jeudi 29 juillet 2010
The Many Uses of Gold
Of all the minerals mined from the Earth, none is more useful than gold. Its usefulness is derived from a diversity of special properties. Gold conducts electricity, does not tarnish, is very easy to work, can be drawn into wire, can be hammered into thin sheets, alloys with many other metals, can be melted and cast into highly detailed shapes, has a wonderful color and a brilliant luster. Gold is a memorable metal that occupies a special place in the human mind.
When Spanish explorers first arrived in the "New World" they met the native South Americans. These two cultures had been separated by a vast ocean, they had never touched one another, they spoke different languages and lived entirely different lives. Yet they had one thing in common - they both held gold in highest esteem and used it to make some of their most important objects.
Throughout the history of our planet almost every established culture has used gold to symbolize power, beauty, purity and accomplishment. Today we continue to use gold for our most significant objects: wedding rings, Olympic medals, Oscars, Grammys, money, crucifixes and ecclesiastical art. No other substance of the same rarity holds a more visible and prominent place in our society. Jewelry: The Primary Use of Gold The production of ornamental objects was probably the first use of gold over 6000 years ago. Gold is found in the pure state, is very easy to work and was probably the first metal used by humans. Today, most of the gold that is newly mined or recycled is used in the manufacture of jewelry. About 78% of the gold consumed each year is used in the manufacture of jewelry. Financial Gold - Coinage, Bullion, Currency BackingBecause gold is highly valued and in very limited supply it has long been used as a medium of exchange or money. The first known use of gold in transactions dates back about 6000 years. Early transactions were done using pieces of gold or pieces of silver. The rarity, usefulness and desirability of gold make it a substance of long term value. Gold works well for this purpose because it has a high value, is durable, portable and easily divisible. Uses of Gold in Aerospace If you are going to spend billions of dollars on a vehicle that when launched will travel on a voyage where the possibility of lubrication, maintenance and repair is absolutely zero, then building it with extremely dependable materials is essential. This is exactly why gold is used in hundreds of ways in every space vehicle that NASA launches.
Gold is used in circuitry because it is a dependable conductor and connector. In addition, many parts of every space vehicle are fitted with gold-coated polyester film. This film reflects infrared radiation and helps stabilize the temperature of the spacecraft. Without this coating, dark colored parts of the spacecraft would absorb significant amounts of heat
Gold is also used as a lubricant between mechanical parts. In the vacuum of space, organic lubricants would volatilize and they would be broken down by the intense radiation beyond Earth's atmosphere. Gold has a very low shear strength and thin films of gold between critical moving parts serves as a lubricant - the gold molecules slip past one another under the forces of friction and that provides a lubricant action.
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