Rhenium is a rare refractory metal that not only has good plastic, mechanical and creeps properties, but also has good wear and corrosion resistance. Rhenium can be processed into rhenium plates, rhenium rods, sheets, as well as wires, and are widely used in aerospace, electronic industry, petrochemical industry, and other fields. According to data released by the United States Geological Survey in 2013, superalloys are the largest consumer of rhenium, accounting for about 80% of the total, and catalysts are the second largest.
The global reserves of rhenium are very small and the price is relatively expensive, therefore, rhenium is mostly used in alloy form. Rhenium, as an alloy additive, can greatly improve the properties of the alloys. Rhenium can form a series of alloys with tungsten, molybdenum, platinum, nickel, thorium, iron, copper and other metals. Rhenium tungsten, rhenium molybdenum, and rhenium nickel superalloys are the most important rhenium alloys, which are widely used in the aerospace and electronics industries.
Tungsten-rhenium alloys and molybdenum-rhenium alloys
Tungsten-rhenium alloy (W-Re alloy) is an alloy composed of tungsten and rhenium. One type is low-rhenium alloys with rhenium content of less than 5%. The other is per-rhenium alloys, which contain 20% to 30% rhenium. The rolling deformation of molybdenum with 35% rhenium can reach 90% at room temperature, and the tensile strength, ductility, and resistivity of molybdenum-rhenium alloys increase with the increase of rhenium content at room temperature. Mo-5%Re and mo-41% Re are commonly used as thermocouple wire materials for aerospace structural materials.
Tungsten-rhenium alloy and molybdenum-rhenium alloy made by adding the appropriate amount of rhenium into tungsten and molybdenum thermocouple wire not only has good plasticity, but also can be processed into various structural materials, and have high hardness, high strength, and high-temperature resistance. Molybdenum-rhenium alloy is often used to manufacture high-speed rotating X-ray tube target material, long life grid plate for microwave communication, space reactor core heating tube, high-temperature furnace heater, and high-temperature thermocouple. Tungsten-rhenium alloy is widely used in high-temperature technology, electric vacuum industry, bulb industry, atomic energy industry, analysis technology, medical treatment and chemical industry and other fields, and is often used in the manufacture of special electronic tube and color picture tube filament, high-temperature components, thermocouple and so on.
Nickel rhenium alloy
The application of rhenium in engines can improve the creep strength of nickel superalloys, which can be used in the manufacture of combustion Chambers, turbine blades and exhaust nozzles of jet engines. Rhenium nickel alloy is the core material of modern jet engine blade, turbine disc, and other important structural components. The use of rhenium can not only improve the performance of nickel-based superalloys but also produce alloys for single crystal blades. Both effects can enable turbines (especially high-pressure turbines) to work at higher temperatures. In addition, by keeping operating temperatures low, the difference between the actual operating temperature and the turbine’s maximum permissible temperature can be widened, thus extending service life.
Effects of rhenium
Rhenium can improve the strength and plasticity of tungsten, molybdenum, and chromium at the same time, which is known as the rhenium effect. For example, if a small amount of rhenium (3% ~ 5%) is added, the starting temperature of recrystallization of tungsten can be increased by 300℃ ~ 500℃. W-Re and Mo-Re alloys, used in aerospace, aviation high-temperature structural parts (nozzle, nozzle, heat shield, etc.), elastic components and electronic components.
Rhenium and its compounds have excellent catalytic activity (rhenium has the highly selective catalytic function for many chemical reactions), so rhenium is often used as a catalyst in the petrochemical industry and other fields.
Catalytic reforming is one of the petroleum refining processes and an important means to improve gasoline quality and produce petrochemical raw materials. Rhenium platinum alloy, as a catalyst in the process of catalytic reforming, can improve the depth of reforming reaction and increase the yield of gasoline, aromatics, and hydrogen. In addition, rhenium can be used as a catalyst for automobile exhaust purification, while rhenium sulfide can be used as a hydrogenation catalyst for cresol and lignin.
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