overview of nanoparticle
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Overview of Nanoparticle & itsapplications to Lubricants
Dr.K.Balamurugan
Associate Professor/Mech. Engg.IRTT, Erode
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Agenda Nanotechnology
Nanoparticles
Lubricants
HS&E issues
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"There's plenty of room at the bottom."
Richard P. Feynman, Ph.D.
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What is
Nanotechnology?
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Nanotechnology is an enabling
technology that will change thenature of almost every human-madeobject in the next century.
-National Science and Technology Council
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What is Nanotechnology?Nanotechnology is about:
Making small objects Manipulating small objects
Creating new materials by varying the
size of the objects Building structures from small objects
This slide is adapted from the presentation on AnIntroduction to Nanotechnology, by Terry Bigioni, posted at
http://www.homepages.utoledo.edu/tbigion/BigioniGroup/Outreach_Home.html
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WHAT IS NANOTECHNOLOGY?
* 1 millimeter = 1,000 micrometers;1 micrometer = 1,000 nanometers
Source: "Nanotech: The Tiny Revolution" by CMP Cientfica (November 2001)
Structures(e.g.materials)
Devices(e.g. sensors)
Systems(e.g. NEMS)
Nanotechnology is themanipulation of matterat the nanometer*scale to create novel
structures, devices andsystems.
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Building Complex Structures with SmallObjects
Top-down(i.e. Lithography)
Bottom-up(i.e. Self-assembly)
Mixing large objects with small
ones(i.e. nanocomposites) Carbon matrix
Nanotube bundles
Composite
fabrication
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Starting frombig thingshas meant producing things with the precision that
we were able to achieve, but -at the same time-
producing lots ofwaste or pollution,and consuming a lot of energy.
As we got better at technology,
precision improved and
waste/pollution diminished,but the approach
was still the same.
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Starting fromsmall things
means absolute precision(down to one single atom !),
complete control of processes(no waste?) and
the use ofless energy(withless CO2, less greenhouse
effect, perhaps you
heard about that on TV).
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Advantages of
starting fromsmall thingsthe distance between the centre of two footballs isbigger than the distance between the centre of two
nuts smaller means nearer(and quicker to connect)
you can dissolve sugar or salt quicker
when it is in powder form and slowerwhen it is in the form of crystals orblocks smaller can becomemore reactive
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Nanotechnology The science of constructing unique materials at
the molecular level, in the scale of 1-100nanometers.
1 nanometer is 1/1000 of a micron, or 1 billionthof a meter.
At this level, it is possible to vary fundamentalproperties of materials (for instance, melting
temperature, magnetization, charge capacity)without changing the chemical composition.
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A DIVERSE SET OF OPPORTUNITIES
1-4
5-8
9-14
15+
Composites
Solar
cells
Lighting
Foodpackaging
Energy/
fuel cells
Energy,
Industrial
PortableEnergy
cells
Bio-materials
Tissue/organregen
NanobioNEMS
Smartimplants
Drugdelivery
Medicaldiagnostics
Medical
applications
Nano-arrays
Years
Chemical
catalysts
Textiles
Coatings &
Powders
LubricantsCoatings
Cosmetics
Paints
Micro-processors
Quantumcomputing
Simple
ICs
Memory/Storage
devices
Sensors
Displays
Devices &Microelectronics
Molecular
circuitry
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Nanotechnology Smaller is Different:
Surface-Effects Dominate
Ratio of surface area to volume become very large
The Macro World is Dominated by: Gravity
Inertia
Magnetism
The Micro World is Dominated by:
Electrostatics Surface Tension
van der Waals Forces
Example: water cannot flow through microfluid tubesdue to its large surface tension.
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Nanoparticle
Particle size less than 100 nm
Physical changes
Surface area to the volume Classical mechanics to quantum mechanics
Transparent
ultrafine particles, clusters, nanocrystals,quantum dots
Organic an inorganic materials Carbon, Graphite, Copper, Mx2, silicate, Ceramic
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Top-down Approaches
milling or attrition
thermal cycles
10 ~ 1000 nm; broad size distribution
varied particle shape or geometry
impurities for nanocomposites and nanograined
bulk materials (lower sintering
temperature)
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Bottom-up Approaches
Two approaches
thermodynamic equilibrium approach generation of supersaturation nucleation
subsequent growth
kinetic approach limiting the amount of precursors for the
growth
confining in a limited space
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Nanoparticle - Production Techniques
Vapour condensation
Chemical synthesis
Solid state process
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Vapour condensation
It involves evaporation of solid metal followedby rapid condensation to form nanosized
clusters that settle in the form of powder.
Used to make metallic and metal oxideceramic nanoparticles
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Vapour condensation
Inert gases are used to avoid oxidation whencreating metal nanoparticles
Reactive oxygen atmosphere is used toproduce metal oxide ceramic nanoparticles.
Final particle size is controlled by processparameters such as temperature, gasenvironment and evaporation rate
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Vapour condensation
Vacuum evaporation on running liquids(VERL)
This uses a thin film of a relatively viscousmaterial, an oil, or a polymer, for instance, ona rotating drum
Chemical Vapour Deposition
Thin films, particles
Adv. : Low contamination levels
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Chemical synthesis
Most widely used technique
It consists essentially of growing nanoparticles ina liquid medium composed of various reactants
Sol-Gel method, SonoChemistry, Precipitation
Better in controlling the final shape of theparticles
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Chemical synthesis
Choosing chemicals that form particles thatare stable, and stop growing, at a certain size
Low-cost and high volume
Contamination by the chemicals
Create surface coatings
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Arrested precipitation
Precipitation under starving conditions: a largenumber of nucleation centers are formed by
vigorous mixing of the reactant solutions.
If concentration growth is kept small, nucleigrowth is stopped due to lack of material.
Particles had to be protected from Oswald Ripening by stabilizers
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Oswald Ripening
The growth mechanism where smallparticles dissolve, and are consumed by
larger particles. As a result the averagenanoparticle size increases with timeand the particle concentration
decreases. As particles increase in size,solubility decreases.
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Solid state process
Grinding or milling can be used tocreate nanoparticles
The milling material, milling time andatmospheric medium will affect theresult
Contamination from the milling material
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Stabilization of Nanoclusters AgainstAggregation
1. Electrostatic stabilizationAdsorption of ions to thesurface. Creates an electrical
double layer which results in aCoulombic repulsion forcebetween individual particles
2. Steric StabilizationSurrounding the metal centerby layers of material that aresterically bulky,Examples: polymers,surfactants, etc
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StabilizersRole of stabilizers: Stabilizing agents/ligands/cappingagents/passivating agents
prevent uncontrollable growth of particles prevent particle aggregation control growth rate controls particle size Allows particle solubility in various solvents
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Other Common Stabilizers1. Organic ligands
Thiols (thioethanol, thioglycerol, etc) Amines
phosphates
2. Surfactants
3. Polymers
4. Solvents (ether, thioether)
5. Polyoxoanions
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Table 3.1
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Common Methods for NanoparticleCharacterization
Particle
Size
Surface
Area
Surface state
Surface
composition
Surface
structure;
TopographySurface
ComplexesElectron Microscopy
X-ray diffraction
Magnetic Measurements AES,
XPS,
SIMS,
EPMA,
EXAFS
LEED
SEM
TEM
EXAFS
IR, UV-Vis, ESR, NMR, Raman
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