The purpose of the alloy is to apply what properties of the alloy?

Industrial Use Because gold has many unique and perfect characteristics, it has unique uses in many industries. For example, it has extremely high corrosion resistance; Good electrical and thermal conductivity; The effective cross section of gold nucleus to capture neutrons is large, and its reflection ability to infrared rays is close to 100%. It has various catalytic properties in gold alloys; Good manufacturability, can be easily processed into ultra-thin gold foil, micron gold thread and gold powder; Gold is easily plated on the surfaces of other metals, pottery and glass; Gold is easy to be welded and forged under certain pressure; Gold can be made into superconductors, organic gold and so on. Specifically, the industrial uses of gold are as follows: a. With the development of science and technology in instrument manufacturing, people have higher and higher requirements for various instruments, and gold is more and more widely used in various precision automation instruments. Winding with pulse line displacement and angular displacement is widely used in industrial measurement and control equipment, and potentiometer occupies an important position. The quality of potential is the decisive factor for the working accuracy of the measurement and control system. This kind of equipment often needs to work for a long time at different temperatures in various industrial environments, so gold or its alloy has become the key material of precision potentiometers. Some materials of precision potentiometer used in testing technology have high specific resistance and resistance temperature coefficient as small as zero. So that the resistance is constant when working (it is difficult to keep constant). Au-Pd-Cr alloy, Au-Pd-Mn alloy, Au-Pd-V alloy and Au-Pd-Fe alloy not only meet the above requirements, but also reach a good level in processing mechanical properties and thermal stability. Thermocouples and resistance thermometers are often used to measure temperature in industry. Thermocouple consists of two kinds of wires with different compositions. Because of the temperature difference at the cold end of the measuring point, the thermoelectric potential can be measured with a millivolt meter, and the temperature can be measured based on the change of the thermoelectric potential of the temperature, so the requirements for the thermal stability of the material are very strict. B. The development of modern science and technology in the electronic industry can be said to be inseparable from the electronic industry, such as electronic information, aerospace, instrumentation, computers, radios, televisions, integrated circuits, etc. These are the results of the rapid development of the electronics industry. The electronics industry is inseparable from the application of gold and other precious metals. The stability, conductivity, toughness and ductility required by electronic components can almost be achieved by gold and its alloys. Therefore, the consumption of gold in the electronics industry accounts for about 70% of the total industrial gold, and the consumption is increasing year by year. C. the application of aerospace industry funds in the aerospace industry is also constantly developing and exploring. Its speed is amazing. Gold plays an important role in the aerospace field because of its corrosion resistance, heat resistance, excellent thermal and electrical conductivity and unique chemical properties. Gold is widely used in aerospace industry. From the manufacture of spacecraft and vehicles to system control, information, measurement, remote sensing, positioning, computers, photography, instrumentation and other equipment are indispensable. Among them, thousands of electronic components, instruments and special materials are inseparable from gold. For example, all kinds of space instruments are plated with gold to prevent solar radiation. D. Lubricating materials In recent decades, the research focus of tribology has changed significantly, that is, from lubrication and lubrication system to material science and technology (including surface engineering). With the development of modern industrial technology, especially in aerospace industry, many working conditions have exceeded the use limit of grease. Therefore, people have to find new lubricating materials to adapt to more complex working environment and create favorable conditions for realizing large-scale, miniaturization, high-speed, heavy-duty and automatic control of mechanical equipment. Many countries, including China, have been studying solid lubricating materials since 1950s. Gold and its alloys play an important role in the field of solid lubricating materials. Solid lubrication is to use solid micro powder, film or composite material instead of grease to isolate the friction surface in relative motion, so as to achieve the purpose of reducing friction and wear resistance. With the progress of modern science and technology, in order to solve the mechanical lubrication under special working conditions such as high load, high vacuum, high and low temperature, strong radiation and strong corrosion, solid lubricating materials have developed from single micro powder, adhesive film or single integral material to composite materials composed of multiple components. The friction material theory shows that the surface energy will affect the surface flow pressure of the material. Soft metal is attached to the surface of the substrate, as long as there is a film with a thickness of several tenths of a micron, it can play a lubricating role. When it rubs against the dual material, the soft metal film will transfer to the surface of the dual material. When the transfer film is formed, friction is generated between the soft metal and the transfer film. The principle of this phenomenon is that the shear strength of soft metal is low, and the adhesion between soft metal and substrate is greater than the ultimate shear strength of soft metal. The lubrication of soft metals such as gold, silver and zinc belongs to this mechanism, and gold is the best solid lubricating soft metal material. E. Chemical industry, nuclear industry and chemical industry use gold alloy to make special materials such as pipes, plates and wires, so as to achieve the purpose of anticorrosion. Gold alloy containing 3% palladium and gold alloy containing 20% palladium are used to produce catalysts for collecting platinum. Generally speaking, gold is the least active catalyst of all metals. The low catalytic activity of gold is determined by the total charge of electrons in D sublayer. So gold can't chemisorb small molecules. Nor can it be used as a catalyst. People used to think that gold and its compounds were the most useless in the field of catalysis. But now, after studying gold, this view has changed a lot. The results show that highly dispersed gold particles attached to alumina or silica carrier can play the best catalytic role in organic chemical hydrogenation. The mechanism is that gold particles on some carriers become electron-deficient, and their properties are similar to those of earlier elements in the periodic table. Highly dispersed gold particles have the properties of platinum group elements. It is proved that the gold film prepared by ultra-vacuum has special catalytic effect and can exchange hydrogen and deuterium. Gold is also a catalyst for isomerization and cracking of hydrocarbons, and some reactions involving oxygen can also be catalyzed by gold, such as oxidation of propylene to propylene hydride and oxidation of methanol to formaldehyde. In addition, gold can also improve the catalytic performance of other metals. Generally speaking, gold can slow down the catalysis. However, it can improve the specificity of catalytic reaction. For example, adding gold to the surface of platinum or iridium catalyst can enhance its selectivity and catalyze the isomerization of isobutane, which can reduce the progress of hydrogenolysis reaction. F. Optical application Gold has unique optical characteristics. Gold can absorb X-rays, while gold alloys containing other elements can change the optical properties related to wavelength. Bright gold plating is used as a stable coating for spacecraft. It plays an important role in controlling the temperature of instruments and components in spacecraft. This is mainly because gold has good scattering and reflectivity to infrared rays in the universe, which can protect astronauts and equipment from cosmic rays. Because gold can change the wavelength of gold alloy, thus changing the color of various metal elements. Using this characteristic of gold, special optical requirements can be achieved through certain coating. For example, a special glass with gold (coated with 0. 13 micron film) can reflect infrared rays back in hot summer and keep the room cool. This film is brown in reflected light and sky blue in incident light. If current passes through this glass, it will be transparent and pollution-free. Gold is used as a phosphor (ZnS: Cu+Zn; Au, AI) is used to display the green primary colors of color picture tubes. This powder is yellow-green, and emits yellow-green light under the excitation of cathode rays or 365nm ultraviolet rays. G. the application of gold in medicine can be traced back to ancient times, and people always think that taking gold can cure all diseases. /kloc-in the third century, the "golden drink" that people took at that time was called a panacea. In China, people also use gold foil to treat children's panic. Gold is also widely used as dental implant material. The univalent sulfhydryl compound of gold (auranofin) is mainly used to treat rheumatoid arthritis. Gold thiomalate (J), a "golden drug", is within the therapeutic concentration range of normal treatment. It has antibacterial effect on diseases caused by mycoplasma and Leishmania. Radioisotopes of gold are widely used in radiotherapy. Gold can be placed in the irradiated area in the form of particles or colloids. Colloidal gold (198Au) is used for radiotherapy of pleural or peritoneal exudates and bladder cancer, that is, when it is necessary to uniformly irradiate irregular surfaces with insoluble radiopharmaceuticals. Colloidal gold is also used for various diagnostic purposes, such as bone marrow scanning or liver and lung angiography, that is, colloidal gold is filled with organs to be studied, and then observed by scintillation photography; Gold foil is used to treat burned skin; Gold vapor laser is used to treat gastric cancer and lung cancer. In medical biology research aimed at human health, precious metals such as gold have become important artificial organ materials and surgical transplant materials because of their good chemical stability, biocompatibility and mechanical properties. Microprobe made of gold and other precious metals has made remarkable achievements in exploring the mysteries of nervous system. For example, gold and precious metals and their alloy materials are used for nerve repair and pacemakers.