Monitoring of oxidation of metals in gas environments for energy production

Monitoring of oxidation in gas environments typical of energy production is essential for determination of lifetime and condition of various components operating at high temperatures. One of the most important phenomena to be monitored is the oxide growth kinetics and its changes during the exposure. Three different monitoring methods have been presented in this paper. First, a conventional method called thermogravimetry based on the weight change measurement during oxidation is reviewed. Second, a novel monitoring technique, HT-CER technique, where contact electric resistance is measured as a function of time and distance of the measuring tip is presented. The third approach described involves a method under development, based on the change of capacitance over two growing oxide surfaces. Simple oxidation in air at a typical temperature for superheater tubes in boilers, 600 °C, has been selected as the reference condition for all of the monitoring methods.