With the development of society, the economic status and application of gold are constantly changing. Its monetary function is declining, and its application in industrial and high-tech fields is gradually expanding.
There are three main categories of demand and uses for gold:
(1) Use as international reserves. This is determined by the monetary commodity properties of gold. Due to the excellent properties of gold, gold has historically served as a currency, 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 With the development of social economy, gold has withdrawn from circulation. After the decoupling of gold from the US dollar since the 1970s, gold's monetary function 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 jewelry has always been a symbol of a person's social status and wealth.
(3) Application in industry and science and technology. Gold has extremely high anti-corrosion stability; good electrical and thermal conductivity; gold nuclei have a large effective cross-section for capturing neutrons; the reflection ability of infrared rays is close to 100%; gold alloys have various catalysts Properties: Gold also has good craftsmanship and is easily processed into ultra-thin gold foil, micron gold wire and gold powder. Precisely because of its many beneficial properties, it has reason to be widely used in modern high-tech industries that are most in need, such as electronic technology, communication technology, aerospace technology, chemical technology, medical technology, etc.
1. Application of gold in instrument manufacturing industry
With the development of science and technology, the requirements for various instruments and meters are becoming higher and higher. The application of gold in various precision automation instruments is also becoming more and more important.
In industrial measurement and control equipment, windings that use pulse-variable linear displacement and angular displacement are widely used. Potentiometers occupy an important position. The quality of the potential is the decisive factor in the working accuracy of the measurement control system. For this reason, this equipment is often required to work for a long time at different temperatures in various industrial atmospheres. This is the reason why gold or alloy is used as the key material of precision potentiometer.
Some parts of the materials used in precision potentiometers used in testing technology have very high specific resistance and a temperature coefficient of resistance as small as close to zero, so that the resistance is constant during operation (remaining constant) Very difficult). In addition to meeting the above requirements, gold-palladium-chromium alloys, gold-palladium-manganese alloys, gold-palladium-vanadium alloys, and gold-palladium-iron alloys have achieved better mechanical properties, thermal stability and other aspects of processing. level.
Thermocouples and resistance thermometers are often used to measure temperature in industry. A thermocouple is composed of two metal wires with different components. The temperature difference between the cold ends of the measuring points causes a thermoelectric potential that can be measured with a millivolt meter. The temperature is measured based on the change in the thermoelectric potential of the temperature. Therefore, it is The thermal stability requirements of materials are very strict.
2. The application of gold in the electronic industry
As we all know, the development of modern science and technology is inseparable from the electronic industry, and it also occupies an important position, such as electronic information, aviation Aerospace, instrumentation, computers, radios, televisions, integrated circuits, etc. are all the result of the rapid development of the electronics industry, and the electronics industry is inseparable from the application of gold and other precious metals. Gold and its alloys can almost meet the requirements for stability, conductivity, toughness, ductility, etc. required by electronic components. Therefore, the amount of gold used in the electronics industry accounts for more than 90% of industrial gold, and the amount is increasing every year.
3. Application of gold in electrical contact materials
In modern communication systems, control systems and electronic computer systems, although their structures are compact and their devices are miniaturized, they should still be used. Guarantees the possibility of carrying out necessary inspections. In this regard, it is technically reasonable to adopt a detachable structure of individual parts and components. Higher requirements for reliability and service life naturally raise the necessity and importance of researching new contacts. Due to the compact arrangement of parts and the increased energy reserve per unit volume, to improve the effectiveness of the system in communication systems, some factors related to the surrounding environment must be considered when developing contact materials, such as excellent conductivity, stable resistance, and excellent Corrosion resistance, processability, thermal stability, etc.
Because gold and gold alloys have the above-mentioned excellent properties, they are widely used in the production of electrical and industrial contacts.
Due to the plateability, high plasticity and good processing properties of gold and gold alloys, various types of electrical contacts for different purposes can be made by pressing, electroplating, coating, electrodeposition and other methods. For example, gold-platinum, gold-copper, gold-silver-indium can be used to make contacts and sliding contacts for communication equipment; telephone relay contacts made of gold-gallium are wear-resistant and can ensure signal transmission: gold-gallium —Palladium is used to make high-strength, corrosion-resistant electrical contacts; gold-copper-palladium is used to make highly elastic contacts; gold is widely used in tongue contacts (tongue reed tubes) made of ferromagnetic alloys; using dispersed oxide (0.05 micron Dispersed granular thorium oxide) can significantly improve the mechanical properties of gold. This material is heat-resistant, anti-oxidation and has strong mechanical properties. It can be used to make industrial relay contacts at high temperatures and for gold-copper-zinc shape alloys. For special purpose wire fusion contacts.
4. Application of gold in conductive materials
Gold wire, gold foil, parts pressed with gold powder, gold alloys, gold-coated alloy materials (such as gold-coated glass, gold-coated Gold ceramics, gold-coated quartz), etc. are widely used as conductor materials in electronic equipment, semiconductor equipment and micro circuits. For example, in the production of semiconductor integrated circuits, the lead frame of the semiconductor integrated circuit is punched out of lead frame material by a high-speed punch. The qualified lead frame is cleaned, partially gold-plated (the thickness of the gold-plated layer is not less than 1 micron), loaded into the chip, and bonded. Semiconductor integrated circuits can be made through processes such as wiring and packaging. Gold and gold alloys are used in the electronics industry for inner and outer leads, such as bonding gold wires for semiconductor devices (according to GB/T8750-1997).
5. Application of gold in gold-based solder
Gold-based solder has many valuable properties, but its wide application in industry is limited simply because of the high price of gold. . With the development of new structural materials in the electronic industry, vacuum technology, atomic energy devices, jet engines for aircraft and rockets, and aerospace devices, the application scope of gold-based solders has become wider.
The property requirements of gold-based solder are mainly wetting performance, welding strength, heat resistance, corrosion resistance, sputtering and process performance.
6. Application of gold in electronic paste
Integrated circuits, which emerged in the 1960s, developed rapidly. In 1967 and 1977, large-scale integrated circuits and very large-scale integrated circuits came out. Integrated circuits have not only become the basis for various advanced technologies. It is also a key technology in the modern information society. Its development has led to the large-scale application of precious metal powders in the microelectronics industry, making precious metal electronic slurries an important foundation for the microelectronics industry.
7. The application of gold in the aerospace industry
The application of gold in the aerospace industry is also constantly developing and developing, and its speed is surprising. Gold is known for its corrosion resistance, heat resistance, and excellent thermal and electrical conductivity. Unique chemical properties play an important role in the aerospace field.
Gold is widely used in the aerospace industry. From the manufacturing of spacecraft and launch vehicles to the system control of aerospace, everything is inseparable from information, measurement, remote sensing, positioning, computers, photography, instruments and other equipment. Among them, thousands of electronic components, instruments, Special materials are inseparable from gold.
Gold plating is used on various cosmic instruments to prevent solar radiation. Some parts of the Apollo spacecraft and astronaut equipment were also gold-plated for this purpose. Because gold has the special properties of high reflectivity and low emissivity, gold is often used in situations where radiation is prevented, such as jet generator nozzles, space device fuel components and heat reflectors. Gold is also used in jet engine and rocket launch components to coat gold heat shields or heat shields. A company in the United States has developed a method of spraying gold on the casing of aircraft engines. The thickness of the sprayed layer does not exceed 0.04 microns, which greatly improves the performance of this type of engine. Radiation-resistant, high-temperature-resistant, and non-corrosive gold-platinum alloys are used as spark chamber materials for jet engines, rockets, and supersonic aircraft engines.
8. Application of gold in lubricating materials
Gold can be made into solid lubricating composite materials through composite electrodeposition method. The coating prepared by composite electrodeposition method has good Overall performance. For example, the gold-copper-nickel-MoS2E four-component self-lubricating composite coating has the advantages of good friction system wear resistance, cold welding resistance, conductivity, and high and low temperature resistance.
The emergence of Jin’s solid lubricants and other special solid lubricants has made up for the lack of bearing materials and the lack of grease performance. Meets the lubrication needs of aerospace and other new products under harsh conditions. Such as antenna systems on artificial satellites, solar cell sail panels, infrared camera self-lubricating bearings, light receiving instrument driving mechanisms, temperature control mechanisms, satellite and arrow separation mechanisms and satellite mounting mechanisms, missile defense systems, atomic energy mechanical systems, etc.
9. Application of gold in the chemical industry
The nuclear chemical industry and the chemical industry use gold alloys to make special tubes, plates, wires and other materials to achieve corrosion protection, radiation protection, High temperature resistance and other requirements.
Gold-platinum alloys are used to make spinnerets for the production of man-made fibers due to their high corrosion resistance and strength; gold alloys containing 3% palladium and gold alloys containing 20% ??palladium are used in the production of man-made fibers. Production of catalysts for platinum recovery. It is generally believed that gold is the least active catalyst of all metals.
10. Application of gold in optics
The optical properties of gold have unique properties. Gold has extremely high properties against certain lights. Gold has the ability to absorb X-rays, and gold alloys containing other elements can change optical properties related to wavelength. The application of gold in optics cannot be replaced by other elements. Bright gold plating, as a stable coating for spacecraft, has a good effect on
controlling the temperature of the internal instruments and components of the spacecraft. This is mainly due to its good scattering and reflectivity of infrared rays in the universe.
Protect astronauts and equipment from cosmic rays.