FIELD OP THE INVENTION:
The present invention relates to a method of synthesis of Nano - TiO2 sol as corrosion Resistant coating material for steel sheets.
BACKGROUND OP THB INVENTION:
Organic titanium compounds are synthesized from TICl4 Nelles process. This compounds have wide application in different fields such as reducing agents, catalyst for esterification/trans esterification, cross linker etc. Since, these compounds have strong affinity towards oxygen to form titanium oxide, then it widely use in coating industries for different applications such as anti-reflective, self-cleaning, antibacterial and corrosion resistance coatings etc. Thin film coating of (TiO2)x of <100 nm thin is virtually transparent and form Ti-O-SI bridge with glass surface is a proven coated product in market. This has reduced fragility of glass. Reflective towards heat producing IR. In hot countries, this has been used on window glass to reduce solar heat of house. This has also been used for solar cell application. Sometime, the mixture of ceramic materials such as zirconates, silicates in titania used for liquid crystal devices, electronic products etc

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Titanates are used as corrosion resistance coatings for tinplates, steels and aluminium. The adhesion of titanates improved by chelating agents such as acetyl acetone. 1.2- propanediol, ethylene glycol, ethanolamine, diethanolamine, triethanolaniine, acetic acid, citrate acid, ethanol and n-butanol etc. There are many techniques for titania deposition on substrates such as ion beam implantation, PVD, CVD, sputtering, plasma spraying etc. All techniques have advantages and disadvantages. A bottom up technique was adopted to prepare nano-particies of titania from its organic compounds through chemical sol-gel process.
According to Jianshum Huang et al., carbon steel can be protected by titania coatings from atmosphere. It has been shown that titania coating under solar light acts as a nan-sacrificial anode and provides cathode protection to metals. A good photo effect can be obtained with a interfadal layer of alpha iron oxide i.e. anatase/alpha-iron oxide/steel This effect can further improved with a multiplayer coating like titania (amorophous) /anatase/Ti-Fe oxide/alpha-iron oxide/steel. The
amorphous layer of titania helps in maintaining photopotential by

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inhibiting oxygen reduction. Therefore, corrosion protection due to titania (anatase) coating prolonged in day and night time.
OBJECTS OP THB INVENTION:
It is therefore, an object of the present invention is to propose a method of synthesis of Nano-TiQa sol as corrosion resistant coating material for steel sheets which eliminates the disadvantage of prior Art.
Another object of the present invention is to propose a method of synthesis of Nano-TiO2 sol as corrosion resistant coating material for steel sheets which adopts a bottom technique to prepare nano-particles of titania from its organic compounds through chemical sol-process.
A still another object of the present invention is to propose a method o; synthesis of Nano-Ti02 sol as corrosion resistant coating material for steel sheets which acts at Room temperature.
A further object of the present invention is to propose a method o synthesis of Nano~TiO2 sol as corrosion resistant coating material fo steel sheets which is Eeo friendly.

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An yet further object of the present invention is to propose a method of synthesis of Nano-Ti02 sol as corrosion resistant coating material for steel sheets which is economic in use.
SUMMARY OF THB INVENTION:
Substrate surface preparation*. Different steel grades D, BDD & IF steel sheets were taken for the investigation. These sheets were cleaned to remove scales and subjected to tri-cationic phosphate base solution to obtain a thin coating of <0.5 micron (2-3 g/m2) phosphate coating in one case. In another case, a high alkaline paste was prepared by mixing sodium nitrite 5 gen, sodium hydroxide 45 gm. water 40gm, tri-sodium phosphate 10 gm and sodium vanadate 1 gm, heated to boiling temperature under stirring for about 1 hr. Bare steel was dipped into this paste and exposed to about 2 hrs and then washed in water an washed steel was exposed to furnace at 525*0 for obtaining alpha iro oxide. The photographs of substrate is shown in Pig. 6 & 7. There ar two different substrate surface were prepared on and over that titani sol was applied.

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Sol -Gel Process: A sol-gel coating is prepared by mixing Ti-precursors in compatible solvent in a nitrogen globe box under stirring at temperature ranges from RT to 90°C. Hydrolysis and condensation reactions are progressed during stirring along with addition of water and catalyst The final sol is usually deposited at RT and after gelation, it is dried and heated for densification.
Synthesis of Sol-Gel titania for corrosion resistance: A room temperature CRT) sol-gel coating was sysnthesised by mixing following chemicals as given in Table-1 & 2 under stirring in nitrogen globe box.
Table : 1 Chemical formulation of sol-gel coatings

6 Tablet 2 Chemical composition of sol-gel coating

Application of sol on steel substrate :
The synthesized sol was applied on the substrate by dipping process where dipping time was 1 min at RT, then followed by slow drying at the rate of 5°C - 10°C for about 2 hrs. then sintered at 350-500oC for 30 min-1 hr at the rate of 10-20°C. The sintered surface is shown in Fig. 8. The coating microstructure, phases, coating elements were analyzed. Corrosion performance of this coating in saline atmosphere was investigated.
TESTING AND RESULT:
The sol particle size and distribution were controlled and analyzed by
melver particle size analyser and TEM respectively. It is shown in fig.l

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and 2. Extent of hydrolysis was monitored by FTIR. The kinetics of hydrolysis is shown in Fig.3. Sol was deliberately hydrolysed to form powders, this powders were under gone TGA/DTA to see the phase changes with temperatures. This is shown in Fig. 4 and 5.
Result and Discussion:
FTIR analysis : Fig. 1 shows the FT-IR spectra of Ti-sol with different time of hydrolysis without addition of acetyl acetone. The 4000-100C cm'1 spectra region shows the absorption bands of the O-H stretching (3700-3200 cm"1), Q-H bending (1650-1200) cm"1) and other organic bonds vibration modes. The absorption bands at the wavelengths fron 1000-400 cm"1 are mainly due to Ti-O vibrational modes. If the hydrolysis reaction proceed, the TI-O-C chemical bond will to destroyed and weakened.
After three hours of stirring, the sharp peak at 3400 cm-1 is obtains indicating strong- OH bond has formed. This is supported by the characteristic peak of Ti-O-C (2800 cm-1) gradually depleted The result can be good evidence that supports our assumption about the

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hydrolysis of titanium propoxide and pdycondensation of the hydrolysis products. The absorption peak from -O-C4H9 (960 cm-1) gradually depleted. The appearance of peak at 690 cm -1 is due to presence of Ti-O-Ti after condensation and the peak at 1650 cm"1 confirmed the presence of hydrone in the xerogel.
Particle si2e analysis of sol-Particle sizes of the optimum sol were analyzed by Zitasizer. It was found that 95% particles are below 100 mm in size. This is shown it Fig.3.
Distribution of particle in the sol analyzed by TEM: TEM was carried out to observe stable distribution of nano particle the Utania sol. These particles are uniformly distributed throughout t sol, it indicates that it is stable sol. Photograph is shown below Fig. 4.
TGA/DTA analysis of powder to find phase transformation temperature This sol was hydrolysed and followed by condensation reaction obtain powder particles. The powders were analysed by TG/DT/ see its thermal behaviour. Fig. G shows the relative mass loss (TG)

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differential thermal analysis (DTA) curves corresponding to the dried powdered in different methods. The endothermic mass loss 9,6% observed for temperatures lower than 110°C can be attributed to water and organics desorption. A significant mass loss (15.2%) accompanied by an intense exothermic peak corresponding to the removal of organics is apparent between 200~300*C. A release of 7.6% mass loss and combustion (exothermic peak) of strongly bonded or adsorbed organic species is verified between 300-400°C. The oxidation of the organic species of complexing matter usually takesplace within this temperature range, as indicated by complexing linkage between titania atoms and organics. The presence of complexed form of acac was confirmed by FTIR spectra of dried powders. The composite powder of titania and silica was shows a endothermic peak below 110°C is due to water loss. The strong exotheric peak between 210-300°C is due to loss of organic species as shown in Fig-6.
XRD analysis of coated steel:
X-ray diffraction analysis was performed at room temperature on a
PANalyticol, Auatrilla. The strong Mo Ko radiation (4O Kv, 6O Ma), a.

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divergence slit of 10, a scatter slit of 10, a receiving slit of 0.3 mm, 20 scan step of 0.020 and the curved-crystal graphic monochrornator for the different beam were used. The XRD analysis was done on the titania coatings (without sintering) and titania coatings (with sintering 4004C). It was found that amorphous peak was observed without sintering and nanocrystalline anatase XRD patterns was observed at 400°C sintering. XRD pattern of composite coatings on steel at 400 °C sintering temperature shows nanocrystalline structure of titania and silica in Pig. 7 and 8.
Microstructure and elemental analysis of coatings by SEM and EDX- as shown in Fig. - 9,10,11 and 12.
ESCA analysis of coatings:
The Ti 2p region obtained on the surface of a titania film produced by sol-gel process. Two pronounced features are observed at binding energies of 459.8 ev and 465.5 ev, evoked by the Ti 2p3/2 and Ti 2pl/2 states respectively. The measured binding energy of the Ti2p3/2 peak and the splitting of the doublet is 6 ev indicating and oxidation

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state of 4+ far titanium. This also indicates that there is no suboxides such as TiO, T12O3 and TI3O5 on the surface. This also indicates that there is no suboxides such as TiO, TI2O3, and T13O5 on the surface. This values is slightly different to the titania coating producesu are ch as by other techniques such as IP and RE. Small differences may be due to the difference in oxidation state or structural arrangement of the atoms as shown in Fig. 13 and 14.
Coating performance*
SST was carried out to see its corrosion resistance properties. It was found that nano-titania coated steel is giving 96 hrs SST resistance as compared to 2 hrs in case of bare steel. The photographs are shown in Fig. 15 and 16.
Explanation:
The portion in titania coating was found corroded. This is due to cracks in the coatings. It was analysed by ESCA. It was found that the devective region have very less titania coatings as depicted in Fig. 17, 18 and 19. It was found prominent iron and oxygen peaks.

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Conclusion:
Titania coating shows corrosion resistant in saline atmosphere. Coating was uniform. The particle size in the range of nano confirms it is nano coating.
DETAILED DBSCRIPTION OP THB ACCOMPANYING FIGURES:
Fig. - 1 Shows FT-IR spectra of Ti-Sol with different time hydrolysis
without addition of acetone. Fig. - 2 Shows FT-IR spectra of Ti-Sol with different time hydrolysi
with addition of acetone.
Fig. - 3 Shows the titania particle distribution in titania sol. Fig. -4 Shows a metallographic structure depicting uniform
distributed particles of Titania sol. Fig. - 5 TG/DTA curves of titania powder.
Fig. - 6 TG/DTA curve of composite powder. (Titania of 10% silica) Fig. - 7 XRD pattern of composite coatings (titania and Silica) sintere
at 400°C . Fig. - 8 XRD pattern of titania coating sintered at 400 °C.

13 Pig. - 9,10,11,12 Shows microstructure and elemental analysis of
coatings by SEM and EDX. Fig. - 13, 14 Shows ESCA analysis.
Pig. - 15 Shows Nano-titaraa coated steel is giving 96 hrs. Fig. - 16 Shows SST Resistance (96 hrs) in bare steel. Fig. - 17, 18, 19 - Shows ESCA analysis of titania coating.

14 WE CLAIM :
1. A method of synthesis of Nano-T102 Sol as corrosion Resistant Coating material comprises :-
- a composition of (in terms of weight).
Titanium isopropoxide
Titanium butoxide - 69-100 gm
2-ethoxy ethanol - 100 - 200 gm.
Acetyl acetone - 12.5-26 gm.
Water - 18.56 gm.
and/or
- a composition of (in terms of weight)
Titanium isopropoxide
Titania butoxidb - 69-112 gm.
2 - ethoxy ethanol - 100-224 gm.
A cetyl Acetone - 12.5 - 25 gm.
Glycidoxy propyl
Trimethoxy Silane - 28-21 gm.
Water- 18-72 gm.

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The above mixture was stirred under 300-400 rpm for about 8 hrs. at 60 oC.
2. A process of coating: Nano- TiOz Sol on steel sheets comprises
following steps;
- steel sheets were cleaned to remove scale;
- the cleaned sheets are undergone a substrate surface
preparation wherein sheets are subjected to a thin coating of
<0.5 micro of tricationic phosphate or a high alkative paste;
- dipping the substrate surface of sheet in a synthesized
Nano-TlOa Sol bath for 1 min at Room temperature followed
by slow drying at the rate of 6 oC - 10 oC for about 2 hours
and
- sintering the coated sheets at 350 °C - 500 oC for 30 min - 1
hour.
3. The process as claimed in claim 2, wherein the substrate surface
preparation by high alkaline pastes comprises a mixture of
sodium nitrite 5 gm., sodium hydroxide 45 gin., waters 40 gm.,
tri-sodium phosphate 10 gm. And sodium vanadate 1 gm, heated
to boiling temperature under stirring for about l hour.

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4. The process as claimed in claim 3, wherein the substrate surface preparation by high alkaline pastes comprising following steps:--
- dipping the bare steel sheet in the paste.
- exposing to about 2 hours,
- washing the sheets with water
- exposing the washed sheets to a furnace at 625 oC for
obtaining alpha iron oxide.
6. The method of synthesis of Nano-TiO2 Sol as corrosion resistant coating material steel sheets as substantially described and illustrated herein with accompanying drawings.
6. The process of coating of Nano TiO2 Sol on steel sheets as
substantially described in claim 2, 3, 4 and illustrated herein with reference to accompanying drawings.

Dated this 6th day of FEBRUARY 2007,

Substrate surface preparation: Different steel grades D, BDD & IF steel sheets were taken for the investigation. These sheets were cleaned to remove scales and subjected to tri-cationic phosphate base solution to obtain a thin coating of <0.5 micron (2-3 g/m2) phosphate coating in one case. In another case, a high alkaline paste was prepared by mixing sodium nitrite 5 gen, sodium hydroxide 45 gm, water 40gm, tri-sodium phosphate 10 gm and sodium vanadate 1 gm, heated to boiling temperature under stirring for about 1 hr. Bare steel was dipped into this paste and exposed to about 2 hrs and then washed in water and washed steel was exposed to furnace at 525oC for obtaining alpha iron oxide. The photographs of substrate is shown in Pig. 6 & 7. There ar two different substrate surface were prepared on and over that titan: sol was applied.

Sol -Gel Process: A sol-gel coating is prepared by mixing Ti-precursors in compatible solvent in a nitrogen globe box under stirring at temperature ranges from RT to 90°C. Hydrolysis and condensation reactions are progressed during stirring along with addition of water and catalyst The final sol is usually deposited at RT and after gelation, it is dried and heated for densification.

Synthesis of Sol-Gel titania for corrosion resistance: A room temperature CRT) sol-gel coating was sysnthesised by mixing following chemicals as given in Table-1 & 2 under stirring in nitrogen globe box.
Table : 1 Chemical formulation of sol-gel coatings

6 Tablet 2 Chemical composition of sol-gel coating

Application of sol on steel substrate :
The synthesized sol was applied on the substrate by dipping process where dipping time was 1 min at RT, then followed by slow drying at the rate of 5°C - 10°C for about 2 hrs. then sintered at 350-500*C for 30 min-1 hr at the rate of 10-20°C. The sintered surface is shown in Fig. 8. The coating microstructure, phases, coating elements were analyzed. Corrosion performance of this coating in saline atmosphere was investigated.