Effect of SO2 in flue gas on coal ash hot corrosion of Inconel 740 alloy – A high temperature electrochemical sensor study

• New high temperature corrosion sensor applied to study the coal ash hot corrosion of Alloy 740.
• EN, EIS, and PDP data from the sensor were compared with the results from weight loss test.
• A reasonable good correlation between the electrochemical data and the actual degradation processes.
• Current noise analysis for the quantitative determination of hot corrosion rate discussed.

Our newly developed high temperature electrochemical sensor was applied to study the effect of SO2 in flue gas on thin film coal ash corrosion of Inconel 740 superalloy at 750 °C. The response of electrochemical noise (EN), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) test data from the sensor is compared with the results from a weight loss test. There is a good correlation between the electrochemical data and the actual degradation processes. The current noise analysis in time and frequency domains for the quantitative determination of hot corrosion rate in service is discussed.