Applications of Iridium and its Alloys



Due to the features of extremely high melting point, super corrosion resistance and high temperature stability, Iridium and its alloys have been widely used in the field of high temperature structural materials as catalysis, high temperature anti-oxidation thermocouple, electrical contact materials, high performance ignition electrode materials, high temperature coating materials, high temperature resistance wires and filament materials in the fields of aerospace, auto spark plug industry, chemical industry, crystal industry, electromechanical instrument industry and medical industry. 

The iridium was applied as pen tip material in the earliest stage and then later the applications have been widely spread on injection needles, balance blades, compass holders and electrical contacts. Because of the high temperature oxidation resistance and thermoelectric performance, the iridium/iridium rhodium thermocouple has become the only precious metal to measure high temperatures up to 2100℃ in the atmosphere; it can be used as container materials for radioactive heat sources; anodized iridium oxide film is also a promising electrochromic material. Ir192 is a kind of γ-ray source to be used for non-destructive testing and radio-chemotherapy. Meanwhile, iridium is a very important alloy, which can also be applied in some special fields such as iridium-rhenium alloy high-temperature coating materials for rocket engine nozzles. The iridium compound also has its unique applications.

In recent years, iridium and iridium alloys have been widely used in the industry of auto spark plugs. With the rapid development of the auto industry, the low fuel consumption and pollution have become the main concerns of engine development so as to reduce the greenhouse effect and environmental pollution. Therefore, the spark plugs need to realize stable ignition and combustion in severe environments such as rarefied combustion, high swirling and EGR (exhaust gas recirculation). The best way is to reduce the electrode diameter of spark plugs and improve the ignition performance. For iridium and iridium alloys, the features of high melting point, high temperature corrosion resistance, high rigidity and low resistance enable them to meet such requirements. Compared with traditional spark plugs, the ones with iridium electrodes are more easily ignited with good fuel economy, low noise and strong power. In the past years, the sales of iridium spark plugs have maintained an annual growth rate of 20% in more than 60 countries all over the world.