Found in nature as molybdenum sulfide and lead molybdate.
The metal is white, silvery and very hard, but is softer and more malleable than tungsten. Scheele discovered it in 1778. It has often been mistaken for graphite and wire ore. It has a high modulus of elasticity and only tungsten and tantalum, more readily available metals, have higher melting points. It is a valuable alloying agent, as it contributes to the quenchability and hardness of quenched and tempered steels. It also improves the strength of steel at high temperatures. Molybdenum is used in alloys, electrodes and catalysts.
It is used in some nickel based alloys, such as "Hastelloy (R)" which are heat resistant and corrosion resistant to chemical solutions. Molybdenum oxidizes at high temperatures. The metal has found recent application in electrodes for electric heating furnaces. The metal is also used in nuclear power applications and for missile and aircraft parts. Molybdenum is of great value as a catalyst in petroleum refining. It has been found in other applications as a filament material in electronic and electrical applications. Molybdenum is an essential trace element in plant nutrition. Some lands are sterile for lack of this element in the soil. Molybdenum sulfide is useful as a lubricant, especially at high temperatures where oils would break down. Almost all ultra-high strength steels with minimum yield strengths up to 300,000 psi (lb / in. 2) contain molybdenum in amounts of 0.25 to 8%.
The addition of a small amount of molybdenum hardens the steel. More than two thirds of molybdenum production is used in alloys.
Molybdenum is used in parts of airplanes and missiles, and also as a filament. Molybdenum is used as a catalyst, particularly in the petroleum industry, to remove organic sulfur compounds from petroleum. It is also used in the composition of stainless steel used in the marine environment, for its high resistance to chemical corrosion.
99Mo is a radioisotope used in industry as a precursor of 99Tc.
Molybdenum is used as an alloy as a silicon support for the production of power semiconductors, thanks to the very close coefficients of expansion of these two materials.
Molybdenum oranges are pigments in the medium orange to bright red-orange range, used in paints, inks, plastics and rubbers.
Molybdenum disulfide is a good lubricant, especially at high temperatures.
Molybdenum is commonly used in the laboratory as a target in x-ray tubes for single crystal diffraction. The Ka line of molybdenum has an average wavelength of 0.070926 nm. Molybdenum, often called Moly, is used in industry as a heating element for vacuum furnaces or high temperature gaseous atmosphere. It is recommended to use it for parts made of titanium or titanium alloy instead of graphite heating elements which pollute the part by deposition of graphite elements during the heat treatment operation. Molybdenum is however fragile in industry due to rapid changes in temperature and pressure which cause grain to grow and make the part brittle. In addition, it would seem that in practice, 25% more energy is necessary in order to obtain the same temperature within the oven when using Moly. This is also more expensive to purchase and as a replacement part. The graphite element cannot be used in the event of too high temperature combined with too low a pressure in order to avoid exceeding the vaporization voltage at the risk of finding all the agglomerated graphite in the cold zone of the furnace.