Electrochemical characterization of some commercial inhibitor used for acid cleaning of steam generators

Rocchini, G.; Perboni, Giorgio

doi:10.1515/corrrev.1988.8.1-2.35

Cited by 9 publications

(4 citation statements)

References 7 publications

(1 reference statement)

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“…1250. The code utilizes the galvanostatic mode and performs measurements at the free corrosion potential over the frequency interval [7,13] kHz with a fixed integration time corresponding to 2000 cycles.…”

Section: Capacitance Methodsmentioning

confidence: 99%

“…Usually the interval [7,13] kHz is examined when reference electrodes such as SCE and Ag-AgCl are used, because experience shows that the response of the electrochemical system is not distorted by the electrode dynamic. Wider interval amplitudes can be examined when metallic reference electrodes are used.…”

Section: Capacitance Methodsmentioning

confidence: 99%

“…Despite the wide diffusion of the linear polarization method of Stern and Geary [6], which was favoured both by the simplicity of the theory and experimental application and the manufacture of commercial equipment based on probes with two or three electrodes [1], an exhaustive study on its correct application [7] has never undertaken, nor has any attempt been made to eliminate some experimental drawbacks that may impair the reliability and validity of information.…”

Section: Introductionmentioning

confidence: 99%

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The corrosion-trend monitoring with the impedance technique

Rocchini

1998

Materials and Corrosion

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The physical meaning of monitoring corrosion rates and states of the metal‐solution interphase using sinusoidal current at various frequencies is discussed. Three methods concerning low‐frequency measurements, area method associated to Nyquist's diagrams and the capacitance of the double layer are examined. The basic concepts underlying the use of these techniques are given and, in the case of low‐frequency signals, some considerations on the mathematical theory based on the Kramers‐Kronig relations between real and imaginary parts of Z(ω) are developed. The examples treated refer to laboratory and pilot‐plant tests and illustrate the usefulness of monitoring electrochemical processes taking place in a very large class of systems. In the case of low‐frequency measurements satisfactory results were obtained, for instance, for iron in 1, 2 and 3 N H2SO4solutions at 25°C and for aluminium brass in a 5 % wt HCl solution at 70°C. The capacitance method was employed to examine the behaviour of iron in 5 % wt HCl solutions containing a corrosion inhibitor at various concentrations at temperatures ranging from 35 to 90°C. Experimental results show that the impedance technique is a valid tool to investigate the behaviour of electrochemical systems without any restraint on the shape of their voltage‐current characteristic. Lastly, some considerations concern specific software developed to perform electrochemical measurements with commercial computerized systems and to process experimental data in real time.

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Section: Capacitance Methodsmentioning

confidence: 99%

Section: Capacitance Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The corrosion-trend monitoring with the impedance technique

Rocchini

1998

Materials and Corrosion

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“…It is necessary to underline that the last two remarks are not restricted to the case under discussion, but our experience has shown that they have a general validity both for pure compounds [29] and for commercial inhibitors [30]. Table 3, concerning the solution inhibited with 0.05 g l -I of inhibitor, compares the values of C obtained with the three methods.…”

Section: Iron In Inhibited Hcl Solutionsmentioning

confidence: 98%

The Evaluation of the interphase capacitance by impedance technique

Rocchini

1995

Materials & Corrosion

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Examination of the behaviour of alloys in their free-corrosion state and of the thermal stability and effectiveness of organic inhibitors for acid media in restraining the kinetics of corrosive processes IS performed using the impedance technique and the value of the differential capacitance of the metal-solution interphase at the open circuit potential. The physical meaning of this quantity and its relationship with the interphase structure are briefly discussed. The problem of the choice of the frequency interval where experimental measurements should be carried out is examined. Mention is then made of some mathematical methods that are useful for processing experimental data in order to compute the values of R,, Rt and C.The main advantages of performing surface-impedance determinations using the galvanostatic mode and specific software for driving commercial systems and of processing experimental data in real time are stressed. Lastly some experimental results, relating to the frequency interval [7, 131 kHz, are reported which refer to the behaviour of some copper alloys in artificial sea water at pH 8.2, 35 "C and the three velocities of 1.0,1.5 and 2.0 ms-1 and of Armco iron in 5% HCI solutions, containing a commercial inhibitor at various concentrations, at temperatures between 35 and 90 "C. These results demonstrate the validity of the proposed methods, which from practical purposes are equivalent, in the high frequency region where the response of the metal-solution interphase to an external sinusoidal excitation is described with a good accuracy by simulating its behaviour with a simple electric network composed by R and C elements in parallel.Untersuchungen zum Verhalten von Legierungen im Zustand der freien Korrosion und zur thermischen Stabilitat und Wirksamkeit yon organischen Inhibitoren fur saure Medien hinsichtlich der Veranderung der Kinetik der Korrosionsprozesse wurden mit Hilfe der Impedanztechnik und der Differentialkapazitat der Metall-Losung-Grenzflache beim Potential im offenen Stromkreis durchgefuhrt. Die physikalische Bedeutung dieser GroBe und ihre Beziehung zur Grenzflachenstruktur werden kurz diskutiert. Das Problem der Wahl des Frequenzintervalls, in dem die experimentellen Messungen durchgefiihrt werden sollten, wird untersucht. Anschlieaend werden einige mathematische Methoden vorgestellt, die fur die Bearbeitung der experimentellen Daten nutzlich sind, um die Werte von R,, R, und C zu berechnen.Die Hauptvorteile der Durchfiihrung von Oberflachen-Impedanz-Bestimmungen mit Hilfe der galvanostatischen Arbeitsweise und spezifischer Software zum Betrieb kommerzieller Systeme sowie der Aufarbeitung der experimentellen Werte in Echtzeit werden genannt.AbschlieBend werden einige experimentelle Ergebnisse, bezogen auf das Frequenzintervall [7, 131 kHz, vorgestellt, die das Verhalten verschiedener Kupferlegierungen in kunstlichem Meerwasser bei pH 8,2, 35°C und Geschwindigkeiten von 1,0, 1,5 und 2,Oms-I sowie Armcoeisen in 5% HCI Losungen, denen ein handelsiiblicher Inhibitor in verschiede...

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A contribution to the understanding of the linear polarization method

Rocchini¹

1992

Corrosion Science

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Electrochemical characterization of some commercial inhibitor used for acid cleaning of steam generators

Cited by 9 publications

References 7 publications

The corrosion-trend monitoring with the impedance technique

The corrosion-trend monitoring with the impedance technique

The Evaluation of the interphase capacitance by impedance technique

A contribution to the understanding of the linear polarization method

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