Platinum (Pt) is a noble metal element (atomic number 78) known for its unique chemical and physical properties. It exhibits extreme resistance to chemical attack and inertness, preventing oxidation even at elevated temperatures. This unreactive nature, combined with a high melting point (1768.3°C) and high density, contributes to its classification as a precious metal. These attributes make platinum valuable, driving its use in applications where reliability and performance under harsh conditions are paramount.
Platinum in Automotive Components
The single largest industrial demand for platinum originates from its application in automotive catalytic converters, which are designed to reduce harmful emissions from internal combustion engines. These devices rely on a thin coating of platinum group metals (PGMs), including platinum, palladium, and rhodium, on a ceramic or metallic substrate.
Within the converter, platinum primarily acts as a redox catalyst. It promotes the oxidation of unburnt hydrocarbons and carbon monoxide into less harmful carbon dioxide and water vapor. Rhodium is predominantly responsible for the reduction of nitrogen oxides (NOx) back into inert nitrogen and oxygen gas.
The extreme environment of a car’s exhaust system mandates the use of metals with platinum’s stability. In diesel vehicles, platinum is particularly effective as a catalyst for converting carbon monoxide and hydrocarbons into harmless emissions at the lower operating temperatures. The durability of platinum ensures the catalytic converter maintains high efficiency for the entire service life of the vehicle, meeting strict global emissions standards.
Platinum in Personal Wearables
Platinum’s use in personal items centers on its aesthetic appeal and superior physical characteristics, particularly for high-end jewelry and luxury watches. The metal is favored for its natural white sheen, which remains bright without tarnishing or requiring rhodium plating, unlike white gold. High-end platinum jewelry is typically 90% to 95% pure.
The density of platinum, approximately 60% greater than that of gold, gives jewelry a substantial feel. Its durability is a significant advantage; when scratched, platinum displaces metal rather than losing it, ensuring the piece retains its volume. This property makes it an excellent choice for setting precious gemstones securely, as the prongs resist wear. Furthermore, its high purity makes it naturally hypoallergenic, a preferred option for individuals with sensitive skin.
Platinum in Modern Electronics
Platinum’s stability, excellent conductivity, and resistance to corrosion make it indispensable in electronic components requiring high precision. It is incorporated into specialized electrical contacts within switches and relays. Unlike common metals, platinum does not readily oxidize or tarnish, preventing the formation of non-conducting films that degrade contact performance.
The metal’s ability to withstand high temperatures is utilized in high-precision temperature sensors called thermocouples. These sensors, often employing platinum alloyed with rhodium, can accurately measure extreme temperatures, sometimes exceeding 1800°C, in industrial and scientific settings. Platinum’s stability ensures consistent thermoelectric properties, crucial for reliable temperature control in manufacturing processes. Platinum has also been used in the magnetic storage layers of high-performance hard disk drives to achieve high data density and signal stability.
Platinum in Medical Devices
Platinum is a material of choice for devices implanted within the human body due to its chemical inertness and biocompatibility. The metal does not react with biological tissues or fluids, nor does it cause allergic reactions. This non-reactive quality ensures that platinum components can remain safely in the body for decades.
Platinum is used to form the electrodes in pacemakers and implantable cardioverter-defibrillators, where its reliable electrical conductivity is essential for regulating heart rhythm. Its radiopacity, or ability to block X-rays, allows medical professionals to precisely place and monitor platinum-tipped catheters and stents using imaging technology. Platinum alloys are also found in specialized surgical tools and micro-coils used to treat brain aneurysms. Furthermore, the metal’s durability and resistance to oral corrosion have led to its use in high-quality dental work.