chapter i introduction - shodhgangashodhganga.inflibnet.ac.in/bitstream/10603/33769/1/...high...

Chapter I

Introduction

Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.

1

CHAPTER I

INTRODUCTION

I.1. Definition of corrosion

Most of the metals, except noble metals such as Au, Pt, etc, exist in nature in

combined form as their oxides, carbonates, hydroxyl carbonates, sulphides, chlorides

and silicates. These are reduced to their metallic states from their ores through

metallurgical processes, which require considerable amount of energy. Thus an

isolated pure metal attained higher energy state than their ores with lower energy

state. When metals are exposed to environment, the surface begins to decay and

becomes ores, through chemical or electrochemical reaction with the environment to

attain the stable lower energy state. Hence corrosion is a process exactly reverse of

extraction of metals from their ores. [1-3]

The term corrosion (Latin: Corrosio – fretting) is defined as the spontaneous

gradual destruction or deterioration of metals by chemical or electrochemical reaction

with its environment. Generally the term corrosion refers to metallic corrosion.

Corrosion is a costly and rigorous material science problem to the society. It degrades

the useful properties of metals like appearance, strength, rigidity and thermodynamic

instability, etc. It causes severe damages in an industrial sector such as cooling water

system, petroleum refineries and high pressure boilers, etc. In practice, it is extremely

dangerous process, which is often hard to identify deterioration well in advance.

The most familiar example of metallic corrosion is rusting of iron, when exposed to

the atmospheric conditions. As a result a layer of reddish scale and powder of oxide

(Fe3O4) is formed, and the iron becomes weak. Another common example is the

formation of green film of basic carbonate [CuCO3 + Cu(OH)2] on the surface of

copper, when exposed to moist-air containing carbon dioxide. Materials other than

metals, such as ceramics, wood and plastics, etc may also undergo corrosion. Though

corrosion is an adverse process, it has few useful applications such as electrochemical

milling, anodizing of aluminium, sacrificial anodic protection and batteries, etc. [4-6].


2

I.2. Historical lessons on corrosion

In 1788, Austin noticed that water, initially neutral, which tends to become

alkaline when it reacts with iron. It was believed that the corrosion was an

electrochemical phenomenon by Thenard and Compartriot in the years 1819 and 1830

respectively. Dela Rive [7] certified the fact that acid attacks impure zinc more

quickly than the relatively pure varieties. The substantiation of the indispensable

association between chemical action and the generation of electric currents has been

studied in the period of 1834 and 1840 [8]. The protection of copper metal in sea

water using either iron or zinc metal has been proposed by sir. Humphrey Davy in

1847. In 1847, Richard Adie [9] established that difference in oxygen concentration in

a flowing stream could give rise to a flow of current between two metals, iron or zinc.

Trends in corrosion study changed rapidly over the years. Around 1950, an

electrochemical study provides extensive interest to study the field of corrosion

[10-12]. In 1970’s, corrosion research was intense in the mechanistic aspects of

various types of corrosion problems [13-19]. In recent years, the corrosion research

has been divided into a number of newer fields in order to make in-depth study.

The optical and surface analytical techniques play an important role in the

understanding of the nature and influence of surface oxides on corrosion of metals

and alloys. The thickness, structure and composition of the thin film formed on the

metal surface have been characterized by the optical and surface analytical

techniques. An electronic device such as computers and microprocessors finds

extensive applications the field of corrosion data analysis [20-22]. The ultimate goal

of all the above mentioned investigations is to reduce corrosion failures.

I.3. Cost of corrosion

According to the National Association of Corrosion Engineers (NACE) –

International Gateway India Section (NIGIS), the cost of corrosion in India alone,

estimated around Rs. 80,000 crore per annum which is may be 6.1% GDP (Gross

Domestic Product) of the nation [23]. It is very essential to reduce this unusual loss in

economy. Hence the industrial sectors must take corrosion prevention action, from the

beginning stage of the issue. The schematic Fig. I.1 shows the classification of

economic losses due to corrosion [24].


3

Schematic Fig. I.1. Cost of corrosion

I.4. Classification of corrosion

Corrosion of metals can be mainly classified into dry and wet corrosion

depending upon the nature of the corrosive environment [25-27].

I.4.1. Dry corrosion

It is also called chemical corrosion. It involves the direct chemical action of

environment / atmospheric gases such as oxygen, halogen, hydrogen sulphide, sulphur

dioxide, nitrogen or anhydrous inorganic liquid with metal surfaces in immediate

proximity. High temperature oxidation of metals and tarnishing of metals such as Cu,

Ag, etc, fall in this class. After the propagation of corrosion, it is also considered as an

electrochemical process with inward diffusion of oxygen and outward diffusion of

metal ions, through the metal oxide layer and electromotive force at the metal oxide

interface is considered as the driving force.

I.4.2. Wet corrosion

It is also called electrochemical corrosion. It occurs when a metal is in contact

with a conducting electrolytic solution or when two dissimilar metals / alloys are


4

either immersed or dipped partially in a solution. The electrochemical reaction occurs

due to the existence of separate ‘anodic’ and ‘cathodic’ areas, between which current

flows through the conducting electrolytic solution. At anodic area, oxidation reaction

takes place, so anodic metal is destroyed by either dissolution in the combined form.

I.5. Types of corrosion

Corrosion of metals exists in various types. The type of corrosion is very

essential in order to identify the cause of corrosion and for the selection of most

efficient method to control the corrosion process. In most corrosion failure analysis, it

is necessary to know the type of corrosion, which has been responsible for the failure.

The different types of corrosion [24, 27] are shown in schematic Fig. I.2.

Schematic Fig. I.2. Types of corrosion


5

I.6. Factors influencing corrosion

The rate and extent of corrosion depends on the nature of the metal and the

nature of the corroding environment [24-27].

Factors associated with the nature of the metal are as follow:

Purity of the metal.

Position in the galvanic series.

Relative areas of the anodic and cathodic parts.

Physical state of the metal.

Nature of the surface film.

Hydrogen over voltage.

Solubility of the corrosion products.

Volatility of the corrosion products.

Factors associated with the nature of the corroding environment are as follow:

Temperature.

pH.

Presence of impurities in atmosphere.

Presence of suspended particles in atmosphere.

Humidity of air.

Concentration of oxygen and formation of oxygen concentration cells.

Conductivity.

Presence or absence of an inhibitor.

Flow velocity of process stream.

Specific nature of the cation and anion present.

I.7. Theories of corrosion

In the beginning of 19th century, it was established that corrosion of metals is

very aggressive in an aqueous environment. Whitney [28] gave the most acceptable

electrochemical theory. The other theories such as acid theory, chemical attack theory,

colloidal theory and biological theory were proved to form a part of electrochemical

theory [29-31].


6

I.7.1. Electrochemical theory

According to this theory the heterogeneity on the metal surface causes the

formation of galvanic cell, which is a basic requirement for corrosion of metals.

This suggests that ultra-pure metals are non-corrodible. There is no particular separate

anodic and cathodic area required for the corrosion to occur. The oxidation and

reduction reactions occur to a larger extent independent of each other on anodic and

cathodic sites. These sites occur indiscriminately over the metal surface and they have

a tendency to shift around on the entire surface thereby causing uniform corrosion.

I.7.2. Electrochemical process

The thermodynamic instability of metals, effects the conversion of metals into

their ores which thermodynamically stable with lower energy. In metallurgy, the

metallic iron is extracted from its chief ore haematite (Fe2O3) which is in low energy

state (Eqn.I.1)

Fe2O3 + 3 C → 4 Fe + 3 CO2 ↑ …………I.1

When steel is exposed to the environment containing moisture, it undergoes corrosion

by reverses to its combined form of thermodynamically stable lower energy state

(Eqn. I.2)

4 Fe + 3 O2 + 2 H2O → 2 Fe2O3 . H2O ………….I.2

Rust

Rusting is an electrochemical process. Microgalvanic cells [32, 33] with local anodes

and cathodes are formed on the metal surface due to heterogeneities in the

composition of metal during the metallurgical process. The heterogeneities of the

metal surface [34, 35] are due to surface defects, grain size of the particles, stress,

compatibility, orientation of the crystals and differential aeration, etc. The grain

boundaries generate centres with different potentials and develop cathodic and anodic

areas as shown in Fig. I.1.


7

Fig.I.1. Steel surface consists of anodic and cathodic areas.

The anodic reaction involves in dissolution of metal as corresponding metallic

ions with the liberation of free electrons (Eqn. I.3), where as the cathodic reaction

consumes electrons either by evolution of hydrogen or absorption of oxygen, based on

the nature of the corrosive environment.

Fe → Fe2+ + 2 e- …………I.3

Evolution of hydrogen-type corrosion usually occurs in acidic environments.

The electrons liberated from the anode move towards cathode, where H+ ion of the

acidic solution are eliminated as hydrogen gas (Eqn. I.4).

2 H+ + 2 e- → H2 …………I.4

This type of corrosion causes displacement of H+ ion from the acidic solution by

metal ions.

Absorption of oxygen-type corrosion occurs in neutral aqueous environment

like NaCl solution in the presence of atmospheric oxygen. The surface of the iron

metal is usually coated with a thin film of iron oxide. However, if this iron oxide film

develops some cracks, anodic areas are created on the metal surface, while the metal

parts act as cathodes. It follows that the anodic areas are small surface parts, while

nearly the rest of the surface of the metal forms large cathodes. The electrons

liberated from the anodic to cathodic areas, through metal, where electrons are

intercepted by the dissolved oxygen (Eqn. I.5).


8

2 H2O + O2 + 4 e- → 4 OH- ………….I.5

Thus it is clear that the formation of anodic and cathodic areas, electrical

contact between the cathodic and anodic part to enable the conduction of electrons,

and an electrolyte through which the ions can diffuse are the essential requirements of

electrochemical corrosion.

I.8. Mechanisms of corrosion process

In most of the corrosion processes, the anodic reaction is always the metal

dissolution and the reduction reaction is either hydrogen evolution or oxygen

absorption. The metals can be categorized into three types based on the differences in

the mechanism of hydrogen evolution, exchange current densities and Tafel slope

values. The metals are with low, intermediate and high over voltages. It is not always

easy to predict corrosion rate of a metal on the basis of hydrogen evolution method

where as little is known about the oxygen absorption mechanism. This reaction occurs

in many steps and also on the oxide covered surface which a poor electron carrier. In

corrosion processes, the anodic reaction is equally complicated and involves the

migration of metal ions from the metal phase to the solution phase where salvation of

ions takes place through several steps. Bockris et al. studied the dissolution and

deposition of iron in various aqueous environments in detail [36].

The five possible mechanisms anticipated for the dissolution and deposition of

iron by Bockris et al. are given as follows:

Mechanism – 1

Fe + OH- + FeOH ↔ (FeOH)2 + e-

(FeOH)2 → 2 FeOH

FeOH ↔ FeOH+ + e-

FeOH+ ↔ Fe2+ + OH-

Mechanism – 2

Fe + H2O ↔ FeOH + H+ + e-


9

FeOH ↔ FeOH+ + e-

FeOH+ + Fe → Fe2OH+

Fe2OH+ → Fe2+

+ FeOH + e-

FeOH → Fe2+ + H2O

+ e-

Mechanism – 3

Fe + OH- → Fe(OH)+ + 2 e-

Fe(OH)+ ↔ Fe2+ + OH-

Mechanism – 4

Fe + OH- ↔ FeOH + e-

FeOH + OH- → FeO + H2O

+ e-

FeO + OH- ↔ HFeO2-

HFeO2- + H2O ↔ Fe(OH)2 + OH-

Fe(OH)2 ↔ Fe2+ + 2 e-

Mechanism – 5

Fe + H2O ↔ FeOH + H+ + e-

FeOH → FeOH+ + e-

FeOH+ + H+ → Fe2+ + H2O

Kabanov [37] and Frumkin [38] studied the first indication of OH- ions are

taking part in metal dissolution although these are present in very small quantity

acidic environments.


10

I.9. Expression for corrosion rate

The corrosion rate (CR) can be expressed in different ways are given as

follows:

ipy – inches per year

mpy – mils per year

μm/y – micrometre per year

mdd – milligram per square decimetre per day

mm/y – millimetre per year

Usually corrosion rates are expressed in mpy and mmpy. The corrosion rates in mpy

and mmpy scales can be calculated from the following expressions (Eqn. I.6 and Eqn.

I.7)

mpy = 534 W / DAT…………….I.6

mmpy = 13.56 W / DAT …………I.7

Where W – Weight loss in grams

A – Area of the specimen in square inches

D – Density of the specimen in gram / cm3 and

T – Immersion period in hours.

If the area is calculated in square centimetres then the expression for mpy and mmpy

are given (Eqn. I.8 and Eqn. I.9) as follows:

mpy = 82.75 W / DAT ……………I.8

mmpy = 87.6 / DAT……………I.9

Where W – Weight loss in milligrams

A – Area of the specimen in square centimetre

D – Density of the specimen; 7.87 gram / cm3 and

T – Immersion period in hours.

There is a monograph available for the calculation of corrosion rate [39].


11

I.10. Methods of corrosion prevention and control

Corrosion is a major industrial problem. It is a natural phenomenon that

cannot be avoided completely, but it can be controlled and prevented. It destructs the

materials gradually by means of chemical or electrochemical reaction. It is a

spontaneous, silent and slow process. So that corrosion mitigation and control

methods shall be properly selected to meet out the specific environment and

operational condition [24, 40, 41]. The various methods employed for corrosion

prevention and control is shown in schematic Fig. I.3.

Schematic Fig. I.3. Corrosion prevention and control methods


12

I.11. Corrosion control by inhibitors and their inhibition action

Inhibition is the most essential area in corrosion science, which has been

extensively studied. Several books [24, 25, 27, 40, 42-49] have been published on

corrosion inhibition of metals and alloys in various aqueous environments. The

University of Ferrara, Italy exclusively conducts a symposium on corrosion inhibition

of metals and alloys once in five years. In India, CECRI organizing various activities

such as International symposium on Advances in Electrochemical Science and

Technology, National Convention of Electrochemists (NCE) and National Congress

on corrosion control (NCC), etc every year on various topics for the development of

corrosion science. The Electrochemical Society of India (ECSI) conducts a national

symposium on Electrochemical Science and Technology every year in various topics

of corrosion science and engineering. Trabanelli and Carassiti [47] have reviewed the

phenomenon of inhibitors. The literature review revealed that various corrosion

inhibitors have been developed and applied to eliminate the corrosion [50].

I.11.1. Corrosion inhibitor

A corrosion inhibitor is a chemical substance that decreases the corrosion rate

of metals and alloys efficiently when added in small concentrations to an aqueous

corrosive environment. The inhibition can be caused by either adsorption or phase

layers on the metal surface [51]. Usually the inhibitors assembling near the phase

boundary system and hence the inhibition takes place. In a sense, an inhibitor can be

considered as a retarding catalyst. From a chemical kinetic point of view inhibition

[52, 53] is defined as the decrease in the rate of one or more partial steps of the entire

electrode reaction such as proton or electron transfer, charge or discharge of the

double layer, charge transfer, mass transports, partial chemical reactions and reaction

with transfer of metal ions and dissolution of metal crystals.

I.11.2. Types of corrosion inhibitors

There are numerous inhibitor types and compositions. Most inhibitors have

been developed by empirical experimentation. It is essential to classify the inhibitors

based on their mechanism, composition and applications.

Putilova et al. classified corrosion inhibitors into three types as follows:


13

Type 1: Those, which form a protective film on the metal surface [54, 55].

Type 2: Those, which reduce the aggressiveness of the corrosive environment.

Type 3: Those, which will form a protective film on the metal surface as well as

reducing the aggressiveness of the corrosive environment.

Based on the corrosive environment, inhibitors can be classified into three

types. They are acid inhibitors, neutral and alkaline inhibitors and vapour phase

inhibitors [56, 57]. Based on the practical applications, inhibitors classified into sever

types those used in refrigeration system, oil refineries, cooling water system and in

radiators [58].

Based on the inhibition mechanism inhibitors classified as follows:

Barrier layer formers:

It includes oxidizers, adsorbed layer formers and conversion layer formers.

These inhibitors are very effective in reducing the rate of both anodic and cathodic

reaction except the oxidizing inhibitors, because which shift the corrosion potentials

of the metal to more positive value where a stable oxide or hydroxide layer is formed

which will be more stable [59, 60].

Neutralizing inhibitors:

These inhibitors remove the H+ ions from the corrosive environment and

hence the aggressiveness of the corrosive environment is reduced [61]. They find

applications in petroleum refineries, hydraulic liquid, boiler treatment and condenser,

etc.

Scavengers:

These inhibitors used to remove corrosive reagents from solution. Examples of

this type of inhibitor are sodium sulphite and hydrazine, which remove dissolved

oxygen from aqueous solution.

Miscellaneous:

These inhibitors include materials such as scale prevention inhibitors and

microbiological growth inhibitors, which reduce rate of corrosion by interference with


14

other chemical reactions. The potentiodynamic polarization data is very much helpful

to classify the inhibitors into anodic [41, 62, 63], cathodic [64, 65] and mixed type

[66, 67]. Fig.I.2. illustrates the significant terms for a freely corroding metal. The line

EaD and EcD represents the anodic and cathodic reactions respectively. The point ‘D’

at which the anodic and cathodic lines intersects each other which results open circuit

corrosion potential (Ecorr) of the metal. This indicates the magnitude of corrosion

current subscript. Fig. I.3. illustrates [24] that the relation of metallic corrosion (D),

protection (F and G) and inhibition (P). Generally the immersed metal may corroding

by reaction under anodic control (EaF) using anodic type inhibitors [62], cathodic

control (EcG) using cathodic type inhibitors [64] and mixed type [66] control (Ea –

EcP) where the inhibitor controls both anodic and cathodic reactions. It very clear

those inhibitors, which control both the reactions, are more effective. It is found that

both anodic and cathodic type inhibitors reduce the corrosion current (anodic: ∆i1,

cathodic: ∆i2) and the mixed type inhibitor reduces the corrosion current more

effectively (∆i3).

Anodic and cathodic inhibitions result greater shifts in anodic and cathodic

Tafel slopes respectively. But in the case of mixed type inhibitors both anodic and

cathodic slopes are shifted to an equal extent or there is not much change in the Tafel

slopes. The anodic [62] and cathodic [64] inhibitors shift the corrosion potential

towards anodic and cathodic sides respectively where as in mixed type inhibitor both

shifts will be observed [67].


15

Fig. I.2. Polarization curve for significant terms for freely corroding metal.

Fig. I.3. Polarization curve relating metallic corrosion, protection and inhibition.


16

I.12. Theories of corrosion inhibition

There were so many national and international conferences and symposiums

have been conducted exclusively on corrosion inhibitors for the searching of

innovation, development and novel ideas of new cost-effective, eco-friendly and high

efficient corrosion inhibitors [40, 68-70]. The mechanism and action of inhibitors in

various corrosive environments such as acidic, alkaline and neutral, etc has been

explained on the basis of adsorption and protective film formation. Especially organic

inhibitors such as carboxylates and amides show very good corrosion inhibition of

metals in contact with aqueous environment. In addition to this, they are

environmentally safe, as they have low toxicities and are readily biodegradable.

The mechanism and action of corrosion inhibitors have been explained by different

theories.

I.12.1. Adsorption theory

Machu [71] puts forward the adsorption theory which predicts the formation

of a porous thin layer of inhibitive molecules with high electrical resistance.

Uhlig [72] investigated that the inhibitor molecules get adsorbed at the surface of the

metal and followed by blocking the active sites and influence the potential of the

metal by virtue of their net charge.

Riggs [73] confirmed that the organic inhibitors forms a very effective

protective layer due to the presence of hetero atoms such as nitrogen, oxygen, sulphur

and phosphorus, etc and the adsorption depends on the nature of metal, environment

and the electrochemical potential of the metal-solution interface. Further the

adsorption is classified into three types as, Π bond orbital adsorption, electrostatic

adsorption and chemical adsorption.

The various studies on corrosion inhibition reflect the relationship between the

characteristics of the electronic interaction at the metal-solution interface and the

structure of the inhibitor molecules in detail [74]. It has been reported that several

carboxylates such as ethylenediaminetetraacetate [75], sodium salicylate [76], sodium

cinnamate [77], anthranilate [78], adipate [79], citrate [80], succinate [81], tartrate

[82] and oxalate [83] have been used as inhibitors. It was also found that amides as an

inhibitor forming a protective layer on metal surface by strong adsorption.


17

I.12.2. Hydrogen over potential theory

This theory explains the action of acid inhibitors. It was believed that

inhibitors increase the hydrogen over potential, which cause increase in cathodic

polarization [84]. Zhu Yan et al. have pointed out that amides are adsorbed on the

anodic and cathodic regions on the metal surface [85]. The organic inhibitors shift the

corrosion potential of the metal in cathodic [64] and anodic [62] sides, which

indicates that their action on cathodic and anodic sites respectively. This theory fails

to explain the inhibitive action of all types of systems.

I.12.3. Protective film formation theory

Evans [86] who considered the “Father of corrosion science” explained the

film formation by the inhibitor molecules over metal surface immersed in neutral and

alkaline environment and he pointed out the formation of insoluble film which

inhibits corrosion extensively. Putilova et al. [40] have identified that the corrosion

inhibition of metals in acidic environment due to formation of a thin layer of insoluble

or slightly soluble corrosion product on the metal surface.

I.12.4. Electrochemical polarization theory

Stern [87] explained the action of passivating inhibitors in various corrosive

environments and suggested that the inhibitors such as chromate get reduced at the

cathodic sites and increase the electrode potential to the noble direction which results

passivation. It has been reported that a very small quantity of the total corrosion

current be associated with cathodic reduction of passivating inhibitors [40].

I.13. Methods of evaluation of corrosion

The methods of evaluation of corrosion include gas volumetric study [88],

weight loss study [63, 90, 91], electrochemical technique such as polarization and AC

impedance spectra [63, 66, 89], determination of surface coverage [64], Fourier

Transform Infrared spectroscopy [90-92], surface characterization studies such as

scanning electron microscopy (SEM) [93-95] and atomic force microscopy (AFM)

[96-105] and biocidal study [106-109].


18

I.13.1. Gas volumetric study

In gas volumetric study the corrosion of metals and alloys in a non-oxidizing

acid environment in the presence of inhibitors can be evaluated by finding the volume

of hydrogen gas released in the presence and absence of additives. The corrosion rate

(CR) obtained from this study is not very accurate due to the appreciable

decomposition reaction of inhibitors. Usually the ability of the inhibitor expressed in

percentage inhibition efficiency (IE) which can be obtained from the formula (Eqn.

I.10).

I E % = (Uninhibited CR – Inhibited CR) x 100 / Uninhibited CR ……..I.10

I.13.2. Weight loss study

The weight loss can be estimated by the immersion of identical specimens for

a constant immersion period and temperature the corrosive environment chosen for

the investigation. The IE is calculated by using the formula (Eqn. I.11).

I E % = [(Wo – W1) / Wo] x 100 ………I.11

Where Wo and W1 are weight loss in the absence and presence of inhibitor

respectively.

I.13.3. Polarization method

This method is widely used for the testing of corrosion inhibitors. It involves

with the estimation of corrosion current during the electrochemical process in the

presence and absence of the inhibitor. The value of corrosion current (Icorr) can be

obtained by intersection of the extrapolated anodic and cathodic Tafel lines using

potentiodynamic method and the IE is calculated from Eqn. I.12.

I E % = [(Icorr – I*corr) / Icorr] x 100 ………I.12

Where Icorr and I*corr are corrosion current in the absence and presence of the

inhibitor.

The IE may also be calculated from the polarization resistance (Eqn. I.13) and

impedance techniques (Eqn. I.14)


19

I E % = [{(1 / Rp*) – (1 / Rp) } / (1 / Rp*)] x 100 ………I.13

Where Rp* and Rp are the polarization resistance in the absence and presence

of the inhibitor respectively.

I E % = [{(1 / Rt*) – (1 / Rt) } / (1 / Rt*)] x 100 ………I.14

Where Rt* and Rt are the charge transfer resistance in the absence and

presence of the inhibitor respectively.

The linear polarization results should always be compared with weight loss

study or other corrosion rate measurements to ensure the correctness of the technique

and its fitness for a particular environment.

I.13.4. Determination of surface coverage

The degree of surface coverage can be calculated using polarization study

using the following relationship (Eqn. I.15).

θ = [1 – (i / io)] ………….…I.15

Where i and io are the corrosion current in the presence and absence of the

inhibitor respectively.

The constancy of slopes of the polarization curve with increasing

concentration of inhibitor is a necessary condition for the calculation of θ, i and io.

The surface coverage values can be calculated from the charge transfer resistance in

the absence and presence of inhibitor (Eqn. I.16).

θ = 1 – [(1 / Rt) / (1 / Rt*)]….………………. I.16

Where Rt* and Rt are the charge transfer resistance in the absence and

presence of inhibitor.


20

I.13.5. Spectroscopic technique

The ultra-violet (UV) [110] and infrared (IR) spectroscopic techniques are

very much useful for the understanding of arrangement of inhibitor molecules on the

metal surface. The IR study interprets the extent of adsorption and the orientation of

inhibitor molecules on the metal surface. The UV spectroscopy is highly useful in the

determination of amount of inhibitors adsorbed over a metal surface. But the same can

be determined exactly by a new technique, reflection spectra. Raman spectroscopy

[111], Auger electron spectroscopy (AES) [112], X-ray diffraction spectroscopy

(XRD) [113], X-ray photoelectron spectroscopy (XPS) [114], Mossbauer

spectroscopy [115], nuclear magnetic resonance (NMR) [116] and fluorescence

spectroscopy [109] are the other techniques to study the influence of corrosion

inhibitors.

I.14. Surface characterization study

The scanning electron microscopy (SEM) provides 2D pictorial representation

of the metal surface. It is very much useful to understand the nature of the protective

film formed on the metal surface in the absence and presence of the inhibitor and to

know the extent of corrosion inhibition.

The atomic force microscopy (AFM) provides 3D images of the metal surface.

It gives a statistical roughness parameters such as average roughness, root-mean-

square roughness and peak-to-valley heights in nano scales, which are very much

helpful to understand the extent of corrosion inhibition.

I.15. Biocidal study

Biocides are used in controlling microbial corrosion of metals and alloys in an

aqueous medium through micelle formation. Biocide such as CTAB and SDS finds

extensive applications in corrosion control of metals in high chloride medium.


References


21

REFERENCES

1. D. Pletcher and F.C. Walsh, “Industrial Electrochemistry”, Chapman and

Hall (1993).

2. L.L. Shreeir, R.A. Jarman and G.T. Burstein, “Corrosion and Corrosion

control”, Vol. I, II, Butterworth-Heinemann, London (1976).

3. R. Winston Revie, “Uhlig’s Corrosion Hand Book”, 2nd Edition, John

Wiley & Sons, INC (2000).

4. J.O’ M. Bockris and A.K.N. Reddy, “Modern Electrochemistry”, Plenum

press, New York, 2 (1977) 1267.

5. D.E. Clark and B.K. Zoitos, “Corrosion of Glass, Ceramics and

Superconductors”, William Andrew Publishing, (1992).

6. H.H. Uhlig, “Corrosion & Corrosion control”, John Wiley & sons (1965).

7. Dela Rive, Ann. Chemistry and Physics, 43 (1830) 425.

8. “Faraday’s Diary”, I-VII, 1820-1822, London-G. Bell & Sons, 1932-

1936.

9. Richard Adie, Philosophical Magazine, 31 (1847) 351.

10. M. Stern and A.L. Geary, J. Electrochem. Soc., 104 (1957) 56.

11. M. Stern, Corrosion, 14 (1958) 440.

12. M. Stern and E.D. Wisert, Proceeding of ASTM, 59 (1959) 280.

13. L. Gaiser and K.E. Heusier, Electrochimica Acta, 15 (1970) 161.

14. K.E. Heusler and L. Gaiser, J. Electrochem. Soc., 117 (1970) 762.

15. P. Robert, Frankenthal, Japan Seminar, March 10-12 (1975) 10.

16. W.J. Lorenz, F. Hilbert, Y. Miyoshi and G. Eichkon, Proc. 5th ICMC,

Tokyo, Japan, May (1972) 74.

17. J.A. Thuiller, Materials Performance, 15 (1976) 9.

18. J. Blackburn, Materials Performance, 16 (1977) 24.

19. R.W. Revie, B.G. Baker and J.O’ M. Bockris, 6th ICMC, Sydney,

Australia, December 3-9 (1975) 1.

20. M.W. Kendig, E.M. Meyer, G. Lindberg and F. Mansfeld, Corr. Sci.,

23 (1983) 1007.

21. G. Rose, Anti-Corr. Meth. and Mater., 28 (1981) 4.

22. R.A. Adey, S.M. Niku and C.A. Brebbia, Ocean Research, 8 (1986) 209.


22

23. S. Maruthamuthu, P. Subramanian and N. Palaniswamy, Proc. CORCON-

2010, Goa, India, September (2010) 21.

24. R. Narayan, “An Introduction to Metallic Corrosion and Its Prevention”,

Oxford Publishing Company, New Delhi (1990).

25. H.H. Uhlig and R. Winston, “Corrosion and Corrosion control”, John

Wiley & Sons, (1985).

26. M. Yasmashita, H. Konishi, T. Kozakura, J. Mizuki and H. Uchida, Corr.

Sci., 47 (2000) 2492.

27. M.G. Fontana, “Corrosion Engineering”, 3rd Edition, Tata McGraw Hill

Education Private Limited, New Delhi (2005) 45.

28. W.R. Whitney, J. Am. Chem. Soc., 25 (1903) 395.

29. W.H. Walker, M. Cadehralm & L.N. Bent, J. Am.Chem. Soc., 29 (1907)

1251.

30. R. Tremont, H. Dejesuscardona, J. Garciaorozco, R.J. Castro and

C.R. Carbrera, J. Appl. Electrochem., 30 (2000) 737.

31. M. Elazhar, M. Traisnel, B. Meroari, L. Gengembre, F. Bentiss and

M. Lagrenee, Appl. Surface Sci., 185 (2002) 197.

32. P. Atkins and De Paula, Physical Chem., 8th Edn, Oxford Univ. Press,

(2006).

33. K.A. Chandler and D.A. Bayliss, “Protection of Steel Structure”, Elsevier

Applied Science Publishers ltd., London (1951).

34. M. Boudart, J. Am. Chem. Soc., 74 (1952) 3556.

35. Victor E. Ostrovskii, Industrial Engg. Che. Res., 43 (2004) 3113.

36. J.O’ M. Bockris and A.K.N. Reddy, “Modern Electrochemistry”, Plenum

Publishers, 2 (1970) 1091.

37. Kabanov, Disc., Faraday Soc., 9 (1947) 259.

38. A.N. Frumkin, “Kinetics of Electrode Processes”, (1940).

39. W.A. Szymanski, “Monographs for Corrosion Rate Calculations”, Corr.,

12 (1956) 21.

40. I.N. Putilova, S.A. Balezin and V.P. Barannik, “Metallic Corrosion

Inhibitors”, G. Ryback and E. Bishap, (Edn.) Permgamon Press (1960) 2.

41. S.A. Kanimozhi and S. Rajendran, Int. J. Electrochem. Sci., 4 (2009) 353.

42. G. Wranglen, “An Introduction to corrosion and protection of metals”,

Chapman & Hall, New York (1985).


23

43. J.O’ M. Bockris, A.K.N. Reddy and M. Gamba-Aldeco, “Modern

Electrochemistry”, Plenum Publishers, New York, 2 (2000).

44. S.H. Avner, “Introduction to Physical Metallurgy”, McGraw-Hill

Publishing Company, New York (2000).

45. J.J. Bergman, “Corrosion Inhibitors”, Macmillan, New York (1963).

46. D.A. Fridrikhsberg, “A course in Colloid chemistry”, Mir Publishers,

Moscow (1986).

47. G. Trabanelli and V. Carassiti, “Advances in Corrosion Science and

Technology”, Plenum Press, New York, (1970) 147.

48. I.L. Rosenfeld, “Corrosion Inhibitors”, McGraw-Hill Int. London (1980).

49. V.A. Goldade, “Plastics for Corrosion Inhibition”, Elsevier Publishers,

London (2005).

50. A. Raman and P. Labine, 89th Symp. “Review of Corrosion Inhibitors

Science”, NACE, (1993) 716.

51. I.L. Rosenfeld, Corr., 37 (1981) 371.

52. J.A. Ali and J.R. Ambrose, Corr. Sci., 33 (1992) 1147.

53. D.H. Lister, R.D. Davidson and E. McAlpine, Corr. Sci., 27 (1987) 113.

54. R.M. Torresi, D. Desouza, J.E.P. DaSivaa and S.I.C. DeTorresi,

Electrochimica Acta, 50 (2005) 2213.

55. D. Dadgarnezland, I. Sheikhshoaie & F. Bauaei, Asian J.Che., 16 (2004)

1109.

56. E. Cano, D.M. Bastidas, J. Simancas, J.A. Lopez Caballern and

J.M. Bastidas, Adsorption Sci., and Tech., 22 (2004) 565.

57. M.A. Quraishi, D. Jamal and V. Bhardwaj, Bull. Electroche., 20 (2004)

459.

58. H.I. Beltran, R. Esquivel, M.L. Cassour, M.A.D. Aguilar, A.J.S. Sanchez,

J.L. S. Sanchez, H. Hopfl, V. Barba, R.L. Garcia, N. Faran and

L.S. Zamudio Reviera, Chemistry – A European J.,11 (2005) 2705.

59. F. Depenyou, A. Doubla, S. Laminsi, D. Moussa, J.L. Brisset, J. Le

Breton, Corr. Sci., 50 (2008) 1422.

60. L. Chenglong, X. Ming, Z. Wei, P. Shihao and C. Paul, Diamond and

Related Mater., 17 (2008) 1738.

61. J. Astermark, J. Voorberg, H. Lenk, D. DiMichele, A. Shapiro,

G. Tjonnfjord & E. Berntorp, J. World Feder. Hemophilia, 9 (2003) 567.


24

62. J. Mabrour, M. Akssira, M. Azzi, M. Zertoubi, N. Saib, A. Messaoudi,

A. Albizane and S. Tahiri, Corr. Sci., 46 (2004) 1833.

63. J. Sathyabama, Susai Rajendran, J.A. Selvi and J. Jeyasundari, The Open

Corr. J., 2 (2009) 76.

64. C. Mary Anbarasi, Susai Rajendran, N. Vijaya, M. Manivannan and

T. Shanthi, The Open Corr. J., 4 (2011) 40.

65. N. Manimaran, S. Rajendran, M. Manivannan and R. Saranya, J. Chem.

Bio. & Phy. Sciences, 2 (2012) 568.

66. J. Wilson Sahayaraj, Patrick Raymond, S. Rajendran and A.J. Amalraj,

J. Electrochem. Soc. India, 56 (2007) 14.

67. A. Jayashree, F.R Selvarani, J.W. Sahayaraj, A.J. Amalraj and

S. Rajendran, Portugaliae Electrochimica Acta, 27 (2009) 23.

68. Susai Rajendran, “Green solution to corrosion problems”, Proc. seminar

on, “Advance. Corrosion control”, Sivakasi, India, July 30-31 (2009) 46.

69. Proceeding of 9th Int. Symp. “Advances in Electrochemical Science and

Technology”, Chennai, India, December 2-4 (2010).

70. G.T. Hefter, N.A. North and S.H. Tan, Corr., 53 (1997) 1-13.

71. W. Machu, Korrosion, U. Metallschutz, 13 (1937) 1.

72. H.H. Uhlig, Z. Elektrochemistry, 62 (1958) 626.

73. O.L. Riggs Jr, “Corrosion Inhibitors”, C.C. Nathan, NACE, Houston,

Texas, (1973) 7.

74. R.C. Ayers and N. Hackerman, J. Electrochem. Soc., 110 (1963) 507.

75. T. Umamathi, J.A. Selvi, S.A. Kanimozhi, S. Rajendran and A.J. Amalraj,

Indian J. Chem.l Tech., 15 (2008) 560.

76. A.E. Mercer, 5th European Symp. Corrosion Inhibitors, Anna Univ.,

Ferrara, Sez. V. Supp. n 7 (1980) 563.

77. A.D. Mercer, ASTM Spe. Tech.l Publi., Philadelphia, USA, 705 (1980) 53.

78. Chem. Res., for the years 1951, 1954 and 1958, Published by HMSO,

London.

79. W. Funke and K. Hamann, Werkstoffe and Korrosion, 9 (1958) 202.

80. S.S.A. Rahim, S.M. Sayyah & M.M.E. Deeb, Mat. Che. Phy., 80 (2003)

696.

81. F.R. Selvarani, S. Santhamadharasi, J.W. Sahayaraj, A.J. Amalraj and

S. Rajendran, Bull. Electrochem., 20 (2004) 561.


25

82. J. Arockia Selvi, S. Rajendran and A.J. malraj, Indian J. Chem. Tech.,

14 (2007) 382.

83. a) M. Natesan & S.V. Iyer, Bull. Electrochem., 6 (1990) 16.

b) C. Giacomelli, F.C. Giacomelli, J.A.A. Baptista & A. Spinelli, Anti-

Corr. Meth. and Mater., 51 (2004) 105.

84. J. Crabtee, Transac. Farad Soc., 9 (1913) 1925.

85. Z. Yan-Li, K. Yukari, K. Yasushi and M. Takashi, Electrochim. Acta,

54 (2009) 7502.

86. U.R. Evans, Z. Eleckrochem., 62 (1958) 619.

87. M. Stern, J. Electrochem. Soc., 105 (1958) 638.

88. E.E. Ebsnso and E.E. Oguzie, Mater. Letters, 59 (2005) 2163.

89. R.C. Kelly, J.R. Scully, D.W. Shoesrnith and R.G. Buchheei,

“Electrochem. Tech. in Corrosion science and Engg”, Dekker Publishers,

New York (2003).

90. K. Nakamoto, “Infrared and Raman Spectra of Inorganic Coordination

Compound”, Wiley Insterscience, New York, (1981) 95.

91. R.M. Silverstein, G.C. Bassler and T.C. Morrill, “Spectrometric Iden.

Organic Compounds”, John Wiley and Sons, New York, (1986) 72.

92. I. Sekine and Y. Hirakawa, Corrosion, 42 (1986) 276.

93. X. Yang, F.S. Pan and D.F. Zhang, Mater. Sci. Forum, (2009) 920.

94. P.K. Gogoi and B. Barthai, Indian J. Chem. Tech., 17 (2010) 291.

95. A. Hamdy, A.B. Farag, A.A. EL-Bassoussi, B.A. Salah and O.M. Ibrahim,

World Appl. Sci. J., 8 (2010) 565.

96. S. Rajendran, B.V. Appa Rao and N. Palaniswamy, Proc. 2nd Arab.

Corrosion Conf., Kuwait, (1986) 483.

97. J.A. Selvi, S. Rajendran & J. Jeyasundari, Zastita Materijala,50 (2009) 91.

98. R. Vera, R. Schrebler, P. Cury, R. Rio and H. Romero, J. Appl.

Electrochem., 37 (2007) 519.

99. Ph. Dumas, B. Bouffakhreddine, C. Amra, O. Vatel, E. Andre, R. Galindo

and F. Salvan, “Quantitative Microroughness Analysis down to the

nanometer scale”, Europhysics Letters, 22 (1993) 717.

100. J.M. Bennett, J. Jahanmir, J.C. Podlesny, T.L. Baiter and D.T. Hobbs,

“Scanning Force Microscopy as a tool for Studying Optical Surfaces”,

Appl. Optics, 34 (1995) 213.


26

101. A. Duparre, N. Kaiser, H Truckenbrodt, M.R. Berger and A. Kohler,

“Microtopography Investigation of Optical surface and Thin films by light

scattering, Optical profilometry and AFMy”, Inl. Symp. Optics, Imaging &

Instrumen., San Diego, CA, Proc. SPIE, 1995 (1993) 181.

102. A. Duaparre, N. Kaiser & S. Jakobs, “Morphology Investigation by AFM

of Thin films & Substances for Excimer Laser mirrors”, Ann. Symp. Opt.

Mater. High Power Lasers, Boulder, CO, Proc. SPIE, 2112 (1993) 394.

103. C. Amra, C. Deumie, D. Torricini, P. Roche, R. Galindo, P. Dumas and

F. Salvan, “Overlapping of Roughness spectra measured in microscopic

(optical) and microscopic (AFM) bandwidths”, Intl. Symp. Optical

Interference Coatings, Proc. SPIE, 2253 (1994) 614.

104. T.R. Thomas, Rough Surface, Longman, New York, (1982).

105. K.J. Stout, P.J. Sullivan and P.A. Mc Keown, “The use of 3D Topographic

analysis to determine the Microgeometric Transfer characteristics of

Textured sheet surfaces through rolles”, Annals CRIP, 41 (1992) 621.

106. R.S. Chaudhary, D.K. Tyagi and Atul Kumar, J. Scientific and Industrial

Res., 66 (2007) 835.

107. P. Shanthy, P. Rengan, A. Thamarai Chelvan, K. Rathika and

S. Rajendran, Indian J. Chem. Tech., 16 (2009) 328.

108. R. Guo, T. Liu and X. Wei, Colloids and Surfaces A: Physicochemical and

Engg. Aspects, 209 (2002) 37.

109. S. Rajendran, S.M. Reenkala, N. Anthony and R. Ramaraj, Corr. Sci., 44

(2002) 2243.

110. Y.Y. Thangam, M. Kalanithi, C. M. Anbarasi and S. Rajendran, Arab. J.

Sci. Engg., 34 (2009) 49.

111. EL-Sayed M. Sherif, R.M. Erasmus and J.D. Comins, J. Colloid and

Interface Sci., 309 (2007) 470.

112. Chenghao Liang and Naibao Huang, Appl. Surface Sci., 255 (2008) 3205.

113. P. Deepa Rani and S. Selvaraj, Rasayan J. Chemistry, 2 (2010) 140.

114. M. Finsgar, S. Fassbender, F. Nicolini and I. Milosev, Corr. Sci., 51

(2009) 525.

115. F. Bentiss, M. Lebrini & M. Lagrenee, J.Heterocyc.Chem., 41 (2004) 419.

116. A. Samide, I. Bibicu, M.S. Rogalski & M. Preda, Corr.Sci., 47 (2005)

1119.


chapter i introduction - shodhgangashodhganga.inflibnet.ac.in/bitstream/10603/33769/1/...high...

Documents