ELEMENT OF THE MONTH
Each month we will explore elements of interest from the periodic table, with a brief history of discovery and development, and a review of uses and applications.
PLATINUM – ATOMIC NUMBER: 78 – CHEMICAL SYMBOL: PT
Platinum is an extremely rare precious metal occurring as only 0.003ppm of the earth’s crust, with annual production of refined platinum of less than 200 tonnes.
It is a dense, ductile, grey-white metal that resists corrosion and is unaffected by hydrochloric or nitric acids, but is soluble in heated aqua regia, a mixture of the two.
It was known in the 16th century as dense grey ‘pebbles’ found in alluvial gold deposits in South America; Its name is derived from the Spanish ‘Platina del Pinto’ meaning ‘little silver of the Pinto river’
Platinum is mostly refined from nickel or copper sulphide minerals and requires complex chemistry, unlike gold or silver that can be isolated by fire refining.
WHERE IS PLATINUM USED?
As a Pure Element
Platinum is predominantly used in catalytic applications, in particular for automotive exhaust system catalytic converters that remove or reduce un-burnt hydrocarbons from engine emissions.
It also has a vital catalytic role in manufacturing high-octane fuels.
There is a rapidly growing application for Platinum as a catalyser in proton exchange membrane fuel cells that can provide power for vehicles, buildings, and manufacturing industries.
Platinum can be electroplated on to a wide range of substrates including nickel super-alloys used in aero engine components. Platinum is diffused into an alloy component such as a turbine blade, to produce an oxidation and corrosion resistant surface.
As an Alloy
Platinum is also widely used in jewellery making, and alloys that contain 5% by weight of cobalt, ruthenium, palladium, or iridium are typically used, depending on the manufacturing process employed. Learn more
Platinum alloys with rhodium are used when high temperature stability is important, such as in thermocouples use to measure temperatures up to 1800 degrees Celsius.
As a Compound
Over the last forty years, platinum compounds have been developed for the treatment of some types of cancer.
Here are some key parameters for platinum, quantifiable using instruments from Helmut Fischer GmbH
- Thickness of platinum coatings on nickel based super alloys in the range 5 to 10 µm, measurable with a non-destructive XRF based instrument such as the Fischerscope XDV-SDD
- Composition analysis of Pt based precious metal alloys to verify fineness prior to hallmarking with an XRF based instrument such as the Fischerscope XAN 250
- Determination of Pt, Pd and Rh content in pressed pellets recovered from recycled automotive catalytic converters using instruments such as Fischerscope XDV-SDD
- Pt concentration in electroplating or other solutions from grams/litre down to low ppm, using a range of XRF based instruments such as Fischerscope XDAL-SDD