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EFFECT OF COATING CONDITION ON THE CORROSION
PROPERTIES OF MILD STEEL SUBSTRATE
KHAIRUL NIZAM BIN ZAINUDDIN
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
EFFECT OF COATING CONDITION ON THE CORROSION
PROPERTIES OF MILD STEEL SUBSTRATE
This report submitted in accordance with requirement of the Universiti Teknikal
Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering
(Engineering Materials) with Honours.
by
KHAIRUL NIZAM BIN ZAINUDDIN
FACULTY OF MANUFACTURING ENGINEERING
2009
1.2.1 UTeM Library (Pind.1/2008)
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA
JUDUL: Effect of Coating Condition on the Corrosion Properties of Mild Steel
Substrate
SESI PENGAJIAN: 2009 Semester 2
Saya Khairul Nizam Bin Zainuddin
mengaku membenarkan tesis (PSM/Sarjana/Doktor Falsafah) ini disimpan di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:
1. Tesis adalah hak milik Universiti Teknikal Malaysia Melaka dan penulis. 2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan
untuk tujuan pengajian sahaja dengan izin penulis. 3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran
antara institusi pengajian tinggi. 4. *Sila tandakan (√)
SULIT
√ TERHAD
TIDAK TERHAD
(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia yang termaktub di dalam
AKTA RAHSIA RASMI 1972)
(Mengandungi maklumat TERHAD yang telah ditentukan
oleh organisasi/badan di mana penyelidikan dijalankan)
Alamat Tetap:
No.1 Jalan Bukit Kempas 1/8,
Taman Bukit Kempas, 81200.
Johor Bahru, Johor
Tarikh: _______________________
Disahkan oleh:
* Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan
dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULIT atau TERHAD.
22 MEI 2009
FAKULTI KEJURUTERAAN PEMBUATAN
Rujukan Kami (Our Ref) : 21 Mei 2009
Rujukan Tuan (Your Ref):
Pustakawan Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) Taman Tasik Utama, Hang Tuah Jaya, Ayer Keroh, 75450, Melaka Saudara, PENGKELASAN LAPORAN PSM SEBAGAI SULIT/TERHAD - LAPORAN PSM SARJANA MUDA KEJURUTERAAN PEMBUATAN (BAHAN KEJURUTERAAN): KHAIRUL NIZAM BIN ZAINUDDIN TAJUK: EFFECT OF COATING CONDITION ON THE CORROSION PROPERTIES
OF MILD STEEL SUBSTRATE Sukacita dimaklumkan bahawa tesis yang tersebut di atas bertajuk “EFFECT OF COATING CONDITION ON THE CORROSION PROPERTIES OF MILD STEEL SUBSTRATE” mohon dikelaskan sebagai terhad untuk tempoh lima (5) tahun dari tarikh surat ini memandangkan ia mempunyai nilai dan potensi untuk dikomersialkan di masa hadapan. Sekian dimaklumkan. Terima kasih. “BERKHIDMAT UNTUK NEGARA KERANA ALLAH” Yang benar, …………………………………………………….. MOHD YUHAZRI BIN YAAKOB Pensyarah, Fakulti Kejuruteraan Pembuatan Universiti Teknikal Malaysia Melaka(UTeM) Karung berkunci 1200, Ayer Keroh, 75450, Melaka
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
Karung Berkunci 1200, Ayer Keroh, 75450 Melaka Tel : 06-233 2421, Faks : 06 233 2414
Email : [email protected]
i
DECLARATION
I hereby declare that this report entitled “EFFECT OF COATING CONDITION ON
THE CORROSION PROPERTIES OF MILD STEEL SUBSTRATE” is the result of
my own research except as cited in the references.
ii
APPROVAL
This report is submitted to the Faculty of Manufacturing Engineering of UTeM as a
partial fulfillment of the requirements for the degree of Bachelor of Manufacturing
Engineering (Engineering Materials) with Honours. The member of the supervisory
committee is as follow:
iii
ABSTRACT
Corrosion is a one problem that encountered in industry particularly against steel.
There is much prevention and solution that researches and engineers applied in order
to stop this problem from occurring in the future. In this project, the corrosion
prevention of tin electroplating is carried out on the mild steel with several specimens.
The implementation of this project is done with all the specimens are through surface
preparation for electroplating, electroplating process with various coating parameters,
determination of thickness coating, surface morphology examination before and after
specimens corroded by using scanning electron microscope and followed by
determination of corrosion rate based on Tafel extrapolation. The standard for
preparation of tin electroplating is according to the ASTM B545, surface preparation
referred to the ASTM B183 and corrosion rate measurement referred to the ASTM
G102. The parameters that involved are current density of coating, times and
constant of solution bath. As a result, the best parameter is determined which from
current density of 6 A/dm² and 10 minutes of coating time. This parameter also
capable to give a less of corrosion rate both condition of coating which are scratched
coating and unscratched coating. The lower of current density is promoting the
formation of tin whiskers and thin of coating but it gives a less of corrosion rate. The
higher of current density promotes formation of cracking and worst of corrosion rate.
iv
ABSTRAK
Kesan keadaan saduran terhadap sifat kakisan ke atas keluli lembut adalah tajuk bagi
projek sarjana muda di mana kajian ini dijalankan untuk mengetahui keadaan saduran
yang paling terbaik sekali berdasarkan pelbagai saduran parameter yang digunakan.
Dalam kajian ini, kaedah saduran elektrik menggunakan bahan timah digunakan
untuk menyadur ke atas keluli lembut. Proses yang dijalankan menggunakan
beberapa spesimen. Perlaksanaan projek ini dilakukan di mana semua specimen
melalui persediaan permukaan spesimen sebelum proses saduran elektrik, proses
saduran elektrik, penentuan ketebalan saduran yang telah dibuat ke atas spesimen
dengan menggunakan scanning electron microscope, pemerhatian mikrostruktur
pada permukaan spesimen sebelum dan selepas proses kakisan berlaku dan akhir
sekali spesimen-spesimen melalui proses penentuan kadar kakisan dengan
menggunakan persisian Gamry. Piawaian yang digunakan dalam kajian ini terdiri
daripada ASTM B545 untuk persediaan spesimen bagi proses saduran elektrik,
ASTM B183 untuk persediaan permukaan spesimen dan ASTM G102 bagi untuk
pengiraan kadar penentuan kakisan. Sebagai keputusan yang diperolehi, parameter
yang terbaik dapat ditentukan iaitu pada ketumpatan arus 6 A/dm² dan 10 minit masa
saduran. Pada parameter ini, ia berupaya untuk memberikan keseragaman saduran
pada permukaan timah, tiada pembentukan rerambut dan menunjukkan kadar
pengaratan yang kurang. Pada ketumpatan arus yang rendah, keputusan dan data
menunjukkan pembentukan rerambut, saduran yang nipis tetapi menunjukkan kadar
pengaratan yang kurang. Pada ketumpatan arus yang tinggi, saduran timah
memberikan keputusan rekahan pada permukaan timah dan data pengaratan pada
kadar yang teruk.
v
DEDICATION
To my beloved parents
Siti Zaleha Bt. Abdul Manaf
Zainuddin B. Karmani
vi
ACKNOWLEDGEMENT
First of all I am grateful to ALLAH S.W.T for blessing me in finishing my final year
project with success in achieving my objectives to complete this project. Secondly I
want to thank my family for giving morale support and encouragement in completing
my project and also throughout my study in UTeM as they are my inspiration to
success. I also would like to thank my supervisor Mr. Mohd Yuhazri Bin Yaakob
and Miss Siti Rahmah Binti Shamsuri for guiding and supervising my final year
project throughout this semester. They have been very helpful to me in finishing my
project and I appreciate every advice that they gave me in correcting my mistakes. I
apologize to both of my supervisor for any mistakes and things that I done wrong
while doing my project. I want to thank all my friends that have given me advice and
encouragement in completing my project. Thank you very much to all and May
ALLAH bless you.
vii
TABLE OF CONTENT
CHAPTER TOPIC PAGES
Declaration i
Approval ii
Abstract iii
Abstrak iv
Dedication v
Acknowledgement vi
Table of Content vii
List of Tables xi
List of Figures xii
List Abbreviations xiv
List of Symbols xv
1 INTRODUCTION 1
1.1 Background 1
1.2 Problem Statement 2
1.3 Objectives 3
1.4 Scopes 3
1.5 Rational of Research 3
1.6 Research Methodology 4
1.7 Thesis Frame 4
2 LITERATURE REVIEW 5
2.1 Introduction 5
2.2 Theory of Corrosion 6
2.3 Coating on Mild Steel 6
2.4 Theory of Electroplating Technique 8
2.4.1 Process Parameters 9
viii
2.4.2 Corrosive Environments 11
2.5 Tin Plating 12
2.5.1 Theory of Electroplating 13
2.6 Kinetic and Mechanic of Electrodeposition
Process 14
2.6.1 Basic Principles 14
2.6.2 Coating Materials 15
2.6.3 Electrodeposited of Tin Plating 16
2.6.4 Types of Electrolytes 17
2.6.5 Mild Steel Expose to NaCl 21
2.6.6 Influence of AC Source on
Corrosion of Mild Steel in NaCl 21
2.6.7 Influence of DC Source on
Corrosion of Mild Steel in NaCl 22
2.6.8 Surface Examination 23
2.7 Thermodynamic of Corrosion 24
2.8 Corrosion Rate Measurement 26
2.8.1 Tafel Extrapolation 27
2.9 Scanning Electron Microscope 28
2.9.1 Magnification 29
3 METHODOLOGY 30
3.1 Introduction 30
3.2 Methodology of Flow Chart 30
3.3 Specimens Preparation 32
3.3.1 Procedure for Specimens Preparation 32
3.4 Electroplating Process 34
3.4.1 Coating Parameters 35
3.4.1.1 Current Density 37
3.4.1.3 Time 37
3.4.1.5 Bath of Acid 37
3.5 Corrosion Rate Measurement 38
3.5.1 Procedure for Software Setup 38
3.5.2 Procedure for Potentiostat Setup 39
ix
3.6 Calculation Corrosion Rate Measurement 40
3.6.1 Corrosion Current Density 40
3.7 Surface Analysis 41
4 ANALYSIS AND DISCUSSION 43
4.1 Thickness Determination 43
4.2 Surface Analysis 47
4.3 Corrosion Rate Analysis 50
4.3.1 Uncoated Mild Steel 50
4.3.2 Unscratched Coating 51
4.3.3 Scratched Coating 52
4.3.4 Analysis Unscratched Coated Mild
Steel 54
4.3.5 Analysis Scratched Coated Mild
Steel 57
4.3.6 Analysis of surface coating after
Corroded 59
4.3.7 Effect pH value 59
4.3.8 Comparison between uncoated,
Unscratched coated
And scratched coating 64
5 CONCLUSION AND RECOMMENDATION 65
5.0 Conclusion 65
5.1 Recommendation 66
REFERENCES 67
APPENDICES
A Gantt chart
B Tafel Graph for Unscratched Coating
C Tafel Graph for Scratched Coating
x
LIST OF TABLES
NO TITLE PAGES
2.1 Electrode Potential of Engineering Metals 18
2.2 Composition and Operating Conditions for Alkaline (Stannate) 20
Tin Plating Electrolytes
2.3 Composition and Operating Conditions for Sulfate (acidic)
Tin Electrolyte 21
2.4 Composition and Operating Conditions for Flouborate Tin (acidic)
Plating Electrolyte 22
2.5 Recommended Thickness for Typical Applications of Tin Deposits
On Metal Substrate 23
2.6 Applied Source Current Density Values for Mild Steel in NaCl 25
3.1 Parameters for Specimens 37
4.1 Data for 10 min Coating With Variables Current Density 44
4.2 Data for 20 min Coating with Variables Current Density 45
4.3 Data for 20 min Coating with Variables Current Density 46
4.4 Surface Morphology for Various Tin Coating Parameters 48
4.5 Data for Uncoated Mild Steel 51
4.6 Data Corrosion Rate Measurement for Unscratched Coated Mild Steel 54
4.7 Data Corrosion Rate Measurement for Scratched Coated Mild Steel 57
4.8 Data Corrosion Rate Measurement for Specimens Exposed in NaOH 62
4.9 Data Corrosion Rate Measurement for Specimens Exposed in HCL 62
xi
LIST OF FIGURES
NO TITLE PAGES
1.1 Stages for PSM 1 4
2.1 Microstructure of Mild Steel 8
2.2 Phenomenon of Chemical Reaction 9
2.3 Schematic Diagram of Electroplating 10
2.4 Schematic Diagram of Plating Tank 12
2.5 Plating Bath 17
2.6 Micrograph of Mild Steel for AC Source 26
2.7 Micrograph of Mild Steel for DC Source 27
2.8 Tafel Extrapolation 30
3.1 Research Methodology of Flow Chart 35
3.2 Dimensions for Specimens 36
3.3 Specimens is Grinding with Several Grade of SiC Abrasive Paper 38
3.4 Specimens is Polishing by Using Silicon Carbide Polishing 38
3.5 Scanning Electron Microscope (SEM) 42
3.6 Euro Cell 45
4.1 Graph for Variables Current Density with 10 minutes Coating 44
4.2 Graph for Variables Current Density with 20 minutes Coating 45
4.3 Graph for Variables Current Density with 20 minutes Coating 46
4.4 Tin Whiskers Mechanism 47
4.5 Tafel Graph for Uncoated Mild Steel 50
4.6 Tafel Graph for Coated Mild Steel at 6 A/cm2 and 10 minutes 51
4.7 Tafel Graph for Scratched Coated Mild Steel at 6 A/cm2 and 10 minutes 53
4.8 Pitting Corrosion on Tin Surface 59
4.9 Tafel Graph for Scratch Coated Exposed in HCL 60
xii
4.10 Tafel Graph for Unscratched Coated Exposed in HCL 60
4.11 Tafel Graph for Scratch Coated Exposed in NaOH 61
4.12 Tafel Graph for Unscratched Coated Exposed in NaOH 61
xiii
LIST OF ABBREVIATIONS
NaCl - Natrium Chloride
Ohm - Measurements to Measure Resistance
µm - Micrometer
g/L - Gram per Liter
A/dm² - Ampere per Decimeter Square
AC - Alternating Current
DC - Direct Current
mpy - Mils per Year
UTeM - Universiti Teknikal Malaysia Melaka
ASTM - American Society for Testing and Materials
SEM - Scanning Electron Microscope
PVD - Physical Vapor Deposition
xiv
LIST OF SYMBOLS
α - Ferrite
Fe - Iron
O2 - Oxygen
H - Hydrogen
H2O - Water
Cl - Chloride
Ni - Níckel
OH - Hydroxide Molecule
Sn - Stannum
icorr - Corrosion Current Density
SnO2 - Stannum Oxide
1
CHAPTER 1
INTRODUCTION
1.1 Background
Corrosion engineering is the application of science and art to prevent or control
corrosion damage economically and safely. Corrosion is defined as the destruction
or deterioration of a material because of reaction with its environment. Most of the
corrosion prevention techniques are coating. This research is presented to identify
which coating conditions on the mild surfaces are suitable due the selected
environment as well as corrosion properties. According to the type of coating, the
tin-electroplating was chosen to coat the materials (Fontana, M.G., 1987).
Now a day, corrosion matter must be prevented to ensure all the materials
particularly made by metals are capable to extend the life span with approaches of
various environments. In the world of engineering, corrosion and coating have a
correlation. Typically, once the metals are fabricated and used for any application,
its must be followed by coating method in order to prevent any corrosion or
deterioration thus retain the mechanical behavior. According to the relation of work
in the industrial field, the applications of electroplating techniques are widely used
such as coating on the watch by using chromium electroplating (Fontana, M.G.,
1987).
This research is implementing to enhance the understanding of how the tin
electroplating is carried out. The thickness of coating is the most influences the
corrosion properties. For example, the steels or metals that will immerse at the salt
water needs undergo the extra protection in order to avoid the materials easy to
damage and corrode (Fontana, M.G., 1987).
2
1.2 Problem Statement
Metal furnishing is the name given to a wide range of process to carry out in order to
modify the surface properties of a metal, example by deposition of a layer of another
metal, alloy, composite, or by forming the oxide film. Currently, the metal steel
industry lay in desire to enhance the value of metal articles by improving their
appearance and in the same time not forgetting the mechanical properties of each
steel application. The trend now is towards surface treatment which will impart
corrosion resistance.
According to the previous research at several industries, pure tin plating can cause a
whisker mechanism on the plating. This is particularly in the electrical components
which widely used tin plating in order to inhibit or prevent the corrosion during its
application. In the HP (Hewlett Packard) products, tin plating is susceptible to the
well-known reliability problem of tin whiskers. Whiskers may form as thin filaments
of tin after plating and can cause electrical shorts and product failures. At this time,
there are several critical and unresolved questions regarding tin plating and tin
whiskers that need to be satisfactorily answered before all of HP can support the
transition to tin plating and begin broadly accepting tin-plated parts (Yip, W. C.,
2006).
In this regard, the plating process parameters and plating chemistries needed to
control the tin plating in a repeatable “no whiskers condition” is not understood
adequately by the plating industry. In order to make tin plating an industry-standard
solution, the plating process parameters and conditions required to eliminate
whiskering need to be widely understood. Thickness of tin plating is also affect tin
whisker growth. Though very thin tin plating retards whisker growth and in reality
very thin tin plating is not applied because tin plating with very thin thickness has
poor corrosion resistance and solderability parts (Yip, W. C., 2006).
This project is basically to do some surface treatment via tin electroplating to form an
optimum condition for the mild steel to sustain its properties. This process of
electroplating would be emphasize the process parameters in order to form a best
3
coating to prevent corrosion particularly in electrical components, automotive parts
such as fuel and brake line components, food beverage and aerospace industry.
1.3 Objectives
(a) Provide a tin coating on the mild steel substrate with various coating
condition by using electroplating method.
(b) Investigate the corrosion properties of mild steel with various coating
conditions once immersed in various corrosive environments.
1.4 Scopes
(a) Select an optimum coating conditions for obtaining corrosion
protection via tin plating.
(b) Improve corrosion resistance of mild steel plate via tin coating.
(c) Identify the best route for coating and fundamental analysis on
expected corrosion control technique.
(d) Compare the corrosion properties that occur on the tin coated mild
steel with various process parameters.
1.5 Rational of Research
In constructing something technology, it must followed by the impact or damage that
may occur. Thus, the project carried out have rational distinctive with a view to
provide ease in the future. Each material according to very element of iron is tending
to the nature of corroded and rust. Therefore, study is carried out with purpose to
provide information on the state best tin plating to prevent corrosion nature when it
use in solution NaCl. Its impact, this project will provide convenience to the future
generation on the state best tin plating when in use something application.
4
1.6 Research Methodology
The methodology chapter is the way of the project from the preparation of specimens
until carry out the testing. The experiment used 15 specimens from mild steel and
coated by tin. In this experiment, NaCl, HCL and NaOH act as the exposure
corrosive. The experiment is done by using the electroplating technique.
Electroplating technique is the process of using electrical current to reduce cations of
a desired material from a solution and coat a conductive object with a thin layer of
the material, such as a metal. The experiment is carried out with various coating
condition and each of specimen will observed to determine the best coating condition
that capable to inhibit corrosion in NaCl. All the specimens will carry out with Tafel
extrapolation to determine the corrosion penetration rate based on the linear
polarization.
1.7 Thesis Frame
This project is done with five main chapters which are introduction, literature review,
methodology, result and discussion. Chapter one briefly explained the objective,
scope, problem statement, rational of research, research methodology and chapter
arrangement. Chapter two is a literature review which consist the definition of
corrosion, theory of corrosion and electroplating, electroplating process and some of
the previous research for tin electroplating. Chapter three is mentioned about the
way of project being done whereas stated the method that will be used from
beginning process until final process. The chapter also included the data of coating
parameters. In chapter four, all the gathered result based on coating and corrosion
properties is attached and also analyzed the data itself. Here, the data of thickness
coating, surface examination and corrosion rate measurement is determined. In
chapter five, it explained the conclusion for overall of this research and
recommendation for the improvement in the future for this research.
5
CHAPTER 2
LITERATURE REVIEW
2.1 Introduction
Corrosion is a destruction or deterioration of a material because of a chemical attack
with its environment. The corrosion behavior represents a tremendous economic loss.
The most techniques to prevent the corrosion are by coating or plating on the surface
of materials (Fontana, M.G., 1987).
Mild steel is a type of steel that contains about 0.1% of weight carbon. Mild steel
also called high carbon steel and the microstructure has two major constituents,
which are pearlite and ferrite. Figure 2.1 mentioned that the light colored region of
the microstructure is the ferrite. The dark regions are the pearlite. It is made up from
a fine mixture of ferrite and iron carbide. Pearlite has a lamellar (plate-like) structure
consisting of alternating plates of α ferrite and cementite (Callister, W.D., 2005).
Ferrite or alpha iron (α-Fe) is a materials science term for iron or a solid solution
with iron as the main constituent with a body centered cubic crystal structure (Henkel,
D. et al., 2002). It is the component which gives steel and cast iron their magnetic
properties. The properties of the steel depend upon the microstructure. Decreasing
the size of the grains and decreasing the amount of pearlite improves the strength,
ductility and the toughness of the steel (Anonymous, 2000).
6
Figure 2.1: Microstructure of Mild Steel (Anonymous, 2000).
2.2 Theory of Corrosion
Most corrosion phenomena are of electrochemical nature and consist of at least two
reactions on the surface of the corroding metal. One of the reactions is the oxidation
also referred to as the anodic partial reaction. The other is a reduction reaction is
referred to as the cathodic partial reaction. Figure 2.2 show the phenomenon of
chemical reaction for metal in electrolytic. For example, the corrosion of iron to
form rust proceeds according to the overall reaction (2.1, 2.2 2.3) (Tullmin, M.,
2000). The reaction is initially formed which the Fe will release 2e-. The electron
which released will combine with oxygen and hydrogen to form hydroxide molecule
(4OH-) (Tullmin, M., 2000).
This reaction includes the dissolution of iron, the reduction of oxygen and formation
of rust:
Fe Fe2+
+ 2e-(anodic) (2.1)
2H2O + O2 + 4e- 4OH
- (cathodic) (2.2)
2 Fe+ 2H2O +O2 2Fe
2+ + 4(OH)
- (2.3)
Ferrite
Pearlite
