High temperature element
Molybdenum has high purity, high temperature resistance, low steam pressure and other characteristics, so that it is often used in the manufacture of high temperature furnace molybdenum heating body and molybdenum structural materials. In the production process of tungsten, molybdenum and hard alloy, most reduction furnaces and sintering furnaces are made by molybdenum wire heating. In the continuous sintering of some iron products, molybdenum rod heating row is used as heating body, and molybdenum rod heating row is hung on both sides of the furnace with molybdenum hooks. This type of furnace is generally in reducing atmosphere or non-oxidizing atmosphere, molybdenum wire can be used to close to melting point in hydrogen and decomposed ammonia, nitrogen can be used to 2000C. When it is higher than 1700C, TZM alloy or lanthanum molybdenum alloy with higher recrystallization temperature and better strength can be used as heating body. Molybdenum has good ablative resistance in melted quartz, and it is used as a current melting electrode in the glass industry. The loss of molybdenum electrode is only 7.8 grams per ton of glass produced, and the service life can be as long as one year. In addition to being used as an electrode, molybdenum is also used as high-temperature structural materials for glass melting, such as guide channels, tubes, crucible, flow orifices, and stirring rods for rare earth smelting. The application of molybdenum instead of platinum in glass fiber wire-drawing furnace is good and the production cost is greatly reduced. The newly developed nuclear fuel sintering furnace is heated by molybdenum net, and the three-phase network heater is braided by φ0.8 mm molybdenum wire. The working temperature can reach 1800-2000C. In addition, molybdenum and its alloy can also be used as hot isostatic pressure furnace frame, heat shield, sintered and steam-coated material boat, SmCo magnet and uranium dioxide sintered backplate, thermocouple and protective sleeve, etc.
Molybdenum silicide (MoSi2) is a widely used material for electric heating elements, which has the characteristics of high temperature oxidation resistance, excellent corrosion resistance and high melting point. Its oxidation resistance is due to the formation of a breathable glass film on the heating surface, so that it is not damaged by oxygen, nitrogen, carbon monoxide and sulfur dioxide, at 1700-2000° K temperature, molybdenum disilicate heating can work for two or three years. But the poor mechanical properties affect the application of molybdenum silicate, if the addition of SiC in molybdenum silicate to form a composite material, the material will disperse silicon carbide into the matrix of molybdenum disilicate, the formation of bimetallic compounds containing molybdenum atoms and silicon atoms, its high temperature strength is 8 times higher than molybdenum disilicate monomer, so that its application prospect is favored.
