The influence of the cathodic process on the interpretation of electrochemical noise signals arising from pitting corrosion of stainless steels

Detection of SCC initiation in austenitic stainless steel by electrochemical noise measurements

“…Assuming a small reduction of the charge and therefore slightly lower dissolved crack width value due to the electron consuming cathodic process (see above and Refs. [23,24]), this crack width value is exactly in the expected range where the Cr content along grain boundaries of a heavily sensitised stainless steel falls below the critical value of 12 wt% [7,25,26], which facilitates metal dissolution. The calculated dissolved metal width of tests 2 and 3 with much smaller cracks are in a very similar range (78 and 83 nm).…”

“…ECN and EPN signals during a CERT test with a slightly sensitised stainless steel ('F') in aqueous thiosulphate solution; increase/decrease of the ECN/EPN baseline signal with small transients cracked area. Furthermore, it has to be considered that, according to Sarmiento Klapper et al [23,24], the cathodic process and the corresponding electron consumption may reduce the amplitude of the ECN signal. On the other hand it is believed that in the investigated corrosion system this effect is rather small, as the cathodic process is expected to be inhibited, respectively, delayed because of the stable passive layer on the stainless steel surface.…”

Microbiologically Influenced Corrosion in UNS S31653: Detection and Analysis Using Electrochemical Noise Technique

“…Therefore, it has been proven that the presence of higher amounts of dissolved oxygen led to a strong cathodic reduction process, resulting in a reduction in the amplitude of the anodic current signal as a result of the corresponding electron consumption. 31 Klapper, et al, 31 have described this mechanism that is shown schematically in Figure 10. The affected electrochemical current noise (ECN) transient obtained for Type 316Ti steel in the medium with a high concentration of dissolved oxygen and the same signal reconstructed using the amplitude ratios of the transients obtained in the medium with a low concentration of dissolved oxygen are shown in Figure 10.…”

Electrochemical noise for corrosion detection

“…EN can be acquired with different experimental confi gurations; however, as a general rule, it works at open circuit potential condition without the need of an external polarization that could infl uence the electrochemical reactions. For this reason, EN is a real on-line, not perturbative, technique for corrosion monitoring and this feature makes it attractive to study corrosion phenomena ( Iannuzzi, Mendez, Avilla-Gray, Malo, & Rinc ó n, 2010 ;Nagiub & Mansfeld, 2001 ;Sarmiento Klapper, Goellner, & Heyn, 2010 ) and to monitor corrosion in industrial plants ( Garc í a-Ochoa et al, 2008 ;Gusmano, Montesperelli, Forte, Olzi, & Benedetti, 2005 ;Iverson & Heverly, 1986 ). EN has been successfully applied in the study of different forms of corrosion, such as pitting ( Gusmano, Montesperelli, & Montalto, 2001 ;Hill & Lillard, 2006 ;Sato, 1976 ), crevice ( Gusmano, Marchioni, & Montesperelli, 2000 ;Zeng, Luo, & Norton, 2004 ), stress corrosion cracking ( Shi, Song, Cao, Lin, & Lu, 2007 ) and microbiologically infl uenced corrosion ( Nagiub & Mansfeld, 2001 ;Padilla-Viveros, Garcia-Ochoa, & Alazard, 2006 ;Zaveri, Sun, Zufelt, Zhou, & Quan Chen, 2007 ), and in performance evaluation of coatings ( Gusmano et al, 2007 ) and inhibitors ( M é sz á ros, M é sz á ros, Pirn á t, & Lengyel, 1996 ;Tan, Bailey, & Kinsella, 1996 ).…”