This module deals with the classification of the engineering materials and their processing techniques. The engineering materials can broadly be classified as:a) Ferrous Metals ,b) Non-ferrous Metals (aluminum, magnesium, copper, nickel, titanium) ,c) Plastics (thermoplastics, thermosets) ,d) Ceramics and Diamond,e) Composite Materials & f) Nano-materials.
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Engineering Materials are classified as metals , non metals.
metals are further classified as ferrous and non ferrous alloys. Nonmetals are classified as ceramics and plastics. Classification of advanced materials like composites are also discussed
This presentation is the basic of engineering materials. More presenetation will be added soon. If you like the work, please click on like button and do share. Thanks
FellowBuddy.com is an innovative platform that brings students together to share notes, exam papers, study guides, project reports and presentation for upcoming exams.
We connect Students who have an understanding of course material with Students who need help.
Benefits:-
# Students can catch up on notes they missed because of an absence.
# Underachievers can find peer developed notes that break down lecture and study material in a way that they can understand
# Students can earn better grades, save time and study effectively
Our Vision & Mission – Simplifying Students Life
Our Belief – “The great breakthrough in your life comes when you realize it, that you can learn anything you need to learn; to accomplish any goal that you have set for yourself. This means there are no limits on what you can be, have or do.”
Like Us - https://www.facebook.com/FellowBuddycom
Engineering Materials are classified as metals , non metals.
metals are further classified as ferrous and non ferrous alloys. Nonmetals are classified as ceramics and plastics. Classification of advanced materials like composites are also discussed
This presentation is the basic of engineering materials. More presenetation will be added soon. If you like the work, please click on like button and do share. Thanks
this ppt describes materials ,metals, ceremics and its types, polymer, composites etc.
u can study more topics of material science on this you tube channel
https://www.youtube.com/playlist?list=PLAd8Bzun6OmL4Sg2sKbDJ1b5PZZ0Vb5Hu
Properties of ceramics; Classification of ceramics; Ceramic raw material; Fabricating and processing of ceramic;Application of Ceramics; Glasses; Clay Products; Structural clay product; Whitewares; Refractories: Fireclay; Silica; Basic refractories; Special refractories; Abrasives; Cements; Advanced Ceramics
This lesson highlights the classification of the engineering materials and their processing techniques. The engineering materials can broadly be classified as:
a) Ferrous Metals
b) Non-ferrous Metals (aluminum, magnesium, copper, nickel, titanium)
c) Plastics (thermoplastics, thermosets)
d) Ceramics and Diamond
e) Composite Materials & f) Nano-materials.
The engineering materials are often primarily selected based on their mechanical, physical, chemical and manufacturing properties. The secondary factors to be considered are the cost and availability, appearance, service life and recyclability.
this ppt describes materials ,metals, ceremics and its types, polymer, composites etc.
u can study more topics of material science on this you tube channel
https://www.youtube.com/playlist?list=PLAd8Bzun6OmL4Sg2sKbDJ1b5PZZ0Vb5Hu
Properties of ceramics; Classification of ceramics; Ceramic raw material; Fabricating and processing of ceramic;Application of Ceramics; Glasses; Clay Products; Structural clay product; Whitewares; Refractories: Fireclay; Silica; Basic refractories; Special refractories; Abrasives; Cements; Advanced Ceramics
This lesson highlights the classification of the engineering materials and their processing techniques. The engineering materials can broadly be classified as:
a) Ferrous Metals
b) Non-ferrous Metals (aluminum, magnesium, copper, nickel, titanium)
c) Plastics (thermoplastics, thermosets)
d) Ceramics and Diamond
e) Composite Materials & f) Nano-materials.
The engineering materials are often primarily selected based on their mechanical, physical, chemical and manufacturing properties. The secondary factors to be considered are the cost and availability, appearance, service life and recyclability.
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Unit I :
Materials : Classification of engineering material, Composition of Cast iron and Carbon steels, Iron Carbon diagram. Alloy steels their applications. Mechanical properties like strength, hardness, toughness, ductility, brittleness, malleability etc. of materials, Tensile test- Stress-strain diagram of ductile and brittle materials, Hooks law and modulus of elasticity, Hardness and Impact testing of materials, BHN, etc.
E-content is a Comprehensive package of teaching material put into hypermedia format. Hypermedia is multimedia with internet deplorability. E-content can not be created by a teaching faculty alone . It needs the role of teacher, Video editor, production assistants, web developers (HTML 5 or Adobe captivate, etc). Analyze the learner needs and goals of the instructional material development, development of a delivery system and content, pilot study of the material developed, implementation, evaluating, refining the materials etc. In designing and development of E-content we have to adopt one of the instructional design models based on our requirements.
Pedagogy is the most commonly understood approach to teaching. It refers to the theory and practice of learning. Pedagogy is often described as the act of teaching. Pedagogy has little variations between traditional teaching and online teaching. Online teaching pedagogy is a method of effective teaching practice specifically developed for teaching via the internet. It has a set of prescribed methods, strategies, and practices for teaching academic subjects in an online (or blended) environment, where students are in a physical location separate from the faculty member.
Technology has changed the possibilities within teaching and learning. Classes, which prior to the digital era were restricted to lectures, talks, and physical objects, no longer have to be designed in that manner. Training in a synchronous virtual classroom can only be successful with the active participation and engagement of the learners. Explore the Virtual Classroom’s features and see how they can support and enhance your tutoring style.
• The monitoring and evaluation of the institutional processes require a carefully structured system of internal and external review. The NAAC expects the Institutions to undertake continuous Academic and Administrative Audits (AAA). This presentation is intended to serve as advisory to all accredited HEIs who volunteer to undertake AAA. The pros and cons of this process are also highlighted. Academic and Administrative Audit is the process of evaluating the efficiency and effectiveness of the administrative procedure. It includes assessment of policies, strategies & functions of the various administrative departments, control of the overall administrative system, etc. This checklist gives an overview what the audit committee members may look into while visiting an institution for this purpose. It invariably follows the Quality Indicators Framework prescribed by Accreditation Council in India.
• The monitoring and evaluation of the institutional processes require a carefully structured system of internal and external review. The NAAC expects the Institutions to undertake continuous Academic and Administrative Audits (AAA). This presentation is intended to serve as advisory to all accredited HEIs who volunteer to undertake AAA.
Chemical analysis data of water samples can not be used directly for understanding. They are to be used for various calculations in order to determine the quality parameters that have a lot of significances. A. Balasubramanian and D. Nagaraju, of the Department of Studies in Earth Science, Centre for Advanced Studies, University of Mysore, Mysore-570006, Karnataka, India have recently brought out a software and its application manual as a good book for reference and execution. The Name of the software is WATCHIT meaning Water Chemistry Interpretation Techniques. This software computes more than 100 parameters pertaining to water quality interpretations. The software follows its own method of approach to determine the required results. Systems International Units are used. Limited input parameters are required. This is suitable for all scientific research, government water quality data interpretations and for understanding the quality of water before using it.
Water conservation refers to reducing the usage of water and recycling of waste water for different purposes like domestic usage, industries, agriculture etc. This technical article highlights most of the popular methods of water conservation. A special note on rainwater harvesting is also provided.
This module gives an overview of general applications of current hydrogeological aspects. It is for the basic understanding of students and research scholars.
Climate Extreme (extreme weather or climate event) refers to the occurrence of a value of a weather or climate variable above (or below) a threshold value near the upper (or lower) ends of the range of observed values of the variable. Extreme weather and climate events, interacting with exposed and vulnerable human and natural systems, can lead to disasters.
WATER RESOURCES PLANNING AND MANAGEMENT POSSIBILITIES IN CHAMARAJANAGAR TALUK...Prof. A.Balasubramanian
Any unplanned development and utilization of water resources with result in water scarcity. In many parts of the developing world. Such a situation exists. In order to do proper planning and
management of water resources, it is necessary to conduct detailed analyses of the factors, which influence the water availability and its uses. In the present study, a comprehensive analysis have been undertaken for proper utilization of water resources in Chamarajanagar Taluk, which has been identified as one of the drought hit districts of Karnataka, in India. The factors analysed in this work are, surface and groundwater availability, land use, cropping pattern, recharge potential of soils and the rainfall pattern in typical areas of Taluk. It is observed that the problem of water scarcity is mainly due to the lack of irrigation planning and management. Hence, a
modified cropping pattern is suggested by taking into consideration of all available water resources and other conditions.
In broad terms, cultural geography examines the cultural values, practices, discursive and material expressions and artefacts of people, the cultural diversity and plurality of society.
It also emphasizes on how cultures are distributed over space, how places and identities are produced, how people make sense of places and build senses of place, and how people produce and communicate knowledge and meaning.
Minerals are formed by changes in chemical energy in systems which contain one fluid or vapor phase. In nature, minerals are formed by crystallisation or precipitation from concentrated solutions. These solutions are called as ore-bearing fluids. Ore-bearing fluids are characterised by high concentration of certain metallic or other elements.
Fluids are the most effective agents for the transport of material in the mantle and the Earth's crust.
Soils are complex mixers forming the skin of the earth's surface. Soil is a dynamic layer in which many complex chemical, physical and biological activities are going on constantly. Soils become adjusted to conditions of climate, landform and vegetation, and will change internally when those controlling conditions change. Soils are products of weathering. Soils play a dominant role in earth's geomorphic processes in a cyclic manner. The characteristics of soils are very essential for several reasons. This module highlights these characteristics.
GIS TECHNIQUES IN WATER RESOURCES PLANNING AND MANAGEMENT IN CHAMARAJANAGAR ...Prof. A.Balasubramanian
The over-exploitation and contamination of groundwater continue to threaten the long-term sustainability of our precious water resources, in spite of the best efforts made by various agencies.
This has many serious implications to the economic development of a country like India. Lack of
judicious planning and integration of environmental consideration to ground water development
projects are primarily responsible for such a state of affair in the ground water sector. Geographical Information Systems could be of immense help in planning sustainable ground water management strategies, especially in hard rock areas with limited ground water potential. Data collected from
Satellite Imagery and through field investigations have been integrated, on a GIS platform, for demarcation and prioritization of areas suitable for ground water development and ground water augmentation. An attempt has also been made to assess the vulnerability of the area to ground water
contamination. This paper demonstrates the utility of GIS in planning judicious management of ground water resources in a typical hard rock area of Chamarajanagar Taluk, Karnataka, state India.
Nanobiomaterials are very effective components for several biomedical and pharmaceutical studies. Among the metallic, organic, ceramic and polymeric nanomaterials, metallic nanomaterials have shown certain prominent biomedical applications. Enormous works have been done to synthesize, analyse and administer the metallic nanoparticles for various kinds of medical and therapeutic applications, during the last forty years. In these analyses, the prominent biomedical applications of ten metallic nanobiomaterials have been reviewed from various sources and works. It has been found that almost nine of them are used in a very wide spectrum of medical and theranostic applications.
A variety of Nano-biomaterials are synthesised, characterised and tested to find out their potentialities by global scientific communities, during the last three decades. Among those, nanostructured ceramics, cements and coatings are being considered for major use in orthopaedic, dental and other medical applications. The development of novel biocompatible ceramic materials with improved biomedical functions is at the forefront of health-related applications, all over the world. Understanding of the potential biomedical applications of ceramic nanomaterials will provide a major insight into the future developments. This study reviews and enlists the prominent potential biomedical applications of ceramic nanomaterials, like Calcium Phosphate (CaP), Tri-Calcium Phosphate (TCP), Hydroxy-Apatite(HAP), TCP+HAP, Si substituted HAP, Calcium Sulphate and Carbonate, Bioactive Glasses, Bioactive Glass Ceramics, Titania-Based Ceramics, Zirconia Ceramics, Alumina Ceramcis and Ceramic Polymer Composites.
The present forest and tree cover of the country is 78.37 million ha in 2007 which is 23.84% of the geographical areas and it includes 2.82% tree cover. This becomes 25.25%, if the areas above tree line i.e., 4000m are excluded from the total geographical area. The forest cover is classified into 3 canopy density classes.
1. Very Dense Forest (VDF) with canopy density more than 70%
2. Moderately Dense Forest (MDF) with Canopy density between 40-70% and
3. Open Forest (OF) with Canopy density between 10-40%
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
2. 2
This module deals with the classification of the
engineering materials and their processing
techniques. The engineering materials can
broadly be classified as:
a) Ferrous Metals
b) Non-ferrous Metals (aluminum, magnesium,
copper, nickel, titanium)
c) Plastics (thermoplastics, thermosets)
d) Ceramics and Diamond
e) Composite Materials & f) Nano-materials.
3. 3
The engineering materials are often primarily
selected based on their mechanical, physical,
chemical and manufacturing properties.
The secondary points to be considered are the
cost and availability, appearance, service life
and recyclability.
4. 4
Metals :
Metals are usually lustrous, ductile, malleable,
and good conductors of electricity
They are divided into 2 categories:
A) FERROUS: the group which contains
mainly iron (Fe). Iron is the most important
metal in industrialized countries
B) NON-FERROUS: other metallic materials
containing no iron likecopper (Cu) or
aluminium (Al)
5. 5
Ferrous metals and alloys (irons, carbon
steels, alloy steels, stainless steels, tool and
die steels)
Nonferrous metals and alloys (aluminum,
copper, magnesium, nickel, titanium,
precious metals, refractory metals,
superalloys)
All the elements are broadly divided into metals
and non-metals according to their properties.
6. 6
Metals are element substances which readily
give up electrons to form metallic bonds and
conduct electricity. Some of the important basic
properties of metals are:
(a) metals are usually good electrical and
thermal conductors,
(b) at ordinary temperature metals are usually
solid,
(c) to some extent metals are malleable and
ductile,
7. 7
(d) the freshly cut surfaces of metals are
lustrous,
(e) when struck metal produce typical sound,
and
(f) most of the metals form alloys. When two or
more pure metals are melted together to form a
new metal whose properties are quite different
from those of original metals, it is called an
alloy.
8. 8
Metallic materials possess specific properties
like plasticity and strength.
Few favourable characteristics of metallic
materials are high lustre, hardness, resistance to
corrosion, good thermal and electrical
conductivity, malleability, stiffness, the
property of magnetism, etc.
Metals may be magnetic, non-magnetic in
nature.
9. 9
These properties of metallic materials are due
to:
(i) the atoms of which these metallic materials
are composed and
(ii) the way in which these atoms are arranged
in the space lattice.
Metallic materials are typically classified
according to their use in engineering as under:
Pure Metals and alloys.
10. 10
Pure Metals:
Generally it is very difficult to obtain pure
metal. Usually, they are obtained by refining the
ore. Mostly, pure metals are not of any use to
the engineers. Materials in this group are
composed of one or more metallic elements
(such as iron, aluminum, copper, titanium,
gold, and nickel), and often also nonmetallic
elements (for example, carbon, nitrogen, and
oxygen) in relatively small amounts.
11. 11
Atoms in metals and their alloys are arranged in
a very orderly manner and in comparison to the
ceramics and polymers, are relatively dense.
With regard to mechanical characteristics, these
materials are relatively stiff, and strong yet are
ductile (i.e., capable of large amounts of
deformation without fracture), and are resistant
to fracture , which accounts for their
widespread use in structural applications.
12. 12
Metallic materials have large numbers of
nonlocalized electrons; that is, these electrons
are not bound to particular atoms. Many
properties of metals are directly attributable to
these electrons. For example, metals are
extremely good conductors of electricity and
heat, and are not transparent to visible light; a
polished metal surface has a lustrous
appearance.
13. 13
In addition, some of the metals (viz., Fe, Co,
and Ni) have desirable magnetic properties.
Metals
Normally metallic materials are combinations
of metallic elements. Metallic materials have
large number of nonlocalized electrons, i.e.
electrons are not bound to particular atoms.
Many properties of metals are directly
attributable to these electrons.
14. 14
All metals are characterized by metallic
properties, e.g. luster, opacity, malleability,
ductility and electrical conductivity. Although
metals compose about three fourth of the known
elements but few find service in their pure form.
The desired properties for engineering purposes
are often found in alloys. Typical examples of
metallic materials are iron, aluminium, copper,
zinc, etc. and their alloys.
15. 15
They can be used either in bulk or powder form.
Metals are extremely good conductors of
electricity and heat are not transparent to visible
light; a polished metal surface has a lustrous
appearance.
Moreover, metals are quite strong, yet
deformable, which accounts for their extensive
use in structural applications.
16. 16
Metallic materials are always crystalline in
nature. Scientists have developed amorphous
(non-crystalline) alloys by very rapid cooling of
a melt or by very high-energy mechanical
milling.
Recently, scientists have developed materials
through rapid solidification called as
quasicrystals.
17. 17
These are neither crystalline nor amorphous, but
form an ordered structure somewhere between
two known structures. These materials are
expected to exhibit far reaching electrical
properties.
Inorganic Materials
These materials include metals, clays, sand
rocks, gravels, minerals and ceramics and have
mineral origin.
18. 18
These materials are formed due to natural
growth and development of living organisms
and are not biological materials.
Rocks are the units which form the crust of the
earth.
The three major groups of rocks are:
(i) Igneous Rocks: These rocks are formed by
the consolidation of semi-liquid of liquid
material (magma).
19. 19
These are called as Plutonic if their
consolidation takes place deep within the earth
and volcanic if lava or magma solidifies on the
earth’s surface.
Basalt is igneous volcanic where as granite is
igneous plutonic.
20. 20
(ii) Sedimentary Rocks:
When broken down remains of existing rocks
are consolidated under pressure, then the rocks
are named as sedimentary rocks, e.g., shale and
sandstone rocks.
The required pressure for the formation of
sedimentary rocks is supplied by the overlying
rocky material.
21. 21
(iii) Metamorphic Rocks:
These rocks are basically sedimentary rocks
which are changed into new rocks by intense
heat and pressure, e.g., marble and slates. The
structure of these rocks is in between igneous
rocks and sedimentary rocks.
Rock materials are widely used for the
construction of buildings, houses, bridges,
monuments, arches, tombs, etc.
22. 22
The slate, which has got great hardness is still
used as roofing material. Basalt, dolerite and
rhyolite are crushed into stones and used as
concrete aggregate and road construction
material.
Another type of materials, i.e. Pozzolanics, are
of particular interest to engineers because they
are naturally occurring or synthetic silicious
materials which hydrate to form cement.
23. 23
Volcanic ash, blast furnace slag, some shales
and fly ash are examples of pozzolanic
materials. When the cement contains 10- 20%
ground blast furnace slag, then it is called
pozzolans-portland cement, which sets more
slowly than ordinary portland cement and has
greater resistance to sulphate solutions and sea
water.
24. 24
Rocks, stone, wood, copper, silver, gold etc. are
the naturally occurring materials exist in nature
in the form in which they are to be used.
However, naturally occurring materials are not
many in number. Nowadays, most of the
materials are manufactured as per requirements.
25. 25
Obviously, the study of engineering materials is
also related with the manufacturing process by
which the materials are produced to acquire the
properties as per requirement.
Copper, silver, gold, etc. metals, which occur in
nature, in their free state are mostly chemically
inert and highly malleable and ductile as well as
extremely corrosion resistant. Alloys of these
metals are harder than the basic metals.
26. 26
Carbonates, sulphates and sulphide ores are
more reactive metals.
Biological Materials
Leather, limestone, bone, horn, wax, wood etc.
are biological materials. Wood is fibrous
composition of hydrocarbon, cellulose and
lignin and is used for many purposes.
27. 27
Apart from these components a small amount of
gum, starch, resins, wax and organic acids are
also present in wood. One can classify wood as
soft wood and hard wood. Fresh wood contains
high percentage of water and to dry out it,
seasoning is done. If proper seasoning is not
done, defects such as cracks, twist, wrap etc.
may occur. Leather is obtained from the skin of
animals after cleaning and tanning operations.
28. 28
Nowadays, it is used for making belts, boxes,
shoes, purses etc. To preserve the leather,
tanning is used.
Following two tanning techniques are widely
used:
(a) Vegetable Tanning: It consist of soaking the
skin in tanning liquor for several days and then
dried to optimum conditions of leather.
29. 29
(b) Chrome Tanning: This technique involves
pickling the skin in acid solution and then
revolving in a drum which contains chromium
salt solution. After that the leather is dried and
rolled. Limestone is an important material
which is not organic but has biological origin. It
mainly consist of calcium carbonate and
limestone. It is widely used to manufacture
cement.
30. 30
In Iron and Steel Industries, limestone in pure
form is used as flux. In early days bones of
animals were used to make tools and weapons.
Nowadays bones are used for the manufacture
of glue, gelatin etc. Bones are laminate of
organic substances and phosphates and
carbonates of calcium. These are stronger in
compression as compared to tension.
31. 31
Organic Materials
Organic materials are carbon compounds and
their derivatives. They are solids composed of
long molecular
chains. The study of organic compounds is very
important because all biological systems are
composed of carbon compounds.
32. 32
There are also some materials of biological
origin which do not possess organic
composition, e.g., limestone.
These materials are carbon compounds in
which carbon is chemically bonded with
hydrogen, oxygen and other non-metallic
substances. The structure of these compounds is
complex. Common organic materials are
plastics and synthetic rubbers which are termed
as organic polymers.
33. 33
Other examples of organic materials
are wood, many types of waxes and petroleum
derivatives.
Organic polymers are prepared by
polymerisation reactions, in which simple
molecules are chemically combined into long
chain molecules or three-dimensional
structures.
34. 34
Organic polymers are solids composed of long
molecular chains. These materials have low
specific gravity and good strength.
The two important classes of organic polymers
are:
(a) Thermoplastics: On heating, these materials
become soft and hardened again upon cooling,
e.g., nylon,polythene, etc.
35. 35
(b) Thermosetting plastics: These materials
cannot be resoftened after polymerisation, e.g.,
urea-formaldehyde,
phenol formaldehyde, etc. Due to cross-linking,
these materials are hard, tough, non-swelling
and brittle. These materials are ideal for
moulding and casting into components. They
have good corrosion resistance.
36. 36
The excellent resistance to corrosion, ease of
fabrication into desired shape and size, fine
lusture, light weight, strength, rigidity have
established the polymeric materials and these
materials are fast replacing many metallic
components.
PVC (Polyvinyl Chloride) and polycarbonate
polymers are widely used for glazing, roofing
and cladding of buildings.
37. 37
Plastics are also used for reducing weight of
mobile objects, e.g., cars, aircrafts and rockets.
Polypropylenes and polyethylene are used in
pipes and manufacturing of tanks.
Thermo-plastic films are widely used as lining
to avoid seepage of water in canals and lagoons.
To protect metal structure from corrosion,
plastics are used as surface coatings.
38. 38
Plastics are also used as main ingredients of
adhesives. The lower hardness of plastic
materials compared with other materials makes
them subjective to attack by insects and rodents.
Because of the presence of carbon, plastics are
combustible. The maximum service temperature
is of the order of 100°C.
39. 39
These materials are used as thermal insulators
because of lower thermal conductivity. Plastic
materials have low modulus of rigidity, which
can be improved by addition of filters, e.g.,
glass fibres.
Natural rubber, which is an organic material of
biological origin, is an thermoplastic material. It
is prepared from a fluid, provided by the rubber
trees.
40. 40
Rubber materials are widely used for tyres of
automobiles, insulation of metal components,
toys and other rubber products.
Polymers
Polymers include the familiar plastic and rubber
materials. Many of them are organic
compounds that are chemically based on
carbon, hydrogen, and other nonmetallic
elements (viz.O,N, and Si).
41. 41
Furthermore, they have very large molecular
structures, often chain-like in nature that have a
backbone of carbon atoms.
Some of the common and familiar polymers are
polyethylene (PE),
nylon,
poly(vinyl chloride) (PVC),
polycarbonate (PC), polystyrene (PS), and
silicone rubber.
42. 42
These materials typically have low densities ,
whereas their mechanical characteristics are
generally dissimilar to the metallic and ceramic
materials—they are not as stiff nor as strong as
these other material types.
However, on the basis of their low
densities,many times their stiffnesses and
strengths on a per mass basis are comparable to
the metals and ceramics.
43. 43
In addition, many of the polymers are extremely
ductile and pliable (i.e., plastic), which means
they are easily formed into complex shapes. In
general, they are relatively inert chemically and
unreactive in a large number of environments.
One major drawback to the polymers is their
tendency to soften and/or decompose at modest
temperatures, which, in some instances, limits
their use.
44. 44
Furthermore, they have low electrical
conductivities and are nonmagnetic. Fiberglass
is sometimes also termed a “glass fiber-
reinforced polymer” composite, abbreviated
“GFRP.”
Many of these are organic substances and
derivatives of carbon and hydrogen. Polymers
include the familiar plastic and rubber
materials.
45. 45
Usually polymers are classified into three
categories: thermoplastic polymers,
thermosetting polymers and elastomers, better
called as rubbers.
Polymers have very large molecular structures.
Most plastic polymers are light in weight and
are soft in comparison to metals.
Polymer materials have typically low densities
and may be extremely flexible and widely used
as insulators, both thermal and electrical.
46. 46
Typical examples of polymers are polyesters,
phenolics, polyethylene, nylon and rubber.
The overriding consideration of the selection of
a given polymer is whether or not the material
can be processed into the required article easily
and economically.
Crude oil supplies the majority of the raw
material for the production of polymers, also
called plastics
47. 47
Polymers can be divided into 3 categories:
Thermoplastics: usually soft and easy to be
recycled
Thermosetting plastics: usually stiff and not
easy to be recycled.
Elastomers: flexible (rubbers)
48. 48
Ceramic materials
The word ceramic is derived from the Greek
word keramikos.
The term covers inorganic non -metallic
materials whose formation is due to the action
of heat Clays, bricks, cements, glass are the
most important ones. These are crystalline
compounds between metallic and non-metallic
elements. They are most frequently oxides,
nitrides and carbides.
49. 49
Ceramics are compounds between metallic and
nonmetallic elements; they are most frequently
oxides, nitrides, and carbides.
For example, some of the common ceramic
materials include
aluminum oxide (or alumina,Al2O3),
silicon dioxide (or silica, SiO2),
silicon carbide (SiC)& silicon nitride (Si3N4).
50. 50
In addition, some are referred to as the
traditional ceramics—those composed of clay
minerals (i.e., porcelain), as well as cement,
and glass.
With regard to mechanical behavior, ceramic
materials are relatively stiff and strong—
stiffnesses and strengths are comparable to
those of the metals. In addition, ceramics are
typically very hard.
51. 51
On the other hand, they are extremely brittle
(lack ductility), and are highly susceptible to
fracture.
These materials are typically insulative to the
passage of heat and electricity (i.e., have low
electrical conductivities, and are more resistant
to high temperatures and harsh environments
than metals and polymers.
52. 52
With regard to optical characteristics, ceramics
may be transparent, translucent, or opaque, and
some of the oxide ceramics (e.g., Fe O ) exhibit
magnetic behavior.
Nowadays graphite is also categorized in
ceramics. The wide range of materials which
falls within this classification include ceramics
that are composed of clay minerals, cement and
glass.
53. 53
Glass is grouped with this class because it has
similar properties but most glasses are
amorphous.
Ceramics are characterised by high hardness,
abrasion resistance, brittleness and chemical
inertness.
Ceramics are typically insulative to the passage
of electricity and heat, and are more resistant to
high temperatures and harsh environments than
metals and polymers.
54. 54
With regard to mechanical behaviour, these
materials are hard but very brittle. These
materials are widely categorized into oxide and
non-oxide ceramics.
Examples Ceramics:
Glasses;
Glass ceramics;
Graphite;
Diamond
55. 55
Composites
A composite is a composition of two or more
materials in the first three categories, e.g.
metals, ceramics and polymers, that has
properties from its constituents. Large number
of composite materials have been engineered.
Few typical examples of composite materials
are wood, clad metals, fibre glass, reinforced
plastics, cemented carbides, etc.
56. 56
Fibre glass is a most familiar composite
material, in which glass fibres are embedded
within a polymeric material.
A composite is designed to display a
combination of the best characteristics of each
of the component materials. Fibre glass acquires
strength from the glass and the flexibility from
the polymer.
57. 57
A composite is composed of two (or more)
individual materials, which come from the
categories discussed above—viz., metals,
ceramics, and polymers. The design goal of a
composite is to achieve a combination of
properties that is not displayed by any single
material, and also to incorporate the best
characteristics of each of the component
materials.
58. 58
A large number of composite types exist that
are represented by different combinations of
metals, ceramics, and polymers. Furthermore,
some naturally-occurring materials are also
considered to be composites—for example,
wood and bone. However, most of those we
consider in our discussions are synthetic (or
man-made) composites.
59. 59
One of the most common and familiar
composites is fiber-glass, in which small glass
fibers are embedded within a polymeric
material (normally an epoxy or polyester).
The glass fibers are relatively strong and stiff
(but also brittle), whereas the polymer is
ductile (but also weak and flexible). Thus, the
resulting fiberglass is relatively stiff, strong,
flexible, and ductile.
60. 60
In addition, it has a low density. Another of
these technologically important materials is the
“carbon fiber-reinforced polymer” (or “CFRP”)
composite—carbon fibers that are embedded
within a polymer.
These materials are stiffer and stronger than the
glass fiber-reinforced materials, yet they are
more expensive.
61. 61
The CFRP composites are used in some aircraft
and aerospace applications, as well as high-tech
sporting equipment (e.g., bicycles, golf clubs,
tennis rackets, and skis/snowboards).
A true composite structure should show matrix
material completely surrounding its reinforcing
material in which the two phases act together to
exhibit desired characteristics.
62. 62
These materials as a class of engineering
material provide almost an unlimited potential
for higher strength, stiffness, and corrosion
resistance over the ‘pure’ material systems of
metals, ceramics and polymers.
Many of the recent developments of materials
have involved composite materials. Probably,
the composites will be the steels of this century.
63. 63
Nowadays, the rapidly expanding field of nano
composites is generating many exciting new
materials with novel properties. The general
class of nano composite organic or inorganic
material is a fast growing field of research.
Significant efforts are going on to obtain control
of nano composite materials depend not only on
the properties of their individual parents but
also on their morphology and interfacial
characteristics.
64. 64
The lamellar class of intercalated organic/
inorganic nano composites and namely those
systems that exhibit electronic properties in at
least one of the composites offers the possibility
of obtaining well ordered systems some of
which may lead to unusual electrical and
mechanical properties.
65. 65
Polymer-based nano composites are also being
developed for electronic applications such as
thin-film capacitors in integrated circuits and
solid polymer electrolytes for batteries.
No doubt, the field of nano composites is of
broad scientific interest with extremely
impressive technological promise.
Other materials coming under this group are:
Reinforced plastics;
67. 67
By high technology we mean a device or
product that operates or functions using
relatively intricate and sophisticated principles;
examples include electronic equipment
(camcorders, CD/DVD players, etc.),
computers, fiber-optic systems, spacecraft,
aircraft, and military rocketry.
68. 68
These advanced materials are typically
traditional materials whose properties have been
enhanced, and, also newly developed, high-
performance materials.
Furthermore, they may be of all material types
(e.g., metals, ceramics, polymers), and are
normally expensive.
69. 69
Advanced materials include semiconductors,
biomaterials, and what we may term “materials
of the future” (that is, smart materials and
nanoengineered materials), which we discuss
below. The properties and applications of a
number of these advanced materials -for
example, materials that are used for lasers,
integrated circuits, magnetic information
storage, liquid crystal displays (LCDs), and
fiber optics.
70. 70
These are new engineering materials which
exhibit high strength, great hardness, and
superior thermal, electrical, optical and
chemical properties.
Advanced materials have dramatically altered
communication technologies, reshaped data
analysis, restructured medical devices,
advanced space travel and transformed
industrial production process.
71. 71
These materials are often synthesized from the
biproducts of conventional commodity
materials and often possess following
characteristics:
• These materials are created for specific
purposes,
• These materials are highly processed and
possess a high value-to weight ratio,
72. 72
• These materials are developed and replaced
with high frequency, and
• These materials are frequently combined into
new composites.
Nowadays, there is considerable interest in
making advanced materials that are usually
graded by chemical composition, density or
coefficient of thermal expansion of material or
based on microstructural features, e.g. a
73. 73
particular arrangement of second-phase
particles or fibres in a matrix.
Such materials are referred as functionally
graded materials.
Instead of having a step function, one may
strive to achieve a gradual change.
74. 74
Such gradual change will reduce the chances of
mechanical and thermal stresses, generally
present otherwise.
We may note that the concept of a functionally
graded material is applicable to any material
metal, polymer or ceramic.
75. 75
Semiconductors
These materials have electrical properties that
are intermediate between electrical conductors
and insulators.
Moreover, the electrical characteristics of
semiconducting materials are extremely
sensitive to the presence of minute
concentrations of impurity atoms; these
76. 76
concentrations may be controlled over very
small spatial regions.
Silicon, Germanium and some more compounds
form the vast majority of semiconducting
crystals.
Semiconductors have electrical properties that
are intermediate between the electrical
conductors (viz. metals and metal alloys) and
insulators (viz. ceramics and polymers).
77. 77
Furthermore, the electrical characteristics of
these materials are extremely sensitive to the
presence of minute concentrations of impurity
atoms, for which the concentrations may be
controlled over very small spatial regions.
78. 78
Semiconductors have made possible the advent
of integrated circuitry that has totally
revolutionized the electronics and computer
industries (not to mention our lives) over the
past three decades.
These semiconducting materials are used in a
number of solid state devices, e.g. diodes,
transistors, photoelectric devices, solar
batteries, radiation detectors, thermistors and
lasers.
79. 79
The semiconductors have made possible the
advent of integrated circuitary that has
completely revolutionized the electronics and
computer industries.
Biomaterials
Biomaterials are employed in components
implanted into the human body for replacement
of diseased or damaged body parts.These
materials must not produce toxic substances and
80. 80
must be compatible with body tissues (i.e., must
not cause adverse biological reactions).
All of the above materials—metals, ceramics,
polymers, composites, and semiconductors—
may be used as biomaterials.
Some biomaterials that are utilized in artificial
hip replacements.
81. 81
Materials of the Future: Smart Materials
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.
The adjective “smart” implies that these
materials are able to sense changes in their
environments and then respond to these changes
in predetermined manners traits that are also
found in living organisms.
82. 82
In addition, this “smart” concept is being
extended to rather sophisticated systems that
consist of both smart and traditional materials.
function).
Actuators may be called upon to change shape,
position, natural frequency, or mechanical
characteristics in response to changes in
temperature, electric fields, and/or magnetic
fields.
83. 83
Four types of materials are commonly used for
actuators:
shape memory alloys,
piezoelectric ceramics,
magnetostrictive materials, and
electrorheological/
magnetorheological fluids.
84. 84
Shape memory alloys are metals that, after
having been deformed, revert back to their
original shapes when temperature is changed.
Piezoelectric ceramics expand and contract in
response to an applied electric field (or
voltage); conversely, they also generate an
electric field when their dimensions are altered.
85. 85
The behavior of magnetostrictive materials is
analogous to that of the piezoelectrics, except
that they are responsive to magnetic fields.
Also, electrorheological and
magnetorheological fluids are liquids that
experience dramatic changes in viscosity upon
the application of electric and magnetic fields,
respectively.
86. 86
Materials/devices employed as sensors include
optical fibers, piezoelectric materials (including
some polymers), and microelectromechanical
devices.
For example, one type of smart system is used
in helicopters to reduce aerodynamic cockpit
noise that is created by the rotating rotor blades.
87. 87
Piezoelectric sensors inserted into the blades
monitor blade stresses and deformations;
feedback signals from these sensors are fed into
a computer-controlled adaptive device, which
generates noise-canceling antinoise.
Smart or intelligent materials form a group of
new and state of art materials now being
developed that will have a significant influence
on many of present-day technologies.
88. 88
The adjective ‘smart’ implies that these
materials are able to sense changes in their
environments and then respond to these changes
in predetermined manners—traits that are also
found in living organisms. In addition, the
concept of smart materials is being extended to
rather sophisticated systems that consist of both
smart and traditional materials.
89. 89
The field of smart materials attempts to
combine the sensor (that detects an input
signal), actuator (that performs a responsive and
adaptive function) and the control circuit or as
one integrated unit.
Acutators may be called upon to change shape,
position, natural frequency, or mechanical
characteristics in response to changes in
temperature, electric fields, and or magnetic
fields.
90. 90
Usually, four types of materials are commonly
used for actuators: shape memory alloys,
piezoelectric ceramics, magnetostrictive
materials, and electrorheological/
magnetorheological fluids. Shape memory
alloys are metals that, after having been
deformed, revert back to their original shapes
when temperature is changed.
91. 91
Piezoelectric ceramics expand and contract in
response to an applied electric field (or
voltage); conversely these materials also
generate an electric field when their dimensions
are altered. The behaviour of magnetostrictive
materials is analogous to that of the
piezoelectric ceramic materials, except that they
are responsive to magnetic fields.
92. 92
Also, electrorheological and
magnetorheological fluids are liquids that
experience dramatic changes in viscocity upon
application of electric and magnetic fields,
respectively. The combined system of sensor,
actuator and control circuit or as one IC unit,
emulates a biological system.
These are known as smart sensors, microsystem
technology (MST) or micromechanical systems
(MEMS).
93. 93
Materials/devices employed as sensors include
optical fibres, piezoelectric materials (including
some polymers) and MEMS.
For example, one type of smart system is used
in helicopters to reduce aero-dynamic cockpit
noise that is created by the rotating rotor blades.
94. 94
Piezoelectric sensors inserted into the blades,
monitor blade stresses and deformations;
feedback signals from these sensors are fed into
a computer controlled adaptive device, which
generates noise cancelling antidose.
MEMS devices are small in size, light weight,
low cost, reliable with large batch fabrication
technology.
95. 95
They generally consist of sensors that gather
environmental information such as pressure,
temperature, acceleration, etc., integrated
electronics to process the data collected and
actuators to influence and control the
environment in the desired manner.
The MEMS technology involves a large number
of materials.
96. 96
Silicon forms the backbone of these systems
also due to its excellent mechanical properties
as well as mature micro-fabrication technology
including lithography, etching, and bonding.
Other materials having piezoelectric,
piezoresistive, ferroelectric and other properties
are widely used for sensing and actuating
functions in conjunction with silicon.
97. 97
Nano Materials
Nano-structured (NS) materials are defined as
solids having microstructural features in the
range of 1–100 nm (= (1–100) × 10−9 m) in at
least in one dimension. These materials have
outstanding mechanical and physical properties
due to their extremely fine grain size and high
grain boundary volume fraction.
98. 98
Usually, the clusters of atoms consisting of
typically hundreds to thousands on the
nanometer scale are called as nanoclusters.
These small group of atoms, in general, go by
different names such as nano particles,
nanocrystals, quantum dots and quantum boxes.
Significant work in being carried out in the
domain of nano-structured materials and nano
tubes since they were found to have potential
for high technology engineering applications.
99. 99
Nano-structured materials exhibit properties
which are quite different from their bulk
properties. These materials contain a controlled
morphology with atleast one nano scale
dimension. Nano crystals, nano wires and nano
tubes of a large number of inorganic materials
have been synthesized and characterized in the
last few years.
100. 100
Some of the nano materials exhibit properties of
potential technological value. This is
particularly true for nano-structures of
semiconducting materials such as metal
chalcogenides and nitrides.
The mixing of nano-particles with polymers to
form composite materials has been practiced for
decades.
101. 101
For example, the clay reinforced resin known as
Bakelite is the first mass-produced polymer-
nanoparticle composites and fundamentally
transformed the nature of practical household
materials. Even before bakelite, nano
composites were finding applications in the
form of nano particle-toughened automobile
tires prepared by blending carbon black, zinc
oxide, and/or magnesium sulfate particles with
vulcanized rubber.
102. 102
Despite these early successes, the broad
scientific community was not galvanized by
nano composites until the early 1990s, when
reports revealed that adding mica to nylon
produced a five-fold increase in the yield and
tensile strength of the material.
Subsequent developments have further
contributed to the surging interest in polymer–
nano particle composites.
103. 103
Nanoengineered Materials
Until very recent times the general procedure
utilized by scientists to understand the
chemistry and physics of materials has been to
begin by studying large and complex structures,
and then to investigate the fundamental building
blocks of these structures that are smaller and
simpler. This approach is sometimes termed
“top-down” science.
104. 104
However, 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 (i.e., “materials by
design”).
105. 105
This ability to carefully arrange atoms provides
opportunities to develop mechanical, electrical,
magnetic, and other properties that are not
otherwise possible.
We call this the “bottom-up” approach, and the
study of the properties of these materials is
termed “nanotechnology”; the “nano” prefix
denotes that the dimensions of these structural
entities are on the order of a nanometer (10^-9
106. 106
m)—as a rule, less than 100 nanometers
(equivalent to approximately 500 atom
diameters).
Materials produced out of nanoparticles have
some special features, e.g.
(i) very high ductility (ii) very high hardness ~4
to 5 times more than usual conventional
materials
(iii) transparent ceramics achievable
107. 107
(iv) manipulation of colour
(v) extremely high coercivity magnets
(vi) developing conducting inks and polymers.
Material science has expanded from the
traditional metallurgy and ceramics into new
areas such as
electronic polymers,
complex fluids,
intelligent materials,
108. 108
organic composites,
structural composites,
biomedical materials (for implants and other
applications),
biomimetics,
artificial tissues,
biocompatible materials,
“auxetic” materials (which grow fatter when
stretched),
elastomers,
109. 109
dielectric ceramics (which yield thinner
dielectric layers for more compact electronics),
ferroelectric films (for non-volatile memories),
more efficient photovoltaic converters, ceramic
superconductors,
improved battery technologies,
self-assembling materials,
fuel cell materials,
optoelectronics,
artificial diamonds,
110. 110
improved sensors (based on metal oxides, or
conducting polymers),
grated light values, ceramic coatings in air (by
plasma deposition),
electrostrictive polymers,
chemical—mechanical polishing,
alkali-metal thermoelectric converters,
luminescent silicon,
planar optical displays without phosphors,
MEMS, and super molecular materials.
111. 111
However, there still remain technological
challenges,
including the development of even more
sophisticated and specialized materials, as well
as consideration of the environmental impact of
materials production.
112. 112
Material scientists are interested in green
approaches, by entering the field of
environmental—biological science, by
developing environmentally friendly processing
techniques and by inventing more recyclable
materials.
113. 113
The following table shows the properties of materials to be considered for different
applications:
Manufacturing
processes
Functional
requirements
Cost considerations Operating
parameters
Plasticity Strength Raw material Pressure
Malleability Hardness Processing Temperature
Ductility Rigidity Storage Flow
Machinability Toughness Manpower Type of material
Casting properties Thermal
conductivity
Special treatment Corrosion
requirements
Weldability Fatigue Inspection Environment
Heat Electrical treatment Packaging
properties
Protection from
fire
Tooling Creep Inventory Weathering
Surface finish Aesthetic look Taxes and custom
duty
Biological effects