3. Introduction
With the advent of Material Science and
Engineering , discovered . The newly
discovered engineering materials find major
application in industry.
The materials are classified as metals and
alloys ,ceramics ,glass ceramics , composites ,
polymers and semiconductors.
In the following section , advanced engineering
materials like glasses , shapes memory alloys ,
biomaterials and energy materials are discussed in
brief . many advanced engineering material have
4. METALLIC
GLASSESMetallic glasses are the newly developed
engineering materials . Metallic glasses share the
properties of both metals and alloys.
Most metals and alloys are crystalline ,i.e.
,their atoms are arranged in some regular
pattern that extends over a long distance . In
contrast , glass is an amorphous , brittle and
transparent solid.
Metallic glasses are to be made by cooling a
molten metal rapidly at a rate of 2×10 Cs.
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5. Types Of Metallic
GlassesMetallic glasses are two types depending on the
base materials used for preparation.
1. Metal-Metal glasses.
Examples : Ni- Nb , Mg-Zn and Cu- Zr
2.Metal-Metalloid glasses-Transitions metals like
Fe, Co,Ni and metalloids like B , Si , C and P
are used
Examples: Fe Co B Si , Fe B Si
67 18 14 78 13 9
6. Preparation
Various rapid cooling techniques such as
spraying , spiinings and laser deposition of
metallic glasses.
The metallic spinning process technique involves
in the preparation of metallic glasses is
illustrates in figure .
7. In this techniques , there is a spinning disc made
of copper . In order to prepare a metallic glass
of a particular type, a suitable combination of
metal-metal or metal-metalloid alloy in its
stoichiometric ratio is taken in a refactory tube
having a nozze at its bottom .The nozzle side of
the tube is placed just over the spinning disc.
An induction heater attached to the refactory
tube melts the alloy . this is kept above iys melting
point till it gets transformed into ahomogeneous
mixture . An inert gas such as helium is made to
flow through the tube containing the homogeneous
mixture . As a result the melt gets ejected through
the nozzle . The ejected rate can be increased the
8. Other techniques
The other techniques used for producing
ribbons of mettallic glasses include:
a) Twin roller-In this techniques a molten
alloy is passed through two rollers rotating
in opposite directions.
b) Melt extraction system-In this techniques
a fast moving roller sweeps off molten
droplet into a strip from a solid rod.
9. Properties of Metallic
Glasses1. The strength of metallic glasses is very
high but they are lighter in weight.
2. They are ductile,malleable,brittle and
opaque.The hardness is very high.
3. The toughness is very high.i.e.,the
fracture resistant is very high(more than
ceramics)
4. They have high elasticity,i.e.,the yield
strength is very high.
5. They have high corrosion resistance.
6. They do not contain any crystalline defects
lke point defects,dislocation,skacking
10. Applications
Metallic glasses are used as transformer core
materials in high power transformers.
These materials are used in the preparation of
magnets for levitated trains , etc.
Metallic glasses can also be used for making
watch cases to replace Ni and other metals which
can cause allergic reactions.
Metallic glasses are used in tap recorder as
heads , in the manufacture of springs and
11. SMART MATERIALS
The smart materials mimic biological functionls ,
viz , sensing actuation and control. These
materials can respond to external stimuli such as
temperature ,pressure ,optical ,electric field ,
moisture ,magnetic field and so on.
Among serval smart materials , shape memory
alloys(SMAs), piezo electric materials and fiber
optic sensors are currrently receiving wide
attension.
12. Shapes memory alloys
(SMA)
Shape memory alloys(SMAs)are metals which
exhibit two unique properties ,shapes memory
effect(SME) and pseudoelasticity or super
elasticity(SE).
These alloys are a unique class of materials
which remember their shape even after servere
deformation,i.e.,when an SMA is once deformed
in the cold shape they will stay defoemed until
heated;upon heating they will spontaneously
13. Types of Shape Memory Allo
These are two of SMAs:
1.The one –way shape memory alloy and
2.The two-way shape memory alloy.
The materials which exhibit shape memory
effect only upon heating are said to have one
way shape memory.
In contrast , some of the materials exhibit
shape memory effect both during heating and
cooling .Hence these materials are said to
have two-way shape memory.
18. Applications of
SMAsThe crystal properties of SMA makes them to
be applied in in a number of different fields.
1) 1.Aircraft and Space Industry
2) 2.Automobile Industry
3) 3.Medical Field
4) 4.Consumer products
19. Advantages of SMAs
1.They have good biocompatibility.
2.They have diverse fields of
application.
3.They provide clean , silent and spark
free working condition.
4.They have good mechanical properties.
21. BIOMATERIALS
The term biomaterial has been defined in so
many different ways . Yet , most generally
, biomaterials are defined as the materials
with novel chemical , physical , mechanical
,or ‘intelligent’ properties produced through
process that mimic biological phenomena.
23. ULTRACAPACITOR
Ultracapasitors ar sometimes called
supercapacitors or elecchemical supertric double
layer Ccpacitor(EDLC) or electrochemical
supercapacitors.
Ultracapacitors are a typeof electrical
components that are capable of holding electrical
charge nearly 10000 times more than a standard
electrolytic capacitor.
The capasitance value of an ultracapacitor is
determined by two-stage principles:
1) Double layer capasitor
2) Pseduocapasitance
Ultracapasitor are divided into three group:
24. Solar cells
Principle:
Solar cells operate on the principle
of photovoltaic action. The photovoltaic
action refers to their voltage-
generating capability . Since the voltage
they generate is proportional to the
intensity of the sunlight , they are also
called Photovoltaic cells.
25. Types of solar
cells
i. Cadmium telluride solar cells
ii.Copper indium Gallium selenide solar
cells
iii.Gallium arsenide multi junction
solar cells
iv.Organic solar cells
