Bite a coin was a necessary precaution when its value depended on the material that formed. A surface layer could mimic the characteristics of gold, hiding a much cheaper composition. And is that a thin layer of gold can do great things.
Fortunately there are many applications that do not involve fraud. Getting the properties of gold for a cheap material has great advantages but is not without problems. The first is how to position and attach it. The easiest method is purely mechanical. Gold is tremendously ductile and malleable , which allows the formation of extremely thin sheets (up to ten thousandth of a millimeter thick). In the form of gold leaf was used for millennia to decorate all kinds of objects.
Although chemical reactions can be used to coat an object, are of little use for gold is a very reactive element ( except mercury). The comment on another occasion.
The method used is electricity. The electroplating
is the coating of a material using electricity. To oversimplify, it would be something to reverse the operation of a battery. Instead of getting electricity from a chemical reaction, uses electricity to form a thin layer of material attached to a piece that acts as an electrode. Using many materials such as zinc and cadmium but gold has its place. Its very low emissivity (0.02) makes it highly valued as insulation against radiation. Do I have to protect a satellite from solar radiation? Nothing better than a sheet of mylar covered in gold. It is so effective that is used in infrared mirrors when looking for top quality. The picture below is part of a mirror I travel to Mars in the failed Mars mission Surveyor. 
course useful as a mirror also be applied in a laser
. Gold covers the resonant cavities to reduce losses and maximize power. Its superb electrical conductivity and resistance to oxidation should use in electrical connections especially important, for example in the electronics of the airbags. You can also save the vision of astronauts against solar radiation
covering their viewers. Or you can protect the crew of some war planes electronics of the electromagnetic radiation produced . But gold will not only serve to hide and protect. One of the many methods used to prepare samples electron microscope is covered with a thin conductive layer. For example, a layer of gold. And if it is true. It is also used in jewelry. But while consuming much of its production still seems a less interesting.
Category: Chemistry
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