Module 1_TME 313.pptx

Course Title: Materials Science
Course Lecturer/ Facilitator : Dr O.O. Ajide
Department of Mechanical Engineering
Faculty of Technology
University of Ibadan, Nigeria
2/21/2023 1

 Module 1: Basic Introduction to the World of Materials & Structure of Atom
 Module 2: Solid State Crystallography
 Module 3: Structure-Composition-Property Relationship of Materials & Performance
(Materials such as metals, alloys, plastics, ceramics, and natural products)
products)
 Module 4: Manufacture and properties of high polymers.
 Module 5: Thermoplastic and thermosetting resins
 Module 6: Heat treatment: annealing, normalizing, tempering and hardening.
 Module 7: Metallic corrosion and protection.
Course Outline
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The following reference books will be helpful:
 Materials Science and Engineering: An Introduction by
William D. Callister, Jr
 Materials Science and Engineering by O.A. Ajaja (LAMLAD
Publications).
 Material Science & Engineering by Er. R.K. Rajput
(KATSON BOOKS).
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 Materials Science and Engineering: An Introduction (John Wiley
2010, 8th Edition) by W.D. Callister & D.G. Rethwisch.
 MSE 209: Introduction to the Science and Engineering of
Materials. An online Lecture Material by Leonid Zhigitei
 Other relevant textbooks/teaching & learning resources (including
You Tube Videos)
2/21/2023 5

2/21/2023 8
Basic Introduction to
the World of Materials
Structure of Atom

 Materials science can be described as the study of the
relationship that exists between the structure and
property of material in relations to its environment.
 Material science is concerned with the investigation of
the relationship among processing, structure, properties
and performance of materials in different environments
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2/21/2023 10
Source: MSE 209 by Leonid Zhigilei

 Materials engineering is the application of sound
knowledge of materials science in the design,
manufacture, fabrications, construction, operation
and maintenance of machines and equipment.
2/21/2023 11

Why do we study material Science?
 Scientists and Engineers (Mechanical, Civil, Industrial,
Agricultural, Chemical, Petroleum, Electrical, Aeronautical,
Marine, Biomedical e.t.c) will at one time or another be
exposed to a design problem involving materials.
 Some examples include a transmission gear, the
superstructure of a building, an oil refinery component or an
integrated circuit chip
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 Of course, materials science and engineering
plays a vital role in this modern age of science
and technology.
 Various kinds of materials are used in industry,
housing, agriculture, transportation e.t.c. to
meet the plant and individual requirements.
2/21/2023 13

 Most of the times, there is a problem of selecting the best
and most suitable materials from many thousands that are
available.
 There are several criteria on which the final decision is
normally based.
 Firstly, the service conditions must be characterised since
this determine the properties required of the material.
 It is on a rare occasion that we can have a material with
maximum or ideal combination of properties. Thus it may
be necessary to trade off one characteristic for another.
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o The classic examples involve strength, ductility, hardenability,
malleability, conductivity e.t.c.
o Most often, a material having high strength and hardness will have
low ductility.
o In such cases, a reasonable compromise between two or more
properties may be necessary.
o Secondly, there is possibility for the deterioration of materials
properties that may occur during service operation.
o For instance, significant reductions in the mechanical strength
may be result from exposure to elevated temperature or corrosive
environments.
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 Furthermore, we consider costs; the economic consideration is
vital in the selection of materials.
 A material may be found that has the ideal set of properties but is
prohibitively expensive.
 Cost is the major reason why copper is more preferred to be used
in electrical cables compared to silver which has a better
conductivity.
 Silver is highly expensive compared to copper. The cost of
finished piece also includes any expense incurred during
fabrication to produce the desire shape.
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 In general, the major factors affecting the selection of materials are:
2/21/2023 17
Service requirements
Cost of processing and materials
Availability of material
Mechanical properties.(strength,
ductility e.t.c)

Chemical Properties
(oxidation, corrosion)
Thermal properties
(expansion, heat capacity )
Electrical properties
(conductivity, resistivity,e.t.c)
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Physical properties (e.g
density, optical, solubility,etc)
Component shape
Dimensional tolerance
Fabrication requirements
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 It can be concluded that the more familiar an engineer or scientist
is with the various characteristics and structure-property
relationships, as well as processing techniques of materials, the
more confident and proficient S/he will be to make judicious
material choices based on these criteria.
 For instance, lightness and strength are the principal criteria in the
choice of Duralumin alloy in manufacturing aircrafts.
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 Major classes of Engineering Materials
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a)Metals/Alloys a)Ceramics a)Polymers a)Composites

2/21/2023 22
a)Semiconductors a)Biomaterials
a)Advanced
materials
Smart
materials

Metals/ Alloys: Metals are element or substances which
readily give up electrons to form metallic bonds and
conduct electricity. Basic properties of metals are:
 Good conductor of heat and electricity
 Metals are usually solid at ordinary temperature
 Metals are malleable and ductile
 Freshly cut surfaces of metals are lustrous (shining)
 Metals are generally strong i.e. high strength
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Metals/ Alloys
 The components or constituent of an alloy depends on the desired
properties of the alloy.
 The properties of an alloy can be totally different from its
constituent substances e.g. 18-8 stainless which contains 18%
chromium and 8% nickel, the alloy is extremely tough,
exceedingly ductile and highly resistance to corrosion.
 It is interesting to note that these properties are quite different
from the behaviour of original carbon steel. Examples of metals
are Sodium, Aluminium; Copper, Gold, Silver, Platinum e.t.c.
examples of alloys are Duralumin, Stainless Steels, e.t.c.
2/21/2023 24

Ceramics: These are compounds between metallic and
nonmetallic elements; they are mostly oxides, nitrides, and
carbides. The wide range of materials that falls within this
classification includes ceramics that are composed of clay
minerals, cement and glass. The basic properties are;
 They have good insulating properties to the passage of
electricity and heat
 They are more resistance to high temperatures and harsh
environments than metals and polymers
 Ceramics are generally hard
 Ceramics are generally brittle
2/21/2023 25

Polymers: These are generally organic compounds that
chemically based on carbon, hydrogen and other nonmetallic
elements.
They are products of polymerization whereby several
monomers are combined to form giant molecules called
polymers. Examples of polymers are plastics and rubber
materials. The basic properties are:
 They generally have low densities
 They are extremely flexible
2/21/2023 26

 Composites: These consist of two or more different materials
embedded within a single piece in order to display a combination
of the best characteristics of each of the component materials. A
familiar example of composites is fiberglass.
 In a fiberglass, glass fibers are embedded in a polymeric material.
Fiberglass acquires strength from the glass and flexibility from the
polymer.
 It is interesting to note that majority of the recent material
developments have involved composite materials e.g computer
hardware. The properties are:
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General properties of composites are:
 They have high strength to weight ratio
 They are generally flexible
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Semiconductors:
 These are materials that have electrical properties that are
intermediate between the electrical conductors and
insulators.
 The electrical characteristics of these materials are
extremely sensitive to the presence of minutes
concentrations of impurity atom, these concentrations may
be controlled over very small spatial regions.
 The semiconductors have made possible the advent of
integrated circuitry that has totally revolutionized the
electronics and computer industries over the past twenty
years.
 Examples of semiconductors materials are Germanium
and Silicon. 2/21/2023 29

Biomaterials:
 These are materials implanted inside the human body for
replacement of damaged or diseased body parts.
 These materials must not produce toxic substances and must
be compatible with body tissues without any adverse
biological reactions.
 Any material whether metals, ceramics, polymers,
composites, and semiconductors may be used as
biomaterials.
 Biomaterials are used as artificial legs, hips, teeth’s, hands,
limbs, nose e.t.c.
2/21/2023 30

Advanced materials:
 In the present day technology, some materials are termed as
Advanced Materials ,while some are called Materials of the Future.
 These are the materials utilised in high-technology applications.
 By high technology, refers to a device or products that operate or
functions using relatively intricate and sophisticated principles.
Examples include electronic equipment (CVRs, CD players, e.t.c.),
computer fiber optics systems, space craft, aircraft, and military
rocketry.
 These advanced materials are typically either traditional material
whose properties have been enhanced or newly developed high
performance materials. Advanced materials are used for Lasers ,
Integrated Circuits (IC) , Magnetic Formation Storage , Liquid
crystal displays (LCDs), fiber optics e.t.c 2/21/2023 31

Materials of the future/smart materials and materials
from nanotechnology.
 Smart or intelligent materials are a group of new and
state- of- the- art materials now being developed that
will have a significant influence on many of our
technologies.
 These imply materials that are able to sense changes in
their environments and then respond to these changes
in predetermined manners.
2/21/2023 32

 Components of smart materials includes some type of sensor (that
detects an input signal), and an actuator (that performs a responsive and
adaptive function).
 Materials employed as sensor includes optical fibers, piezoelectric
materials and electromechanical devices.
2/21/2023 33

 For instance, one type of smart system is used in
helicopters to reduce the aerodynamic cockpit noise that is
created by the rotating rotor blades.
 Piezoelectric sensors inserted into the blades, monitor
blade stresses and deformations; feedback signals from
these sensors are fed into a computer. Control adaptive
devices which generate noise-cancelling effect (i.e anti-
noise effect).
2/21/2023 34

Nanomaterials & Nanotechnology:
 With the advent of scanning probe microscopes which permit
observation of individual atoms and molecules, it has become possible
to manipulate and move atoms and molecules to form new structures
and thus design new materials that are built from simple atomic level
constituents.
 Nanotechnology can be defined as the technology that provides
opportunities to carefully arrange atoms with the aim of developing the
mechanical, electrical, magnetic and other properties that might not have
been possible.
 The study of such properties as a result of manipulations of atoms is
called nanotechnology; ‘nano’ denotes that the dimensions of these
structural entities are on the order of nanometer (10−9m).
2/21/2023 35

 Nanotechnology refers to the technology in which materials
properties are manipulated in order of 1 to 100 nanometers
(Nanoscale).
 Such materials synthesized through this process are called
Nanomaterials.
 One of the most common examples of nanotechnology materials is
carbon nanotube.
 Other examples of engineered nanomaterials include: carbon
buckeyballs or fullerene, metal or metal oxide nanoparticles (e.g.,
gold, titanium dioxide); quantum dots, among many others.
 There is no doubt that in the future, technological advancement
will greatly employ the use of nanotechnology materials.
2/21/2023 36

Modern materials challenges:
 In spite of the tremendous achievements made so far in
materials development, there are still challenges on the
needs to improve the quality of lives.
 For instance, nuclear energy holds some promise in
improving our epileptic power but the need for developing
material for easy disposal of radioactive waste become a
challenge; significant quantities of energy are involved in
transportation.
2/21/2023 37

 Reducing the weight of automobiles, aircraft, trains and other
transportation vehicles as well as increasing engine or operating
temperatures will enhance fuel efficiency.
 There is need for research in developing materials of low density
capable of withstanding high temperatures.
 The use of solar energy as an alternative source of electricity
generation is becoming a centre of general interest; unfortunately,
most materials used as solar cells are highly expensive.
 There is urgent need to develop materials that are less expensive
and more efficient.
2/21/2023 38

 Environmental quality depends on our ability to control pollution
(air or water pollution).
 Pollution techniques employ variety of materials. There is need to
develop materials that are non-toxic or harmful.
2/21/2023 39

In conclusions,
 As long as we continue to desire better quality of lives, improved
infrastructural facilities and reliable service conditions, there will
continue to be the needs for MATERIALS DEVELOPMENTS.
 Also the world at large will continue to yearn for Materials
Scientists and Engineers in developing these materials.
 As engineering students from this premier university of Ibadan ,
you may be the material scientists and engineers the world is
waiting for in MATERIALS DEVELOPMENTS!!!!!!!
2/21/2023 40

ASSIGNMENT 1
Write a term paper titled “Materials Science and
Engineering: A robust link for High Performance
Industrial Applications”.
2/21/2023 41

 All materials are obtained from matters. Matters are solid, liquid
or gas. Matters are made up of atom in which John Dalton referred
to as the smallest indivisible particles.
 Some of the important properties of solid materials depend on
geometrical atomic arrangements and also the interactions that
exist among constituent atoms or molecules.
2/21/2023 42

The electrons:
 In 1897, J.J Thomson, while studying the passage of electricity
through the gasses at low pressure, observed that the rays of light
appear to travel in straight lines from the surface of the cathode
and move away from it in the discharge tube.
 These rays are called cathode rays since they start from the
cathode of the discharge tube. Crookes studied the properties of
these cathode rays as follows:
2/21/2023 43

Crookes studied the properties of these cathode rays as
follows:
 They travels in straight line and cast shadows
 They are negatively charged
 They have high kinetic energy and can induce some
chemical reactions that causes fluorescence on glasses
 They have considerable momentum
2/21/2023 44

 These properties of the cathode rays were best explained by J.J
Thomson by his hypothesis that the cathode rays consists of a
stream of particles, each of mass m and charge e = 1.602 ×
10−19
C , originating at the cathode of the discharge tube.
 These particles are called electrons. J.J Thomson determined
the ratio between the electronic charge and mass of the
electron ( 𝑒
𝑚 ) and found its value as -1.76 × 1011 𝐶 𝐾𝑔.
2/21/2023 45

 Protons: This has a unit of positive charge and contained in the nucleus
of an atom. It has the same charge e = 1.602 × 10−19C as electron. The mass
of proton is 1.672 × 10−27
kg.
 Neutrons: These are electrically neutral particles and 1.0018 times
heavier than protons. The mass of each neutron is 1.675 × 10−27
kg.
2/21/2023 46

Particles Charge Mass
Electrons -1.602 × 10−19
C, negatively charged 9.11 × 10−31
kg
Protons +1.602 × 10−19
C, positively charged 1.672× 10−27
kg.
Neutrons No charge 1.675 × 10−27
kg.
2/21/2023 47
Table 1: Electrical Properties of Atomic Particles

 Atomic number (z): This can be defined as the number of protons in the
nucleus of an atom. It is also called proton number. It is also called proton
number. For an electrically neutral atom, the number of protons is equal
to the number of electrons
 Mass number (A): This is defined as sum of the number of protons and
neutrons within the nucleus of an atom. The number of protons is the
same for all atoms of a given element, the number of neutron may vary.
A =Z +N
2/21/2023 48

 Isotopes: These are elements with the same atomic numbers but
different atomic masses (mass numbers). Examples of isotopes
are 1
1
𝐻,1
2
𝐷, 1
3
𝑇( for hydrogen), 17
35
𝐶𝑙 , 17
37
𝐶𝑙 (for chlorine), 6
12
𝐶, 6
14
𝐶
(for carbon), e.t.c. the phenomenon is called isotopy.
 As illustration, isotopes of chlorine have 75% of 17
35
𝐶𝑙 and 25% of
17
37
𝐶𝑙 . The average atomic weight is calculated as follows:
 Average atomic weight = (25/100 ) ×37 + (75/100 ) × 35)
 Atomic weight =35.50 which is approximately 35.5
2/21/2023 49

 Isobars: These are elements with the same mass numbers but
different atomic numbers. The total number of protons and neutrons
in each of their nuclei is also the same. Examples of isobars are 20
40
𝐶𝑎
and 18
40
𝐴𝑟 , 7
14
𝑁 and 6
14
𝐶.
 Isotones: These can be defined as those elements with different
atomic number (Z) and mass number (A) but the same number of
neutrons (N). For instance 6
13
𝐶 and 7
14
𝑁 has the same number of
neutrons (7 neutrons) but different Z and A.
2/21/2023 50

 Atomic models: Electrons are common to all elements and form a
common building block of all matters.
 In order to have a proper understanding of the extra-nuclear electronic
structure , mainly with the help of positive rays and mass spectroscopy ,
several atomic models about atomic structure have been advanced over
the years after obtaining quantitative measurements on the electrons and
positive rays.
2/21/2023 51

 The most important atomic models are:
(a) Thomson’s atomic model
(b) Rutherford’s Nuclear Atomic Model
(c) Bohr’s Atomic Model
(d) Somerfield-Wilson’s Atomic Model
(e) Modern atomic model (vector atomic model)
2/21/2023 52

 Thomson’s atomic model:
2/21/2023 53

Thomson model failed to account for the
following:
i. The scattering of α-particle incident on
thin gold foil
ii. The emission of spectral series by the
atoms
2/21/2023 54

 Rutherford α-particles scattering experiment established the
correctness of the uniform distribution of positive charge in a sphere
of atomic dimensions in the Thomson’s atomic model.
 Rutherford’s results can be explained only if it is assumed that
the positive charge in a sphere or atom is concentrated in the
centre and the negatively charged particles surround it loosely,
leaving enough space for α-particles to pass through i.e. atoms
have a large empty space.
2/21/2023 55

Niel-Bohr’s Atomic Model:
 In order to remove the drawbacks of the Rutherford’s atomic
model, the famous Danish physicist , Niel Bohr in 1913, put
forward some new proposals based on the quantum idea which
had been proposed by max Planck some years earlier.
 Bohr considered the simplest of all atoms which is hydrogen
atom. Bohr postulates are summarised as follows:
1. In the case of hydrogen atom, there is single electron which
can revolve round the nucleus in certain definite orbits known
as stationary orbits.
The electrons are permitted to have only that orbit for which the
angular momenta of the planetary electron are integral multiple of
ℎ /2𝜋 or ħ. h denotes Planck’s constant.
2/21/2023 59

2. When the electron revolves in a stationary orbit, it does not emit
electromagnetic radiation as predicted by electromagnetic theory of
light.
o Radiation occurs only when an electron falls from a higher energy
state to a lower energy state.
o If the transition is from an orbit of higher energy E2 to an orbit of
energy E1 then the energy hv of the emitted radiation, according to
Planck’s law will be given by equation hv = E2 –E1
o Light is not emitted by an electron when moving in one of its
stationary orbit but it eject light
o only when it jumps from one orbit to another . This is Bohr second
postulate.
2/21/2023 60

e)Modern Atomic Model (Vector Atomic Model)
 This is the most widely accepted modern atomic
model. it is also known as quantum model of the
atom.
 In this model of the atom, all the principal
quantized terms are represented by vectors.
 This model takes into account electron spin while
retaining the feature of planetary movement of
electrons in circular orbits (circular or orbitals)
and movement of electron in different plane of
 Sommerfeld model.
2/21/2023 64

 Based on this model, several investigators have calculated the
fine structure separations of various energy levels and studied the
effect of electric and magnetic fields on spectral lines , which is
not possible from Sommerfeld’s model.
 The modern atomic model postulates are summarised as follows
in the next slide.
2/21/2023 65

 Quantum number : This can be described as a series of
discrete numbers which catalog the state of an electron
in an atom.
 It is derived from wave mechanic.There are four
quantum number: they are
a. Principal quantum number (n)
b. Orbital or Azimuthal Quantum number (l)
c. Magnetic Quantum number (𝑚𝑙)
d. Magnetic Spin Quantum number (𝑚𝑠)
2/21/2023 67

ATOMIC STRUCTURE AND
MATTER
2/21/2023 73

ATOMIC STRUCTURE AND
MATTER
2/21/2023 83

PERIODIC TABLE
 Not less than 109 elements have been discovered by scientists.
 Mendeleev discovered that if the elements are arranged in the order of
their increasing atomic weights, the elements with their similar properties
occur at regular intervals.
 Mendeleev gave a law which states that the properties of the elements are
periodic functions of their atomic numbers.
 Moseley proposed a periodic table in which the elements were arranged
in the increasing order of atomic number.
 This table has 7 horizontal rows known as periods and 8 vertical columns
known as groups. These groups are further divided into groups IA to
VIIA, IB to VIIB and VIII.
2/21/2023 86

Module 1_TME 313.pptx

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