Modern engineering materials

MODERN ENGINEERING
MATERIALS
BY DERAK DAVIS

INTRODUCTION
TO MODERN ENGINEERING MATERIALS
1

There have been a number of science fields which have helps to
producing new engineering materials.
Some of the fields are the Nano engineering and the forensic
engineering.
Hundreds and hundreds of scientists and inventors are working
and experimenting continuously to make this world a better place
to live.
These new inventions have gradually changed the course of
living of people, these New engineering materials are not a result
of single engineering technology but these are obtained or
produced from a blend of different technologies.
Some of the Modern Engineering Materials are discussed here.

EXAMPLES
OF MODERN ENGINEERING MATERIALS
2

AEROGEL
◇ Aerogel holds 15 entries in the Guinness Book
of Records.
◇ Nick name “Frozen Smoke”.
◇ Aerogel was first created by Samuel Stephens
Kistler in 1931, as a result of a bet with Charles
Learned over who could replace the liquid in
"jellies" with gas without causing shrinkage.
◇ Aerogels are produced by extracting the liquid
component of a gel through supercritical drying.
◇ This allows the liquid to be slowly dried off
without causing the solid matrix in the gel to
collapse from capillary action, as would happen
with conventional evaporation.
◇ Kistler's later work involved aerogels based
on alumina, chromium and tin dioxide.

◇ Aerogel is a material that is 98.2% air.
◇ Aerogels are good thermal insulators because they almost nullify 2 of the three
methods of heat transfer – conduction and convection.
◇ They are good conductive insulators because they are composed almost entirely
of gases, which are very poor heat conductors.
◇ They are good convective inhibitors because air cannot circulate through the
lattice.
◇ Aerogels are poor radiative insulators because infrared radiation passes through
them.
◇ Owing to its hygroscopic nature, aerogel feels dry and acts as a strong desiccant.
◇ Aerogels by themselves are hydrophilic, but chemical treatment can make
them hydrophobic.
◇ The slight colour it does have is due to Rayleigh scattering of the
shorter wavelengths of visible light by the Nano-sized dendritic structure.
PROPERTIES OF AEROGEL

◇ A chemical absorber for cleaning up spills.
◇ A catalyst or a catalyst carrier.
◇ Silica aerogels can be used in imaging devices, optics, and light guides.
◇ Thickening agents in some paints and cosmetics.
◇ As components in energy absorbers.
◇ Laser targets for the National Ignition Facility.
◇ A material used in impedance matchers for transducers, speakers and range
finders.
◇ In water purification, chalcogels have shown promise in absorbing the heavy
metal pollutants mercury, lead, and cadmium from water.
◇ In aircraft de-icing, a new proposal uses a carbon nanotube aerogel. A thin
filament is spun on a winder to create a 10 micron-thick film, equivalent to an A4
sheet of paper.
◇ Thermal insulation transmission tunnel of the Chevrolet Corvette (C7).
APPLICATIONS OF AEROGEL

NANO MATERIALS
◇ Material possessing grain size of the order of a
billions of a meter.
◇ Used in variety of structural and non structural
application.
◇ This materials are composed of grains, they
are usually invisible to the naked eye.
◇ Nano crystalline material has grain on the order
of 1 - 100 nm.
NANO TECHNOLOGY
Nano Technology is a field of applied science and
technology which deals with the matter on the
atomic and molecular scale, normally 1 – 100 nm,
and fabrication of devices with critical dimensions
that lie within that size range.

TOP – DOWN APPROACH
◇ The removal or division of
bulk material to produce the
desired micro structure.
◇ It is the proccess of
breaking down bulk
materials to nano size.
BOTTOM – UP APPROACH
◇ Molecules even nano
particles used as the
building block for producing
complex nano structure.
◇ The nano particle are made
by building atom by atom.
SYNTHESIS OF NANO MATERIALS

◇ Can store more electrical energy than bulk material. Because of their large
grain boundary.
◇ Linear and Non – linear optical properties can be finely modified by
cotrolling crysal dimension.
◇ Increased surface area cause increases the chemical activity.
◇ Hardness, elastic modulus, fracture, fatigue strength increased at
nanometer scale.
◇ Thermal coductivity greater than bulk material.
PROPERTIES OF NANO MATERIAL

◇ Since they are stronger, lighter, etc. They are used to make hard metals.
◇ Smart magnetic fluids are used in vaccum seal, magnetic seperators, etc.
◇ Used in giant magneto resistant spin values.
◇ Nano – Micro Electro Mechanical Systems are used in ICs, Optical
Switches, Pressure Sensors, etc.
◇ Used in energy storage devices like hydrogen storage devices, magnetic
refrigeration and in ionic batteries.
◇ Used to store information in small chips.
◇ Nano – structured Ceramic is the main component in sythetic bones.
APPLICATIONS OF NANO MATERIAL

CARBON NANOTUBE
◇ Carbon nanotubes (CNTs) are allotropes of
carbon with a cylindrical nanostructure.
◇ Owing to the material's exceptional strength and
stiffness, nanotubes have been constructed with length-
to-diameter ratio of up to 132,000,000:1, significantly
larger than for any other material.
◇ In addition, owing to their extraordinary thermal
conductivity, mechanical, and electrical properties,
carbon nanotubes find applications as additives to
various structural materials.
◇ The chemical bonding of nanotubes involves
entirely sp2-hybrid carbon atoms. These bonds, which
are similar to those of graphite and stronger than those
found in alkanes and diamond (sp3-hybrid carbon
atoms), provide nanotubes with their unique strength.

Single-walled
◇ SWNTs have a diameter of close to
1 nanometre, and can be many
millions of times longer.
◇ The way the graphene sheet is
wrapped is represented by a pair of
indices (n,m). The integers n and m
denote the number of unit vectors
along two directions in the
honeycomb crystal lattice of graphene.
If m = 0, the nanotubes are
called zigzag nanotubes, and if n = m,
the nanotubes are called
armchair nanotubes. Otherwise, they
are called chiral.
Multi-walled
◇ MWNTs consist of multiple rolled layers
(concentric tubes) of graphene.
◇ There are two models that can be used to
describe the structures of multi-walled
nanotubes.
◇ Russian Doll model, sheets of graphite
are arranged in concentric cylinders.
◇ Parchment model, a single sheet of
graphite is rolled in around itself,
resembling a scroll of parchment or a
rolled newspaper. The interlayer distance
in multi-walled nanotubes is close to the
distance between graphene layers in
graphite, approximately 3.4 Å.
TYPES OF CARBON NANOTUBES

◇ Carbon nanotubes are the strongest and stiffest materials yet discovered in
terms of tensile strength and elastic modulus respectively.
◇ its specific strength of up to 48,000 kN·m·kg−1 is the best of known materials,
compared to high-carbon steel's 154 kN·m·kg−1 .
◇ In theory, metallic nanotubes can carry an electric current density of 4 ×
109 A/cm2, which is more than 1,000 times greater than those of metals such
as copper.
◇ The temperature stability of carbon nanotubes is estimated to be up to 2800 °C
in vacuum and about 750 °C in air.
◇ very good thermal conductors along the tube, exhibiting a property known as
“ballistic conduction”.
◇ Carbon nanotubes have useful absorption, photoluminescence (fluorescence),
and Raman spectroscopy properties.
PROPERTIES OF CARBON NANOTUBES

◇ The Boeing Company has patented the use of carbon nanotubes for structural
health monitoring of composites used in aircraft structures. This technology will
greatly reduce the risk of an in-flight failure caused by structural degradation of
aircraft.
◇ Tips for atomic force microscope probes.
◇ In tissue engineering, carbon nanotubes can act as scaffolding for bone growth.
◇ These 3D all-carbon scaffolds/architectures may be used for the fabrication of the
next generation of energy storage, super capacitors, field emission transistors,
high-performance catalysis, photovoltaics, and biomedical devices and implants.
◇ CNT-based yarns are suitable for applications in energy and electrochemical
water treatment when coated with an ion-exchange membrane.
◇ CNT-based yarns could replace copper as a winding material.
◇ There is also ongoing research in using carbon nanotubes as a scaffold for
diverse microfabrication techniques.
APPLICATIONS OF CARBON NANOTUBES

BIOMATERIALS
◇ A biomaterial is any substance that has been
engineered to interact with biological systems for
a medical purpose - either a therapeutic (treat,
augment, repair or replace a tissue function of the
body) or a diagnostic one.
◇ Biomaterials can be derived either from nature or
synthesized in the laboratory using a variety of
chemical approaches utilizing metallic
components, polymers, ceramics or composite
materials.
◇ A biomaterial is used to replace part of a living
system or to function in intimate contact with
living tissue of a human body. Alone or as part of
a complex system, is used to direct, by control of
interactions with components of living systems,
the course of any therapeutic or diagnostic
procedure.

◇ Bio inert: The term bio inert refers to any material that once placed in the
human body has minimal interaction with its surrounding tissue. Examples of
these are stainless steel, titanium, alumina, partially stabilised zirconia, and
ultra high molecular weight polyethylene.
◇ Bioactive: Bioactive refers to a material, which upon being placed within the
human body interacts with the surrounding bone and in some cases, even soft
tissue. Prime examples of these materials are synthetic hydroxyapatite
[Ca10 (PO4)6(OH)2], glass ceramic A-W and bio glass.
◇ Bioresorbable: Bioresorbable refers to a material that upon placement within
the human body starts to dissolve (resorbed) and slowly replaced by
advancing tissue (such as bone). Calcium oxide, calcium carbonate and
gypsum are other common materials that have been utilised during the last
three decades.
TYPES OF BIOMATERIAL

◇ Joint replacements.
◇ Bone plates.
◇ Intraocular lenses (IOLs) for eye surgery.
◇ Bone cement.
◇ Artificial ligaments and tendons.
◇ Dental implants for tooth fixation.
◇ Blood vessel prostheses.
◇ Heart valves.
◇ Skin repair devices (artificial tissue).
◇ Cochlear replacements.
◇ Contact lenses.
◇ Surgical sutures, clips, and staples for wound closure.
◇ Pins and screws for fracture stabilisation.
◇ Surgical mesh.
APPLICATIONS OF BIOMATERIAL

METALLIC GLASSES
◇ An metallic glass (also known as amorphous
metal or glassy metal) is a solid metallic
material, usually an alloy, with a disordered
atomic-scale structure.
◇ Amorphous metals are non-crystalline, and have
a glass-like structure.
◇ But unlike common glasses, such as window
glass, which are typically electrical insulators,
amorphous metals have good electrical
conductivity.
◇ There are several ways in which amorphous
metals can be produced, including extremely
rapid cooling, physical vapour deposition, solid-
state reaction, ion irradiation, and mechanical
alloying.

◇ Metallic glasses have very high strength and are stronger than metals because the
absence of grain boundaries and dislocations.
◇ The structure of metallic glass is Tetrahedral Close Packing (TCP).
◇ These are having very high corrosion resistance.
◇ They have high workability and ductility.
◇ The electrical resistivity is found to be high (greater than 100)/ due to this eddy
current loss is very small.
◇ Metallic glasses have both soft and hard magnetic properties.
◇ These are highly reactive and stable.
◇ It can also act as a catalyst.
◇ They do not have any crystal defects such as grain boundaries and dislocations.
◇ They have high corrosion resistance due to random ordering.
◇ Eddy current loss is very small due to high resistivity.
◇ It obeys both soft and hard magnetic properties
PROPERTIES OF METALLIC GLASSES

◇ Metallic glasses are used as reinforcing elements in concrete, plastic and rubber.
◇ Metallic glasses are used to make pressure vessels and to construct larger fly
wheels for energy storage.
◇ They are used to make accurate standard resistors, Magnetic resistance sensors
and computer memories.
◇ These are used in tape recorder heads, cores of high power transformers and
magnetic shields.
◇ Metallic glasses are used as core in motors.
◇ These are used to make razor blades and different kinds of springs.
◇ Metallic glasses can be used as superconductor for producing high magnetic fields
and magnetic levitation effect.
◇ Metallic glasses are used to make containers for nuclear waste disposal and
magnets for fusion reactors.
◇ Metallic glasses are used in marine cables, chemical filters, inner surfaces of
reactor vessels, etc.,
APPLICATIONS OF METALLIC GLASSES

PROGRAMMABLE MATTER
◇ Programmable matter is matter which has the
ability to change its physical properties (shape,
density, moduli, conductivity, optical properties,
etc.) in a programmable fashion, based upon
user input or autonomous sensing.
◇ Programmable matter is thus linked to the
concept of a material which inherently has the
ability to perform information processing.
◇ DARPA Information Science and Technology
group (ISAT) examined the potential of
programmable matter. This resulted in the 2005–
2006 study "Realizing Programmable Matter",
which laid out a multi-year program for the
research and development of programmable
matter.

◇ Complex fluids: The physical properties of several complex fluids can be modified
by applying a current or voltage, as is the case with liquid crystals.
◇ Metamaterials: Metamaterials are artificial composites that can be controlled to
react in ways that do not occur in nature.
◇ Shape-changing molecules: An active area of research is in molecules that can
change their shape, as well as other properties, in response to external stimuli.
These molecules can be used individually or to form new kinds of materials.
◇ Electro permanent magnets: An electro permanent magnet is a type
of magnet which consists of both an electromagnet and a dual material permanent
magnet, in which the magnetic field produced by the electromagnet is used to
change the magnetization of the permanent magnet.
◇ Claytronics: The catoms will be sub-millimetre computers that will eventually have
the ability to move around, communicate with other computers, change colour,
and electrostatically connect to other catoms to form different shapes.
EXAMPLES OF PROGRAMMABLE MATTER

METAMATERIAL
◇ A metamaterial is a material engineered to have a
property that is not found in nature.
◇ The materials are usually arranged in repeating
patterns, at scales that are smaller than
the wavelengths of the phenomena they influence.
◇ Metamaterials derive their properties not from the
properties of the base materials, but from their
newly designed structures.
◇ Their precise shape, geometry, size, orientation
and arrangement gives them their smart properties
capable of manipulating electromagnetic waves: by
blocking, absorbing, enhancing, or bending waves,
to achieve benefits that go beyond what is possible
with conventional materials.
◇ Appropriately designed metamaterials can affect
waves of electromagnetic radiation or sound in a
manner not observed in bulk materials.

◇ Negative index: In negative-index metamaterials (NIM), both permittivity
and permeability are negative, resulting in a negative index of refraction.
These are also known as double negative metamaterials or double
negative materials (DNG).
◇ Single negative: Single negative (SNG) metamaterials have either negative
relative permittivity (εr) or negative relative permeability (µr), but not both.
◇ Double positive medium: Double positive mediums (DPS) do occur in
nature, such as naturally occurring dielectrics. Permittivity and magnetic
permeability are both positive and wave propagation is in the forward
direction. Artificial materials have been fabricated which combine DPS,
ENG and MNG properties.
CLASSIFICATION OF METAMATERIAL
Single negative (SNG) metamaterials have either negative relative permittivity (εr) or negative relative permeability (µr), but not both

◇ Metamaterial antennas are a class of antennas that use metamaterials to improve
performance. Demonstrations showed that metamaterials could enhance an
antenna's radiated power.
◇ A metamaterial absorber manipulates the loss components of metamaterials'
permittivity and magnetic permeability, to absorb large amounts
of electromagnetic radiation. This is a useful feature for photo detection and solar
photovoltaic applications.
◇ A super lens is a two or three-dimensional device that uses metamaterials, usually
with negative refraction properties, to achieve resolution beyond the diffraction
limit (ideally, infinite resolution).
◇ Seismic metamaterials counteract the adverse effects of seismic waves on man-
made structures.
◇ Metamaterials can control sound or light signals.
APPLICATIONS OF METAMATERIAL

CLAYTRONICS
◇ Claytronics is an abstract future concept that
combines nanoscale robotics and computer
science to create individual nanometre-scale
computers called claytronic atoms, or catoms,
which can interact with each other to form tangible
3D objects that a user can interact with. This idea is
more broadly referred to as programmable matter.
◇ Claytronics consists of a collection of individual
components called claytronic atoms, or catoms.
◇ The researchers at Carnegie Mellon University
have developed various prototypes of catoms.
These vary from small cubes to giant helium
balloons.
◇ In the current design, the catoms are only able to
move in two dimensions relative to each other.
Future catoms will be required to move in three
dimensions relative to each other.

◇ The featured application of claytronics is a new mode of communication.
Claytronics will offer a more realistic sense to communication over long
distance called pario. Similar to how audio and video provide aural and visual
stimulation, pario provides an aural, visual and physical sensation. A user will
be able to hear, see and touch the one communicating with them in a realistic
manner. Pario could be used effectively in many professional disciplines from
engineering design, education and healthcare to entertainment and leisure
activities such as video games.
◇ The advancements in nanotechnology and computing necessary for
claytronics to become a reality are feasible, but the challenges to overcome
are daunting and will require great innovation.
FUTURE APPLICATIONS OF CLAYTRONICS

SHAPE-MEMORY ALLOY
◇ A shape-memory alloy (SMA, smart
metal, memory metal, memory alloy, muscle
wire, smart alloy) is an alloy that "remembers" its
original shape and that when deformed returns to
its pre-deformed shape when heated.
◇ This material is a lightweight, solid-state alternative
to conventional actuators such
as hydraulic, pneumatic, and motor-based
systems.
◇ Shape-memory alloys have applications
in robotics and automotive, aerospace and
biomedical industries.
◇ It is also called as smart materials or intelligent
materials or Active materials.
◇ SMAs also display super elasticity, which is
characterized by recovery of unusually large
strains

One-way memory effect
◇ When a shape-memory alloy is in its cold state (below As), the metal can be
bent or stretched and will hold those shapes until heated above the transition
temperature. Upon heating, the shape changes to its original. When the metal
cools again it will remain in the hot shape, until deformed again.
◇ With the one-way effect, cooling from high temperatures does not cause a
macroscopic shape change.
◇ A deformation is necessary to create the low-temperature shape.
◇ On heating, transformation starts at As and is completed at Af (typically 2 to
20 °C or hotter, depending on the alloy or the loading conditions). As is
determined by the alloy type and composition and can vary
between −150 °C and 200 °C.
DIFFERENT SHAPE-MEMORY EFFECTS

Two-way memory effect
◇ The two-way shape-memory effect is the effect that the material remembers two
different shapes: one at low temperatures, and one at the high-temperature
shape.
◇ A material that shows a shape-memory effect during both heating and cooling is
said to have two-way shape memory.
◇ This can also be obtained without the application of an external force (intrinsic
two-way effect). The reason the material behaves so differently in these
situations lies in training. Training implies that a shape memory can "learn" to
behave in a certain way. Under normal circumstances, a shape-memory alloy
"remembers" its low-temperature shape, but upon heating to recover the high-
temperature shape, immediately "forgets" the low-temperature shape. However, it
can be "trained" to "remember" to leave some reminders of the deformed low-
temperature condition in the high-temperature phases.
DIFFERENT SHAPE-MEMORY EFFECTS

Properties of Ni – Ti alloy
Ni – Ti is a compound of Nickel and
Titanium and it finds many applications
in the field of engineering due to the
following properties.
◇ It has greater shape memory strain.
◇ It has more thermal stability and
excellent corrosion resistance.
◇ It has higher ductility and more stable
transformation temperatures.
◇ It has better bio-compatibility and it
can be electrically heated.
PROPERTIES OF SHAPE-MEMORY ALLOYS

◇ Eye glass frames: We know that the recently manufactured eye glass
frames can be bent back and forth and can retain its original shape
within fraction of time.
◇ Helicopter blades: The life time of helicopter blades depends on
vibrations and their return to its original shape. Hence shape memory
alloys are used in helicopter blades.
◇ Coffee Valves: Used to release the hot milk and the ingredients at a
certain temperature.
◇ It is used as Micro – Surgical instruments.
◇ It is used as a thermostat valve in cooling system.
◇ It is used to make antenna wires in cell phones.
◇ It is used as flow control devices.
◇ Toys: We might have seen toys such as butterflies, snakes etc., which
are movable and flexible.
APPLICATIONS OF SHAPE-MEMORY ALLOYS

INTERMETALLIC COMPOUND
◇ Intermetallic compound, any of a class of
substances composed of definite proportions of
two or more elemental metals, rather than
continuously variable proportions (as in solid
solutions).
◇ The crystal structures and the properties of
intermetallic compounds often differ markedly
from those of their constituents.
◇ In addition to the normal valences of their
components, the relative sizes of the atoms and
the ratio of the total number of valence electrons
to the total number of atoms have important
effects on the composition of intermetallic
compounds.

◇ Magnetic materials e.g. alnico, sendust, Permendur, FeCo, Terfenol-D.
◇ Superconductors e.g. A15 phases; niobium-tin.
◇ Hydrogen storage e.g. AB5 compounds (nickel metal hydride batteries).
◇ Shape memory alloys e.g. Cu-Al-Ni (alloys of Cu3Al and
nickel); Nitinol (NiTi)
◇ Coating materials e.g. NiAl
◇ High-temperature structural materials e.g. nickel aluminide, Ni3Al
◇ Dental amalgams which are alloys of intermetallic Ag3Sn and Cu3Sn
◇ Gate contact/ barrier layer for microelectronics e.g. TiSi2
◇ Laves phases (AB2), e.g., MgCu2, MgZn2 and MgNi2.
PROPERTIES AND EXAMPLES OF INTERMETALLIC COMPOUND

CONCLUSION
OF MODERN ENGINEERING MATERIALS
3

Thanks!
Any questions?
You can find me at:
fb@DerakDavisT
derakdavis@yandex.com

Modern engineering materials

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