Shunt Layers on Superconducting Tapes

Superconductivity is the phenomenon whereby some materials exhibit zero resistance to the passage of an electric current when cooled to low temperatures. Various superconducting materials are used in a range of applications including MRI imaging, catheter steering, transport (magnetic levitation trains) and fault current limiters. The most recent generation of materials require the use of a metallic shunt top layer to give a degree of thermal and electrical protection should a fault in the superconducting tape develop.  Sputtered gold and silver-gold alloy layers have so far shown the best combination of properties for this application including electrical and thermal conductivities, contact resistance, specific heat capacities, oxidation potential, lattice constant, and coefficient of linear expansion.

Measurement Devices

Although they aren’t the most accurate means of measuring temperature, thermocouples have sufficient accuracy for most applications and find widespread use. Gold has found use in thermocouples both for low temperature and higher temperature measurements. Gold-alloy wires have also been used for potentiometers.

Gold-Palladium Alloys in Spark Plug Electrodes

The first generation of long-life spark plugs with corrosion resistant platinum or gold-palladium (typically 60Au-40Pd) electrodes were marketed in the mid-1980’s. In recent years it appears platinum, and more recently, iridium electrodes have found greater favour with manufacturers and consumers, although plugs containing gold-palladium electrodes can still be sourced from some outlets.