Molybdenum - universal metal
People learned molybdenite long ago. Only its resemblance to galena and graphite played a bad joke. All three minerals were called the same - Molybdaena.
The main properties of molybdenum
The metal has a high specific gravity of 10.2 g / cm3, an important property of molybdenum is its refractoriness - this is a consequence of the strong interatomic bonds of the element due to the unfilled internal electron shell. The result of the physical properties inherent in the metal is a number of advantages that molybdenum and its alloys possess:
good electrical conductivity;
low thermal expansion;
high mechanical strength.
In the last paragraph, the metal is slightly inferior to tungsten, but surpasses it in the availability of pressure treatment. Another important specificity of the substance, which provided it with a place as an alloying additive to other metals and their alloys, is its high anticorrosive ability.
Molybdenum is a chemical element with atomic number 42 in the periodic table, where it is a close neighbor to tungsten and chromium. Molybdenum is characterized by a light gray color and a metallic sheen. The most important properties inherent in this element are its refractoriness. In addition, element No. 42, as well as the alloys in which it is present, have heat resistance, thermal expansion, high electrical conductivity and mechanical strength, which undoubtedly are advantages. It should be noted that molybdenum takes the second place in strength, giving way to the leader of tungsten, but ahead of it in the availability of pressure treatment.
In most cases, molybdenum acts as a binder to other metals and their alloys due to its anti-corrosion properties.
Some characteristics of the item:
density 10.2 g / cm³;
the crystal lattice is body-centered, cubic;
melting point 2623 ° C;
Mohs hardness 4.5.
The chemical properties are largely due to oxidation states: +2, +3, +4, +5, +6 (the latter is the most stable).
The metal practically does not react with hydrogen and nitrogen.
Under normal conditions, molybdenum does not react with air gases. It starts to oxidize when heated above 400 ° C.
When exposed to reducing agents in a slightly acidic environment, it forms molybdenum blue. These substances are used as dyes (for example, in dyeing silk).
How to get Molybdaenum
Obtaining molybdenum can be divided into several stages:
Flotation enrich the ore. The result is molybdenum concentrates, their three grades.
Production from MoO3 concentrates, the so-called “Cinder”, pure molybdenum anhydride is isolated from cinder by distillation or chemical processing. The purity of the product is not less than 99.975%.
Molybdenum powder with a grain size of 0.5-2 microns is obtained by reduction of anhydride with hydrogen.
Application: from light bulb to rocket
Most of the products from molybdenum are consumed by electronics.
The use of metal in rocket technology is increasing: for lining rockets and capsules, in nozzles of rocket engines, in solid fuel rockets.
Molybdenum wire is used for the production of thermocouples, incandescent lamps, and heaters for high-temperature electric furnaces.
Molybdenum tapes and wire are in demand in the lighting industry, from which electrodes for melting glass are made.
The use of molybdenum and its alloys in nuclear energy, in the production of cooling pipelines, and shells of fuel assemblies is widespread.
More than 2/3 of the metal produced is used in metallurgy as an alloying additive to steel.
Molybdenum sulfide is an excellent high-temperature lubricant for parts, it is coated with bullets, it is used in the manufacture of ceramic products as an additive in clay (to obtain blue or red colors)..