Research Article The Corrosion Performance of Galvanized...

Hindawi Publishing CorporationInternational Journal of CorrosionVolume 2013 Article ID 267353 9 pageshttpdxdoiorg1011552013267353

Research ArticleThe Corrosion Performance of Galvanized Steel inClosed Rusty Seawater

Shuan Liu12 Huyuan Sun1 Ning Zhang12 and Lijuan Sun1

1 Key Laboratory of Marine Environmental Corrosion and Bio-Fouling Institute of OceanologyChinese Academy of Sciences Qingdao 266071 China

2Graduate University of Chinese Academy of Sciences Beijing 100049 China

Correspondence should be addressed to Huyuan Sun sunqdioaccn

Received 19 July 2013 Accepted 21 October 2013

Academic Editor W Ke

Copyright copy 2013 Shuan Liu et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The corrosion performance of galvanized steel in closed rusty seawater (CRS) was investigated using weight loss Tafel polarizationcurve and electrochemical impedance spectroscopy Scanning electron microscopy (SEM) and energy dispersive spectroscopy(EDS) were carried out for morphological and chemical characterization of the rust layer absorbed on the zinc coating Effectsof temperature and hydrostatic pressure on corrosion resistance of galvanized steel were studied Results indicated that rust layercould induce pitting corrosion on the zinc coating under the Clminus erosion high temperature accelerated the corrosion rate of zinccoating and inhibited the absorption of rust layer the polarization resistance (119877

119901

) of galvanized steel increased with the increaseof hydrostatic pressure in CRS

1 Introduction

The PVC encapsulated galvanized steel wire is widely appliedin submarine cable project in recent years [1] PVC is coatedon the surface of galvanized steel by thermal compressionThis PVC coating can prevent the penetration of seawaterand air and then inhibit the corrosion of galvanized steelHowever the failure of PVC will result in the penetrationof seawater with immersion time and the initial rust layerproduced on the surface of the galvanized steel cannot falloff because the coating of PVC Thus the galvanized steelwas always immersed in a closed saturated rusty seawaterenvironment (Figure 1)

It is acknowledged that when galvanized steel is exposedto marine environment the main corrosion products(Zn5

(OH)2

Cl8

) have been found in longer exposure periods[2 3]When the galvanized steel is coated by PVC and used ascables in seawater the corrosion performance of galvanizedsteel under this closed rusty seawater (CRS) is primary inthe process of metallic corrosion [4 5] It is expected that thecorrosion performance of galvanized steel may be differentsince the rust layer affects corrosion-related processessuch as the mass transport of dissolved oxygen [6 7]

the stability of the passive film and the hydration of thedissolved metal ions [8ndash10] There are few reports regardingthe corrosion behavior of galvanized steel under closed rustyseawater environment

In our previous works it had been demonstrated thatClminus concentration and pH have very important effects oncorrosion behavior of galvanized steel under simulated rustlayer solution [11 12] In the present work the saturatedZn5

Cl2

(OH)8

seawater is used to simulate the closed rustyseawater (CRS) environment The corrosion performance ofgalvanized steel in CRS was investigated by means of con-ventional electrochemical techniques including polarizationcurve and electrochemical impedance spectroscopy (EIS)Effects of temperature and hydrostatic pressure on corrosionresistance of galvanized steel were studied in detail

2 Experimental

21 Experimental Design The electrochemical tests werecarried out in a closed environment and the experimentalapparatus was depicted in Figure 2 An important issue isthat the cell remains well-sealed To meet this requirement

2 International Journal of Corrosion

Seawater penetration

PVC coating

Galvanized steel wire

Rust

Rusty seawater

(a) (b)

Figure 1 Schematic diagram of galvanized steels coated by PVC (a)the failure zone of the PVC coating (b) the corroded surface of thegalvanized steel

Working electrodeReference electrode and Luggin capillary

Counter electrode

CRS solutionHydrostatic pump

Pressure gauge

Figure 2 Schematic diagram of the electrochemical test cell underdifferent hydrostatic pressures in CRS solution

the cell was fabricated with high precision and the edge wassealedwith epoxyTheworking electrodewasmachined fromcommercial galvanized steel with a composition of the zinccoating containing (wt) 02Mn 004C 001 P 0008S 0036 Ti and the balance zinc The exposed area of theelectrode was 1 times 1 cm2 the side surface of the specimenwas sealed by epoxy and a copper wire was connected tothe backside of each electrode Before each test the workingsurface of the electrode was degreased with ethanol thencleaned with distilled water and then dried in air Counterelectrode was a platinum sheet and reference electrode was asaturated calomel electrode (SCE) All potentials in this paperwere reported in the SCE scale

22 Test Medium The seawater used in the experimentwas taken from Huiquan Bay of Qingdao (east longitude119∘301015840sim121∘001015840 north latitude 35∘351015840sim37∘091015840 pH 787sim792and salinity 3026permilsim3038permil) The closed rusty seawater(CRS) was prepared by adding Zn

5

(OH)2

Cl8

to seawaterand more Zn

5

(OH)2

Cl8

precipitation was added to the testsolution to maintain saturation [11] The experiment wascarried out in March 2013 (the ambient temperature wasabout 293K) and the hydrostatic pressure of the test solutionwas controlled with a SB-25ndash6 manual hydraulic pump

23 Weight Loss Measurement According to ISO standards8407-1991 weight loss tests were conducted in seawater and

Seawater CRS0

1

2

3

4

5

Medium

Cor

rosio

n ra

te ( 120583

g cmminus2

hminus1)

Figure 3 Corrosion rate of galvanized steel immersed at 01MPahydrostatic pressure and 293K in seawater and CRS solution after30 days

CRS at ambient temperature The specimens were weighedbefore the tests To determine the loss of weight the spec-imens were removed after 30 days and the rust layer wasscraped off by a surgical bladeThe residual rust on specimenwas removed by immersion in NH

4

Cl solution (100 gL) at343K for 5min washed with abundant distilled water driedand then weighed to determine their mass loss

24 Electrochemical Experiments Tafel polarization curveswere acquired using an EGampG 2273 potentiostat at a scan rateof 05mVs and the electrochemical parameters were fittedby CView2 software For the linear polarization measure-ment a sweep range of minus10 to +10mV versus OCP at a sweeprate of 0166mVs was used and the polarization resistance(119877119901

) was determined from the slope of the potential (119864)versus current (119894) curve in the vicinity of the corrosion poten-tial [13]The EIS measurements were performed at OCP witha 10mV AC perturbation at the frequency from 100 kHz to10mHz with 5 points per decadeThe frequency sweep of theEIS was always taken from high to low ZView2 software wasused to analyze the EIS data with equivalent circuits Boththe polarization curves and EIS measurements were repeatedthree times for the reproducibility

25 Surface Characterization Themicrostructure of the rustlayer absorbed on the surface of electrode was observed andrecorded by using aKYKY-2800B SEM and the field emissionenergywas 10 keVThe chemical composition of the corrosionproducts was determined using a GENESIS 4000 energydispersive spectroscopy (EDS) attached to the SEM

3 Results and Discussion

31 Weight Loss Measure Figure 3 showed the corrosion rateof specimens immersed in seawater and CRS after 30 daysat ambient temperature The corrosion rate of galvanizedsteel in CRS (452 120583gcm2 h) was 216 times faster than that

International Journal of Corrosion 3

Seawater CRS solution

2d 2d

14d

14d

7d

7d

minus06

minus08

minus10

minus12

minus08

minus10

minus12

minus14minus8 minus6 minus4 minus2 0minus8 minus6 minus4 minus2

log (i Amiddotcmminus2)log (i Amiddotcmminus2)

Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)

Figure 4 Tafel polarization curves of galvanized steel immersed at 01MPa hydrostatic pressure and 293K in seawater and CRS solution afterdifferent immersion times

Table 1 Electrochemical parameters of galvanized steel calculatedfrom polarization curve at 01MPa and 293K in seawater and CRSsolution

119864corrV versus SCE

119894corr120583Acmminus2

120573119886

mVdec120573119888

mVdecSeamdash2d minus1036 1517 1586 2203Seamdash7d minus1073 2291 13253 2342Seamdash14d minus1089 3712 1483 2355CRSmdash2d minus1041 1858 577 2112CRSmdash7d minus1043 2556 416 1863CRSmdash14d minus1075 5834 352 1964

in seawater (209 120583gcm2 h) suggesting that corrosion ofgalvanized steel in CRS solution proceeded much faster thanthat in seawater

32 Corrosion Behavior of Galvanized Steel in Seawaterand CRS Figure 4 showed the Tafel polarization curves ofgalvanized steel in seawater and CRS solution under differentimmersion times respectively The corrosion parametersfitted from the Tafel region of Figure 4 using Powersuitesoftware were listed in Table 1The corrosion potential (119864corr)shifted to the negative direction with immersion time inseawater and CRS indicating the further degradation of thezinc coating In CRS solution the evolution of corrosion cur-rent density (119894corr) was similar to that of seawater howeverboth of the 120573

119886

and 120573119888

values were smaller and the 119894corr waslarger than that in seawater indicating that the rust layerabsorbed on the electrode surface accelerated the corrosionrate of galvanized steel [14]These results were consistent withthe weight loss measurement completely

321 The Effect of Temperature on Corrosion Behavior in CRSSolution TheEIS evolution of galvanized steel after exposureto CRS under different temperature was shown in Figure 5

To obtain the electrochemical parameters two equivalent cir-cuits shown in Figures 6(a) and 6(b) were used for fitting EISdata of galvanized steel in CRS under different temperaturerespectively The corresponding electrochemical parameterswere listed in Table 2 From the Bode plots of Figure 5 thereare two time constants occurred during the whole immersiontimes [15 16] The capacitive semicircle at high frequencyis associated with the rust layer absorbed on the electrodesurface and the capacitive semicircle at the medium-lowfrequency is attributed to the double layer capacitance andcharge-transfer resistance [17 18] When the temperaturewas 293K a Warburg impedance corresponding to oxygendiffusion appeared at the low frequency Figure 6(a) wasused to fit the EIS data only displaying two capacitive loopswhereas the second one (Figure 6(b)) was used to fit the EISdata displaying a Warburg impedance

In the equivalent circuit the capacitance is replaced by theconstant phase angle element 119876 because a dispersion effectcan be caused by microscopic roughness in the CRS solution[19]119876 is expressed as 120596minus119899119884

0

sdot (cos 1198991205872 + 119895 sin 1198991205872) where1198840

and 119899 are the constant and exponent respectively 120596 isthe angular frequency in rad sminus1 (120596 = 2120587119891) and 1198952 = minus1is an imaginary number [20] 119877

119904

is the solution resistance1198761

and 119877119891

are the capacitance and resistance of rust layerrespectively 119876

2

is the double layer capacitance and 119877ct is thecharge transfer resistance119882 represents the oxygen diffusionimpedance [21]

The diameter of the semicircle of impedance spectrumincreased with immersion time at different temperatures andthe corresponding EIS fitting results (119877

119891

and 119877ct) of galva-nized steel were shown in Figure 7 The 119877

119891

increased withtime at low temperature (273sim293K) suggesting the thicknessof rust layer absorbed on the electrode was thickenedHowever The 119877

119891

decreased with time at high temperature(313sim333K) Obviously the 119877

119891

values at high temperature(313sim333K) were much lower than those at low temperature(273sim293K) indicating that the high temperature inhibited


1600

1200

800

400

00 1000 2000 3000 4000 5000

600

500

400

300

200

100

0

0 300 600 900 1200

0 300 600 900 1200

300

240

180

120

60

0

150

120

90

60

30

0

0 100 200 300 400 500 600 minus2 minus1 0 1 2 3 4 5

minus2 minus1 0 1 2 3 4 5



75

60

45

30

15

60

45

30

15

0

60

45

30

15

0

80

60

40

20

0

273K 24h273K 48h

273K 96h273K 192h

273K 24h273K 48h

273K 96h273K 192h

293K 24h293K 48h

293K 96h293K 192h

293K 24h293K 48h

293K 96h293K 192h

313K 24h313K 48h

313K 96h313K 192h

313K 24h313K 48h

313K 96h313K 192h

333K 24h333K 48h

333K 96h333K 192h

333K 24h333K 48h

333K 96h333K 192h

Nyquist

Nyquist

Nyquist

Nyquist

Bode

Bode

Bode

Bode

minusZ998400998400

(Ωcm

2)

Z998400 (Ω cm2)

minusZ998400998400

(Ωcm

2)

Z998400 (Ω cm2)

minusZ998400998400

(Ωcm

2)

Z998400 (Ω cm2)

minusZ998400998400

(Ωcm

2)

Z998400 (Ω cm2)

log f (Hz)

log f (Hz)

log f (Hz)

log f (Hz)

003Hz

minusph

ase a

ngle

(deg

)minus

phas

e ang

le (d

eg)

minusph

ase a

ngle

(deg

)minus

phas

e ang

le (d

eg)

Figure 5 EIS curves of galvanized steel in CRS solution at 01MPa under different temperatures


Rs

Q1 Q2

Rf Rct

(a)

Rs

Q1 Q2

Rf RctW

(b)

Figure 6 Two equivalent circuit models used to fit the experiment impedance data of galvanized steel in SRL solution

0 48 96 144 1920

400

800

1200

1600

273K293K

313K333K

Time (h)

Rf

(Ωcm

2)

(a)

0

2000

4000

6000

273K293K

313K333K

0 48 96 144 192Time (h)

Rct

(Ωcm

2)

(b)

Figure 7 Changes of 119877119891

(a) and 119877ct (b) in CRS solution at 01MPa under different temperatures

Table 2 EIS fitting parameters of galvanized steel after various immersion times in CRL solution at 01MPa under different temperatures(273 293 313 and 333K)

Timehours

119877119904

Ω cm21198761

120583F cmminus2 Hz1minus1198991 1198991

119877119891

Ω cm2Q2


119877ctΩ cm2

WΩ cm2

273K

24 001 756 059 1235 1025 059 5523 mdash48 001 1223 074 1356 2418 068 4862 mdash96 001 5358 062 1478 915 058 5900 mdash192 001 8956 061 1563 1018 065 6123 mdash

293K

24 001 96 054 6251 3124 094 4392 mdash48 001 142 078 6902 916 091 5308 00041296 001 212 095 7145 2428 061 4599 000462192 001 1405 085 7002 1352 059 5215 00189

313 K


333K



minus0990

minus0995

minus1000

minus1005

minus1010

minus0940

minus0945

minus0950

minus0955

minus0960

minus0965

minus0955

minus0960

minus0965

minus0970

minus0975

minus0980

minus0915

minus0920

minus0925

minus0930

minus0935

minus6 minus4 minus2 0 2 4 minus04

minus04minus04 minus02

minus08 00

00 00 04

04

04

08

0208

01MPa 02MPa

03MPa 04MPa

i (120583A cmminus2) i (120583A cmminus2)

i (120583A cmminus2)i (120583A cmminus2)

Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)

Figure 8 Linear polarization curves of galvanized steel under different hydrostatic pressure in CRS solution at 293K after 2 days

0

10

20

30

40

50

60

Hydrostatic pressure (MPa)00 01 02 03 04

Rp

(KΩ

cm2)

Figure 9 Evolution of 119877119901

estimated by linear polarization curves under different hydrostatic pressure in CRS solution at 293K after 2 days

the adsorption of the rust layer When the temperature wasconstant the119877ct almost kept invariantThe119877ct values at 273Kwere much larger than those at 293K 313 K and 333K inCRS indicating that the high temperature accelerated thecorrosion rate of galvanized steel in CRS [22]

322 The Effect of Hydrostatic Pressure on Corrosion Behaviorin CRS Solution The linear polarization curves of galvanizedsteel under different hydrostatic pressure in CRS were shownin Figure 8 119864corr shifted from a negative value to a positiveone with the increase of hydrostatic pressure and the linear


Test zone for EDS

10120583m

(a)

Zn

ZnZnO

1 2 3 4 5 6 7 8 9 10 11

(keV)

(b)

Test zone for EDS

10120583m

(c)

Zn

Zn

Zn

OMn

Cl

ClC

Ti

Ti

Fe Fe1 2 3 4 5 6 7 8 9 10 11

(keV)

(d)

Figure 10 SEM and EDS analysis of galvanized steel immersed in CRS solution in 01MPa (a) SEM image of galvanized steel beforeimmersion (b) EDS result of (a) (c) SEM image of galvanized steel immersed in CRS solution at 01MPa hydrostatic pressures after 14days (d) EDS result of (c) in the pitting area

10120583m

(a)

10120583m

(b)

10120583m

(c)

10120583m

(d)

Figure 11 SEM images of galvanized steel immersed in CRS solution under different temperatures in 01MPa after 14 days (a) 273K (b)293K (c) 313 K (d) 333K


10120583m

(a)

10120583m

(b)

Figure 12 SEM images of galvanized steel immersed in CRS solution under different hydrostatic pressure at 293K after 2 days (a) 01MPa(b) 04MPa

polarization curves became nonlinear gradually These weredue to the reason that under high hydrostatic pressure therust layer was tightly absorbed on the surface of galvanizedsteel (Figure 12)Thus the fitted zonewas chosen in the linearregion (from minus5 to +5mV versus 119864corr) and Figure 9 showedthe variations of 119877

119901

as a function of different hydrostaticpressure It was observed that the 119877

119901

increased from 223 to4918 KΩ cm2 with the increase of hydrostatic pressure from01 to 04Mpa indicating that the corrosion resistance ofgalvanized steel improved with the increase of hydrostaticpressure in CRS

33 Surface Analysis SEM and EDS were employed to inves-tigate the corrosion behavior of galvanized steel under CRSat different temperatures Figure 10 showed the SEM andEDS results of specimen before immersion and after 14days immersion in CRS respectively Evidently the zinccoating was smooth compact and completely covered on thespecimen surface no corrosion was found before immersion(Figure 9(a)) Zn and O elements were observed beforeimmersion When the specimen is immersed in CRS after14 days needle-like rust layer was absorbed on the electrodesurface and the zinc coating was damaged under the erosionof Clminus Zn Fe Cl Ti C and O elements were observed inthe pitting zone Figures 11 and 12 showed the SEM images ofgalvanized steel under different temperatures (273 293 313and 333K) after 14 days and different hydrostatic pressures(01 and 04MPa) after 2 days in CRS solution respectivelyLoose rust layer was absorbed on the zinc coating at 273Khowever pitting corrosion occurred on the surface of spec-imen at 293K the zinc coating was damaged seriously at313 K and 333K When the hydrostatic pressure was 01MPasome spherical rust layer was absorbed on the surface Therust layer was turned into needle-like shape and absorbedadherently and compactly when the hydrostatic pressurewas 04MPa The SEM results indicated that the corrosionof galvanized steel was accelerated with temperature butinhibited under high hydrostatic pressure in CRS solution

4 Conclusion

(1) In closed rusty seawater (CRS) solution the rust layerabsorbed on the surface of galvanized steel acceler-ated the corrosion rate of zinc coating Pitting corro-sion occurred on the surface of galvanized steel zinccoating was damaged by the erosion of Clminus

(2) The corrosion rate of galvanized steel increased withtemperature because high temperature inhibited theabsorption of rust layer and reduced the charge-transfer resistance in CRS solution

(3) The polarization resistance of galvanized steel in-creased with the increase of hydrostatic pressure inCRS solution

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors wish to acknowledge the financial support of theNational Science Foundation of China (no 41076046)

References

[1] H Sun B Zang S Liu L Sun and H Fan ldquoEffects of Zn(OH)2

on corrosion behavior of hot dipped Zn coating in freshwaterrdquoAdvanced Materials Research vol 399ndash401 pp 152ndash155 2012

[2] I Odnevall and M Westdahl ldquoThe formation of Zn4

Cl2

sdot

(OH)4

SO4

sdot5H2

O in an urban and an industrial atmosphererdquoCorrosion Science vol 36 no 9 pp 1551ndash1559 1994

[3] Y Li ldquoFormation of nano-crystalline corrosion products on Zn-Al alloy coating exposed to seawaterrdquo Corrosion Science vol 43no 9 pp 1793ndash1800 2001

[4] X G Zhang Corrosion and Electrochemistry of Zinc PlenumPress New York NY USA 1996


[5] T E Graedel ldquoCorrosion mechanisms for aluminum exposedto the atmosphererdquo Journal of the Electrochemical Society vol136 no 4 pp 204ndash212 1989

[6] J Duan S Wu X Zhang G Huang M Du and B HouldquoCorrosion of carbon steel influenced by anaerobic biofilm innatural seawaterrdquo Electrochimica Acta vol 54 no 1 pp 22ndash282008

[7] L Bousselmi C Fiaud B Tribollet andE Triki ldquoThe character-isation of the coated layer at the interface carbon steel-naturalsalt water by impedance spectroscopyrdquo Corrosion Science vol39 no 9 pp 1711ndash1724 1997

[8] C Cachet F Ganne G Maurin J Petitjean V Vivier and RWiart ldquoEIS investigation of zinc dissolution in aerated sulfatemediummdashpart I bulk zincrdquo Electrochimica Acta vol 47 no 3pp 509ndash518 2001

[9] C Cachet F Ganne S Joiret et al ldquoEIS investigation of zincdissolution in aerated sulphatemediummdashpart II zinc coatingsrdquoElectrochimica Acta vol 47 no 21 pp 3409ndash3422 2002

[10] T Tsuru ldquoVarious electrochemical approaches for corrosionengineeringrdquoCorrosion Engineering vol 59 no 11 pp 404ndash4092010

[11] S Liu H Y Sun L J Sun and H J Fan ldquoEffects of pH andClminus concentration on corrosion behavior of the galvanized steelin simulated rust layer solutionrdquo Corrosion Science vol 65 pp520ndash527 2012

[12] H Y Sun S Liu and L J Sun ldquoA comparative study onthe corrosion of galvanized steel under simulated rust layersolution with and without 35wtNaClrdquo International Journalof Electrochemical Science vol 8 pp 3494ndash3509 2013

[13] Y Zou J Wang and Y Y Zheng ldquoElectrochemical techniquesfor determining corrosion rate of rusted steel in seawaterrdquoCorrosion Science vol 53 no 1 pp 208ndash216 2011

[14] H Huang X Guo G Zhang and Z Dong ldquoThe effectsof temperature and electric field on atmospheric corrosionbehaviour of PCB-Cu under absorbed thin electrolyte layerrdquoCorrosion Science vol 53 no 5 pp 1700ndash1707 2011

[15] S Liu Y Gu S L Wang et al ldquoDegradation of organic pollu-tants by a Co

3

O4

-graphite composite electrode in an electro-Fenton-like systemrdquo Chinese Science Bulletin vol 58 pp 2340ndash2346 2013

[16] X N Liao F H Cao L Y Zheng et al ldquoCorrosion behaviourof copper under chloride-containing thin electrolyte layerrdquoCorrosion Science vol 53 no 10 pp 3289ndash3298 2011

[17] Y L Cheng Z Zhang F H Cao et al ldquoA study of thecorrosion of aluminum alloy 2024-T3 under thin electrolytelayersrdquo Corrosion Science vol 46 no 7 pp 1649ndash1667 2004

[18] S Liu X R Zhao H Y Sun R P Li Y F Fang and Y PHuang ldquoThe degradation of tetracycline in a photo-electro-Fenton systemrdquo Chemical Engineering Journal vol 231 pp 441ndash448 2013

[19] A P Yadav H Katayama K Noda H Masuda A Nishikataand T Tsuru ldquoSurface potential distribution over a zincsteelgalvanic couple corroding under thin layer of electrolyterdquoElectrochimica Acta vol 52 no 9 pp 3121ndash3129 2007

[20] H L Huang Z H Dong Z Y Chen and X P Guo ldquoThe effectsof Clminus ion concentration and relative humidity on atmosphericcorrosion behaviour of PCB-Cuunder adsorbed thin electrolytelayerrdquo Corrosion Science vol 53 no 4 pp 1230ndash1236 2011

[21] W Li H Tian and B Hou ldquoCorrosion performance of epoxycoatings modified by nanoparticulate SiO

2

rdquo Materials andCorrosion vol 63 no 1 pp 44ndash53 2012

[22] A Popova E Sokolova S Raicheva and M Christov ldquoAC andDC study of the temperature effect on mild steel corrosionin acid media in the presence of benzimidazole derivativesrdquoCorrosion Science vol 45 no 1 pp 33ndash58 2003

Submit your manuscripts athttpwwwhindawicom

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CorrosionInternational Journal of

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Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


Seawater penetration

PVC coating

Galvanized steel wire

Rust

Rusty seawater

(a) (b)

Figure 1 Schematic diagram of galvanized steels coated by PVC (a)the failure zone of the PVC coating (b) the corroded surface of thegalvanized steel

Working electrodeReference electrode and Luggin capillary

Counter electrode

CRS solutionHydrostatic pump

Pressure gauge

Figure 2 Schematic diagram of the electrochemical test cell underdifferent hydrostatic pressures in CRS solution

the cell was fabricated with high precision and the edge wassealedwith epoxyTheworking electrodewasmachined fromcommercial galvanized steel with a composition of the zinccoating containing (wt) 02Mn 004C 001 P 0008S 0036 Ti and the balance zinc The exposed area of theelectrode was 1 times 1 cm2 the side surface of the specimenwas sealed by epoxy and a copper wire was connected tothe backside of each electrode Before each test the workingsurface of the electrode was degreased with ethanol thencleaned with distilled water and then dried in air Counterelectrode was a platinum sheet and reference electrode was asaturated calomel electrode (SCE) All potentials in this paperwere reported in the SCE scale

22 Test Medium The seawater used in the experimentwas taken from Huiquan Bay of Qingdao (east longitude119∘301015840sim121∘001015840 north latitude 35∘351015840sim37∘091015840 pH 787sim792and salinity 3026permilsim3038permil) The closed rusty seawater(CRS) was prepared by adding Zn

5

(OH)2

Cl8

to seawaterand more Zn

5

(OH)2

Cl8

precipitation was added to the testsolution to maintain saturation [11] The experiment wascarried out in March 2013 (the ambient temperature wasabout 293K) and the hydrostatic pressure of the test solutionwas controlled with a SB-25ndash6 manual hydraulic pump

23 Weight Loss Measurement According to ISO standards8407-1991 weight loss tests were conducted in seawater and

Seawater CRS0

1

2

3

4

5

Medium

Cor

rosio

n ra

te ( 120583

g cmminus2

hminus1)

Figure 3 Corrosion rate of galvanized steel immersed at 01MPahydrostatic pressure and 293K in seawater and CRS solution after30 days

CRS at ambient temperature The specimens were weighedbefore the tests To determine the loss of weight the spec-imens were removed after 30 days and the rust layer wasscraped off by a surgical bladeThe residual rust on specimenwas removed by immersion in NH

4

Cl solution (100 gL) at343K for 5min washed with abundant distilled water driedand then weighed to determine their mass loss

24 Electrochemical Experiments Tafel polarization curveswere acquired using an EGampG 2273 potentiostat at a scan rateof 05mVs and the electrochemical parameters were fittedby CView2 software For the linear polarization measure-ment a sweep range of minus10 to +10mV versus OCP at a sweeprate of 0166mVs was used and the polarization resistance(119877119901

) was determined from the slope of the potential (119864)versus current (119894) curve in the vicinity of the corrosion poten-tial [13]The EIS measurements were performed at OCP witha 10mV AC perturbation at the frequency from 100 kHz to10mHz with 5 points per decadeThe frequency sweep of theEIS was always taken from high to low ZView2 software wasused to analyze the EIS data with equivalent circuits Boththe polarization curves and EIS measurements were repeatedthree times for the reproducibility

25 Surface Characterization Themicrostructure of the rustlayer absorbed on the surface of electrode was observed andrecorded by using aKYKY-2800B SEM and the field emissionenergywas 10 keVThe chemical composition of the corrosionproducts was determined using a GENESIS 4000 energydispersive spectroscopy (EDS) attached to the SEM

3 Results and Discussion

31 Weight Loss Measure Figure 3 showed the corrosion rateof specimens immersed in seawater and CRS after 30 daysat ambient temperature The corrosion rate of galvanizedsteel in CRS (452 120583gcm2 h) was 216 times faster than that



2d 2d

14d

14d

7d

7d

minus06

minus08

minus10

minus12

minus08

minus10

minus12



Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)





120573119886

mVdec120573119888




119886

and 120573119888





0



119904


and 119877119891


2



119891


119891


119891


119891



1600

1200

800

400

00 1000 2000 3000 4000 5000

600

500

400

300

200

100

0

0 300 600 900 1200

0 300 600 900 1200

300

240

180

120

60

0

150

120

90

60

30

0

0 100 200 300 400 500 600 minus2 minus1 0 1 2 3 4 5




75

60

45

30

15

60

45

30

15

0

60

45

30

15

0

80

60

40

20

0

273K 24h273K 48h

273K 96h273K 192h

273K 24h273K 48h

273K 96h273K 192h

293K 24h293K 48h

293K 96h293K 192h

293K 24h293K 48h

293K 96h293K 192h

313K 24h313K 48h

313K 96h313K 192h

313K 24h313K 48h

313K 96h313K 192h

333K 24h333K 48h

333K 96h333K 192h

333K 24h333K 48h

333K 96h333K 192h

Nyquist

Nyquist

Nyquist

Nyquist

Bode

Bode

Bode

Bode

minusZ998400998400

(Ωcm

2)

Z998400 (Ω cm2)

minusZ998400998400

(Ωcm

2)

Z998400 (Ω cm2)

minusZ998400998400

(Ωcm

2)

Z998400 (Ω cm2)

minusZ998400998400

(Ωcm

2)

Z998400 (Ω cm2)

log f (Hz)

log f (Hz)

log f (Hz)

log f (Hz)

003Hz

minusph

ase a

ngle

(deg

)minus

phas

e ang

le (d

eg)

minusph

ase a

ngle

(deg

)minus

phas

e ang

le (d

eg)



Rs

Q1 Q2

Rf Rct

(a)

Rs

Q1 Q2

Rf RctW

(b)


0 48 96 144 1920

400

800

1200

1600

273K293K

313K333K

Time (h)

Rf

(Ωcm

2)

(a)

0

2000

4000

6000

273K293K

313K333K

0 48 96 144 192Time (h)

Rct

(Ωcm

2)

(b)




Timehours

119877119904

Ω cm21198761


119877119891

Ω cm2Q2


119877ctΩ cm2

WΩ cm2

273K


293K

24 001 96 054 6251 3124 094 4392 mdash48 001 142 078 6902 916 091 5308 00041296 001 212 095 7145 2428 061 4599 000462192 001 1405 085 7002 1352 059 5215 00189

313 K


333K



minus0990

minus0995

minus1000

minus1005

minus1010

minus0940

minus0945

minus0950

minus0955

minus0960

minus0965

minus0955

minus0960

minus0965

minus0970

minus0975

minus0980

minus0915

minus0920

minus0925

minus0930

minus0935



minus08 00

00 00 04

04

04

08

0208

01MPa 02MPa

03MPa 04MPa



Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)


0

10

20

30

40

50

60


Rp

(KΩ

cm2)






Test zone for EDS

10120583m

(a)

Zn

ZnZnO

1 2 3 4 5 6 7 8 9 10 11

(keV)

(b)

Test zone for EDS

10120583m

(c)

Zn

Zn

Zn

OMn

Cl

ClC

Ti

Ti

Fe Fe1 2 3 4 5 6 7 8 9 10 11

(keV)

(d)


10120583m

(a)

10120583m

(b)

10120583m

(c)

10120583m

(d)



10120583m

(a)

10120583m

(b)



119901


119901



4 Conclusion






Acknowledgment


References




Cl2

sdot

(OH)4

SO4

sdot5H2
















3

O4








2










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





2d 2d

14d

14d

7d

7d

minus06

minus08

minus10

minus12

minus08

minus10

minus12



Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)





120573119886

mVdec120573119888




119886

and 120573119888





0



119904


and 119877119891


2



119891


119891


119891


119891



1600

1200

800

400

00 1000 2000 3000 4000 5000

600

500

400

300

200

100

0

0 300 600 900 1200

0 300 600 900 1200

300

240

180

120

60

0

150

120

90

60

30

0

0 100 200 300 400 500 600 minus2 minus1 0 1 2 3 4 5




75

60

45

30

15

60

45

30

15

0

60

45

30

15

0

80

60

40

20

0

273K 24h273K 48h

273K 96h273K 192h

273K 24h273K 48h

273K 96h273K 192h

293K 24h293K 48h

293K 96h293K 192h

293K 24h293K 48h

293K 96h293K 192h

313K 24h313K 48h

313K 96h313K 192h

313K 24h313K 48h

313K 96h313K 192h

333K 24h333K 48h

333K 96h333K 192h

333K 24h333K 48h

333K 96h333K 192h

Nyquist

Nyquist

Nyquist

Nyquist

Bode

Bode

Bode

Bode

minusZ998400998400

(Ωcm

2)

Z998400 (Ω cm2)

minusZ998400998400

(Ωcm

2)

Z998400 (Ω cm2)

minusZ998400998400

(Ωcm

2)

Z998400 (Ω cm2)

minusZ998400998400

(Ωcm

2)

Z998400 (Ω cm2)

log f (Hz)

log f (Hz)

log f (Hz)

log f (Hz)

003Hz

minusph

ase a

ngle

(deg

)minus

phas

e ang

le (d

eg)

minusph

ase a

ngle

(deg

)minus

phas

e ang

le (d

eg)



Rs

Q1 Q2

Rf Rct

(a)

Rs

Q1 Q2

Rf RctW

(b)


0 48 96 144 1920

400

800

1200

1600

273K293K

313K333K

Time (h)

Rf

(Ωcm

2)

(a)

0

2000

4000

6000

273K293K

313K333K

0 48 96 144 192Time (h)

Rct

(Ωcm

2)

(b)




Timehours

119877119904

Ω cm21198761


119877119891

Ω cm2Q2


119877ctΩ cm2

WΩ cm2

273K


293K

24 001 96 054 6251 3124 094 4392 mdash48 001 142 078 6902 916 091 5308 00041296 001 212 095 7145 2428 061 4599 000462192 001 1405 085 7002 1352 059 5215 00189

313 K


333K



minus0990

minus0995

minus1000

minus1005

minus1010

minus0940

minus0945

minus0950

minus0955

minus0960

minus0965

minus0955

minus0960

minus0965

minus0970

minus0975

minus0980

minus0915

minus0920

minus0925

minus0930

minus0935



minus08 00

00 00 04

04

04

08

0208

01MPa 02MPa

03MPa 04MPa



Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)


0

10

20

30

40

50

60


Rp

(KΩ

cm2)






Test zone for EDS

10120583m

(a)

Zn

ZnZnO

1 2 3 4 5 6 7 8 9 10 11

(keV)

(b)

Test zone for EDS

10120583m

(c)

Zn

Zn

Zn

OMn

Cl

ClC

Ti

Ti

Fe Fe1 2 3 4 5 6 7 8 9 10 11

(keV)

(d)


10120583m

(a)

10120583m

(b)

10120583m

(c)

10120583m

(d)



10120583m

(a)

10120583m

(b)



119901


119901



4 Conclusion






Acknowledgment


References




Cl2

sdot

(OH)4

SO4

sdot5H2
















3

O4








2










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




1600

1200

800

400

00 1000 2000 3000 4000 5000

600

500

400

300

200

100

0

0 300 600 900 1200

0 300 600 900 1200

300

240

180

120

60

0

150

120

90

60

30

0

0 100 200 300 400 500 600 minus2 minus1 0 1 2 3 4 5




75

60

45

30

15

60

45

30

15

0

60

45

30

15

0

80

60

40

20

0

273K 24h273K 48h

273K 96h273K 192h

273K 24h273K 48h

273K 96h273K 192h

293K 24h293K 48h

293K 96h293K 192h

293K 24h293K 48h

293K 96h293K 192h

313K 24h313K 48h

313K 96h313K 192h

313K 24h313K 48h

313K 96h313K 192h

333K 24h333K 48h

333K 96h333K 192h

333K 24h333K 48h

333K 96h333K 192h

Nyquist

Nyquist

Nyquist

Nyquist

Bode

Bode

Bode

Bode

minusZ998400998400

(Ωcm

2)

Z998400 (Ω cm2)

minusZ998400998400

(Ωcm

2)

Z998400 (Ω cm2)

minusZ998400998400

(Ωcm

2)

Z998400 (Ω cm2)

minusZ998400998400

(Ωcm

2)

Z998400 (Ω cm2)

log f (Hz)

log f (Hz)

log f (Hz)

log f (Hz)

003Hz

minusph

ase a

ngle

(deg

)minus

phas

e ang

le (d

eg)

minusph

ase a

ngle

(deg

)minus

phas

e ang

le (d

eg)



Rs

Q1 Q2

Rf Rct

(a)

Rs

Q1 Q2

Rf RctW

(b)


0 48 96 144 1920

400

800

1200

1600

273K293K

313K333K

Time (h)

Rf

(Ωcm

2)

(a)

0

2000

4000

6000

273K293K

313K333K

0 48 96 144 192Time (h)

Rct

(Ωcm

2)

(b)




Timehours

119877119904

Ω cm21198761


119877119891

Ω cm2Q2


119877ctΩ cm2

WΩ cm2

273K


293K

24 001 96 054 6251 3124 094 4392 mdash48 001 142 078 6902 916 091 5308 00041296 001 212 095 7145 2428 061 4599 000462192 001 1405 085 7002 1352 059 5215 00189

313 K


333K



minus0990

minus0995

minus1000

minus1005

minus1010

minus0940

minus0945

minus0950

minus0955

minus0960

minus0965

minus0955

minus0960

minus0965

minus0970

minus0975

minus0980

minus0915

minus0920

minus0925

minus0930

minus0935



minus08 00

00 00 04

04

04

08

0208

01MPa 02MPa

03MPa 04MPa



Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)


0

10

20

30

40

50

60


Rp

(KΩ

cm2)






Test zone for EDS

10120583m

(a)

Zn

ZnZnO

1 2 3 4 5 6 7 8 9 10 11

(keV)

(b)

Test zone for EDS

10120583m

(c)

Zn

Zn

Zn

OMn

Cl

ClC

Ti

Ti

Fe Fe1 2 3 4 5 6 7 8 9 10 11

(keV)

(d)


10120583m

(a)

10120583m

(b)

10120583m

(c)

10120583m

(d)



10120583m

(a)

10120583m

(b)



119901


119901



4 Conclusion






Acknowledgment


References




Cl2

sdot

(OH)4

SO4

sdot5H2
















3

O4








2










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Rs

Q1 Q2

Rf Rct

(a)

Rs

Q1 Q2

Rf RctW

(b)


0 48 96 144 1920

400

800

1200

1600

273K293K

313K333K

Time (h)

Rf

(Ωcm

2)

(a)

0

2000

4000

6000

273K293K

313K333K

0 48 96 144 192Time (h)

Rct

(Ωcm

2)

(b)




Timehours

119877119904

Ω cm21198761


119877119891

Ω cm2Q2


119877ctΩ cm2

WΩ cm2

273K


293K

24 001 96 054 6251 3124 094 4392 mdash48 001 142 078 6902 916 091 5308 00041296 001 212 095 7145 2428 061 4599 000462192 001 1405 085 7002 1352 059 5215 00189

313 K


333K



minus0990

minus0995

minus1000

minus1005

minus1010

minus0940

minus0945

minus0950

minus0955

minus0960

minus0965

minus0955

minus0960

minus0965

minus0970

minus0975

minus0980

minus0915

minus0920

minus0925

minus0930

minus0935



minus08 00

00 00 04

04

04

08

0208

01MPa 02MPa

03MPa 04MPa



Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)


0

10

20

30

40

50

60


Rp

(KΩ

cm2)






Test zone for EDS

10120583m

(a)

Zn

ZnZnO

1 2 3 4 5 6 7 8 9 10 11

(keV)

(b)

Test zone for EDS

10120583m

(c)

Zn

Zn

Zn

OMn

Cl

ClC

Ti

Ti

Fe Fe1 2 3 4 5 6 7 8 9 10 11

(keV)

(d)


10120583m

(a)

10120583m

(b)

10120583m

(c)

10120583m

(d)



10120583m

(a)

10120583m

(b)



119901


119901



4 Conclusion






Acknowledgment


References




Cl2

sdot

(OH)4

SO4

sdot5H2
















3

O4








2










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




minus0990

minus0995

minus1000

minus1005

minus1010

minus0940

minus0945

minus0950

minus0955

minus0960

minus0965

minus0955

minus0960

minus0965

minus0970

minus0975

minus0980

minus0915

minus0920

minus0925

minus0930

minus0935



minus08 00

00 00 04

04

04

08

0208

01MPa 02MPa

03MPa 04MPa



Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)

Eve

rsus

SCE

(V)


0

10

20

30

40

50

60


Rp

(KΩ

cm2)






Test zone for EDS

10120583m

(a)

Zn

ZnZnO

1 2 3 4 5 6 7 8 9 10 11

(keV)

(b)

Test zone for EDS

10120583m

(c)

Zn

Zn

Zn

OMn

Cl

ClC

Ti

Ti

Fe Fe1 2 3 4 5 6 7 8 9 10 11

(keV)

(d)


10120583m

(a)

10120583m

(b)

10120583m

(c)

10120583m

(d)



10120583m

(a)

10120583m

(b)



119901


119901



4 Conclusion






Acknowledgment


References




Cl2

sdot

(OH)4

SO4

sdot5H2
















3

O4








2










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Test zone for EDS

10120583m

(a)

Zn

ZnZnO

1 2 3 4 5 6 7 8 9 10 11

(keV)

(b)

Test zone for EDS

10120583m

(c)

Zn

Zn

Zn

OMn

Cl

ClC

Ti

Ti

Fe Fe1 2 3 4 5 6 7 8 9 10 11

(keV)

(d)


10120583m

(a)

10120583m

(b)

10120583m

(c)

10120583m

(d)



10120583m

(a)

10120583m

(b)



119901


119901



4 Conclusion






Acknowledgment


References




Cl2

sdot

(OH)4

SO4

sdot5H2
















3

O4








2










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




10120583m

(a)

10120583m

(b)



119901


119901



4 Conclusion






Acknowledgment


References




Cl2

sdot

(OH)4

SO4

sdot5H2
















3

O4








2










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials















3

O4








2










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



Research Article The Corrosion Performance of Galvanized...

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Transcript of Research Article The Corrosion Performance of Galvanized...