PROCESS OF FABRICATING NANO-SURFACE COATING AND METHODS OF

TESTING THEIR PROPERTIES

Veereshgouda S.N.12GAMB4017

M.E. Adv. Materials Tech.U.V.C.E., BANGALORE

The beginning..

contents

• Nano coatings : what and why?• Materials used

-Small Case study- titanium dioxide• Classification of nanocoatings.• Different Processes used.• Case study: coating of Bio-Implants • Testing of nanocoating

Coating

• Nanocoating are coating that produced by usage of some

components at nanoscale to obtain desired properties.

• Nanocoatings can be categorized as nanocrystalline,

multilayer coatings with individual layer thickness of

nanometers.

• Nanostructured coatings offer great potential for various

applications due to their superior characteristics that are not

typically found in conventional coatings.

Nanocoating

Titanium dioxide is hydrophilic due to its high surface energy, hence water does not form drops on a surface coated with it, film instead.

Photo catalytic TiO2 absorbs UV radiation from sunlight/fluorescent lamps

Produce pairs of electrons and

holes.

Electron of the valence band of titanium dioxide becomes excited when illuminated by light.

The excess energy of this excited electron promoted the electron to the conduction band of titanium dioxide therefore creating the negative-electron (e-) and positive-hole (h+) pair.

The positive-hole of TiO2 breaks apart the water molecule to form hydrogen gas and hydroxyl radical. The negative-electron reacts with oxygen molecule to form super oxide anion. (Both known as photo-produced radicals)

These photo-produced radicals are powerfuloxidizing species and can cause the deterioration of organiccontaminants or microbials pieces on the particle surface.

MECHANISM of Self-cleaning photocatalytic nanotitanium dioxide (TiO2)

Classification of Coating

Properties

Functional Coating

Self- Assembled Nanophase

Coating

FUNCTIONAL COATING

The term ‘functional coatings’ describes systems which represent

other than the classical properties of a coating (decoration and

protection). Functional coating come up with additional functionality.

This functionality depend upon the actual application of a coated

substrate.

Self-cleaning

Easy-to clean (anti-graffiti)

Antifouling

Soft feel

Antibacterial

Durability Reproducibility

Easy application and cost

effectiveness

Tailored surface

morphology

Environmental friendliness

Expectations of functional coatings Examples of functional coating

• Functional coatings perform by means of physical, chemical, mechanical and thermal properties.

• Chemically active functional coatings perform their activities either at:

– Film–substrate interfaces (anticorrosive coatings), – In the bulk of the film (fire-retardant or intumescent coatings)– Air–film interfaces (antibacterial, self-cleaning)

Bulk film properties

Film/ substrate interface properties

Air/ Film interfaces properties

Self Assembly

• Under specific conditions, some materials can spontaneously assemble into organized structures. This process provides a useful means for manipulating matter at the nanoscale. http://nimet.ufl.edu/nanomed.asp

SNAP Coating System

COATING APPLICATIONDip coating

SNAP SOLUTION MIXINGCross-linking agent Surfactant

SOL-GEL PROCESSHydrolysis Condensation

Preparation of SNAP (Self-Assembled Nanophase Protection)

Fig. Schematic representation of sol-gel process of synthesis of nano-materials

1. SNAP solutions were prepared by drop-wise addition of 42.8 ml

glycidoxypropyltrimethoxysilane (GPTMS) and 8.9 ml

tetramethoxysilane (TMOS) to 64.8 ml solution of 0.05 M acetic acid in

doubly distilled deionized (DDI) water.

2. The application solutions were prepared by diluting the aged SNAP

solution with water and subsequent addition of a crosslinking agent

(DETA) and surfactant.

3. The final mixture was vigorously stirred and applied to the cleaned

aluminum alloy panels by dip-coating.

SNAP Procedures

CONVENTIONAL CLASSIFICATION

Chemical vapour deposition-CVD

• Atomic layer epitaxy

• Plasma-Enhanced CVD

• Electrostatic spray assisted vapour deposition

Physical vapour deposition-PVD

• Electron beam physical vapor deposition

• Sputter deposition

• Vacuum deposition

• Cathodic arc deposition(Arc-PVD)

• ION BEAM SPUTTERING TECHNIQUE.

• Molecular Beam epitaxy

SPRAYING

• High velocity oxygen fuel( HOVF)

• Plasma spraying

• Arc spray

Chemical and electrochemical

• Plating• Electroplating• Electroless

plating• Solgel process• Anodizing

Physical vapour deposition-PVD• PVD is a process of transferring growth species from a source or

target and deposit them on a substrate to form a film.• The process proceeds atomistically and mostly involves no chemical

reactions.• In general, those methods can be divided into two groups:

evaporation and sputtering.– In evaporation, the growth species are removed from the source by thermal

means.– In sputtering, atoms or molecules are dislodged from solid target through

impact of gaseous ions (plasma).

• Each group can be further divided into a number of methods, depending on specific techniques applied to activate the source or target atoms or molecules and the deposition conditions applied.

Evaporation

Sputtering • Sputtering is to use energetic ions to knock atoms or molecules

out from a target that acts as one electrode and subsequently deposit them on a substrate acting as another electrode

Dip coating

Stages of the dip coating process: dipping of the substrate into the coating solution, coating of substrate (wet layer ) by solvent evaporation

Plastic dip coating

Dipping Wet layer formation

Solvent evaporation

Coating technique

Processing or coating for organic coating

Spray coating

Refurbished ion-beam-sputterer

• Fast cycling Coater for SiO2, TiO2, Ta2O5

• For multi-layers and mixtures

Nano-coatings the thought and the actions- Riccardo DeSalvo, Shiuh Chao et al. - National Tsing Hua University in Taiwan

• Conductive nanocoating on textiles atomic layer deposition(VCD)

Processing for inorganic and hard coating

Refurbished ion-beam-sputterer

Kaufman-type ion beam sputter system in a class 100 clean compartment within a class 10,000 clean room Previously used to develop low-loss mirror coatings for ring-laser gyroscope

Sputter target and rotator

Exchangeable twin target holder

Kaufman ion gun and neutralizer25

Implantable Materials - Coatings

For: Catheters, heart valves, artificial hips

Implants confuse the cells responsible for tissue regeneration and causes the body to react as if it had encountered foreign material.

The body's natural response to foreign material is to wall it off with scar-like tissue. This reaction can disrupt device performance.

© 2003 by Glenn Fishbine

Nanocoatings in the exact shape of specific proteins can protect devices from such disruptions.

P-h curve

• Indentor used: Berkovich diamond indenter – 3 sided pyramidal shape– Tip radius 50-100nm

• We plot P-h curve• We use H= hardness of indentor,

– In conventional tests A is the projected area at maximum load

– In nano-indentation A is area function

References

• G. Cao, Nanomaterials, Imperial college press• J. Malzbender et al Measuring mechnical

properties of Coatings, Reports, Elsevier Imprints.

To end my presentation..

THANKS TO:• My Family- For Providing Resources Like Laptop, Money Etc.• You all- for being here and listening to me with patience.• Last but not the least- The GOOGLE and student and research community across the world for providing knowledge and content for free access.