Characteristics and uses of rhenium

Rhenium is a rare, silvery-white, lustrous, dense metal. It resists corrosion and oxidation but slowly tarnishes in moist air. Of the elements, only carbon and tungsten have higher melting points and only iridium, osmium, and platinum are more dense. Rhenium is one of the five major refractory metals (metals with very high resistance to heat and wear). The other refactory metals are tungsten, molybdenum, tantalum and niobium. Rhenium compounds include oxides, halides and sulfides.
Rhenium is used with platinum as catalysts in the production of lead-free, high-octane gasoline. The metal is used in alloys for jet engines and in tungsten and molybdenum based alloys. It is widely used as filaments for mass spectrographs. Rhenium is also used as an electrical contact material. Rhenium catalysts are exceptionally resistant to poisoning from nitrogen, sulfur and phosphorous and are useful in the hydrogenation of fine chemicals.