Corrosion and Corrosion Inhibition Study of Galvanized Steel in Salty Acidic and Basic Media

118 Pages·2013·2.42 MB·English

Ministry of Higher Education
and Scientific Research
University of Baghdad
College of Science

Corrosion and Corrosion Inhibition
Study of Galvanized Steel in Salty
Acidic and Basic Media

A Thesis
Submitted to the
College of Science -University of Baghdad
In Partial Fulfillment of the Requirements for the
Degree of Master of Science in Chemistry

By
Hayfaa Abdulameer Abbas
(B.Sc. 1981
)

Supervised By
Prof. Khulood A.Al-Sa΄adi

2012 A.D. 1433 A.H.
Supervisor Certification

I certify that this thesis was prepared under my supervision at the
University of Baghdad, College of Science as a partial requirement for the
Degree of Master of Science in Physical Chemistry.

Signature:
Supervisor: Dr. Khulood A.Al-Sa ̓ adi
Title:Professor
Address: Baghdad University –College of Science-Chemistry Department
Date: / / 2012

In view of the available recommendation, I forward this thesis for
debate by the examination committee.

Signature:
Name: Dr. Mohammed Rufaa΄t
Head of Chemistry Department
College of Science
Baghdad University
Date: / / 2012
Examination Committee

We certify that have read this thesis and as examining committee,
examined the student in its contents and that in our opinion it is adequate
for the partial fulfillment of the requirements for the degree of Master in
physical chemistry, with ( ) standing.

Chairman Member
Signature: Signature:
Name: Dr.Mouayed Q.Al. Abachi Name: Dr. Rana Afif
Title: Professor Title: Assist Professor
Date: / / 2012 Date: / / 2012

Member Supervisor/Member
Signature: Signature:
Name:Dr.Abdulkarem M.A. Alsamuraee Name : Dr.Khulood A.Al-Sa̕ adi
Title: Lecture Title: Professor
Date: / / 2012 Date: / / 2012

Approved by the College of Science

Signature:
Name: Dr. Saleh M. Ali
Title: Professor
Dean of the College of Science
Date: / / 2012
[ ]
ﻢﻴﻈﻌﻟا ﻲﻠﻌﻟا ﷲا قﺪﺻ
(76) ﺔﻳﻵﺍ ﻒﺳﻮﻳ ﺓﺭﻮﺳ
Dedication

To….
My family…who provided me the support
and encouragement to continue my post
graduate study with my warmest love and
appreciation.
Acknowledgment

I am a sincerely grateful to Allah for enabling and helping
me to perform and finish this work.
I would like to express my deep thank to my supervisor, Dr.
Khulood A. Alsa´adie for the supervision encouragement,
valuable advice , continuous help and support during the course
of this work.
I also express sincere gratitude to Dr. Abdulkareem
Mohammed Ali Alsamuraee for providing me a experimental
facilities.
My deepest thanks to Dr. Mohammed Rufaa´t the head of
the Chemistry Department, for his help and encouragement.
I would like to express my appreciation to my sister wafa
for her continuous cooperation.
My thank are also extended to all staff members of the
Chemistry Department / College of Science / University of
Baghdad for every bit of support they offered me during the
course of my study.

Hayfaa
I

Contents

No. Title Pag No.
Contents
I

List of abbreviation IV

L ist of figures V

List of Tables VII

A bstract VIII

Chapter one -Introduction
1.1 Metallic Corrosion 1
1.2 Corrosion In Aqueous Solutions 2
1.3 Polarization 2
1.3.1 Concentration Polarization 3

1.3.2 Activation Polarization 4

1.4 Polarization Curve 4

1.5 Pitting 6
1.5.1 Cyclic Pitting Scans and Pitting Potentials 7

1.6 Determination of Corrosion Rates 9
1.7 Corrosion Control 11

1.7.1 Corrosion Inhibition Method 12

1.7.1.1 Organic Inhibitor 14
1.7.2 Cathodic Protection Method 14

18 Protection Efficiency 15

1.9 Zinc Metal 16

1.10 Galvanized Steel 18

1.10.1 Hot Dip Galvanizing Process 18

1.11 L iterature Survey 19

1.12 The Aim and Scope of the Research 24
II

Chapter two -Experimental part

2.1 The Potentiostatic Set – Up 25
2.1.1 M lab Potentiostat / Galvanostat 25
2.1.2 Host Computer 26
2.1.3 The Thermostat 26
2.1.4 The Magnetic Stirrer 26
2.2 Corrosion Cell 26
2.3 Electrodes Description 27
2.3.1 Working Electrode 27
2.3.2 R eference Electrode 28
2.3.3 Auxiliary Electrode 28
2.4 M aterials and Chemicals 29
2.5 Hexamine 29
2.6 Preparation of solution 30
2.7 Typical Experimental Procedure 30
Chapter Three -Result and Discussion

The Polarization Curves 33
3 1
3.2 Corrosion Current Density and Corrosion Potential 42

3.3 The Tafel Slopes 45
3.4 Kinetics of Corrosion 46

3.5 Thermodynamics of Corrosion 51
3.6 Weight loss 57
3.7 Cyclic Pitting Scan 59

Chapter four -Result and Discussion

4.1 The Polarization Curves 64
4.2 Protection Efficiencies 67
4.3 The surface coverage 68
III

4.4 Thermodynamic of Inhibition 69
4.5 Kinetic of Corrosion 71
E ffect of Temperature on the Weight and
4.6 73
Penetration Loss
4.7 Cyclic Pitting Scans 74
4.8 Inhibition Action 75
Chapter Five -Conclusion and Suggestion

5.1 Conclusion 77

5.1.1 The corrosion process 78
5.1.2 The Inhibition process 73
5.2 Suggestion 79
References
References 81
IV

List of abbreviation

Meaning abbreviation
Metal M
Overpotential (overvoltage) η
De-electronation reaction i
Electrontion reaction i
Potential E
Equilbrium potential E
eq
Exchange current density i
o
Polarized potential for cathodic electrode E
p,c
Polarized potential for anodic electred E
p,a
Diffusion cofficient D
Concentration polarization ή
c
Limiting current density i
L
Thickness of diffusion δ
The concentration C
Pitting potential E
p
Corrosion current i
corr
Corrosion potential E
corr
Equilibrium potential for metal E
e,M
Matel velance z
Faraday constant F
Gas constant R
Absolute temperature T
Anodic tafel slope b
a
Cathodic tafel slope b
c
Polarization resistance R
p
Overpotential for activation polarization η
a
The passive currenr density i
pass
The passive potential E
pass
The critical current i
crit
The critical potential E
crit
Breakdawn potentilal or pitting potential E
p
Re-passivation potenntial E
R
Excheng current density for metal i
o,M
Excheng current density for solution i
o.so
The protection efficiency P
The metal surface covered θ