Molybdenum Stock

What is Molybdenum?

Molybdenum (pronounced muh-lib-duh-nuh m), frequently called “moly,” is an element on the periodic table that was discovered in 1871 by Carl Scheele. This element is vitally important to nearly every phase of our economy, and even to our personal health. It works behind the scenes to enable technologies that have revolutionized the world.

Pure moly has a very high melting point [2622 °C (4752 °F)]. Only four metallic elements (tantalum, osmium, rhenium, and tungsten) melt at higher temperatures.

Tungsten (https://www.rembar.com/our-stock/tungsten) is the only metal whose thermal expansion coefficient is smaller than moly’s, and molybdenum’s heat capacity (https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Book%3A_Introductory_Chemistry_(CK- 12)/17%3A_Thermochemistry/17.04%3A_Heat_Capacity_and_Specific_Heat) is only about 60% of that

of common metals like iron, nickel, and cobalt.

These seemingly random properties work together to make it an ideal material for many applications, a fact that has remained true even as technology has continued to evolve.

Modern Applications of Molybdenum

As electronics moved from the world of vacuum tubes to solid-state devices, new applications replaced the old. Transistors create heat that must be removed to avoid early device failure. In addition, the silicon wafers from which transistors are made are quite fragile.

Moly, with its high thermal conductivity and a thermal expansion coefficient that is closely matched to silicon’s, is crucial in removing heat from and providing a strong and robust base for power transistors. Moly heat sinks are used in tiny diodes carrying minuscule amounts of current, power transistors operating at thousands of volts and amps, and devices of all sizes in between. Combined with copper as a cladding or as an intimate mixture of bonded particles, moly is used in power modules for hybrid cars and mobile phone base stations. Moly thin films are found in the circuitry of liquid-crystal display (LCD) screens and advanced solar- powered modules.

Molybdenum components process high-temperature liquids other than glass. Alloyed with tungsten, Moly is an ideal material to handle molten zinc because it resists zinc corrosion. Synthetic sapphire, the extremely scratch-resistant material often seen in bar-code scanner windows, laser windows, and armor, with a melting temperature of 2030-2050 °C (3686-3722 °F), is processed in moly crucibles.

Hot processing of solids is another area where moly excels. The most impressive of these processes is hot isothermal forging, where both the workpiece (usually a nickel-based superalloy jet engine part) and the dies themselves are heated in inert atmosphere or under vacuum to between 1830 °F and 2190 °F (1000 °C to 1200 °C). Forging pressure is then applied to both the tool and the workpiece for a controlled time.

“Superplastic” deformation during the process produces a near-net-shape forging with greatly reduced machining cost and better mechanical properties compared to traditionally forged parts. Only dies and other components made from molybdenum TZM (Mo-0.5% Ti-0.08% Zr) and MHC (Mo-1/2% Hf- 0.025% C) alloys can withstand this process.

Other hot working applications for these alloys include piercing plugs for seamless steel tubing production and dies for hot extruding brass alloys.