(Invited) Novel in-Situ Methods for Real-Time Monitoring of Corrosion

Abstract

The presentation will introduce recently developed new techniques that allow real-time monitoring of corrosion processes. The approach is based on simultaneous measurement of the cathodic kinetics of the H2 evolution reaction (HER) and the O2 reduction reaction (ORR) in real-time. The universal and non-destructive, in-situ methods based on monitoring the rates of the cathodic reactions enable the determination of sensitive, real-time corrosion rates for both atmospheric corrosion and immersion.In the case of immersion, HER monitoring e.g. with gravimetric buoyancy H2 measurements is well established. Recently it was shown that gravimetric H2 measurements are also suitable to monitor atmospheric H2-type corrosion (for Mg alloys) [1]. A novel approach to measure HER rates during atmospheric exposure is introduced in this work. This is based on determining the pressure increase in a hermetically closed chamber with a pressure sensor. Regarding ORR, both volumetric measurements and pressure sensor based techniques are applicable to monitor the rate of consumption of O2 gas. In addition, a fibre optic O2 sensor can be employed to monitor ORR rates both under immersion and atmospheric corrosion conditions. A combination of these methods enables to monitor ORR and HER simultaneously. Therefore, also corrosion systems where both HER and ORR contribute to the cathodic reaction can be monitored (e.g., Fe and Zn corrosion). Examples for the different corrosion cases studied with this new respirometric approach will be demonstrated [2]. Combining the above described approaches with a flow cell setup expands the possible corrosion scenarios to be investigated. The flow cell enables switching between exposure conditions (such as, electrolyte composition, temperature, flow rate, etc.) with a real-time response of the corrosion rate.In addition of being of interest for corrosion monitoring, the techniques described moreover reveal details on time-dependent mechanisms of corrosion reactions.[1] M. Strebl, S. Virtanen, J. Electrochem. Soc. 166 (2019) C3001-C3009.[2] M. Strebl, M. Bruns, S. Virtanen, J. Electrochem. Soc. 167 (2020) 021510.