Classification of molybdenum and molybdenum materials
1. Pure molybdenum and high purity molybdenum
(1) Pure molybdenum
It includes sintered molybdenum products (such as crucible, etc.) and processing molybdenum plate, molybdenum bar, molybdenum strip, molybdenum wire, molybdenum sheet and profile, etc. they are still the main application forms of molybdenum materials and account for a large proportion of molybdenum materials.
(2) high purity molybdenum
With the development of LSI, tungsten and molybdenum are required to be used as wiring materials, barrier materials and gate materials. It is mainly used for molybdenum target and molybdenum silicide target, semiconductor and wiring material, as well as other high-tech materials, as well as rocket nozzle, catalyst, chemical reagent, etc. This kind of material requires high purity (at least 5N or 6N), so it needs special chemical and physical purification. At present, foreign countries have developed from research stage to industrial application stage, while domestic research is still in the primary stage.
2. High temperature molybdenum and molybdenum rare earth alloys
This is a kind of molybdenum alloy which can improve the high temperature performance and other properties of molybdenum by doping. In order to improve the high temperature performance and working life of pure molybdenum used as high temperature material, high temperature molybdenum (doped molybdenum) and molybdenum rare earth alloy were developed on molybdenum materials according to the principle of doped tungsten wire and the development of tungsten rare earth alloy. High temperature molybdenum can increase the recrystallization temperature from 1000 ~ 1100 ℃ of molybdenum to 1500 ~ 1600 ℃, and its tensile strength at 20 ℃ can reach 1400MPa, which greatly expands the service range and service life of molybdenum materials at high temperature, and has been widely used at home and abroad. At the same time, the research also shows that molybdenum cerium, molybdenum lanthanum and other molybdenum rare earth alloys have better high temperature performance than pure molybdenum, but also have better electronic emission performance, so they have been applied in electronic information industry.
3. High temperature and high strength molybdenum alloy
This is a kind of molybdenum alloy which improves the high temperature performance of molybdenum by the principle of solution strengthening and precipitation hardening. In addition to being used as high-temperature structural materials, a large number of these alloys are used as mold materials for high-temperature hot working of various metals, such as die-casting dies for black and non-ferrous metals, piercing plug for seamless steel pipes, isothermal forging dies for titanium alloys and superalloys, etc. At present, the most commonly used alloys are still molybdenum titanium zirconium (TZM) and molybdenum titanium zirconium carbon (TZC) developed in the 1960s. A large number of them are used in piercing plug of seamless steel pipe and other hot working dies in China, which is one of the main uses of molybdenum materials. After the 1980s, molybdenum zirconium hafnium (ZHM) and the alloys with rare earth elements added on them have been developed successively. The high temperature strength at 1100 ℃ of these alloys is 20-50% higher than that of TZM alloys. They have been used in isothermal forging dies of superalloys abroad.
4. Molybdenum copper alloy
MoCu alloy is actually a pseudo alloy composed of two immiscible metals, which has the characteristics of Mo and Cu and has good comprehensive properties. Molybdenum copper alloy has high conductivity, low adjustable coefficient of thermal expansion, non-magnetic, low gas content, good vacuum performance, good machinability and special high-temperature performance. Molybdenum copper alloy has good strength and plasticity at room temperature and medium temperature. When the temperature exceeds the melting point of copper, the copper in the material can liquefy, evaporate, absorb heat and play a cooling role. This property can be used as high temperature materials for special purposes, such as nozzle throat lining resistant to gunpowder combustion temperature, electric contact under high temperature arc, etc.
Because of these properties, Mo Cu alloy has a broad application prospect. It mainly includes: vacuum contact, conductive heat dissipation elements, instrument components, high-temperature parts of rockets and missiles with slightly lower operating temperature and other weapon parts, such as extended range gun, etc.; solid dynamic seal, reinforcing rib of sliding friction, water-cooled electrode head of high-temperature furnace, and electric machining electrode, etc. In recent years, with the development of electronic industry, the demand for molybdenum copper sheet is increasing. Generally, the molybdenum copper blank after infiltration is used and rolled to produce the required sheet.
5. Molybdenum tungsten alloy
Molybdenum tungsten alloy with 10 ~ 40% tungsten content has good corrosion resistance to liquid metal, which is mainly used for heater sleeve and temperature measuring sleeve in hot-dip plating industry. In hot-dip plating industry, molten metal solution with a certain temperature is needed. Tungsten molybdenum alloy has the characteristics of long service life and no pollution in this environment.
6. Molybdenum rhenium alloy
Due to the "rhenium effect" (adding a small amount of rhenium (3% ～ 5%) can increase the recrystallization starting temperature of molybdenum by 300 ℃ ~ 500 ℃), the properties of molybdenum rhenium alloys have been greatly improved, the strength, plasticity and weldability of the alloys have been improved at the same time, and the alloys have a lower ductile brittle transition temperature. Therefore, molybdenum rhenium alloys have been widely used in aerospace and electronic industries Application. The molybdenum rhenium alloy with 11% ~ 50% rhenium content has the best performance, and the molybdenum rhenium alloy with 40% ~ 50% rhenium content is the most widely used.
MoRe alloy has higher resistivity than other transition metal alloys, and its elongation can reach 15% ~ 20%, so it can be used as thermal element of resistance furnace. Elements made of Mo-50Re alloy wire and sheet can be used in heaters and reflectors with temperature up to 2400K, and these components can be manufactured and assembled by welding. Mo-47Re alloy has high tensile strength and good ductility, which is of great significance for the production of micro cross-section foil and elastic components of ultra-fine wire. In addition, Mo-41Re, Mo-47.5Re, Mo-50Re, Mo-5Re-0.5Hf are also used as structural materials of rocket thrusters.
Molybdenum rhenium wires are also used as high temperature thermocouples. Due to the high cost of molybdenum rhenium alloy, its industrial application is limited, but it is widely used in high-tech industry.
