Introduction to new materials

By Keval K. Patil
By Keval Patil- 8668584494
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 Composites:
 Basic concepts of composites,
 Processing of composites,
 Advantages over metallic materials,
 Various types of composites and their applications
 Nano Materials:
 Introduction,
 Concepts,
 Synthesis of nanomaterials,
 Examples,
 Applications and
 Nano composites
 An overview to Smart materials
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 A composite material is made by combining two or more
materials – often ones that have very different properties.
 The two materials work together to give the composite unique
properties.
 However, within the composite you can easily tell the different
materials apart as they do not dissolve or blend into each other.
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 Higher specific strength than metals, non-metals and even alloys.
 Lower specific gravity in general.
 Improved stiffness of material.
 Composite maintain their weight even at high temperatures.
 Toughness is improved.
 Fabrication or production is cheaper.
 Creep and fatigue strength is better.
 Controlled Electrical conductivity is possible.
 Corrosion and oxidation resistance.
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 They generally have two phases:-
1. Matrix Phase.
2. Dispersion Phase.
1. Matrix Phase :-
 It is the continuous material constituent which encloses the composite
and give it its bulk form.
 Matrix phase may be metal , ceramic or polymer.
2. Dispersion Phase:-
 It is the structure constituent , which determines the internal structure
of composite.
 Dispersion Phase is connected to matrix phase by bonding
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Composite.
Particle-reinforced Fibre-reinforced Structural
Large particle Dispersion-
strengthened
Continuous
(Alignment)
Discontinuous
(Short)
Laminates Sandwich
panels
Aligned Randomly
oriented
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REINFORCEMENTS
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 One form of composites is particulate reinforced composites with concrete being a
good example. The aggregate of coarse rock or gravel is embedded in a matrix of
cement. The aggregate provides stiffness and strength while the cement acts as the
binder to hold the structure together.
 There are many different forms of particulate composites. The particulates can
be very small particles (< 0.25 microns), chopped fibres (such as glass), platelets,
hollow spheres, or new materials such as Bucky balls or carbon nano-tubes. In
each case, the particulates provide desirable material properties and the matrix acts as
binding medium necessary for structural applications.
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 Some polymeric materials to which fillers have been added are really large- particle composites.
The fillers modify or improve the properties of the material. Example of large- particle composite
is concrete, which is composed of cement (the matrix), and sand and gravel (the
particulates).Particles can have quite a variety of geometries, but they should be of approximately
the same dimension in all direction (equated).
 For effective reinforcement, the particles should be small and evenly distributed throughout the
matrix. The volume fraction of the two phases influences the behavior; mechanical properties are
enhanced with increasing particulate content.
 Rule of mixture: equation predict that the elastic modulus should fall between an upper and
lower bound as shown:
 Example: Fig. 1.1 plots upper and lower bound Ec – versus Vp curves for a copper –
tungsten composite; in which tungsten is the particulate phase.
 Where:-
Ec: elastic modulus of composite
Ep: elastic modulus of particle
Em: elastic modulus of matrix
Vm: volume fraction of matrix
Vp: volume fraction of particle
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 Dispersion-strengthened means of strengthening materials where in very small particles
(usually less than 0.1 µm) of a hard yet inert phase are uniformly dispersed within a load –
bearing matrix phase.
 The dispersed phase may be metallic or nonmetallic, oxide materials are often used.
 Figure 1.2 Comparison of the yield strength of dispersion-strengthened sintered
aluminum powder (SAP) composite with that of two conventional two-phase high- strength
aluminum alloys. The composite has benefits above about 300°C. A fiber- reinforced
aluminum composite is shown for comparison.
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 The Rule of Mixtures in Fiber-Reinforced Composites
 Strength of Composites - The tensile strength of a fiber-reinforced composite
(TSc) depends on the bonding between the fibers and the matrix.
 Figure 1.3 The stress-strain curve for a fiber-reinforced composite. At low stresses
(region l), the modulus of elasticity is given by the rule of mixtures. At higher stresses
(region ll), the matrix deforms and the rule of mixtures is no longer obeyed.
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 Continuous & Aligned
 The fibres are longer than a critical length
which is the minimum length necessary such
that the entire load is transmitted from the
matrix to the fibres.
 If they are shorter than this critical length,
only some of the load is transmitted.
 Fibre lengths greater that 15 times the
critical length are considered optimal.
Aligned and continuous
 fibres give the most effective strengthening
for fibre composites.
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 Discontinuous & Aligned
The fibres are shorter than the critical length. Hence discontinuous fibres are less effective in
strengthening the material, however, their composite modulus and tensile strengths can
approach 50-90% of their continuous and aligned counterparts.
And they are cheaper, faster and easier to fabricate into complicated shapes.
 Random
This is also called discrete, (or chopped) fibres. The strength will not be as high as with
aligned fibres, however, the advantage is that the material will be isotropic and cheaper.
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STRUCTURAL COMPOSITES
 A structural composite consists of both homogeneous and composite material.
There properties depend on, the characteristic properties of the constituent materials
as well as the geometric design.
 Structural composite are of two types:-
1.Laminar compost 2.Sandwich panel
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LAMINAR COMPOSITE
 It consists of panels or sheets which
are two dimensional. These panels
possess preferred directions to
achieve high strength.
 Such s
with
an a
streng
uccessively oriented layers are stacked one above
preferred directions and then are cemented. Such
rrangement or orientation ensures varying highest th
with each successive layer involved in material.
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SANDWICH PANEL
 Sandwich panel is also a kind of
layered composite. It consists of ‘faces’
and ‘core’
 With increase in thickness of core, its
stiffness increases as seen in the most
common sandwich panel
‘honeycomb’.
 Faces:-They are formed by two strong
outer sheets.
 Core:-Core is layer of less dense
material.
 Honeycomb:-Structure which contain
thin foils forming interlocked
hexagonal cells with their axes oriented at
right angles in the direction of face
sheet.
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 In automobile industries (e.g. Steel
&Aluminium body)
 Marine applications like shafts,
hulls, spars (for racing boats)
 Aeronautical application like
components of rockets, aircrafts
(business and military), missiles
etc.
 Communication antennae,
electronic circuit boards (e.g. PCB,
breadboard)
 Safety equipment like ballistic
protection and Air bags of cars.
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 Nanomaterials are commonly defined as materials with an
average grain size less than 100 nanometers
 Nanomaterials have extremely small size which having at least
one dimension 100 nm
 One billion nanometers equals one meter
 The average width of a human hair is on the order of 100,000
nanometers
 A single particle of smoke is in the order of 1,000 nanometers
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 One dimensional nanomaterial: This type of material has one
dimension arrangement of atoms in the nanoscale range. The
examples for one dimension nanomaterial are surface coatings
and thin films.
 Two-dimensional nanomaterial: This type of material has two
dimension arrangements of atoms in the nanoscale range. The
examples for two dimension nanomaterial are biopolymers,
nanotubes, and nanowires.
 Three-dimensional nanomaterial: This type of material has
three dimension arrangements of atoms in the nanoscale range.
The examples for three dimension nanomaterial are fullerenes.
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 It is observed that the properties are distinct on the nanoscale from those at
the larger scale.
 The properties like quantum, mechanical and thermodynamical become vital
at the nano level and these are not seen at the macroscopic level.
 The nanoscience is based on the fact that along with the physical dimensions
of the materials the properties of the materials also change.
 The transformation in the properties of the materials in these confined spaces
is because of the changes in the electronic structure of the materials.
 The properties of the materials are distinct at the nano level due to the
following two reasons:
 Increased surface area
 Quantum confinement effect
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The properties of the nanomaterials depend on the crystal structure and size and few
properties of the nanomaterials are explained below:
 Physical properties
 Mechanical properties
 Magnetic properties
 Optical properties
 Thermal properties
 Surface area
 Catalytic activity
 Electrical properties
 Semiconductors
 Superconductors
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 Physical properties: In the nanoscale range, surface area to volume enhances. This
enhancement transforms the surface pressure and results in a change in the
interatomic spacing.
 Mechanical properties: The nanomaterials have the application on both the low
temperatures and high temperatures. So, the mechanical properties of the
nanomaterials are studied at low temperatures and also at the high temperatures.
 Magnetic properties: The magnetic behavior of the nanomaterials is size
dependent. In the tiny ferromagnetic particles, the magnetic properties are distinct
from that of the very large material. In the range of nanoscale, magnetic material
has a single magnetic domain. As an outcome, the remanent magnetization and
coercive field exhibit a strong dependence on the size of a particle.
 Optical properties: If the particles of a semiconductor are made tiny then the
effects of quantum come into play which limits the energies at which the electrons
and holes can exist in the particles.
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 Thermal properties: The nanocrystalline materials are expected to have a
low conductivity of thermal when compared with the conventional materials.
 Surface area: Nanomaterials have large surface area and the nanocrystal’s
surface area is inversely proportional to the crystal’s size.
 Catalytic activity: Nanomaterials can be availed as effective catalysts in
many reactions.
 Electrical properties: Nanomaterials exhibit electrical properties in between
semiconductors and metals depending on the chirality of the molecules and
diameter of the molecules.
 Semiconductors: Most of the nanomaterials play the role of a
semiconductor and these nanowires which have the feature of being a
semiconductor are used in making distinct components.
 Superconductors: Few nanomaterials behave as the superconductors.
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The nanomaterials have its applications in distinct fields and few of
them are as follows:
 Material technology
 Information technology
 Biomedicals
 Energy storage
 The carbon nanotubes and nanowires are utilized in making many
components.
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What is a Rheological Material and how do they work?
 Generally, a rheological material is a material which can change is physical
state very quickly in reaction to a stimulus.
 Rheological materials only react when an electric or magnetic field is
applied.
 The material always changes between a liquid and a solid state (Lord Corp).
 While rheological materials that react to an electric field (ER) have some
very specific uses and are more well known, in almost all cases
magnetorheological (MR) materials are more practical.
 Unlike ER materials, they function in the presence of impurities and only
low voltages are needed to stimulate them.
 For this reason, ER materials will be omitted from the following explanation
(Lord Business Unit).
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Introduction to new materials

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