A SEMINAR REPORT

A SEMINAR REPORT
ON
NANO PRETREAT

YOGANANDA INSTITUTE OF TECHNOLOGY AND SCIENCE
(Approved by AICTE, NEW DELHI & affiliated to JNTUA, Anantapur)MOHANREDDY NAGAR, ELAMANDAYAM (V), RENIGUNTA (M), TIRUPATHI-517520, A.P
2012-2015

BACHELOR OF TECHNOLOGY
IN
CIVIL ENGINEERING
By N.JAMUNAPRIYA (134P5A0108)
YOGANANDA INSTITUTE OF TECHNOLOGY AND SCIENCE
DEPARTMENT OF CIVIL ENGINEERING
(Approved by AICTE, NEW DELHI & affiliated to JNTUA, Anantapur)MOHANREDDY NAGAR, ELAMANDAYAM (V), RENIGUNTA (M), TIRUPATHI-517520, A.P
2012 – 2016

CERTIFICATE
This is to certify that the seminar report entitled,
"NANOPRETREAT"
Is a bona fide work done by
N.JAMUNAPRIYA (134P5A0108)
For the partial fulfillment of the requirements for the award of B.Tech Degree in
CIVIL ENGINEERING, JNT University, Anantapuramu.

Seminar supervisor Head of the department
(CHANDRAREDDY) (C.SIVA KUMAR PRASAD, M.Tech)


Submitted for seminar held on _____________________
CONTENTS
INTRODUCTION…………………………………………….

WHAT IS CORROSIN? ………………………………………

CORROSION OF METALS…………………………………..

TYPES OF CORROSIONS…………………………………....

CORROSION THEORY……………………………………….

Methods to Control/prevent Corrosion………

What are the methods for preventing corrosion? ............................................................................

Defects due to coatings………………………………

NANO PRETREAT…………………………………………….

BASIC DATA…………………………………………………..

What happens on the application of nanopretreat……………………………………………..

Bonding & Role of NANO PRETREAT………………….

Importance of Bonding of Rebar With Concrete

conclusion
INTRODUCTION:
Every year millions of tones of steel is produced all over the world. Out of which 25% is destroyed just because of "RUSTING"
The effects of "RUSTING / CORROSION" are three fold.
1) It results in dissolution of steel, causing cracking of bar in cross section and ductility.
2) Generation of expensive corrosion products causing cracking, spilling and delaminating of the concrete cover.
3) It causes loss of bond capacity due to concrete damage.

What is Corrosion?

Corrosion is defined as "the degradation of materials by chemical reaction with the environment in which the material resides." This is because of metal oxidation. As metals have a tendency to return to their natural state, it is a natural process which produces either salt or oxides. It requires four elements - anode, cathode, an electrolyte, and a metallic path.

Corrosion Materials

Some Points about Corrosion Materials has Given Below:-
They are the materials which are the cause of corrosion.
They are toxic in nature.
They have very harmful effects as they have a tendency to attack metals and destroy their strength.
They also affect the human body, especially tissues. Some acids and bases are included in that.
For example, HCl, nitric and sulfuric acid and bases like sodium hydroxide and ammonia.
Metal Corrosion

Metal corrosion is the main cause of metal destruction, like steel rusts due to immersion in seawater. Similarly iron reacts with oxygen to form rust by exposure to moist air.

Iron rust is iron oxide Fe2O3. XH2O where X is the amount of complexed water with ferric oxide, which can vary. It shows the color of rust (black to yellow to orange).


Corrosion of Metals

It is a very complex process which is completed in the following steps.
Oxidation of iron- First the iron gets oxidized into ferrous ions [Fe (II)] with the loss of two electrons.
Fe [Math Processing Error] Fe+2 + 2 e-
The ferrous ions again get oxidized into ferric ions [Fe(III)] in the presence of water and oxygen.
Fe+2 [Math Processing Error] Fe+3 + e-
These electrons from the above reactions are used to reduce oxygen.
O2(g) + 2 H2O + 4e- [Math Processing Error] 4 OH-

The ferric ions combine with oxygen and form ferric oxide [iron (III) oxide]. This ferric oxide gets hydrated with water.
The complete chemical reaction for rust formation is shown below. The mechanism for the rusting process is similar to the electrochemical cell. The electrons formed during the oxidation of iron is conducted through the metal. Thus, the iron ions diffuse from the water layer to the metal surface where oxygen is present.

This is an electrochemical cell where iron acts as the anode and oxygen gas as the cathode. The aqueous solution of ions behaves like a "salt bridge" as shown in the figure.


Rusting happens faster in the presence of moisture rather than in a dry environment. This process is also affected by some other factors like the presence of other salts, which increases the rate of rusting, because the presence of salt enhances the conductivity of the aqueous solution formed at the surface of the metal.

So the rusting of iron and steel is completed rapidly near the ocean (salty) or with salt.






TYPES OF CORROSION:
There are different types of corrosion which depend on the environment surrounding the material, type of material, chemical reaction etc. Some general types of corrosion are described below.
1. Uniform Corrosion

This is also called General corrosion. It is a very common method of corrosion. It deteriorates the whole surface of the metal and makes the surface thin. The damage is done at a constant rate on the entire surface. It can be easily detected by it's appearance. It can be controlled but if it is not, it then destroys the whole metal.



2. Galvanic Corrosion

This type of corrosion occurs with an electrolyte like seawater. Metals have different values of electrical potentials.
When they become electrically connected and put in an electrolyte, the more active metal which has a high negative potential becomes the anode. Due to it's high negative potential, it corrodes fast. But the less active metal becomes the cathode.


The flow of electric current continues till the potentials are equal between both electrodes. So at the joint where the two non similar metals meet, the galvanic corrosion appears.
The Galvanic Series shows the list of metals from the most active to the least active (most noble). Thus galvanic corrosion can be controlled by selecting the two metals which are close in series. As platinum is the least active, it is also less active for corrosion.



3. Pitting Corrosion

This occurs because of random attacks on particular parts of the metal's surface. This makes holes which are large in depth. These holes are called "pits". The pit acts as the anode while the undamaged part of the metal is the cathode. It begins with a chemical breakdown in the form of a scratch or spot. The pitting process makes the metal thinner and increases fatigue. For example, it can be very harmful in gas lines.


4. Stress Corrosion Cracking (SCC)

It is a complex form of corrosion which arises due to stress and corrosive environment. This generates brittle and dry cracks in the material. The brittle cracks can inter or Trans granular morphology. The stress is developed in the material due to bending or stretching of the material. It also affects only at a particular section of material.

The main reasons for stress corrosion are welding, heating treatments, deformation etc. It is very difficult to detect the cracks or detect stress corrosion because they combine with active path corrosion. The active path corrosion occurs generally along grain or crystallographic boundaries. Stress corrosion is strongly affected by alloy
composition.

5. Corrosion fatigue

This occurs in the presence of a corrosive environment like saltwater. It is a combination of cyclic stress and corrosion. Corrosion fatigue is produced when a metal breaks at a stress level which is lower than its tensile strength. It is strongly affected by the environment in which the metal resides which affects the initiation and growth rate of the cracks. These cracks are too fine to detect easily. So the stress coupons (metal sample) are used to detect the corrosion.

It can be produced by the influence of various types of stress like stresses applied, thermal expansion, thermal contraction, welding, soldering, cleaning, heating treatment, construction process, casting etc. To prevent corrosion fatigue, the designing and construction process of the materials should be done properly, by eliminating any stress and environmental factors and by eliminating crevices.





6. Intergranular Corrosion

In the granular composition of metals and alloys, grains (small crystals) are present and their surfaces join with each other. This forms the grain boundaries. Thus the grains are separated by grain boundaries.
Intergranular corrosion is also known as inter crystalline corrosion. The Intergranular corrosion is developed on or near the grain boundaries of a metal. This can be due to welding, stress, heat treating or improper service etc. The metal can loose its strength due to the Intergranular corrosion.

7. Crevice Corrosion

It is also known as concentration cell corrosion. This is due to the trapping of liquid corrosive between the gaps of the metal. As the electrolyte has aggressive ions like chlorides, the corrosion reaction is started after settling of liquid in gaps. Oxygen is consumed during the reaction.

Thus an anodic area is developed near the oxygen-depleted zone while the external part of the material acts as a cathode. Crevice corrosion is similar to pitting corrosion.
It' very difficult to detect crevice corrosion. It can be initiated by materials like gaskets, fasteners, surface deposits, washers, threads, clamp etc.

8. Filiform corrosion

It is a type of concentration cell corrosion. This develops on coated metallic surfaces with a thin organic film. The corrosion generates the defect on the protective coating of metallic surface. The filaments of corrosion product is the cause of degradation of the coating. The filaments look like thin threads. They exist as long branching paths.

The actively growing filaments do not intersect the inactive filaments. The reflection process takes place when filaments collide with each other. Filiform corrosion is a very specific process because it only affects the surface's appearance, not the metallic material.

9. Erosion Corrosion

It is also called flow-assisted corrosion. This is due to the movement of corrosive liquids on metal surface which damages the material. It can be seen in ship propellers which are constantly exposed to sea water or in soft alloys. The damage can be seen as waves or rounded holes etc. It shows the flow of the corrosive liquid. It can be controlled by the use of hard alloys, managing the velocity and flow pattern of the fluid.


10. Fretting Corrosion

It is a form of erosion-corrosion. It shows as the combined effect of corrosion and fretting of metal. Due to this corrosion, the material surface starts to disappear. Fretting corrosion exists in the form of dislocations of the surface and deep pits. Oxidation is the main cause of fretting corrosion. It can be controlled by using lubricates, controlling movement etc.








Corrosion Theory

1. Water on the metal surface dissolves CO2 and O2 from the air.







2. Fe in contact with dissolved CO2 and O2 undergoes oxidation.
Fe [Math Processing Error] Fe2+ + 2e- - Anode



3. Electrons lost by Fe are taken by H+
H+ + e- [Math Processing Error] H

4H + O2 [Math Processing Error] 2H2O
On multiplying the first equation by 4 and adding to the second,

The dissolved O2 can take electrons directly also.



4. Fe2+ reacts with dissolved O2 and water


Rust (Hydrated ferric oxide)


Causes of Corrosion

Given below are some of the factors that cause corrosion.
Reactivity of metal
Presence of impurities
Presence of air, moisture, gases like SO2 and CO2
Presence of electrolytes

Methods to Control/prevent Corrosion
There are five primary methods of corrosion control:
Material selection
Coatings
Inhibitors
Cathodic protection
Design
Each is described briefly here and in more detail in subsequent chapters.

Material Selection
Each metal and alloy has unique and inherent corrosion behavior that can range from the high resistance of noble metals, for example, gold and platinum, to the low corrosion resistance of active metals, for example, sodium and magnesium. Furthermore, the corrosion resistance of a metal strongly depends on the environment to which it is exposed, that is, the chemical composition, temperature, velocity, and so forth. The general relation between the rate of corrosion, the corrosivity of the environment, and the corrosion resistance of a material is:
Corrosivity of environment /corrosion resistance of metal = rate of corrosive attack
For a given corrosion resistance of the material, as the corrosivity of the environment increases, the rate of corrosion increases. For a given corrosivity of the environment, as the corrosion resistance of the material increases, the rate of corrosion decreases.
Often an acceptable rate of corrosion is fixed and the challenge is to match the corrosion resistance of the material and the corrosivity of the environment to be at or below the specified corrosion rate.
Often there are several competing materials that can meet the corrosion requirements, and the material selection process becomes one of determining which of the candidate materials provides the most economical solution for the particular service. Consideration of corrosion resistance is often as important in the selection process as the mechanical properties of the alloy. A common solution to a corrosion problem is to substitute and alloy with greater corrosion resistance for the alloy that has corroded.
Coatings
Coatings for corrosion protection can be divided into two broad groups—metallic and nonmetallic (organic and inorganic). With either type of coating the intent is the same, that is, to isolate the underlying metal from the corrosive media.
Metallic Coatings.
The concept of applying a more noble metal coating on an active metal takes advantage of the greater corrosive resistance of the noble metal. An example of this application is tin-plated steel.
Alternatively, a more active metal can be applied, and in this case the coating corrodes preferentially, or sacrificially, to the substrate. An example of this system is galvanized steel, where the sacrificial zinc coating corrodes preferentially and protects the steel.
Organic Coatings.
The primary function of organic coatings in corrosion protection is to isolate the metal from the corrosive environment. In addition to forming a barrier layer to stifle corrosion, the organic coating can contain corrosion inhibitors. Many organic coating formulations exist, as do a variety of application processes to choose from for a given product or service condition.
Inorganic coatings
include porcelain enamels, chemical-setting silicate cement linings, glass coatings and linings, and other corrosion resistant ceramics. Like organic coatings, inorganic coatings for corrosion applications serve as barrier coatings. Some ceramic coatings, such as carbides and silicides, are used for wear-resistant and heat resistant applications, respectively.

Inhibitors
Just as some chemical species (e.g., salt) promote corrosion, other chemical species inhibit corrosion. Chromates, silicates, and organic amines are common inhibitors. The mechanisms of inhibition can be quite complex. In the case of the organic amines, the inhibitor is adsorbed on anodic and cathodic sites and stifles the corrosion current.
Other inhibitors specifically affect either the anodic or cathodic process. Still others promote the formation of protective films on the metal surface.
The use of inhibitors is favored in closed systems where the necessary concentration of inhibitor is more readily maintained. The increased use of cooling towers stimulated the development of new inhibitor/ water-treatment packages to control corrosion and biofouling. Inhibitors can be incorporated in a protective coating or in a primer for the coating. At a defect in the coating, the inhibitor leaches from the coating and controls the corrosion.

Cathodic
Protection Cathodic protection suppresses the corrosion current that causes damage in a corrosion cell and forces the current to flow to the metal structure to be protected. Thus, the corrosion or metal dissolution is prevented.
In practice, cathodic protection can be achieved by two application methods, which differ based on the source of the protective current.
An impressed-current system uses a power source to force current from inert anodes to the structure to be protected. A sacrificial-anode system uses active metal anodes, for example, zinc or magnesium, which are connected to the structure to provide the cathodic-protection current.



What are the methods for preventing corrosion?

Corrosion of metals can be prevented if the contact between metal and air is cut off. This is done in a number of ways. Some of the methods are given below:

Corrosion can be prevented if the metal is coated with something which does not allow moisture and oxygen to react with it.

Coating of metals with paint, oil, grease or varnish prevents the corrosion of metals.

Coating of corrosive metals with non-corrosive metals also prevents corrosion. Some of the methods by which metals can be coated with non-corrosive metals are:

Galvanizing: It is process of giving a thin coating of zinc on iron or steel to protect them from corrosion. Iron is galvanized by dipping it in molten zinc. It is then taken out and allowed to cool. Galvanizing is an effective methods of protecting steel because even if the surface is scratched, the zinc still protects the underlying layer.

Tinning: It is the process of giving a coating of tin, i.e., molten tin. Cooking vessels, made of copper and brass get a greenish coating due to corrosion. This greenish coating is poisonous. Therefore they are given a coating of tin to prevent corrosion.

Electroplating: In this method of a metal is covered with another metal using electrolysis. Silver-plated spoons, gold-plated jewelry, etc, are electroplated.

Anodizing: In this method metals like copper and aluminum are electrically coated with a thin strong film of their oxides. This film protects the metals from corrosion.

Alloying: Corrosion can be also prevented by alloying some metals with other metals. The resultant metals called alloys do not corrode easily, e.g. stainless steel.

Defects due to coatings
Abrasion
Description: The mechanical action of rubbing, scraping, scratching, gouging or erosion.
Probable Causes: Removal of a portion of the surface of the coating or in severe cases removal to expose the substrate by contact with another object such as the use of metal chains for lifting, cargo, fenders, or the grounding of a ship.
Prevention: Use of abrasion resistant coatings formulated with particular regard to resins and extender pigments. With severe cases of abrasion the effects will only be reduced or limited by an abrasion resistant coating.




Blistering (General)

Description: Dome shaped projections or blisters in the dry paint film through local loss of adhesion and lifting of the film from the underlying surface. Blisters may contain liquid, vapour, gas or crystals.
Probable Causes: Many mechanisms can be involved including osmotic gradients associated with soluble salts, soluble pigments, corrosion products, retained solvents and solvents from cargoes. Non-osmotic blistering associated with electro endosmosis, cathodic disbonding, thermal gradients related to cold wall effects and compressive stress.
Prevention: Ensure correct surface preparation and application. Apply a suitable coating system after testing for soluble salts. Consider the possibility of the different blister mechanisms in the particular environment.
Repair: Depending upon size and type of blistering, remove blistered areas or entire coating system and repair or fully recoat.

Bubbles Or Bubbling
Description: Bubbles within a paint film appear as small blisters. These may be intact or broken (to leave a crater). Can be found in excessively thick paint films, especially if spray applied, and also with roller application. This should not be confused with blistering.
Probable Causes: Trapped air/solvent within the coating which is not released before the surface dries. Air entrainment during mixing. High ambient temperature during application. Also seen when overcoating antifouling without removal of the leached layer and zinc silicates. Can be found with factory applied coatings where application is by dipping, electrodeposition or roller coating.
Prevention: Spray application - adjust viscosity with thinners and follow data sheet requirements for maximum application temperature. Use correct mixing equipment to ensure air is not stirred in during mixing. Apply a mist coat. Add defoaming agent to emulsion paints.
Repair: Depending on extent and severity of bubbling, abrade or remove the offending coat(s) and recoat.



Checking
Description: Fine cracks which do not penetrate the topcoat of a paint system. Some checking can be so minute that it is impossible to see without magnification.
Probable Causes: Typically a formulation and/or a specification problem. As with cracking, stresses are developed which cause the surface of the paint film to become brittle and crack. Limited paint flexibility.
Prevention: Use a correctly formulated coating system.
Repair: Abrade and clean surface then apply an undercoat/topcoat to suit.





Cracking
Description: The splitting of a dry paint film through at least one coat to form visible cracks which may penetrate down to the substrate. Cracking comes in several forms, from minute cracking to severe cracking.
Probable Causes: Cracking is generally a stress related failure and can be attributed to surface movement, ageing, absorption and desorption of moisture and general lack of flexibility of the coating. The thicker the paint film the greater the possibility it will crack.
Prevention: Use correct coating systems, application techniques and dry film thicknesses. Alternatively, use a more flexible coating system.
Repair: Abrade to remove all cracked paint. Correctly reapply the coating system or use a more flexible system and one less prone to cracking.


Erosion
Description: Selective removal of paint films from areas or high spots.
Probable Causes: The wearing away of the paint film by various elements such as rain, snow, wind, sand etc. Found to be more prominent on brush applied coatings because of the uneven finish.
Prevention: Use a suitable coating system with resistance to surface erosion/abrasion.
Repair: Clean surface free from contamination and apply a coating system formulated and tested for the specific environment.


Fading
Description: Discolouration or gradual decrease in colour of paint when exposed to sunlight/weather. May be accompanied by loss of gloss. In some situations it may resemble chalking but without the powdery surface. Fading tends to accelerate in the presence of moisture.
Probable Causes: Incorrect pigmentation; use of non light stable organic pigments; atmospheric contamination; porous substrate.
Prevention: Use correct coating systems which resist UV light and fading. Use a coating with light stable pigments.
Repair: Abrade and clean the surface and apply a light stable coating system.

Bloom (Blush)
Description: A hazy deposit on the surface of the paint film resembling the bloom on a grape, resulting in a loss of gloss and a dulling of colour.
Probable Causes: Paint film exposed to condensation or moisture during curing especially at low temperature (common phenomenon with amine cured epoxies). Incorrect solvent blend can also contribute to blooming.
Prevention: Apply and cure coating systems under correct environmental conditions and follow the manufacturer's recommendations.
Repair: Remove bloom with clean cloth or suitable solvent cleaners. If necessary, apply undercoat/topcoat following manufacturer's recommendations.




Wrinkling

Description: The development of wrinkles in the paint film during drying.
Probable Causes: Usually due to the initial formation of a surface skin with solvent based paints. Can arise from overcoating before the previous coat has adequately hardened. Over thickness particularly with alkyd coatings.
Prevention: Use correct coating specification and materials and ensure adequate mixing, application and curing by following the paint suppliers' recommendations.
Repair: Remove defective coatings. Abrade, clean and recoat.










Anti Rust Coating
Nanopretreat
Nanopretreat Chemistry -
Nanopretreat is a unique antirust formulation made especially for Mild Steel. And the system in formulation gets activated as soon as it comes in contact with steel.
 Presence of complex salts of Vanadium and tungstates in formulation with other Active Ingredients react with iron to build a stable and stout micro crystalline structure or nanocomposite which protects the steel surface from corrosion and increases paintability.The coat is not applied from outside but the coat is generated from the metal itself. So the coat becomes inseparable part of the mild steel.
When the nanopretreat is applied on the steel surface there is a formation of millions of nuclie on the activated surface. And the coat is generated through the surface and becomes inseparable part and provides rust resistance as well as increases bond strength.
NANOPRETREAT … very effective and feasible rust remover and antirust compound for mild steel 

CLEANING OF RUSTED REBARS
Initially cleaning of rusted steel rebars by cleaning solution shall be done. We shall dip the rebars in the said initial cleaning solution to remove pitted /highly corroded areas of steel. This initial dipping shall by done for approximate 8-10 minutes or the dipping time may be reduced to 4-5 minutes depending on quantity of rust. 
CLEANING THE REBAR WITH ALKALINE DETERGENT:
Once the initial removal of dust/ rust/pitting is done by cleaning solution each rebar shall be washed thoroughly with high quality detergent solution to. Which when again shall be washed with plain water to make ready for coating treatment. As per our principle and working method we treat each rebar special so we take utmost care to make coating near to perfection. We use high quality HDPE dipping tanks for washing and coating purpose

COATING WITH NANOPRETREAT ANTI RUST COMPOUND.
On final rinsing, rebars shall be ready for coating. We shall coat at a time 2-3 rebars depending on diameter. It will take 2-3 minutes for coating of each rebar.

 All coating shall be done by dipping method so that 100% area can be covered effectively.Each coated rebar shall be placed in tilted position for removal of excess liquid. It takes about 10-15 minutes for complete drying of rebar. Coated and dried rebars can be put on plastic sheet or wooden platform to avoid excess contact with dust / mud.Cured rebar can immediately be used in construction on very next day.

Nanopretreat prevents corrosion in 4 ways:-


Stops Formation of Fe 2+ & Fe 3+ ions.

Forms a Fine and Tenacious coat on the Surface of Steel.

Stops Ingress of Water

Fights Against Atmospheric Pollution

Water-based patented formulation
 
Inorganic in nature
 
Eco-Friendly (Complies with ROHS standards)
 
Non-toxic
 
Non-inflammable
 
Nanocoated structures stable even at -196o to +400o C
 
2 to 5micron thickness Coat, so practically no change in gauge of substrate
 
Nanopretreat coated rebars and MS structures show ~ 100% bond strength increase
 
Nanopretreat coated steel can be painted, powder-coated & electroplated very well
 
Easy to use - paint, spray or dip methods
 
Excellent Corrosion Resistance properties
 
Scratch-proof. Only grinding or filing can affect surface







BASIC DATA
Viscosity(fords cup-4) = 13 seconds @30º Celsius.

Sp. Gravity = 1.1 gm/cc.

Ph. Value: 1.5 to 3.5 (we can give tailor made solutions as per steel specification).

Conforms to ROHS Standard (Reduction of Hazardous Substance - DIRECTIVE 2002/95/EC).
Nanopretreat does not contain Lead, hexavalent Chromium, Mercury, Cadmium, polybrominated Biphenyls & diphenylethers.
 

What happens on the application of nanopretreat?
On applying NANOPRETREAT on the surface of the steel the special formula penetrates into the very fine cracks, holes and crevices where it reacts with free ion particles to form complex water soluble compounds in the form of very tenacious layer of COAT which becomes an inseparable part of iron which in due course protects steel from rusting. In this case NANOPRETREAT does not allow iron to form Fe ions, thereby stopping initiation of rusting. Moreover water repellent formula of NANOPRETREAT does not allow water to invade in the steel. NANOPRETREAT fights against corrosion in four different manners by :
- Stopping formation of Fe 2+ ions.

- Forming fine and tenacious film on surface of steel.

- checking ingrace of water.

- Fights against atmospheric pollution.
It is well known fact that on rusting of iron or steel, it goes on swelling, which brings direct pressure on concrete, adhered to it.
This results in cracking and pilling of concrete which allows more and more water, water vapors and results vigorous in rusting, thus, affecting the strength of construction. It is accepted that 0.25mm gap in concrete is enough to start corrosion in the steel, covered by cement concrete.

Bonding & Role of NANO PRETREAT.
When the regular rebars come in direct contact with moisture and water, resulting in direct corrosion on the surface of steel rod which separates the rod and the bonding cement slurry, which results into bond or grip stresses.
This causes the rod does not obtain "stress transfer phenomenon". Hence the beam looses its strength and becomes demolished even if sufficient reinforcement is provided. The NANO PRETREAT prevents all such recurrences only because nano coat prevents rusting process and keeps bond stress intact.
Present coatings available in the market are in the form of thin layer of epoxy and polymers which cause a loose coat between steel and concrete (construction wants bond of concrete with steel and not with other lose film), over which during loading condition, rod gets separated from concrete hence there is decrease in bond stresses but the NANO PRETREAT applied on steel rod provides rusting resistance as wel as good bond stress as nano coating acts as a part and parcel of steel.








Importance of Bonding of Rebar With Concrete



"The picture clearly indicates weak bonding of concrete with steel resulted into severe cracking of concrete."

The importance of bonding of concrete with steel rebars
The expert civil engineers opine, in case of beam, the compression load is taken by concrete and tensile load is taken by steel when beam is loaded .These compression stresses in concrete and tensile stresses in steel act as a balancing couple to counteract the applied load but this happens only when there is perfect grip between steel and concrete. Hence bond strength is important.
If such bonding strength between the concrete and steel is not achieved, it happens just as a steel rod is pierced into an over sized bore of concrete. Which ultimately decreases power and strength of beam and consequently collapse.






CONCLUSION


Nano pretreatment which are used for coating on all types of metals like steel, aluminium, zinc and its alloys, magnesium substrate etc. This process is a dramatic improvement in ecological as well as in economics. These processes are free of heavy metals such as nickel, magnesium and zinc and are subject to restriction in the field of worker safety or waste disposal.
 
Some of the advantages of nano pretreatment are:

It reduces waste disposal, cleaning and maintenance as it forms very low sludge. 

It can be operated in ambient temperature.

It also reduces process time significantly.

The coating gives good paint adhesion as it penetrates deeply into the surface.

It reduces process time and cost as it eliminates passivating step.

It is suitable for all conventions powder and wet paint coating. It creates an inorganic extremely high density layer incorporating Nano particles resulting in a conversion layer on the order of nanometer thick whereas phosphate coat gives in the order of microns thick. Our nano pretreatment chemicals available for both dip and spray mode of application