Platinum Iridium used in jewelry and surgical pins.They are much harder, stiffer, and more resistant to chemicals than pure platinum, which is relatively soft.
Platinum–iridium is also very resistant to high-temperature electric sparks and is widely used for electrical contacts and sparking points.
Precision resistors and slide wire potentiometers utilise considerable quantities of 10
and 20 per cent iridium-platinum.
The combination of moderate resistivity, low temperature coefficient and high corrosion
resistance exhibited by these alloys is of great value in the construction of high quality
Platinum Iridium used as bridge wire in catridge igniters & electric detonators.
Electrical contact applications account for a fair proportion of the iridium-platinum alloys
supplied to industry. The high hardness and low contact resistance of the 10 and 20 per
cent iridium alloys make them particularly suitable for low current, low pressure
applications where dust contamination prejudices the performance of softer materials.
In medium current applications when resistance to hammering becomes important alloys
containing up to 20 per cent of iridium are sometimes employed. A recent study showed
that material transfer from the cathode was proportional to the number of coulombs
passed through the arc and decreased steadily with iridium contents up to 35 per cent (30).
Pfann (31) has shown that interesting results can be achievcd by pairing a negative 20 per
cent iridium-platinum contact with a positive contact of pure gold. With medium currents
the material transfer caused by an asymmetrical molten bridge was found to balance
the other transfer processes, thus minimising contact wear.