass is about 70Gpa (Giga Pascals). It can withstand temperatures up to 295?C. All of these properties make it the most suitable choice for car windscreens, as it can withstand much more stress and pressure, and is a stronger and safer option that normal glass. ...read more.

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