Post on 27-May-2015
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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.