Application of molybdenum and molybdenum alloy products
In refractory metals, molybdenum and its alloys have good thermal conductivity, conductivity and low expansion coefficient. They have high strength at high temperature (1100 ~ 1650 ℃), and are easy to process compared with tungsten. Therefore, their products are widely used in aerospace and nuclear industries, electronics, building materials, instruments and other industries.
1. Military industry
Molybdenum alloy plays an important role in military industry because of its excellent heat resistance and high temperature mechanical properties. It can be used as flame guide and combustion chamber of aircraft engine, throat, nozzle and valve of liquid rocket engine of spacecraft, nozzle of rocket, end of reentry vehicle, skin, wing, guide plate and protective coating material of satellite and spacecraft. Mo Cu alloy can be used as air rudder and high temperature connector of missile. Because of its high sound velocity and high density, molybdenum can be used in the liner of armor piercing projectile. Molybdenum has low coefficient of thermal expansion and high conductivity, which makes it a sealing material for high speed rotation of liquid engine. Molybdenum has low thermal expansion coefficient and good thermal conductivity, and its dimensional stability is especially good under the strong effect of solar radiation. The satellite antenna made of metal molybdenum mesh can keep its parabolic shape, and its weight is lighter than that of graphite composite antenna.
Molybdenum has small neutron absorption cross section, good strength, good stability to nuclear fuel and good corrosion resistance to liquid metal. It can be used as protective sheet for armor element of converter in nuclear fusion reactor. Molybdenum boat is also widely used in nuclear fuel processing in the nuclear industry.
2. Electronic industry
Tungsten, molybdenum and other refractory metal materials have always been important materials for electronic industry and electric light source. Molybdenum has good electrical conductivity and high temperature performance, especially its coefficient of thermal expansion is very close to that of glass. It is widely used in manufacturing the core wire, lead out, hook, bracket, side bar and other parts of spiral filament in bulb, and used as grid and anode support material in electronic tube. With the development of new electronic devices and new light sources, higher and more complex requirements are put forward for the performance, quality and variety of these materials. For example, with the improvement of LED light efficiency and the continuous decline of cost and price in recent years, its application fields are increasingly extensive and rich, especially the demand for large-scale LCD panel, lamp and white light lighting parts has increased rapidly With the improvement of requirements, tungsten and molybdenum products are more and more widely used in this industry chain. Molybdenum materials are widely used in the field of LED lighting quartz glass, high temperature oxide crystal of LED epitaxial chip, heater in the process of LED epitaxial growth, and LED light-emitting electrode.
In the electric vacuum industry, molybdenum is widely used in support, lead, grid and other parts. Molybdenum disc can also be used as heat shield of power transistor and substrate and heat sink of silicon rectifier. In VLSI, molybdenum is used as metal oxide semiconductor gate, and the bimetallic effect can be eliminated by installing the integrated circuit on molybdenum. The ultra thin seamless molybdenum tube (about 15 UM) can be used as anode support for high definition TV picture tube. The image scanning lines of this kind of TV set are 1125, which is 2 times higher than that of ordinary TV set.
Molybdenum copper material has high thermal conductivity, its thermal expansion coefficient matches with ceramic and semiconductor materials in electronic industry, and has high heat resistance, so it has been widely used as packaging material. At the same time, the multilayer sandwich structure Cu / Mo / Cu, Cu / MoCu / Cu began to be applied. Table 1 shows the performance of some packaging materials.
3. Coating industry
With the rapid development of the electronic information industry, the application of molybdenum as sputtering target is increasing linearly. Sputtering target is the basis of obtaining thin film materials. With the rapid development of thin film science and the continuous progress of thin film technology, the research of target materials has been greatly developed. The application fields of sputtering targets include planar display, semiconductor, magnetic recording storage, optical recording storage, solar energy, machinery, automobile, glass, decoration and other industries. Among the various targets, Mo target has many excellent characteristics, so it is widely used in planar display industry, thin film solar cell industry, semiconductor industry, medical industry, mechanical processing industry and solid lubrication.
In recent years, more and more attention has been paid to molybdenum alloy targets as electrodes and wiring materials for LCD (liquid crystal display) and PDP (plasma display) displays. In TFT-LCD, gate electrode is a key component. In the past, Cr / Al was mainly used as gate electrode material. With the development of large-scale and high-precision flat panel display, the specific impedance and membrane stress of molybdenum are only 1 / 2 of that of chromium. At the same time, hexavalent Cr will be produced in the etching process, which is harmful to the environment and health Mo / Al is used as gate electrode material, so the demand for Mo target is increasing. In the application of molybdenum target, the research of molybdenum alloy is more and more. In order to further improve the corrosion resistance (discoloration) and adhesion (film peeling) of pure molybdenum, adding V, Nb, W, Ta in molybdenum will make the specific resistance, stress and corrosion resistance better.
In the field of solar cells, the unification of low price and high efficiency has always been the goal of solar energy development. After the development of high-cost solar cells based on silicon (monocrystalline silicon, polycrystalline silicon), low-cost thin-film solar cells will become the main force in the solar cell market in five years. In thin film solar cells, back electrode materials are needed, and Mo target has the advantages of glass corrosion resistance, high temperature resistance and good conductivity, so it becomes the first choice of back electrode materials.
In addition, Mo targets can be co sputtered with other targets or used under other process conditions, and are widely used in semiconductor wiring, medical treatment, machining and solid lubrication.
Another important application of molybdenum in coating industry is spray plating. Molybdenum spray plating is widely used in piston rings, bearings, extrusion equipment, engine block, turbine parts and other high wear-resistant parts to improve wear resistance.
4. Processing industry
In vacuum furnace and protective atmosphere electric furnace, molybdenum and molybdenum alloy products are widely used in heating body, heat shield, fixing parts, chassis, guide rail and boat dish. Due to its high corrosion resistance and high temperature resistance, large-scale molybdenum cyanides are widely used in surface coating industry, single crystal production industry, diamond and cubic BN production.
The service life of molybdenum alloy plug used in seamless steel pipe piercing is more than ten to dozens times longer than that of tool steel plug. The application of high temperature and high strength molybdenum alloy as isothermal forging die in the processing of titanium alloy and high temperature alloy parts in aviation industry, and other applications such as die casting die for non-ferrous metal, etc.
With the rapid development of die and mold industry, EDM technology has been widely used. Molybdenum wire is an ideal electrode wire for WEDM. It can cut various steel and cemented carbide, and process parts with extremely complex shapes. Its EDM is stable and can effectively improve the accuracy of the die.
5. Glass building materials industry
As an emerging industry, the building materials industry has been developing and growing both at home and abroad. Molybdenum electrode used in glass and glass fiber production furnace has the advantages of low energy consumption, long service life, high product quality and good environmental conditions. Molybdenum has good corrosion resistance in molten glass, and the reaction product of molybdenum with glass solution is colorless, so it will not have adverse effect on glass products. Therefore, molybdenum is widely used as heating electrode, flow port and agitator for melting glass.
6. Instrument industry
Because molybdenum has a low coefficient of thermal expansion and no magnetism, in many parts of instruments and meters that require no such conditions and have certain expansion coefficient requirements, the expansion coefficient of molybdenum based nonmagnetic fixed expansion alloy can be easily adjusted by adding the composition of alloy elements, so as to adapt to the expansion coefficient of its matching component materials.
