Shankershinh Vaghela Bapu

Institute of Tecnology

Ω Engineering Physics Ω

Advanced Engineering Materials

YASHPALSINH VAGHELAYATIN DESAILAKSHMI VIMALKISHAN PATELSAGRIKA MAURYASHREY PATEL

Presented by

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 been

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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Types Of Metallic Glasses

Metallic 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

PreparationVarious 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 .

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 pressure of the inert gas .Thus a glassy alloy ribbon starts getting formed over the spinning disc.

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.

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 faults,etc.

ApplicationsMetallic 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 standard resistances.

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.

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 return to their original predetermined hot shape.

Types of Shape Memory AlloysThese 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.

Temperature-Induced Transformation

Stress-induced Transformation

Shape memory Effect

Super Elasticity (Pseudoelasticity)

Applications of SMAs The crystal properties of SMA makes them

to be applied in in a number of different fields.

1) 1.Aircraft and Space Industry2) 2.Automobile Industry3) 3.Medical Field4) 4.Consumer products

Advantages of SMAs1.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.

5.They are flexible.

Disadvantages of SMAs

1.SMAs manufacturing and machining cost in high.

2.They have poor fatigue properties.

3.They have low energy efficiency.

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.

Types Of BiomaterialsThe biomaterials are in general classified

into the following types:

1.Metal and alloys

2.Polymers

3.Ceramics

4.Composites.

ULTRACAPACITORUltracapasitors 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 capasitor2) PseduocapasitanceUltracapasitor are divided into three group:(a)double layer capacitors ,(b)

pseudocapacitors (c)hybrid capacitors.

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.

Types of solar cells

i.Cadmium telluride solar cellsii.Copper indium Gallium

selenide solar cellsiii.Gallium arsenide multi

junction solar cellsiv.Organic solar cells

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