Molybdenum is a transition metal element with a value of 42 on the periodic table. Its chemical symbol is molybdenum. Molybdenum is silvery white, hard and tough. It is not eroded by air at room temperature and does not react with hydrochloric or hydrofluoric acid.
When molybdenum is burned in the air, it gives off a golden light. Molybdenum ions of different oxidation states have different colors. It was not until 1893, more than 100 years after the discovery of molybdenum, that Mawson melted a mixture of carbon and molybdenum trioxide in an electric furnace, producing for the first time cast metals containing between 92% and 96% molybdenum.
Although molybdenum has been discovered more than 200 years ago, the large-scale exploitation and utilization of molybdenum is still in this century, especially in recent decades.
Molybdenum and molybdenum alloys have been widely used for their high strength, low thermal expansion coefficient, good thermal and electrical conductivity, strong corrosion resistance of molten glass, molten salt and metal liquid, good wear resistance of thin coating and so on.
Alloy steels, stainless steels, tool steels and cast iron are the main application fields of molybdenum, whose output determines the demand for molybdenum. Adding molybdenum can improve the corrosion resistance of stainless steel. Adding molybdenum to cast iron can improve the strength and wear resistance of cast iron. Nickel-based superalloy containing 18% molybdenum has the characteristics of high melting point, low density and small thermal expansion coefficient, and is used to manufacture various high temperature components in aerospace and other fields. Molybdenum is widely used in electronic devices such as electron tubes, transistors and rectifiers. Pure
molybdenum wire is widely used in high temperature electric furnace, EDM and WEDM. Molybdenum is used to make radio and X-ray equipment. Molybdenum is widely used in other alloys and chemical industry. The addition of molybdenum to alloy steel can improve the elastic limit, corrosion resistance and permanent magnetic properties of alloy steel. Molybdenum oxide and molybdate are excellent catalysts in chemical and petroleum industries.
Molybdenum disulfide is an important lubricant in aerospace and machinery industries. In addition, because of its unique sulfur resistance, molybdenum disulfide can catalyze the hydrogenation of carbon monoxide to alcohol under certain conditions.
Molybdenum is also gradually used in nuclear power, new energy and other fields.
Molybdenum is also one of the essential trace elements in plants. Plants can't live without it. Molybdenum can be used as microelement fertilizer in agriculture.
Molybdenum is found in various tissues of the human body. The total amount of copper in adult body is 9mg, and the copper content in liver and kidney is the highest. Molybdenum-99 is one of the radioisotopes of molybdenum and is used in the preparation of technetium-99 in hospitals. Technetium-99 is a radioactive isotope that can be used to examine internal organs. Molybdenum-99 used for this purpose is usually absorbed by alumina powder and stored in a relatively small container. When molybdenum-99 decays, technetium-99 is formed.
Molybdenum alloy is a nonferrous alloy composed of molybdenum and other elements. The main alloying elements are titanium, zirconium, hafnium, tungsten and rare earth elements. Molybdenum alloy has good thermal conductivity, electrical conductivity and low expansion coefficient. High strength at high temperature (1100 ~ 1650℃), easier to process than tungsten. It can be used as gate and anode of electron tube, supporting material of electric light source, die casting and extrusion die, spare parts of spacecraft, etc.
After the end of World War I, molybdenum demand fell sharply. In order to solve this problem, it is necessary to develop new application fields. Soon, the new low molybdenum alloy steel was accepted in the automotive industry. Since then, the research and development of molybdenum as alloying element in steel and other fields has entered a new stage.
In the late 1930s, molybdenum was widely used as an industrial raw material. The reconstruction after World War II stimulated the development and research of molybdenum application in the industrial field and opened up a broad market for many molybdenum-containing tool steels. At present, alloy steel, stainless steel, tool steel and cast iron are still the main application fields of molybdenum.
