1.0 ABSTRACT:

In the last two decades, nanotechnology has been playing an increasing important role in

supporting innovative technological advances to manage the corrosion steel. This engineering

corrosion assignment reviews;

i. Applications related to the management of steel corrosion, including the use of

nanotechnology to produce high-performance steel.

ii. To produce coatings with superior abrasion resistance and good corrosion resistance.

iii. To enhance the surface of steel designed for oxidizing and corrosive environments.

iv. To prepare nano-sized additives for anti-corrosion coatings or intelligent corrosion

protection systems, or for reducing the corrosion risk of the service environment.

2.0 INTRODUCTION:

Steel is a type of widely-used engineering material for many industries and can be found

in manufacturing, construction, defense, transportation, medical, and other applications. The

corrosion of steel as a result of chemical or electrochemical reaction with its service environment

is a spontaneous process, which can compromise the materials integrity and impact assets,

environment, and people if no measures are taken to prevent or control it. The corrosion of steel

is generally electrochemical in nature, and may take many forms such as uniform corrosion,

galvanic corrosion, pitting corrosion, crevice corrosion, underdeposit corrosion, dealloying,

stress corrosion cracking (SCC), corrosion fatigue, erosion corrosion, and microbially influenced

corrosion (MIC). In addition to cathodic protection, there are many traditional technologies

available to mitigate the corrosion of steel, by either enhancing the inherent corrosion resistance

and performance of the steel itself (e.g., use of stainless steel in place of carbon steel for rebar in

concrete), or reducing the corrosivity of the service environment (e.g., electrochemical chloride

extraction for steel-reinforced concrete), or altering the steel/electrolyte interface (e.g., corrosion

inhibitors, metallic coatings, non-metallic coatings, and surface treatment of steel). These

countermeasures can be used individually or synergistically in the practices of managing steel

corrosion.

Over the last two decades, significant advancements have been made to improve the

management of steel corrosion through research, development, and implementation; and

nanotechnology has been playing an increasing important role in supporting innovative

technological advances. First of all, improved understanding of corrosion and inhibition

mechanisms has been continually achieved through characterization and modeling of the steel

surface and corrosion products at various length scales down to the nanometer scale.

Secondly, nanotechnology has been employed to enhance the inherent corrosion

resistance and performance of the steel itself, by achieving the desirable finely crystalline

microstructure of steel (e.g., nano-crystallization) or by modifying its chemical composition at

the nanometer scale (e.g., formation of copper nanoparticles at the steel grain boundaries).

Metallurgy approaches to the production of high-performance steel with a fine-grain structure

and/or self-organization of strengthening nanophases (carbides, nitrides, carbonitrides,

intermetallides) have been burgeoning under the guide of nanotechnological principles, including

nanoprocesses for steel smelting and microalloying, mechanical pressure treatment (e.g., intense

plastic deformation), and heat treatment (e.g., superfast quenching of melts). One such

technology commercialized in the U.S produces high-performance carbon steels that feature a

“three-phase microstructure consisting of grains of ferrite fused with grains that contain

dislocated lath structures in which laths of martensite alternate with thin films of austenite”.

Thirdly, nanotechnology has been employed to reduce the impact of corrosive

environments through the alternation of the steel/electrolyte interface (e.g., formation of

nanocomposite thin film coatings on steel). Significant improvements in the corrosion protection

of steel have been reported through the co-deposition of Ni-SiC or Ni-Al2O3 nanocomposite

coatings on mild steel and the application of TiO2-naoparticle sol-gel coatings or multilayer

polyelectrolyte nanofilms on 316L stainless steel. The incorporation of nano-sized particles (e.g.,

polyaniline/ ferrite, ZnO, Fe2O3, halloysite clay, and other nanoparticles) into conventional

polymer coatings also significantly enhanced the anti-corrosive performance of such coatings on

steel substrates.

2.1 CHARACTERISTICS OF NANOTECHNOLOGY:

Nanotechnology (NT) is the production and use of materials with purposely engineered

features close to the atomic or molecular scale. NT deals with putting things together atom by-

atom and with structures so small they are invisible to the naked eye. It provides the ability to

create materials, devices and systems with fundamentally new functions and properties. The

promise of NT is enormous. It has implications for almost every type of manufacturing process

and product. Potential NT applications in the next few decades could produce huge increases in

computer speed and storage capacity, therapies for several different types of cancer, much more

efficient lighting and battery storage, a major reduction in the cost of desalinating water, clothes

that never stain and glass that never needs cleaning. While the benefits are almost limitless, they

will be realized only if the potential adverse effects of NT are examined and managed. NT is

new, but the effort to understand and manage its effects will be long-term. As the world

community tries to reduce the adverse effects of the technology, our understanding of these

effects will steadily increase. At the same time, as the technology advances and commercial

applications multiply, new challenges and problems will arise.

2.2 FIELDS OF APPLICATION:

2.2.1 Steel Bulk Materials with Excellence Corrosion Resistance

Nanotechnology has been utilized in endowing the steel bulk materials with excellent corrosion

resistance and other enhanced properties, mainly by refining their crystal grains to the nanometer

scale. The steel substrate with a nanophased grain structure tends to have less defects or

inhomogenities where corrosion attack traditionally initiates and/or propagates.

2.2.2 Decorative and Protective Coatings with Superior Abrasion Resistance

Nanotechnology has been utilized in decorative and protective coatings featuring superior

abrasion resistance (which helps to prevent erosion corrosion and mechanical damage of the

surface) and good corrosion resistance. The most recent invention in this category deals with a

plastic, ceramic or metallic article having on at least a portion of its surface a smooth coating

with the appearance of brass, nickel and stainless steel. Among the multiple superposed coating

layers, a metallic strike layer was produced through physical vapor deposition (PVD). When

cathodic arc evaporation (CAE) is used for PVD, adding a low percentage of oxygen during

deposition was reported to have the effect of reducing the number of macroparticles and thus

rendering a dense nascent PVD layer with fewer defects. For zirconium, the resulting strike layer

exists either as amorphous to nano-size crystals up to 50 nm or as preferentially-oriented crystals

dominantly in (112) direction and up to 80 nm in size, with a small percentage of amorphous

refractory oxide acting as precipitation hardening particles. By maintaining the flow ratio of

oxygen to argon into the vacuum chamber during CAE, a stoichiometric zirconium oxide layer

(preferably between 10 to 30 nm thick) is then deposited on the strike layer, which provides

another non-conductive barrier layer to improve resistance to corrosion and pitting.

2.2.3 Protective Coatings to Manage Damaging Oxidation and Corrosion

Nanotechnology has been utilized in surface treatments to improve the performance and

service life of steel and other alloys used in oxidizing and corrosive environments. A recent

invention is directed to nanoparticle surface treatments and methods of providing such treatments

for forming a beneficial oxide coating (e.g., thin and nonspalling oxide layers) on alloys, thereby

providing the substrate with enhanced resistance to damaging oxidation and corrosion under

extreme conditions. The disclosed method relates to such nanoparticles as cerium oxide,

nanoceria, or an oxide of an element selected from the group consisting of aluminum, silicon,

scandium, titanium, yttrium, zirconium, niobium, lanthanum, hafnium, tantalum, thorium, and

other rare earth elements. One possible mechanism is that these elements exhibit a reactive

element effect (REE) that decreases the oxide scale growth rate and reduces scale spallation by

improving the scale-alloy adhesion.

2.2.4 Nano-sized Additives for Anti-corrosion coatings or for Managing the Corrosivity of

Service Environment

Nanotechnology has been utilized in preparing nanosized additives for coatings used to

protect steel and other metals from corrosive environments. A recent invention is directed to a

process for preparing dispersion additives useful for anti-corrosion coatings. First, a polymer

having ether or amine groups (e.g., polyethylene oxide, polyethylene glycol, polyether amine and

polyglycol esters) is dissolved in a solvent at the concentration of 5-35 wt%. Then, a metal salt

(e.g., chloride, bromide, chromate and acetate salts of Zn, Fe, Ni, or Cr) dissolved separately in

the same solvent at the concentration of 4-10 wt % is added. The polymer and the salt are

allowed to digest for an extended period to form a complex, which is then reacted at 10-30°C

with an alkali (e.g., sodium hydroxide, potassium hydroxide and liquid ammonia) for 4-8 hours

to form a colloidal precipitate. Finally, the precipitate is separated from the reaction mixture by

centrifugation or filtration and then dried and ground to fine powder (with particle size of 2-50

nm, preferably 3-5 nm). The resulting powder can be used as nano-particulate dispersion additive

in coatings to prevent corrosion of steel substrates in harsh environments (e.g., seawater).

2.2.5 Nanotechnology for Intelligent Corrosion Protection Systems

The last by not the least interesting field of application for nanotechnology is its use for

intelligent corrosion protection systems. A recent invention discloses a novel approach for the

preparation of “smart” corrosion-inhibiting pigment and its use in self-healing anti-corrosion

coatings in the form of a powder or a suspension, in which nanoparticles (e.g., SiO2, ZrO2,

TiO2, CeO2 nanoparticles) are coated layer-by-layer (LbL) with one or more layers of polymer

or polyelectrolyte shell (e.g., poly (alkylene-imine), polyalkyleneglcol, and biopolymers and

polyamino acids) responsive to a specific stimulus or trigger. These particles thus act as

nanoscale reservoirs for the effective storage of the corrosion inhibitor (e.g., quinaldic acid and

mercaptobenzotriazole). The method of producing the intelligent coatings was reported to be

cost-effective and easy-to-implement, as the nanoreservoirs provide prolonged release of the

inhibitor. The corrosion inhibitors are released in a regulated fashion, mainly to the damaged

coating zones and/or corrosion defects where they are most needed, thereby providing active,

long-term corrosion protection of the coated substrate (e.g., steel and aluminum alloys).

3.0 CORROSION OF STEEL WITHIN CONCRETE AND ROLE OF

NANOTECHNOLOGY IN PREVENTION

It is well known that mild steel (m.s) embedded in concrete, when rusts, causes severe

damage to the structure. The mechanism, by which it is attacked, is different from humid

atmosphere and marine conditions. In initial stages due to alkalinity of the cement, there is a

high pH (Hydrogen ion concentration). Hence steel is in a passive state. With time, due to

porosity of concrete, there is ingress of carbon dioxide (CO2) from the atmosphere. This reacts

with lime in cement to form calcium carbonate. This results in lowering of pH and hence loss

of passivity as well as increase in porosity of the concrete cover. When atmosphere oxygen and

moisture penetrate through this cover, they react with steel to form rust. However at some other

site the oxygen will not have access. Then sites rich in oxygen and poor in oxygen form a

galvanic couple which initiates corrosion at anode i.e. site where there is oxygen deficiency. In

this way the entire steel rod under goes corrosion (rust).

Fe Fe++ +2e ̄

2e + H2O+ 1/2O2 2OH-

Fe+ H2O+ 1/2O2 Fe++ + 2OH-

4Fe+ 8 OH- 4Fe(OH) 2 +O2 2Fe2O3-H2O+2H2O – RUSTING

The mechanism is schematically shown in Figure

The corrosion products need more volume, which causes tensile stress on the concrete, leading to

cracks, thus paving an easier way for the corrosives and weakening of the bond between steel

and concrete. This results in the separation of concrete from the main structure.

In chloride media (marine atmosphere) the mechanism is different .In the initial stages there is a

loss of passivity, but chloride ions also diffuse through the concrete along with oxygen. This

oxygen form hydroxyl ion. At oxygen deficient state, this is anode formation leading to Fe++

4Fe++ + 8cl 4FeCl2 +8e-

Now the chloride ions and hydroxyl both migrate to the anodic site to neutralize the positive of

Fe++. However due to higher mobility, chloride ions react with Fe++ to form the chloride. This

salt hydrolyses to generate acid and cause local corrosion. With time, this results in formation of

crevice and finally leads to the cleavage. The chloride attack on steel in concrete is catastrophic

and needs proper attention.

2.1 FUNDAMENTAL PRINCIPLES OF CORROSION PROTECTION THROUGH

NANO VAPOUR PHASE INHIBITORS

The spirit of innovation has been extended to the field of corrosion prevention where the

substrate is not accessible for application. In this case, nano particles travel to the substrate

through vapour phase and protect the rebar from corrosion. Such materials are also known as

vapour phase corrosion inhibitors or penetrating type. In designing a volatile corrosion-inhibiting

compound, we have to observe ourselves that the compound will have an appreciable vapour

pressure as well as the capability of forming a stable bond with the metal surface. Therefore the

chemical compounds used as a volatile inhibitor, must not have a too high or too low vapour

pressure but an optimum one.

2.2 NANOTECHNOLOGY IN REINFORCED BAR PROTECTION IN EMBEDDED

CONCRETE.

Steel becomes conducive to corrosion after chlorides and carbonation breakdown its

natural passivating protection. When volatile, migrating corrosion inhibitor travels to the steel

substrate it forms a layer of protection. Using X-rays this protective layer has been measured

(20-100nm) thick at the molecular level.

Vaporises and migrates to all reused areas and cavities.

Vapour condenses on all metal surfaces.

Ions dissolve in moisture water layer.

Protective ions are attracted to metal surfaces.

Ions form a thin molecular protective layer at the metal surface.

Thus penetrating type inhibitor is used in concrete mixture during construction of new structures

and during the rehabilitation of old structures. It migrates through the old concrete and seeks any

ferrous metal in the structure. The thin layer of inhibitor prohibits chemical reaction between

chlorides and steel in the structure.

3.0 OPINION AND SUGGESTION

3.1 Formation of Nanocomposite Thin Film Coatings on Steel

Nanotechnology has been employed to reduce the impact of corrosive environments through

the alternation of the steel/electrolyte interface. Significant improvements in the corrosion

protection of steel have been reported through the co-deposition of Ni-SiC or Ni-Al2O3

nanocomposite coatings on mild steel and the application of TiO2-nanoparticle sol-gel coatings

or multilayer polyelectrolyte nanofilms on 316L stainless steel. The incorporation of nano-sized

particles (e.g., polyaniline/ ferrite, ZnO, Fe2O3, halloysite clay, and other nanoparticles) into

conventional polymer coatings also significantly enhanced the anti-corrosive performance of

such coatings on steel substrates.

3.2 Nano-sized Additives for Anti-corrosion Coatings or for Managing the Corrosivity of

Service Environment

Nano-sized additives have also been utilized to reduce the corrosion risk of the service

environment. A recent invention is directed to the use of nanoparticles to treat a high-

temperature water system in order to reduce the susceptibility of high-strength materials to stress

corrosion cracking (SCC). For instance, nanoparticles of a material comprising noble metals can

be applied to the system to lower the electrochemical corrosion potential of the high-strength

material in the high temperature water environment. The system is further treated with a

material comprising zinc (e.g., zinc nanoparticles). The low corrosion potential is designed to

facilitate the transport of zinc into cracks and its penetration or incorporation into oxide films,

thereby adequately mitigating SCC.

3.3 Nanotechnology for Intelligent Corrosion Protection Systems

The method of producing the intelligent coatings was reported to be cost effective and easy

to implement, as the nanoreservoirs provide prolonged release of the inhibitor. The corrosion

inhibitors are released in a regulated fashion, mainly to the damaged coating zones and/or

corrosion defects where they are most needed, thereby providing active, long-term corrosion

protection of the coated substrate. For instance, multiphasic nanoparticle compositions can be

prepared by electrically jetting polymer fluid in a side by side configuration.

4.0 CONCLUSION

Corrosion is a natural process that compromises the material’s integrity and thus impacts assets,

environment, and people. Nanotechnologies are set to transform the global industrial landscape.

The speed with which this change is occurring is breathtaking. Based on the method of

nanotechnology the material are enhancing the critical engineering properties such as

weldability, resistance to intergranular corrosion and stress corrosion cracking. There are few

method that involved such as nano-coating process such as polymer nano-composite coatings,

Al2O3, Fe3O4, Ce(NO3)3, nano-plates and nano-films. Nanotechnology will prevent Oxidation

and dissolution, prevent electrolyte from reaching the metal surface or keep the concentration at

a low level, Limit water and oxygen transport to the metal Interfere with the corrosion reaction

and If corrosion does begin, prevent or reduce its spread as you can see, a variety of down-to-

earth applications, from chromium replacements to anti-corrosion protective coatings, already

benefit racks, in barrels and even by brush plating on strip, sheet, wire and rods. Nanotechnology

has brought fundamental changes to the methods of mitigating corrosion risk at the

steel/electrolyte interface. The revolutionary properties of nano-materials provide evolutionary

properties to coatings. Nanotechnology approaches have resulted in coatings with improved

adhesion and barrier and corrosion resistance.Nano-engineered and smart coatings provide the

basic function of coatings and achieve results that cannot be attained in any other way.

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

FACULTY OF MANUFACTURING ENGINEERING

CORROSION ENGINEERING & DEGRADATION (BMFB 4213)

ASSIGNMENT 1: ROLE OF EMERGING NANOTECHNOLOGIES IN CORROSION PREVENTION &

LATEST INNOVATION IN CORROSION ENGINEERING

Prepared by:

MOHD AZRUL B. DRAHMAN B050810178 (4BMFB 1)

MOHD SAFUAN B. ANUAR B050910116 (4BMFB 1)

MOHD AZZIM B. NORDIN B050810167 (4BMFB 2)

FASIHAH BINTI CHE MUNI B050810093 (4BMFB 2)

RIANAH BT JIREN B050910060 (4BMFB 2)

SITI SAINILLAH BT SULAIMAN B050910279 (4BMFB 1)

Prepared for:

DR. MOHD WARIKH

4.0 REFERENCES

1. Nanotechnology –Enhanced Coatings in Oil and Gas Author, Dr Abdelmounam M.Sherik,

Abduljalil H.Al-Rasheed, Hassan Al-Ajwad etc Saudi Aramco Journal of Tecnology

SPRING 2008.

2. Applications of nanotechnology and nanomaterials in Construction Zhi Ge and Zhili Gao

First International Conference on Construction in Developing Countries "Advancing and

Integrating Construction Education, Research and Practice "August 4-5, 2008, Karachi,

Pakistan.

3. Canadian Company is Engineering Innovative Materials for the Future of Metal Finishing.

4. Regulating Nanotechnologies: Risk, Uncertainty and the Global Governance Gap,F.

Robert,J.Nico.