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Nanocomposites. By Milind Arbatti Instructor: Dr. Tzeng 7970. Introduction. What are Composite materials? Theory behind Composites Limitations of Composite materials Welcome to the world of nanocomposites! Theory behind nanocomposites Making of nanocomposites

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nanocomposites

Nanocomposites

By

Milind Arbatti

Instructor: Dr. Tzeng

7970

Nanocomposites

introduction
Introduction
  • What are Composite materials?
  • Theory behind Composites
  • Limitations of Composite materials
  • Welcome to the world of nanocomposites!
  • Theory behind nanocomposites
  • Making of nanocomposites
  • Properties of nanocomposites
  • Applications
  • Limitations
  • Questions

Nanocomposites

definition of composite materials
Multiphase material

Usually exhibits properties of both phases

Usually improves performance over either individual phase

Composites have already been discussed

Multiphase metal alloys, or ceramics or polymers

Example, pearlitic steels, alt. layers a + Fe3C

There are also composites spanning materials classes (e.g. ceramic and metals)

Definition of Composite Materials

mse.iastate.edu/mate271/lectures/ 7%20-%20Composites.ppt

Nanocomposites

theory
Theory!
  • Composites often have only two phases
  • Matrix phase
    • continuous - surrounds other phase
  • Dispersed phase
    • discontinuous phase

Matrix (light)

Dispersed phase (dark)

mse.iastate.edu/mate271/lectures/ 7%20-%20Composites.ppt

Nanocomposites

classification of artificial composites
Classification of Artificial Composites

Composites

Particulate

Fiber

Structural

Large

Dispersion

Laminates

Sandwich

Particle

Strengthened

Panels

Continuous

Discontinuous

Aligned

Random

mse.iastate.edu/mate271/lectures/ 7%20-%20Composites.ppt

Nanocomposites

properties of composites
Properties of Composites

Dependent on:

  • constituent phases
  • relative amounts
  • geometry of dispersed phase
    • shape of particles
    • particle size
    • particle distribution
    • particle orientation

For a given matrix/dispersed phase system:

  • Concentration
  • Size
  • Shape
  • Distribution
  • Orientation

mse.iastate.edu/mate271/lectures/ 7%20-%20Composites.ppt

Nanocomposites

parameters

mse.iastate.edu/mate271/lectures/ 7%20-%20Composites.ppt

Parameters

Concentration

Orientation

Distribution

Size

Shape

Nanocomposites

slide8

Rule of Mixtures

Actual

Values

Upper bound

*

*

E - particulate

*

*

*

E- matrix

*

*

Lower bound

conc. of particulates

http://www.eng.umass.edu/plastics/nano.ppt

Nanocomposites

fiber reinforced composites
Technologically, the most important type of composite.

Characterized in terms of specific strength or specific modulus = strength (or E) per weight

usually want to maximize specific strength and modulus

Subclasses:

Short fiber and continuous fiber lengths

Fiber Phase

Requirements for the fiber

The small diameter fiber must be much stronger than the bulk material

High tensile strength

(Wiskers, Fibres, Wires)

Matrix Phase

Function

Binds fibers together

Acts as a medium through which externally applied stress is transmitted and distributed to the fibers

Protects fiber from surface damage

Separates fibers and prevents a crack from one fiber from propagating through another

Fiber-Reinforced Composites

http://www.eng.umass.edu/plastics/Composites.ppt

Nanocomposites

influence of fiber length
Influence of Fiber Length
  • Mechanical properties depend on:
      • mechanical properties of the fiber
      • how much load the matrix can transmit to the fiber
        • depends on the interfacial bond between the fiber and the matrix
  • Critical fiber length - depends on
      • fiber diameter, fiber tensile strength
      • fiber/matrix bond strength

Critical fiber length - lc

lc = sfd/2tc

where

d = fiber diameter

tc = fiber-matrix bond strength

sf = fiber yield strength

mse.iastate.edu/mate271/lectures/ 7%20-%20Composites.ppt

Nanocomposites

influence of fiber orientation
Influence of Fiber Orientation
  • Fiber parameters
    • arrangement with respect to each other
    • distribution
    • concentration
  • Fiber orientation
    • parallel to each other
    • totally random
    • some combination

mse.iastate.edu/mate271/lectures/ 7%20-%20Composites.ppt

Nanocomposites

limitations of composites
Limitations of Composites
  • Properties of material are highly anisotropic due to orientation fibers
  • Modulus in direction of alignment is a function of the volume fraction of the E of the fiber and matrix
  • Modulus perpendicular to direction of alignment is considerably less (the fibers do not contribute)
  • Loss of transparency
  • Loss Optical/Electrical/Chemical (barrier) Properties

Nanocomposites

welcome to the nano world
Welcome to the “Nano”World !!!
  • A broad class of materials, with microstructures modulated in zero to three dimensions on length scales less than 100 nm.
  • Materials with atoms arranged in nanosized clusters, which become the constituent grains or building blocks of the material
  • Any material with at least one dimension in the 1-100m range

Nanocomposites

classes of nanostructured materials
Classes of nanostructured materials
  • Range, from zero dimensional atom clusters to three dimensional equiaxed grain structure.  Each class has at least one dimension in the nanometer range

zero modulation dimensionalitythree dimensionally modulated

Nanocomposites

properties
Properties
  • Tiny particels with very high aspect ratio, and hence larger surface area.
  • Larger surface area enables better adhesion with the matrix/surface.
  • Improvement in the mechanical performance of the parent material.
  • Better transparency due to small size(>wavelength of light).

Nanocomposites

nanoparticles
Nanoparticles
  • A lot of research literature in this area.
  • Common in everyday life.
  • Examples include film materials, catalyst, ion exchangers, nanocrystals, semiconductors - quantum dots, molecular diodes.

Source: www.kodak.com

http://rescomp.stanford.edu/~gcronin/sld007.htm

Nanocomposites

nanoclays
Nanoclays
  • Silicates layers separated by an interlayer or gallery.
  • Silicates layers are ~ 1 nm thick, 300 nm to microns laterally.
  • Polymers as interlayers.
  • Tailor structural, optical properties

http://rescomp.stanford.edu/~gcronin/sld0011.htm

Nanocomposites

nanofibers nanotubes
Nanofibers - Nanotubes
  • Nanotubes in metal, metal oxide and ceramic matrix have also been fabricated.
  • Typical fabrication process is by hot-pressing the powdered matrix with the nanotubes.
  • Nanotubes in polymer matrices by mixing, then curing.
  • Most important filler category in nanocpomposites

http://rescomp.stanford.edu/~gcronin/sld0012.htm

Nanocomposites

nanocomposites1
Nanocomposites
  • Constituents have at least one dimension in the nanometer scale.
    • Nanoparticles (Three nano-scale dimensions)
    • Nanofibers (Two nano-scale dimensions)
    • Nanoclays (One nano-scale dimensions)

Nanocomposites

characteristics
Characteristics

http://rescomp.stanford.edu/~gcronin/sld008.htm

Nanocomposites

characteristics of polymer layered silicates
Characteristics of Polymer Layered Silicates
  • Due to the layer orientation, polymer-silicate nanocomposites exhibit stiffness, strength and dimensional stability in two dimensions (rather than one). In addition, because of the length scale involved that minimizes scattering, nanocomposites are usually transparent. Furthermore, PLS [Polymer-Layered Silicate] nanocomposites exhibit a significant increase in thermal stability as well as self-extinguishing characteristics.
  • Uniform dispersion of these nanoscopically sized filler particles (or nanoelements) produces ultra-large interfacial area per volume between the nanoelement and host polymer. This immense internal interfacial area and the nanoscopic dimensions between nanoelements fundamentally differentiate PNCs from traditional composites and filled plastics. Thus, new combinations of properties derived from the nanoscale structure of PNCs provide opportunities to circumvent traditional performance trade-offs associated with conventional reinforced plastics, epitomizing the promise of nano-engineered materials.

www.me.berkeley.edu/nti/tan1.ppt

Nanocomposites

slide23

Nanocomposites

  • Multi-constituent materials.
  • Superior overall properties compared to constituent properties e.g. optical clarity, strength, stiffness, permeability.
  • Ability to tailor properties.

www.me.berkeley.edu/nti/tan1.ppt

Nanocomposites

continued
Continued……
  • From the structural point of view, the role of inorganic filler, usually as particles or fibers, is to provide intrinsic strength and stiffness while the polymer matrix can adhere to and bind the inorganic component so that forces applied to the composite are transmitted evenly to the filler. Meanwhile, the polymer matrix can also protect the surface of the filler from damage and keep the particle apart to hinder crack propagation.
  • Nanocomposite materials can achieve much better properties than just the sum of its components as a result of interfacial interaction between the matrix and filler particles.

www.me.berkeley.edu/nti/tan1.ppt

Nanocomposites

synthesis of nanocomposites
Chemical Synthesis:

Gas Phase Synthesis

Chemical Vapor Condensation

Combustion Flame Synthesis

Liquid Phase Synthesis

Others –

Mechanical Deformation

Thermal recrystallization

Synthesis of Nanocomposites

Nanocomposites

gas phase synthesis synthesis of ultra pure metal powders and compounds of metal oxides ceramics
The nano powder formed normally has the same composition as the starting material.

The starting material, which may be a metallic or inorganic material is vaporized using some source of energy

The metal atoms that boil off from the source quickly loose their energy. These clusters of atoms grow by adding atoms from the gas phase and by coalescence

A cold finger is a cylindrical device cooled by liquid nitrogen. The nano particles collect on the cold finger

The cluster size depends on the particle residence time and is also influenced by the gas pressure, the kind of inert gas, i.e. He, Ar or Kr and on the evaporation rate of the starting material. The size of the nano particle increases with increasing gas pressure, vapor pressure and mass of the inert gas used.

http://www.rpi.edu/dept/materials/COURSES/NANO/moraes/page1.html

Gas Phase Synthesis(Synthesis of ultra pure metal powders and compounds of metal oxides(ceramics) )

Nanocomposites

chemical vapor condensation

http://www.rpi.edu/dept/materials/COURSES/NANO/moraes/page2.htmlhttp://www.rpi.edu/dept/materials/COURSES/NANO/moraes/page2.html

Chemical Vapor Condensation
  • the precursor vapor is passed through a hot walled reactor. The precursor decomposes and nano particles nucleate in the gas phase. The nano particles are carried by the gas stream and collected on a cold finger. The size of the nano particles is determined by the particle residence time, temperature of the chamber, precursor composition and pressure.

Nanocomposites

combustion flame synthesis

http://www.rpi.edu/dept/materials/COURSES/NANO/moraes/page2.htmlhttp://www.rpi.edu/dept/materials/COURSES/NANO/moraes/page2.html

Combustion Flame Synthesis
  • Energy to decompose the precursor may be supplied by burning a fuel-air mixture with the precursor. In order to reduce agglomeration of the particles in the flame, the flame is specially designed to be low pressure.
  • If you have observed the flame of a candle, you would have noticed that the flame consist of a blue center and a yellow to red periphery. This is because the temperature in the flame varies with position in the flame. Such a variation in the temperature profile of the flame would cause nanoparticles of different sizes to grow in the different regions of the flame. This is avoided by designing the flame to have a 'flat temperature profile' i.e. a constant temperature across its width.

Nanocomposites

liquid phase synthesis

http://www.rpi.edu/dept/materials/COURSES/NANO/moraes/page3.htmlhttp://www.rpi.edu/dept/materials/COURSES/NANO/moraes/page3.html

Liquid Phase Synthesis
  • Two chemicals are chosen such that they react to produce the material we desire
  • An emulsion is made by mixing a small volume of water in a large volume of the organic phase. A surfactant is added. The size of the water droplets are directly related to the ratio of water to surfactant. The surfactant collects at the interface between the water and the organic phase. If more surfactant were to be added, smaller drops would be produced and therefore, as will become apparent, smaller nano-particles.

Nanocomposites

carbon nanotubes
Carbon nanotubes
  • Tubular form of carbon with nanoscale diameter
  • Folding a 2D sheet of graphene in different directions
  • Electronic properties depend on direction of folding
  • Doping of semiconducting carbon nanotubes

From: http://www.seas.upenn.edu/mse/images/nanotube1.jpg

Nanocomposites

laser ablation method to fabricate carbon nanotubes
Laser ablation method to fabricate carbon nanotubes
  • Laser vaporises target (graphite + catalyst)
  • Carbon nanotubes from cooling mixture particles
  • Proportion of catalyst controls type of nanotubes

http://www.ifw-dresden.de/iff/11/spec/areas/fullerenes/spec_full_nano.html

Nanocomposites

applications

Park et. al., Block copolymer lithography: Periodic arrays of ~1011 holes in 1 square centimeter, Science, 276, 1401-1404, 1997

APPLICATIONS
  • Composite Industry –

Drastic improvement in the mechanical performance of materials.

Estimated Modulus

Nanocomposites

barrier properties

http://www.rpi.edu/dept/materials/COURSES/NANO/moraes.html

Barrier Properties
  • The silicate blocks are arranged alternately. Imagine a drop of water trying to get through the PLS barrier compared to a conventional filled polymer. The water drop would face more barrier going through the PLS nanocomposites because of the layered silicates arrangement.
  • Uses: 

Packaging in food, medical and pharmaceutical industry

Nanocomposites

thermal barrier coatings tbc for aircraft gas turbine engines
Thermal Barrier Coatings(TBC) for Aircraft Gas Turbine Engines

Protection Required against:

  • High temperatures (gas T's up to approximately 2000 C and component T's of approximately 1200 C!)
  • High partial pressures of oxygen
  • High heat fluxes

TBC’s such as Alumina, Pt-Aluminide

Higher gas temperatures ==> higher engine efficiency

  • Lower component temperatures (so they don't fail)
  • Reduced cooling air requirements
  • Moderation of thermal transients
  • A decrease in the severity of engine hot spots by 80-150C below normal values.

http://www.rpi.edu/dept/materials/COURSES/NANO/stewart/index.htm

Nanocomposites

nanocrystalline diamond thin films
Nanocrystalline Diamond Thin Films
  • Uses based on Physical Strength

Cutting Tools

Protective Coatings

Composite Additives

Nanocomposites

membranes
Membranes
  • Commonly made from Alumina, (Al2O3 ), Titania, (TiO2) , and Zirconia, (ZrO2)
  • Membranes made of nanometer sized grains are stronger, less brittle and have higher temperature resistance than bulk ceramics. Pore sizes are on the order of 3-5 nanometers.
  • Current uses:

Hemodialysis, Plasmapheresis - Separation of blood components and plasma from whole blood

  • Potential uses: High temp catalytic reactions , solid oxide fuel cells

http://www.rpi.edu/dept/materials/COURSES/NANO/narang/index.html

Nanocomposites

drug delivery
Drug Delivery

Attributes of Nanoparticulate Systems

  • provide a better penetration of the particles inside the body.
  • can be used for intramuscular or subcutaneous applications
  • minimizes the irritant reactions at the injection site.
  • exhibit greater stability, in both longer shelf storage lives and uptake times.
  • and can be designed to elicit the desired kinetics, uptake, and response from the body(i.e. Biocompatibility).

http://www.rpi.edu/dept/materials/COURSES/NANO/bio.htm

Nanocomposites

medical
Medical
  • Nanoceramics have already shown outstanding osteoblast proliferation (Webster et al.).
  • If a hierarchical approach that mimics natural bone can be created for nanomaterials, these cellular interactions may be improved even further.
  • Additionally, the corresponding increase in mechanical properties may allow previously unsuitable materials to become viable options for future implants.

Nanocomposites

summary of applications
Summary of Applications
  • Nanocomposite materials and coatings:
    • Thermal and environmental barriers
    • Wear resistant coatings and parts
    • Tailored optical barriers
    • Flame retardant plastics
  • High surface area nanostructures:
    • Catalysts (molecule specific)
    • Energy storage media (nanoparticles, nanotubes)

Nanocomposites

hierarchical nanostructures
Hierarchical Nanostructures
  • Ultrahigh-strength, tough structural materials
  • Ductile and strong cements
  • Net-shape formed ceramic parts
  • Magnetic/thermoelectric thermal management
  • New materials for MEMS
  • Smart materials with embedded sensors and actuators

Nanocomposites

slide41

Limitations!

  • To date one of the few disadvantages associated with nanoparticle incorporation has concerned toughness and impact performance. Nanoclay modification of polymers such as polyamides, could reduce impact performance.
  • Research will be necessary to develop a better understanding of formulation/structure/property relationships, better routes to platelet exfoliation and dispersion etc.
  • Economically feasible.

Nanocomposites

my questions
My Questions
  • Which geometrical factor plays an important role in nanocomposites?
  • Mention the processes for the synthesis of nanocomposites and explain any one of them in detail.

Nanocomposites

questions
Questions?

Nanocomposites

slide44
1.Date:06/20/2003
  • 2.Presenter’s name: Milind Arbatti
  • 3.Title of presentation:Nanocomposites
  • The following is for the class to fill out and turn in at the end of each class:
  • Name of student turning in this form _______________________
  • 4.From 1 to 10 (ten being the best), how do you grade the materials presented? ______
  • 5.From 1 to 10 (ten being the best), were complete references given for each side? ______
  • 6.From 1 to 10 (ten being the best), how well is the presentation understandable? _______
  • 7.From 1 to 10 (ten being the best), how are the glossary, questions and problems presented? ______
  • 8.Suggestion:

Nanocomposites