History
(L. iris, rainbow) Tennant discovered iridium in 1803 in the residue left
when crude platinum is dissolved by aqua regia. The name iridium is
appropriate because its salts are multi colored.
Applications
Although its principal use is as a hardening agent for platinum, iridium
is also used to make crucibles and devices requiring high temperatures. It
is also used for electrical contacts and is slowly finding it way into
medical devices that are implanted into the body.
The element is also alloyed with osmium and is used for fountain pen nibs
and compass bearings.
Properties
Iridium, a metal of the platinum family, is white, similar to platinum but
with a slight yellowish cast. Because iridium is very hard and brittle, it
is hard to machine, form, or work.
It is the most corrosion-resistant metal known, and was used in making the
standard meter bar of Paris, which is a 90 percent platinum and 10 percent
iridium alloy. This meter bar was replaced in 1960 as a fundamental unit
of length.
Iridium is not attacked by any of the acids nor by aqua regia, but is
attacked by molten salts, such as NaCl and NaCN. The specific gravity of
iridium is only very slightly lower than osmium, which is generally
credited as the heaviest known element. Calculations of the densities of
iridium and osmium from the space lattices give values of 22.65 and 22.61
g/cm, respectively. These values may be more reliable than actual
physical measurements. At present, therefore, we know that either iridium
or osmium is the densest known element, but the data do not yet allow
selection between the two.
Sources
Iridium occurs uncombined in nature with platinum and other metals of this
family in alluvial deposits. It is commercially obtained from osmiridium a
by-product of platinum production. It is also recovered as a by-product
from the nickel mining industry.
Iridium is generally available as wire spooled onto spools or random
length piece rod, strip, ribbon, foil or sheet. It is usually rolled from
plate and slit to required widths which is the reason for the random
lengths as the material is very hard to fabricate without many
intermediate anneals to keep the material somewhat ductile. H Cross
Company can provide this material 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
measuring 10 feet minimum. 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 |
