History
Platinum, like gold, has a long and distinguished history. Its use began
in antiquity and it has undergone a resurgence in popularity over the last
200 years. The metal was held in high esteem during early Egyptian times
and native people in South and Central America worked it as early as 100
B.C. Spanish conquistadors discovered platinum artifacts among the gold
they were seeking when they came to the new world. They named the curious
metal "platina," or "little silver." They also considered it worthless,
and discarded it. The metal didn't reach Europe until the 18th century,
but then it caught on in a big way. King Louis XVI elevated it by terming
it "the metal of kings." For centuries, the only large amounts of platinum
outside of South America were found in Russian mines. Russia used platinum
coins in the 19th century. In Spain, some gold coins were faked by
gold-plating platinum coins.
Today, platinum is far more valuable than
gold. Platinum's initial uses were probably limited by its hardness and
its very high melting point. The early forging and casting techniques made
it quite a difficult metal to work with. In the latter part of the 19th
century, and the first half of the 20th, platinum was the premier metal
for all-important jewelry. Platinum dominated the world of jewelry design
during the Edwardian era, and the Art Deco period well into the 1930s.
This all came to an abrupt end in World War II, when platinum was declared
a strategic metal and its use banned for all non-military purposes.
Properties
Platinum is the last element in the Group VII of the periodic table. It is
a silvery metal, soft, dense, very ductile and malleable. Its electrical
conductivity is comparatively low, and its coefficient of expansion is the
lowest of the commercial metals. Platinum is untarnished by air, but
vaporizes appreciably at red heat. The halogens, including fluorine, have
no effect at ordinary temperature, and single mineral acids do not
dissolve platinum. Aqua Regia and a mixture of hydrochloric and chloric
acids dissolve the metal. It is also attacked at high temperature by fused
mitrates, acid sulfates, hydroxides, peroxides, sulfides, iodine,
phosphorous, arsenic, carbon, silicon, selenium, and tellurium.
Sources
The six metals of the platinum group (pgm) occur in nature in close
association with one another and with nickel and copper. They are among
the least abundant of the Earth's elements. Of the few known deposits,
those in South Africa and Russia are by far the largest. There are less
than ten significant pgm mining companies in the world.
Uses
The following are some of the many uses for platinum.
- Jewelry
- Wire and vessels for laboratory use
- Thermocouple elements
- Electrical contacts
- Corrosion-resistant apparatus
- In dentistry
- Platinum-cobalt alloys have magnetic properties
- Coating missile nose cones, jet engine fuel nozzles
- The metal, like palladium, absorbs large volumes of hydrogen, giving
it up at red heat
- In the finely divided state platinum is an excellent catalyst (such as
the contact process for producing sulphuric acid). Also as a catalyst
for cracking oil and as a catalyst in fuel cells and in catalytic
converters for cars
- Platinum anodes are extensively used in cathodic protection systems
for large ships and ocean-going vessels, pipelines, steel piers
- Platinum wire glows red hot when placed in the vapor of methanol -
acting as a catalyst to convert the alcohol into formaldehyde. This has
been used commercially to produce cigarette lighters and hand warmers
- Sealed electrodes in glass systems
- Laboratory vessels, corrosion-resistant equipment
- Dentistry
- In antipollution devices in cars
- Platinum/osmium 90/10 alloy is used in implants such as pacemakers and
replacement valves
H Cross Company can provide Platinum in two purities and a variety of
forms. We supply the standard 99.95% commercially pure grade and we also
can supply material with a purity of 99.999% for special applications such
as filament materials. H Cross Company can provide these materials in wire
sizes from .005" diameter up to .100" diameter, strips and ribbons from
.0005" thick to .020" thick and from .020" to .100" wide and in sheet or
foil form from .0005" thick to .020" thick and up to 2" wide. Please
email us if you have needs outside of these ranges, as we will always try to be
of assistance for your specific requests.
Packaging
Each H. Cross Company product is delivered in packaging specifically
designed for the product's application. As an example, wire is furnished
on returnable plastic reels, each containing a single length of wire.
Strips, Ribbons, Sheets and foils are flat packed to prevent damage during
shipping. If required, H. Cross Company can adapt standard packaging
methods or develop new ones for your special needs. |
