corrosion rate

The corrosion of carbon steel in oil-in-wateremulsions under controlled hydrodynamic

conditions

HaydeÂ e Quiroga Becerraa, C. Retamosoa, DigbyD. Macdonaldb,*

aChemical Engineering School (Escuela de IngenierõÂa QuõÂmica), Industrial University of Santander

(Universidad Industrial de Santander), AA 678, Bucaramanga, ColombiabCenter for Advanced Materials, Pennsylvania State University, University Park, PA 16802, USA

Received 26 March 1999

Abstract

The e�ect of the oil content on the corrosion of AISI-SAE 1010 carbon steel in oil-in-water emulsions under controlled hydrodynamic conditions was studied by means ofpotentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The

systems that were studied included brine (0.2 wt% NaCl), surfactant solution (Dioctylsodium sulfosuccinate, 1 wt%, +NaCl, 0.2 wt%), and oil-in-water emulsions, in which theaqueous phase was the surfactant solution and the oil phase was a mineral oil. Corrosion

studies employed various controlled hydrodynamic systems, which included a rotating diskelectrode (RDE) and a jet impingement electrochemical cell (JIEC), with the workingelectrode located in the stagnant region on the jet axis or on the wall jet region (displaced

from the axis). This study found that the e�ect of the oil content on the electrochemicalactivity of carbon steel (as indicated by the current density in the active state) varies withthe `internal phase relationship', IPR. For emulsion with low IPR (oil contents up to 20

wt%), the electrochemical activity was slightly higher than that of the base surfactantsolution. The electrochemical activity of emulsions with medium IPR (oil contents between20 and 45 wt%) showed no major variation with oil content, while for emulsions with highIPR (oil contents between 45 and 70 wt%) the activity was diminished. The data are

0010-938X/00/$ - see front matter # 2000 Published by Elsevier Science Ltd. All rights reserved.

PII: S0010 -938X(99)00068 -2

Corrosion Science 42 (2000) 561±575

* Corresponding author. Present address: Pure and Applied Physical Sciences Division, SRI

International, 333 Ravenswood Ave., Menlo Park, CA 94025, USA. Tel.: +1-650-859-3195; fax: 1-605-

859-3250.

E-mail address: [email protected] (D.D. Macdonald).

explained in terms of a model that postulates the formation of an `oily phase' on the steelsurface, the stability of which depends on the magnitude of the hydrodynamically induced

shear stress at the interface. However, the coverage of the oil phase on the surface ispostulated to depend on the normalized IPR, such that as the IPR increases the coveragealso increases. Furthermore, the oil phase is envisioned to facilitate the cathodic partial

process (reduction of oxygen) due to the enhanced solubility of oxygen compared withwater, while inhibiting the dissolution of the metal (anodic partial process). Because the twopartial processes are strongly coupled, the corrosion rate is predicted to pass through a

maximum with increasing oil content of the emulsion, as observed. # 2000 Published byElsevier Science Ltd. All rights reserved.

Keywords: Carbon steel; Oil-in-water emulsions; Hydrodynamics; General corrosion

1. Introduction

Oil-in-water emulsions are heterogeneous systems, in which a nonpolar or oilyphase (mineral oil) is dispersed in the form of small drops in the polar or waterphase (distilled and deionized water). Emulsions are produced and exist inmetastable form due to the action of mechanical agitation and the presence ofsurfactant molecules that diminish the interfacial tension. Emulsi®ed systems haveacquired great importance in industrial applications due to certain inherentcharacteristics. These include facilitating the transport of soluble, activeingredients in either the watery phase or in the oily phase (used bypharmacological and beauty industries, and in the production of fungicides) andreducing the viscosity of heavy oils. The latter is important for reducing the costof transporting heavy oils through pipes and channels in the petroleum andpetrochemicals industries [1].

In spite of the wide use of emulsions, very little attention has been paid to theelectrochemical and corrosion behaviors of metals in contact with emulsi®edsystems. Fundamental information on the conductivity of emulsions and electrodepotential is very limited [2,3], although some work has been reported on theelectrochemistry of microemulsions systems [4±7]. In general, the theory ofelectrochemical processes in emulsions is speci®c to each application, for instance,emulsi®cation and demulsi®cation processes [1] or electrodeposition of emulsionssystems [8±11]. In the speci®c case of oil-in-water emulsions, where the continuousphase is aqueous, metallic corrosion is expected, because of the water present inthe system. However, oil is known to wet metals, so that destabilization of theemulsion at the interface could signi®cantly alter the corrosion behavior comparedwith that for the aqueous phase alone. The corrosion rate may also be a�ected bychanges in the rate of transport of oxygen to and reactants from the metalsurface, due to the presence of oil in the system [12±15]. A thoroughunderstanding of these factors requires a detailed knowledge of the rheologicalproperties of the system.

The rheological behavior of an emulsion can be Newtonian or non-Newtonian,

H.Q. Becerra et al. / Corrosion Science 42 (2000) 561±575562

depending on its composition. Emulsions with a low ratio of dispersed phase tothe continuous phase (the oil content or the `IPR') generally exhibit Newtonianbehavior while emulsions with high IPR values behave as pseudoplastic ¯uids [16].It has been found [13,14] that for kerosene (and other light mineral oils)-in-wateremulsions with medium and high internal phase ratios, the rheological propertiesslightly depart from Newtonian behavior and obey the Casson model [17],described by the following expression:

t1=2 � t1=2c �D1=2m1=2 �1�

where t is the shear stress (Pa), tc is the minimal value of shear stress at which thematerial su�ers plastic deformation (Pa), D is the shear rate (sÿ1), and m is theviscosity of the emulsion (cp). The change in the rheological behavior of theemulsions with oil content around 40% could explain various phenomena that areobserved when electrochemical experiments are made with emulsions [14,15]. Theaverage emulsion viscosity is logarithmically related to IPR, with m increasing withincreasing IPR.

Studies of the electrochemical behavior of metallic surfaces in contact withemulsions under controlled hydrodynamic conditions can help to develop anunderstanding of the e�ect of the oily phase on corrosion processes. Previousstudies [18,19] have employed rotating disk electrodes (RDEs) to study masstransfer under laminar and turbulent ¯ow conditions as well as to investigate thekinetics of corrosion reactions. However, in order to more accurately stimulate®eld and/or plant conditions, a jet impingement electrochemical cell (JIEC) wasemployed in the present work. A JIEC allows one to control the hydrodynamicsof the system over a wide range of conditions (e.g., shear rate) and to obtainturbulent ¯ow with a high shear stress on the surface. Several patterns of ¯ow canbe obtained, depending on the location of the working electrode. Thus, theelectrode can be placed directly in front of the nozzle, where the mass transferrate is independent of the radial position and the ¯ow regime is considered to bemainly laminar (stagnant region, r < Rnozzle). Alternatively, the electrode may belocated at some radial distance from the central point (wall jet region, r > 2.5Rnozzle), where fully developed turbulent ¯ow exists, but where the turbulentintensity and mean ¯ow rate decays with distance from the central stagnant point.In this latter region, momentum is transferred away from the surface and the ¯owis known as `self preserving', but it eventually becomes laminar [20] at su�cientlylarge radial distances.

In this paper, the electrochemical behavior of AISI-SAE 1010 carbon steel incontact with oil-in-water emulsions under controlled hydrodynamic andelectrochemical conditions is analysed. Our principal objective was to ascertain therelationship between the corrosion rate, as determined by electrochemicalmethods, and the oil content of the emulsion and the hydrodynamic conditions.Data from these studies is considered to be essential for developing anunderstanding of the role of the oil in modifying the corrosion rate andmechanism.

H.Q. Becerra et al. / Corrosion Science 42 (2000) 561±575 563

2. Experimental

2.1. Preparation of the emulsions

The most stable emulsions were found to have the following aqueous phasecomposition: distilled and deionized water, anionic surfactant agent TRITONGR-7 M (Dioctyl sodium sulfusuccianate, 1 wt%), and sodium chloride, 0.2 wt%.The oily phase was a light mineral oil with a viscosity of 2 cp and a density of0.89 g/cm3.

Optimization of the emulsion composition and preparation process, as well ascharacterization of the emulsion in terms of particle size, viscosity, wettability,electrical conductivity, and pH was carried out as the Colombian PetroleumInstitute, in consultation with the Rheology and Interfacial Phenomena Group.Pseudo-ternary phase diagrams were used to determine the emulsion compositionwith the highest degree of stability, as described elsewhere [21,22].

Average drop size was determined using a particle size analyzer manufacturedby Malvern Instruments, MASTER PARTICLE SIZER MG-02. The distributionof drop size obtained in all cases was unimodal with an average of 11 mm.Rheological properties were measured using a Haake Rotovisco RV-20Rheometer. Table 1 shows the experimentally measured viscosity for emulsionswith di�erent oil content as determined at a shear rate of 10 sÿ1.

2.2. Preparation of the metallic samples

AISI-SAE 1010 carbon steel, with the composition shown in Table 2, was usedas the test material. Before each experiment, the samples were polished to 1200grit using SiC paper and were ®nally polished to a mirror ®nish using 0.05 mmAl2O3 powder.

2.3. Experimental cells

The diameter of the rotating disk electrode (RDE) was 0.5 cm. The referenceelectrode was a standard saturated calomel electrode (SCE) coupled to a Lugginprobe, whose tip was located between the working and the counter electrodes. Thecounter electrode was a platinum wire in serpentine form and protected by aporous membrane. Both the reference electrode and the counter electrode werelocated in a manner that they did not perturb the ¯ow lines of the emulsiontoward and from the working electrode. The rotation rate of the RDE was

Table 1

Viscosity values for di�erent oil contents

Oil percentage 0 2 5 10 20 50 70

Average viscosity, cp [g/m�s] 1 1.3 1.5 1.75 2 10 17


between 0 and 2500 rpm; however, most of the experiments were carried out at800 rpm. At rotation rates higher than 800 rpm, no major e�ects of rotation ratewere observed in the electrochemical activity.

The jet impingement electrochemical cell, shown schematically in Fig. 1, wasfabricated after the design of E®rd [23]. The main geometric parameters were:

Table 2

AISI-SAE 1010 carbon steel composition

Compound metal sample AISI-SAE 1010

C 0.106 0.08±0.13

Mn 0.509 0.30±0.60

P 0.013 0.040 max.

S 0.010 0.050 max.

Si 0.058

Cu 0.007

Ni 0.028

Cr 0.005

V 0.003

Mo 0.008

Ti 0.001

As 0.002

Al 0.029

Nb 0.007

Co 0.007

Sn 0.004

Fe Balance

Fig. 1. Schematic representation of the jet impingement electrochemical cell.


. Nozzle and working electrode diameter=0.625 cm,

. Vertical distances from the nozzle to the working electrodes, h = 4�d,h = 2.54 cm.,

. Radial distances for the location of the electrode in the wall jet region x = 5�r,x = 1.5875 cm.

The reference electrode was a standard calomel electrode/Luggin probe, with the

tip being located between the working and the counter electrode. The counter

electrode was a platinum cylinder located in the entrance to the cell.

The ¯ow loop that was employed with the JIEC consisted of a 20 l tank for

Fig. 2. In¯uence of oil content on the polarization of AISI-SAE 1010 carbon steel in contact with o/w

emulsions using the Rotating Disk Electrode at 800 rpm: (a) 0±45 wt% oil; (b) 45±70 wt% oil.


emulsion storage, a centrifugal pump, and an on-line ¯ow rate measurementsystem. The emulsion temperature was 25228C.

2.4. Electrochemical techniques

Electrochemical experiments were preformed using a Gamry Instruments PC3potentiostat controlled by CMS100 software. The polarization curves weremeasured by varying the applied potential from ÿ1.0 V vs SCE up to 2.0 V., at asweep rate of 1 mV/s. Before each experiment, the open circuit potential (OCP)was recorded for 300 s. Electrochemical impedance measurements were performedat the corrosion potential over the frequency range from 10 kHz to 100 mHz, witha voltage perturbation amplitude of 20 mV, using a Voltech Instruments TF2000Frequency Response Analyzer. In order to standardize the specimen surface, thesamples were left at the OCP for 300 s, then polarized at ÿ1.0 V vs SCE for 300 s,and, ®nally, the impedance was measured at the OCP that was previouslydetermined. Compliance of the impedance data with the constraints of LinearSystems Theory (LST) was veri®ed by Kramers±Kronig (K±K) transformation[24±29].

3. Results and discussion

Polarization curves for carbon steel in o/w emulsions of di�erent oil content,obtained using the rotating disk electrode and the jet impingement cell, are shownin Figs. 2 and 3, respectively. In Fig. 2, the polarization curves obtained from therotating disk electrode at 800 rpm in the surfactant solution (aqueoussolution+1% GR-7 M+0.2% NaCl) and in emulsions with oil contents of 20, 40,

Fig. 3. In¯uence of oil content on the polarization curves for AISI-SAE 1010 carbon steel in contact

with o/w emulsions as determined using the JIEC. The specimen was located in the stagnant region.

Fluid velocity at the nozzle is 3.58 m/s.


45, 50, 60, and 70%, are presented. Under the laminar ¯ow conditions providedby the rotating disk electrode (Re was calculated to be between 48 and 817compared with 2 � 105 for transition to turbulent ¯ow), a decrease in cathodiccurrent with increasing oil content is observed. An anodic peak is observed for alloil contents; however, the peak current density decreases with increasing oilcontent in the emulsion up to 45%. For all contents over 45%, the peak currentdensity increases. The observed relationship between the anodic peak and the oilcontent in the emulsion under laminar ¯ow conditions indicated the existence ofan oil-surfactant ®lm on the metallic surface.

At 800 rpm, the cathodic current density for an o/w emulsion with an IPR of20% was slightly higher than that of the surfactant solution (IPR=0%).However, experiments performed at a rotation rate of 400 rpm indicate that for o/w emulsions with low IPR (2, 5, 10% oil) the cathodic current density showed atendency to be slightly higher than that for the surfactant solution, but thedi�erences are very small. Therefore, an increase in the oil content of the o/wemulsions with low IPR seems to favor the cathodic processes, but when the oilcontent exceeds 20% the cathodic activity of the metal diminishes.

Polarization curves that were obtained using the jet impingement cell, when theworking electrode was located in the stagnant region and when the ¯uid velocityat the nozzle was 3.58 m/s, are presented in Fig. 3. The polarization curvesobtained for the stagnant region at a ¯uid velocity at the nozzle of 7.17 m/s, and

Fig. 4. In¯uence of oil content on the electrochemical impedance of AISI-SAE 1010 carbon steel in

contact with o/w emulsions. Rotating Disk Electrode at 800 rpm.


those for the wall jet region at ¯uid velocities at the nozzle of 3.58 and 7.17 m/s,were very similar to those shown in Fig. 3. Those data have been presented inprevious publications [30±33].

Under the drastic ¯ow conditions existing in the JIEC (high ¯uid speeds at thenozzle and low emulsion viscosity), the characteristic anodic peak in thepolarization curves obtained with the rotating disk electrode is not observed(compare Figs. 2 and 3). Furthermore the current at high anodic potentialobserved with the JIEC is considerably higher than that observed with the RDE

Fig. 5. E�ect of oil content on the electrochemical impedance behavior of AISI-SAE 1010 carbon steel

in contact with oil/water emulsions as determined using the JIEC. The specimen was located in the

stagnant region. Fluid velocity at the nozzle 7.17 m/s (a) and 3.58 m/s (b).


at equivalent oil contents, indicating that the electrochemical processes that occurin this region of potential are highly sensitive to ¯ow-induced shear.

Nyquist diagrams obtained for the rotating disk electrode and the jetimpingement cell with the working electrode located in the stagnant region fortwo ¯uid velocities at the nozzle (3.58 m/s and 7.17 m/s) are shown in Figs. 4 and5. The Nyquist diagrams for the jet impingement cellÐwall jet region and forboth ¯uid velocities at the nozzleÐare similar to those shown in Fig. 5 for thestagnant region. A marked increase in the polarization and ohmic resistances isobserved for oil contents in the emulsion between 45 and 50 wt%. This iscommon for both of the hydrodynamic systems employed, but the impedances atboth ends of the frequency range observed under laminar ¯ow conditions usingthe RDE is considerably higher than those observed in the JIEC in either thestagnant and wall jet regions. These data, again, indicate the presence of a shear-sensitive phenomenon at the steel/emulsion interface.

In the speci®c case of the polarization resistance, derived from the Nyquistdiagrams shown in Fig. 4, for the rotating disk electrode, three di�erent behaviorsbecome evident. For low IPR (o/w emulsions with 0, 5, 10, 20 wt% oil) thepolarization resistance seems to increase with oil content; for medium IPR (20, 40,45%) this parameter does not change strongly with the oil content, and for highIPR (45, 50, 60%) it markedly increases with oil content once again. In the caseof the impinging jet cell, we observed that the solution resistance variedsigni®cantly with the oil content in the emulsion, is independent of the ¯uid

Fig. 6. Change in the corrosion rate of AISI-SAE 1010 carbon steel vs oil content in the emulsion.

RDE at 800 rpm.


velocity at the nozzle, and is independent of the working electrode location. The

polarization resistance (diameter of the locus at the real axis) seemed to display a

sinusoidal behavior with the percentage of oil in the emulsion, and is dependent

on the ¯uid velocity at the nozzle and on the region where the working electrode

is located.

The variation of the corrosion rate, calculated from the potentiodynamic

polarization curves (by Tafel extrapolation) and impedance measurements (using

the polarization resistance, obtained from the Nyquist diagrams, and Tafel slopes)

[12], is shown in Fig. 6 with respect to oil content of the emulsion for the rotating

disk electrode. The corrosion rate remains relatively constant for oil contents in

the emulsion up to 20%. Further additions of oil reduce the corrosion rate

sharply. This behavior is quite similar to that of the cathodic current density, as

was noted earlier.

The in¯uence of oil content on the corrosion rate, when measured in the JIEC,

in which the hydrodynamic conditions are characterized by higher Reynolds

numbers and shear stresses than those of the RDE, and with the electrodes

located in the stagnant region and for the two ¯uid velocities at the nozzle, is

shown in Fig. 7. The corrosion rate is observed to increase with oil content for

emulsions with low IPR (5, 10, 20%), whereas for oil contents over 40% (40, 50,

Fig. 7. Change in the corrosion rate of AISI-SAE 1010 carbon steel vs oil content in the emulsion.

JIEC, stagnant region.


65%) the corrosion rate decreased. Again the behavior of the corrosion rate is

very similar to that of the cathodic limiting current density.

For the JIEC assembly with the working electrode in the wall jet region,

corresponding to the most drastic hydrodynamic conditions used in this work, the

corrosion rate is not strongly a�ected by the oil content in the emulsion, provided

that it is less than 40% (Fig. 8). Oil contents higher than 40% reduce the

corrosion rate, independent of the ¯uid velocity.

The ®ndings reported in this paper are consistent with the formation of a thin

layer of an `oily phase' on the metal surface, the stability of which depends on the

oil content of the emulsion and the magnitude of the hydrodynamically-induced

shear at the interface. Thus, in all cases, increasing the oil content (to r20% in

the case of the RDE and r40% in the JIEC in the stagnant region) results in a

shift in the high frequency intercept of the impedance locus on the real axis to

higher values, indicating an increase in the resistance of the phase(s) between the

metal surface and the tip of the reference electrode. However, the formation of

this layer is not abrupt, as indicated by the continuous nature of the corrosion

rate vs oil content data shown in Figs. 6±8. Thus, the bell-shaped nature of the

corrosion rate vs oil content curves indicates that the rate of attack on the metal

is determined by a competition between oil adsorption, which decreases the

Fig. 8. Change in the corrosion rate of AISI-SAE 1010 carbon steel vs to the oil content in the

emulsion. JIEC, wall jet region.


corrosion rate with increasing oil content, and some process by which theformation of the oily phase on the surface enhances the corrosion rate (see below).The principal e�ect of increasing shear is to increase the corrosion rate, with thee�ect possibly being greatest at low oil contents (compare Figs. 7 and 8). In thecase of RDE, oil adsorption appears to be the dominant process, whereas for thejet impingement system the process that facilitates attack at low oil contentsappears to play a major role in determining the corrosion behavior.

It is important to note that, in the latter case, in both the stagnant and all jetregions, the corrosion rate increases with oil content for low oil contents. Thisbehavior is mathematically described by a function of the form, Corrosion Rate(CR)A y(1ÿy ), where y is the coverage of the surface by the oily phase.Assuming that y is proportional to the normalized oil content of the emulsion(IPR '), we obtain CRA IPR ' (1ÿIPR ') where 0 < IPR '< 1.0. The corrosion ratevs IPR behavior therefore is determined by the product of two linearly varyingsub-functions, IPR ' and (1ÿIPR '). The ®rst subfunction appears to correspond tothe oily phase facilitating the transport of oxygen to the metal surface, which issupported by the higher solubility of oxygen in light mineral oil than in water[34,35]. Thus, the role of the adsorbed oily phase is to facilitate the cathodic(oxygen reduction) partial reaction. However, the immediate product from thecorrosion of iron is an ionic species, Fe2+ or (Fe3+), whose solubility in the oilyphase is expected to be very low. Thus, the oily phase on the surface is expectedto inhibit the anodic partial reaction, such that the rate decreases with (1ÿIPR '),with the e�ect becoming dominant at high IPR '. Because the anodic and cathodicpartial reactions are coupled, the net e�ect is the competition of two opposinge�ects and hence the observed bell-shaped dependence of corrosion rate on oilcontent of the emulsion.

4. Summary and conclusions

The corrosion and electrochemical behaviors of AISI-SAE 1010 carbon steel inoil-in-water emulsions under controlled hydrodynamic conditions have beenexplored with the objective of de®ning the mechanisms involved. This work hasfound that:

1. Both the rotating disk electrode (RDE) and the jet impingementelectrochemical cell (JIEC) are convenient experimental systems for studyingthe e�ects of hydrodynamic and mass transfer factors on the corrosion of steelin oil-in-water emulsions.

2. The electrochemical behavior of the steel, as re¯ected in potentiodynamicpolarization and electrochemical impedance spectroscopic (EIS) data, is foundto be a sensitive function of oil content and the hydrodynamically-inducedshear stress at the metal interface.

3. The results are consistent with a model that postulates that the surface of thesteel is partially covered by an oily phase, the coverage of which depends upon


the oil content of the emulsion and the magnitude of the hydrodynamicallyinduced shear stress at the interface. The adsorbed oily phase is considered tofacilitate the cathodic partial reaction (O2 reduction), because of the highersolubility of oxygen in oil than in water, whereas it inhibits the anodic partialreaction (iron dissolution) due to the low solubility of ionic species (Fe2+ orFe3+) in the oil.

Acknowledgements

This investigation was supported by COLCIENCIAS and the Center forAdvanced Materials at Pennsylvania State University. The authors wish to expresstheir thanks to Prof. Nobuyoshi Hara and to Drs Elizabeth and Janusz Sikora fortheir advice, to Dr K. D. E®rd for the technical material on the jet impingementcell design, and to Dr Donald Heaney for his assistance in building the JIC andhydrodynamic loop. Also, the support and advice of Eng. Jorge Luis Grosso andDr Jorge H. Panqueva is gratefully acknowledged.

References

[1] P. Becher (Ed.), Encyclopedia of Emulsion Technology, Applications, Marcel Dekker Inc, New

York and Basel, 1985.

[2] R.E. Meredith, ChW Tobias, J. Electrochem. Soc. 108 (3) (1961).

[3] Ortega B. Artalejo, Trillo C. Fauli, Carrascosa A. del Pozo, Pre-formulation of emulsions, con-

ductimetric study (PreformulacioÂ n de emulsiones, estudio conductimeÂ trico), Industria

FarmaceuÂ tica, 1987.

[4] R.A. Mac Kay, Advances in Coll. Interf. Sci. 15 (1981).

[5] R.A. Mac Kay, N.S. Dixit, J. Phys. Chem. 86 (1982) 4593.

[6] R.A. Mac Kay, J. Phys. Chem. 86 (1982) 4756.

[7] C.A. Jones, L.E. Weaner, R.A. Mac Kay, J. Phys. Chem. 84 (1980) 1495.

[8] F. Beck, H. Guder, J. Electrochem. Soc. 134 (1987) 2416.

[9] E. Sudol, E.A. Mohamed, Ind. Eng. Chem., Prod. Res. Dev. 24 (1985) 550.

[10] C.C. Ho, A. Humayun, E.A. Mohamed, J. Vanderho�, Some aspects of cathodic electrodeposi-

tion of epoxi latexes as corrosion resistant coatings, in: Corrosion Control by Organic Coatings,

NACE, 1981, pp. 111±121.

[11] M. Uebner, M. Ng Ka, J. Appl. Polymer Sci. 36 (1988) 1525.

[12] M.G. Fontana, in: Corrosion Engineering, 3rd ed., McGraw Hill, 1986, pp. 15±17.

[13] C. Retamoso et al., Electrochemical processes in emulsions (Procesos ElectroquõÂmicos en

Emulsiones), Final Report, UIS-Colciencias-ICP Project, Bucaramanga, Colombia, 1993.

[14] D.Y. PenÄ a, MSc. thesis, Industrial University of Santander, Bucaramanga, Colombia, 1994.

[15] F. Echeverria, MSc. thesis, Industrial University of Santander, Bucaramanga, Colombia, 1995.

[16] L.L. Schramm, Emulsions, fundamentals and applications in the petroleum industry, Advances in

Chemistry Series 231, American Chemical Society, Washington DC, 1992, Chapter 4, 139.

[17] A.H.P. Skelland, Non Newtonian Flow and Heat Transfer, John Wiley and Sons, 1967.

[18] Yu V. Pleskov, V. Yu Filinovskii, The Rotating Disk Electrode, Consultants Bureau, New York,

1976.

[19] V.G. Levich, Physicochemical Hydrodynamics, Prentice Hall Inc, 1962.


[20] J.L. Dawson, C.C. Shih, D.G. John, D.A. Eden Electrochemical testing of di�erential ¯ow

induced corrosion using jet impingement rigs. In: Proceedings of Corrosion 1987, Paper number

453, NACE, USA.

[21] D.Y. PenÄ a, C. Vasquez, C. Retamoso, J. Grosso, J. Villarreal, Oil in water emulsions corrosivity

under stagnant conditions, in: Proceedings of First Corrosion Congress, NACE Latin America

Region and First Venezuelan Corrosion Congress, 6±11 November, 1994.

[22] H. Quiroga, J.H. Panqueva, J.L. Grosso, C. Retamoso, Pseudo-ternary phase diagram used as a

guide for obtaining stable emulsions, in: Proceedings of International Symposium about Micelles,

Microemulsions and monolayers, University of Florida, Gainesville, FA, USA, 1995.

[23] D. E®rd, E.J. Wright, J.A. Boros, T.G. Hailey, Correlation of steel corrosion in pipe ¯ow with jet

impingement and rotating cylinder tests, in: Corrosion, NACE, 1993.

[24] D.D. Macdonald, M. Urquidi-Macdonald, J. Electrochem. Soc. 137 (1990) 515.

[25] D.D. Macdonald, M. Urquidi-Macdonald, J. Electrochem. Soc. 132 (1985) 2316.

[26] M. Urquidi-Macdonald, S. Real, D.D. Macdonald, J. Electrochem. Soc. 133 (1986) 2018.

[27] M. Urquidi-Macdonald, S. Real, D.D. Macdonald, Electrochimica Acta 35 (1990) 1559.

[28] H.A. Kramers, Physiol. Zool. 30 (1929) 522.

[29] R.I. Kronig de, J. Opt. Soc. Am. 12 (1926) 547.

[30] H. Quiroga, D.D. Macdonald, C. Retamoso, J. Panqueva, J.L. Grosso, Corrosiveness of o/w

emulsions under controlled hydrodynamic conditions. DC and AC measurements, in: Proceedings

of 190th Meeting. The Electrochemical Society, San Antonio, Texas, 6±11 October 1996.


emulsions under controlled hydrodynamic conditions (Corrosividad de emulsiones aceite en agua,

o/w, bajo condiciones hidrodinaÂ micas controladas), in: Proceedings of National Corrosion

Congress (Memorias Congreso Nacional de CorrosioÂ n), Paipa, Colombia, 4±6 August 1997.


emulsions under controlled hydrodynamic conditions (Corrosividad de emulsiones aceite en agua,

o/w, bajo condiciones hidrodinaÂ micas controladas), in: Proceedings of National Congress of

Chemical Engineering (Congreso Nacional de IngenierõÂ a QuõÂmica). MedellõÂ n, Colombia, 6±8

August 1997.

[33] H. Quiroga, Corrosiveness of oil in water emulsions under hydrodynamic conditions, PhD thesis,

Chemical Engineering School, Industrial University of Santander, Colombia, 1998.

[34] The National Research Council of the United States of America, International Critical Tables of

Numerical Data, Physics, Chemistry and Technology, III, 255±263, 1933.

[35] Atherton Seidell, Solubilities of Inorganic and Metal Organic Compounds, 3rd ed., I, 1940.


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