Platinum and the Refractory Oxides

The reactions between platinum and the refractory materials in contact with it, described in earlier articles in this series, account for many of the thermocouple failures that occur under practical industrial conditions. Reducing atmospheres accentuate such tendencies, although several factors usually cooperate to cause complete failure. This article examines the way in which platinum:rhodium-platinum thermocouples behave in service under both oxidising and reducing conditions and also in vacuum furnaces.