INTRODUCTION TO MATERIALS SCIENCE

POORNAPRAJNA INSTITUTE OF SCIENTIFIC RESEARCHBENGALURU.

Lecture By : Vijaykumar .S.M

Materials science is an interdisciplinary field applying the synthesis characterization and properties of material to various areas of science and engineering.

What is MATERIAL SCIENCE ?

What Properties we are searching in a material ?

1. Strength , Hardness , flexibility.2.Thermal ,magnetic and electrical Properties.3. Stability .4. Catalyst (Acidic or basic )5. Reusability and eco friendly .6. Low Cost.

Based on above properties apply them in day today Material .

CLASSES OF MATERIALSIONIC CRYSTALS COVALENT MATERIALSMETAL & ALLOYSSEMICONDUCTORSSUPERCONDUCTORSPOLYMERSCOMPOSITE MATERIALS CERAMICSINORGANIC GLASSESCATALYSTS

IONIC CRYSTALS ionic Bond is Formed by transfer of electrons

Example: NaCl,KCl,MgCl2 etc Synthesis : NaCl is currently produced by evaporation of seawater or brine from other sources.

Mg(OH)2+ 2 HCl → MgCl2(aq) + 2 H2O

Properties of Ionic Crystals

1. Solid Crystals have high melting point.2. They Conduct electricity in molten state.3. Low thermal conductivity.4. Soluble in polar solvents.

APPLICATION OF IONIC CRYSTALS NaCl is Used for cooking purpose which make food tasty.

preservation of cheese, dairy products, meat, pickles and sauces.

CaCl2 salt is used as Road salt to remove snow fallen on road in Cold countries .it lowers the freezing point water.

Potassium chloride produced is used for making fertilizer since the growth of many plants is limited by their potassium intake.

KCL It is used in preparation of salt bridge which connects both the half concenteration cells.

COVALENT MATERIALS

Example :Diamond, Graphite, Fullerene etc

Covalent bond formed by the Sharing of electrons

DIAMOND highest hardness and thermal conductivity of any bulk material. A diamond is a transparent crystal of tetrahedral bonded carbon atoms (sp3) diamond lattice face centered cubic structure

Cutting and Drilling - diamonds are frequently embedded in saw blades. Polishing pads – It is used polish hard surface

GRAPHITE Graphite has a layered, planar structure with hexagonal lattice of Carbon atoms (SP2 ).

graphite powder with clay mixed in as a binding agent are used in synthesis of pencil.

FULLURENE

Fullerene is molecule composed entirely of carbon, in the form of a hollow sphere.

Carbon is SP2 hybridization.

Fullerenes consist of 20 hexagonal and 12 pentagonal rings .

Fullerenes are currently applied in cosmetics and sports goods industries .

fullerenes are also used in slow drug delivery in a body

METALS&ALLOYS Metallic bonding is the bonding between atoms within metals.

Alloy is homogeneous mixture of two or more elements

Example : copper ,Aluminum , Brass, Stainless steel etc.

Properties of metals and alloys

1.High tensile strength.2.They exhibit magnetic properties. 3.High Electrical conductivity.

Cupro – Nickel alloy

APPLICATION OF METALS AND ALLOYS

Due to Their electric properties they are used in electric wire and Electrical devices .

Stainless steel alloy is milled into coils, sheets, plates, bars, wire, and tubing to be used in cookware, hardware , surgical instruments.

Brass can be used for the metallic coatings of several lock ,Watch etc.

SEMICONDUCTORS the bonding is covalent (electrons are shared between atoms). Their electrical properties depend strongly on minute proportions of dopants. Examples: Si, Ge etc

Dopants: Boron (3 rd group element )

Phosphorus (5th group element)

PROPERTIES OF SEMICONDUCTORS

1. They are crystalline and amorphous

2.The conductivity properties lie In-between insulator and conductors.

3. Their conductivity varies with temperature.

APPLICATION OF SEMICONDUCTORS

Si wafer in photovoltaic cells to convert light energy to electric energy.

Semiconductor memory uses semiconductor-based integrated circuits to store information.

A transistor is a semiconductor device used to amplify and switch electronic signals

SUPERCONDUCTORS An element , intermetallic alloy or compound that will conduct electricity without resistance below certain Temperature.

Example: YBa2Cu3O7(-178°C),Pb(-265.83°C)etc.

PROPERTIES SUPERCONDUCTORS

1.Meissner effect :Superconductors are diamagnetic compounds which repel magnetic field.

2.Josephson effect:When 2 superconductors sheets are separated by small thin insulating material the current can pass through without any voltage.

APPLICATION OF SUPERCONDUCTORS

Based on Meissner effect trains can be made to "float" on strong superconducting magnets, virtually eliminating friction between the train and its tracks.Speed :581 KPh in shanghai.

SQUID's are capable of sensing a change in a magnetic field over a billion times weaker than the force that moves the needle on a compass . With this technology, the body can be probed to certain depths without the need for the strong magnetic fields associated with MRI's.

SYNTHETIC POLYMERS Polymer: High molecular weight molecule made up of a small repeat unit (monomer).

A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-Aexample : polyester ,nylon Bakelite etc.

Types of polymers:1. Thermoplastics: can be processed by melting (several cycles of heating and cooling are possible for thermally stabilized polymers) example: PVC,PET etc

2. Thermosets: cannot be melted or dissolved to be processed: chemical decomposition occurs before softening. example: Vulcanized rubber Bakelite.

Synthesis of Nylon

Decanedioyl dichloride in C2H2Cl4

1,6-diaminohexane in aqueous sodium carbonate.

NYLON 6,10

6 indicates the no carbon atoms in amine compound10 indicates the no of carbon atoms in carbonyl chloride

APPLICATION OF SYNTHETIC POLYMERPolypropylene the polymer we are using from morning to night

COMPOSITE MATERIALS Two inherently different materials that when combined together produce a material with properties that exceed the constituent materials.

Composite materials consist of two main materials.1.Reinsforcement(Strong load carrying material) EX: aramide, carbon ,fiberglass

2.Matrix (imbedded weaker material) EX: polypropylene ,polyvinyl chloride etc.

Composite Materials offers1.High Strength2.Light Weight3.Design Flexibility

•Transfer Load to Reinforcement•Temperature Resistance•Chemical Resistance

•Tensile Properties•Stiffness•Impact Resistance

APPLICATION OF COMPOSITE MATERIALS Carbon fiber composites with polymer matrices, have become the advanced composite materials for aerospace, due to their high strength, high Modulus and low cost.

Helmet and bullet proof jacket Made Up of Aramide Composite material

Fiber-reinforced plastics have reached the stage where they could be used for making wheels.

CERAMICSCeramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling.Example: clay ,Mixed oxides like alumina Zirconia Etc

PROPERTIES OF CERAMICS

1. Ceramics are Strong solid inert materials.

2. They withstand chemical erosion due to Acid and Caustic.

3. These can withstand high temperature of about 1000 °C to1600°C.

TYPES OF CERAMICS

1.Whitewares clays

2.Refaracotories Have high Silicon or Aluminium oxide content. 3.Abrasives. Natural garnet, diamond, Silicon carbide.

APPLICATION OF CERAMIC MATERIALS

WHITE WARES are used in including tableware, wall tiles, pottery products and sanitary ware

REFRACTORIES are used in making fire bricks silica crucible and ovens. Due to there low thermal conductivity and high strength to temperature

Sandpaper is a very common coated abrasive.

GLASSESGlass is an amorphous (non-crystalline) solid material and typically brittle and optically transparent.

Silica(SiO2) is a common fundamental constitute of glass.

Synthesis of glass

1. Mixture of soda ash ,limestone, sand and broken glass in dry condition.

2. send to furnace and heat to 1600°C3. Molding.4. Annealing.5. shaping.6. Marketing .

APPLICATION OF GLASSES

Borosilicate glasses formerly called Pyrex are often used laboratory reagents due to their resistance to chemical corrosion and heat

fancy glass started to become significant branches of the decorative arts.

CATALYSTCatalyst is substance which alters the rate of reaction without itself undergoing any chemical change in the reaction

Acid catalyzed reaction usually catalysed by acidsEx:H2SO4, HCl, AlCl3, HF,BF3 etc.

Operational Difficulties1. Corrosive and toxic.2. difficult to handle.3. effluent disposal.4. product separation.

Solid Acid catalyst

• Zeolites aluminosilicate• Heteropolyacids H3PW12O40

• Sulfated zirconia So4-2 /Zr02

• Mixed oxides Al2O3 ,ZnO

ZeoliteZeolites are micro porous crystalline aluminosilicates with Si & Al Tetrahedral Framework .

Calcination

Tetrapropyl ammonium bromide

Acidity arises from Framework aluminium

SHAPE SELECTIVITY IN ZEOLITESReactant selectivityReactant molecules are to large to diffuse through the Zeolite pore

Product selectivityProduct are bulky to diffuse out of the pore . They are converted into less bulky group.

Restricted Transition state SelectivityReaction involving transition state would require more space than available in the cavities or pores.

Magnetic_5c69_0_2.3gp

Magnetic levitation train

Magnetic_1a94_0_2.3gp

Magnetic levitation

Synthesis of Nylon Composite materials

SynthesisNylon_3941_0_2.3gp Composite_f0a6_0_2.3gp