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Gold is a metal discovered and used earlier by human beings. Because it is rare, special and precious, it has been regarded as the first hardware since ancient times, and has the title of "king of metals", enjoying an incomparable reputation with other metals, and its prominent position is almost eternal. It is precisely because of this "noble" status that gold once became a symbol of wealth and luxury, and was used as a financial reserve, currency, jewelry and so on. So far, the application of gold in the above fields still occupies a major position.
With the development of society, the economic status and application of gold are constantly changing. Its currency function is declining, and its application in industrial and high-tech fields is gradually expanding.
Gold has three main uses:
1. Used as international reserve: This is determined by the monetary property of gold. Because of its excellent characteristics, gold has played a role as a currency in history, such as a measure of value, a means of circulation, a means of storage, a means of payment and a world currency. With the development of social economy, gold has withdrawn from the circulation field. Since the decoupling of gold and the dollar in 1970s, the gold function of money has also weakened, but it still maintains a certain monetary function. At present, gold still occupies a very important position in the international reserves of many countries, including major western countries.
2. Used as jewelry decoration: Gorgeous gold ornaments have always been a symbol of one's social status and wealth.
3. Application in industry and science and technology: Because of its unique and perfect characteristics, gold has extremely high corrosion resistance stability; Good electrical and thermal conductivity; The gold nucleus has a large effective cross section to capture neutrons; The reflection ability of infrared ray is close to100%; It has various catalytic properties in gold alloys; Gold also has good manufacturability and can be easily processed into ultra-thin gold foil, micron gold thread and gold powder; Gold is easy to be plated on the surface of other metals, pottery and glass, and it is easy to be welded and forged under certain pressure. Gold can be made into superconductors and organic gold. It is precisely because it has so many beneficial properties that it is justified to be widely used in the most needed modern high-tech industries, such as:
(1) Application of Gold in Instrument Manufacturing Industry
With the development of science and technology, the requirements for various instruments and meters are getting higher and higher. The application of gold in various precision automation instruments is becoming more and more important.
Winding with pulse linear displacement and angular displacement is widely used in industrial measurement and control equipment. Potentiometer occupies an important position, and the quality of potentiometer is the decisive factor for the working accuracy of measurement and control system. Because of this, this kind of equipment often needs to work for a long time at different temperatures in various industrial atmospheres. This is why the precision potentiometer uses gold or alloy as the key material.
The precision potentiometer used in testing technology has high resistivity of some materials and the temperature coefficient of resistance is as small as zero, so the resistance is constant when working (it is difficult to keep constant). Gold-palladium-chromium alloy, gold-palladium-manganese alloy, gold-palladium-vanadium alloy and gold-palladium-iron alloy not only meet the above requirements, but also reach a good level in processing mechanical properties and thermal stability.
(2) The application of gold in electronic industry
The stability, conductivity, toughness and ductility required by electronic components, together with gold and its alloys, can almost meet the requirements. Therefore, the consumption of gold in the electronics industry accounts for more than 90% of industrial gold, and the consumption is increasing year by year.
(3) Application of gold in conductive materials
Gold wire, gold foil, parts pressed with gold powder, gold alloy and gold alloy materials (such as gold-plated glass, gold-plated ceramics and gold-plated timing) are widely used as conductor materials in electronic equipment, semiconductor devices and microcircuits. For example, in the production of semiconductor integrated circuits, the lead frame of semiconductor integrated circuits is made of lead frame material by high-speed punching machine, and the qualified lead frame can be made into semiconductor integrated circuits only after cleaning, local gold plating (the thickness of gold plating layer is not less than 1 micron), die mounting, wire bonding and packaging. Gold and gold alloys are used as internal leads and external leads in electronic industry, such as bonding wires of semiconductor devices (according to GB/T 8750- 1997).
Gold is also widely used in electrical contact materials, gold-based solders, electronic pastes, aerospace industry, lubricating materials, chemical industry, optics and medicine.