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Rhenium, Re, 75
Transition metal
3459 K (3186 °C)
5869 K (5596 °C)
Hexagonal closest sphere packing
21 g/cm³ (at 25 °C)
7-8
19.3 - 10-⁶ Ω-cm (at 20 °C)
Physical properties
Rhenium is a shiny, silvery, very dense and exceptionally temperature-resistant transition metal. It has one of the highest melting points of all elements. This makes rhenium particularly valuable for applications in which materials have to withstand extreme temperatures, high mechanical stress and aggressive environments.
Rhenium is significantly heavier than many industrial metals and is one of the densest stable elements. It has good wear resistance; its corrosion resistance is also given at moderate temperatures, but decreases at higher temperatures in air, as rhenium begins to oxidize noticeably from around 600 °C. Despite its extreme properties, rhenium is easy to forge and weld because it remains permanently ductile - however, it is usually used as an alloy component due to its rarity.
Characteristic properties
Rhenium is one of the rarest elements in the earth's crust. It does not occur in any significant deposits of its own, but is mainly obtained as a by-product during the processing of molybdenum and copper ores. This low natural availability makes the supply complex.
Its most important property is its extreme heat resistance. In high-temperature alloys, rhenium improves mechanical stability and creep resistance, i.e. the ability of a material to remain dimensionally stable even under permanent stress at high temperatures.
Meaning and applications
Rhenium is particularly important for high-performance applications. Its most important applications are nickel-based superalloys in turbine blades of modern aircraft engines and gas turbines, where it increases the load-bearing capacity at extreme temperatures and improves efficiency.
Rhenium also plays an important role in catalyst technology - particularly in platinum-rhenium catalysts for oil processing. Other areas of application include thermocouples, special contacts, X-ray technology and high-temperature components.
Due to its rarity, the complex extraction process and its importance for aerospace and energy technology, rhenium is considered a strategically important specialty raw material.