Iridium: Key Uses, Properties, and Industrial Applications

Iridium: Key Uses, Properties, and Industrial Applications

Iridium is a rare transition metal in Group VIII of the periodic table, with symbol Ir, atomic number 77, and atomic weight 192.2. It occurs in the earth’s crust at roughly one part in ten million, typically alongside other platinum‑group elements in alluvial ores.

Iridium Uses & Properties

Industrial Applications

Iridium’s extraordinary melting point (2,446 °C), hardness, and corrosion resistance make it indispensable for high‑temperature, high‑wear components. In its pure form or as part of iridium‑platinum or osmium‑iridium alloys, it is used to fabricate porous spinnerets for polymer extrusion (e.g., rayon), compass bearings, and weight‑scale components. It also serves as a durable alloy additive in aerospace and marine engineering; iridium‑titanium alloys line underwater pipelines, and iridium‑containing alloys are employed in long‑term aircraft engine parts. Pure platinum has a Vickers hardness of 56 HV, whereas 50 % iridium alloys can exceed 500 HV. In high‑temperature instruments, iridium alloys resist arc erosion, making them ideal for spark‑plug contacts, and iridium catalysts are used in the Cativa process to convert methanol into acetic acid.

Medical Applications

The radioisotope Ir‑192 is a pivotal gamma‑ray source for non‑destructive testing and brachytherapy. In brachytherapy, a sealed Ir‑192 source is positioned adjacent to or within tumorous tissue to deliver localized radiation, effectively treating prostate, cholangiocarcinoma, and cervical cancers.

Scientific Uses

The International Prototype Meter, established in 1889, is an alloy of 90 % platinum and 10 % iridium and is maintained by the International Bureau of Weights and Measures near Paris. Spacecraft such as Voyager, Viking, Pioneer, Cassini‑Huygens, Galileo, and New Horizons have employed iridium‑sealed radioisotope thermoelectric generators; iridium’s high‑temperature strength allows it to encapsulate plutonium‑238 in environments up to 2,000 °C. The Chandra X‑ray Observatory’s mirrors feature a 60‑nm iridium coating, chosen after extensive testing that confirmed iridium’s superior X‑ray reflectivity compared to nickel, gold, and platinum.

Iridium Uses in X‑ray Telescopes

Fundamental Properties

Iridium appears as a lustrous white metal with a slight yellow tint. It is hard, brittle, and has an extremely high melting point of 2,446 °C, making traditional casting impractical; powder metallurgy is the preferred fabrication method. Iridium retains excellent mechanical properties above 1,600 °C, and its boiling point places it tenth among all elements. It is the second‑densest metal (0.12 % less dense than osmium). Its chemical resistance is unmatched—at elevated temperatures it resists acids, aqua regia, molten metals, and silicates.

Conclusion

We hope this overview of iridium’s uses and properties has deepened your understanding of this remarkable metal. For further insights into iridium and other refractory metals, visit Advanced Refractory Metals (ARM). ARM, headquartered in Lake Forest, California, is a global leader in the manufacture and supply of high‑quality refractory metals such as tungsten, molybdenum, tantalum, rhenium, titanium, and zirconium.