The history of molybdenum

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A brief history of molybdenum: Before the 18th century, molybdenum was considered to be lead. For many centuries, molybdenite (MoS2) and graphite were considered to be the same thing. Molybdenum was in use even before it was discovered; in the 14th century, Japan used molybdenum-containing steel to make swords, and in the 16th century, molybdenum ore was used in pencils just like graphite. The element molybdenum was discovered by C.W. Scheele in 1778; he decomposed molybdenite with nitric acid to obtain molybdic acid and molybdenum salts, and molybdenum oxide was produced in the same year. In 1781, the Swede Görelim obtained metallic molybdenum by reducing molybdenum trioxide, and P.J. Hjelm obtained pure metallic molybdenum in 1782. In 1893, M. Moissan heated a mixture of carbon and molybdenum dioxide using an electric furnace, thereby obtaining cast molybdenum metal at 92%–96% purity. In the early 19th century, Berzelius obtained purer molybdenum metal by reducing molybdenum trioxide with hydrogen. In the 19th century, it was discovered that adding molybdenum to steel resulted in properties similar to those of tungsten steel with a similar composition. After the production process for ferromolybdenum was successfully developed in 1900, it was the production of molybdenum steel that saw rapid growth in 1910. Because it was discovered at that time that molybdenum steel could meet the special properties required for gun steel materials. Since then, molybdenum has become an important component in various structural steels designed for heat resistance and corrosion resistance, as well as an important component in non-ferrous metal alloys such as nickel and chromium alloys. At the beginning of the 20th century, molybdenum was still used in industry for certain compounds; ammonium molybdate was employed as a phosphorus reagent, while molybdenum blue was used as a pigment. The industrial production of molybdenum metal and its widespread use in the electrical industry began around the same time as that of tungsten metal (in 1909). Since the powder metallurgy and pressure processing techniques for producing these two types of dense materials have been developed successfully, they can be used for production. During World War II, the American company Clemax Molybdenum developed the vacuum arc melting method. Using this method, molybdenum ingots weighing 450–1000 kg were produced, paving the way for the use of molybdenum as a structural material. With the continuous development of powder metallurgy, it was already possible to produce billets weighing 180 kg in the 1950s. In the late 1950s, research on molybdenum focused primarily on exploring the compositions and production methods of heat-resistant molybdenum alloys. China began mining molybdenum in 1914, but due to imperialist exploitation and domestic backwardness, there was no molybdenum smelting industry until 1949. After the founding of the People’s Republic of China, China’s molybdenum smelting industry was developed from scratch. On September 26, 1953, a reagent production team led by Zheng Liangyong managed to produce China’s first generation of tungsten filaments under the rudimentary conditions available at the Shanghai Light Bulb Factory ； In 1954, the first molybdenum wire was produced. At the end of the 1950s, China began to develop its molybdenum metallurgy industry, such as the Yangtze River Smelting Plant (now the Cemented Carbide, Tungsten and Molybdenum Branch in Zhuzhou). From the late 1960s to the early 1970s, China’s molybdenum metallurgy industry saw the addition of many new factories and began to develop in the direction of deeper processing. At the end of the 1960s, research on molybdenum metallurgy focused on achieving ultra-high purity on the one hand, and on adding certain elements artificially to meet specific performance requirements on the other. From the late 1970s to the early 1980s, Zhuzhou Cemented Carbide Factory and Shanghai Institute of Steel Research collaborated to successfully develop a liquid-phase doping process for molybdenum, taking this process to a new level. In the mid-1980s, China began to introduce a large number of equipment and technologies, which enabled its molybdenum metallurgy industry to reach a new level and narrowed the gap with world standards. After more than 40 years of development, China’s molybdenum industry has achieved a certain level of proficiency in areas such as exploration, mining, ore processing, hydrometallurgy, powder metallurgy, pressure processing, and the application of molybdenum products, and it holds a significant position in the world. Physical properties of molybdenum: Molybdenum is a rare metal with a high melting point; it belongs to the VIB group in the fifth period (the second longest period) of the periodic table. It is a white metal that resembles steel in appearance. It has a high melting point, a very low vapor pressure, and a slow evaporation rate as well. It has better ductility than tungsten, is easy to work under pressure, and can be processed into very thin foils and very fine wires. Molybdenum has lower strain and strength limits than tungsten, and its thermal expansion coefficient is similar to that of glass. Atomic number: 42; Relative atomic mass: 95.94; Relative density: 10.2; Melting point, °C: 2622±10; Boiling point, °C: 4804. The chemical properties of molybdenum: Molybdenum is very stable at room temperature ； At 400°C, slight oxidation occurs (an oxidized color can be observed), and above 600°C, the metal oxidizes rapidly to molybdenum trioxide ； Above 700°C, water vapor strongly oxidizes molybdenum to MoO2. Molybdenum does not undergo any change with hydrogen up to its melting temperature. However, when molybdenum is heated in hydrogen, it can absorb a portion of the hydrogen to form a solid solution; for example, at 1000°C, 100 g of metallic molybdenum can absorb 0.5 cm3 of hydrogen, and at 300°C, hydrogen is absorbed by the fine particles of molybdenum. Below 150°C, molybdenum does not react with hydrogen at all ； Above 1500°C, molybdenum reacts with nitrogen to form nitrides. For example, no reaction is observed even at 2400°C. Carbon, hydrocarbons, and carbon monoxide begin to interact with molybdenum at 800°C to form (Mo2C). Carbon dioxide oxidizes molybdenum at temperatures above 700°C. Chlorine reacts with molybdenum at room temperature to form Mo5Cl. Iodine does not react chemically with molybdenum. Bromine reacts with molybdenum under red-hot conditions. In the presence of moisture, all halogens react with molybdenum at room temperature. When boron reacts with molybdenum under heating conditions. Sulfur reacts with molybdenum at temperatures above 44°C, or hydrogen sulfide does so at 800°C, to form molybdenum disulfide. At room temperature, molybdenum is very stable in hydrochloric acid and sulfuric acid ； Molybdenum begins to dissolve when heated to 80–100°C. Metal molybdenum dissolves in nitric acid and aqua regia at room temperature, with the dissolution rate increasing when heated. Metal molybdenum dissolves in hydrogen peroxide to form H2Mo2O11 and H2MoO6. Molybdenum is stable in hydrofluoric acid, but dissolves rapidly in a mixture with nitric acid. A mixture with a volume ratio of nitric acid:sulfuric acid:water of 5:3:2 can be used as a solvent for molybdenum. The molybdenum core wrapped with tungsten coils is dissolved using this method. Molybdenum is very stable in alkaline solutions at room temperature, but it may be corroded in hot alkaline solutions. Hot molten alkali can strongly oxidize molybdenum metal; in the presence of an oxidizing agent, the oxidation of molybdenum occurs rapidly, resulting in the formation of molybdic acid.