introduction to Material Science and engineering

1. INTRODUCTION TO MATERIALS SCIENCE & ENGINEERING DR.RABIUL HUSSAIN Assistant Professor School of Material Science and Engineering Jimma Institute of Technology Jimma University E-mail: rabiul786@gmail.com Mobile: 0966882081

2. What is a Material? • A material is a physical substance used to make things. • Metals, plastics, ceramics, glass and fibres are some main categories of materials. • If we look around, everything we see is made from a material, sometimes more than one material..

3. Properties of Materials: • A property of a material is a description of the characteristics which it has. They are adjectives which tell us about the material. • Materials have different properties and characteristics depending on what they are used for. • Some materials are hard, others are soft. Some are strong, others are weak.

4. What is material science? Definition 1: A branch of science that focuses on materials; interdisciplinary field composed of physics and chemistry. Definition 2: Relationship of material properties to its composition an use. What is a material scientist? • A person who uses his/her combined knowledge of physics, chemistry and metallurgy to exploit property-structure combinations for practical use.

5. What is Materials Science? • Materials science involve investigating the relationships that exist between the structure and properties of materials What is Materials Engineering? • Materials engineering involve, on the basis of these structure property correlation, design/engineer the structure of a material to produce a predetermined set of properties. Who is Materials Engineer? • To create new product/systems using existing materials • To develop new techniques for processing materials

6. Some important terminology: • Composition means the chemical make-up of a material. • Structure means a description of the arrangements of atoms or ions in a material. • Synthesis is the process by which materials are made from naturally occurring or other chemicals. • Processing means different ways for shaping materials into useful components or changing their properties.

7. What is MATERIAL SCIENCE ? Materials science is an interdisciplinary field applying the synthesis characterization and properties of material to various areas of science and engineering. 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 .

8. CLASSES OF MATERIALS • IONIC CRYSTALS • COVALENT MATERIALS • METAL & ALLOYS • SEMICONDUCTORS • SUPERCONDUCTORS • POLYMERS • COMPOSITE MATERIALS • CERAMICS • INORGANIC GLASSES • CATALYSTS

9. 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 • Solid Crystals have high melting point. • They Conduct electricity in molten state. • Low thermal conductivity. • Soluble in polar solvents.

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

11. COVALENT MATERIALS • Covalent bond formed by the Sharing of electrons Example :Diamond, Graphite, Fullerene etc • 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

12. GRAPHITE • Graphite has a layered, planar structure with hexagonal • lattice of Carbon atoms (SP2 ). • graphite powder with clay mixed in as a binding agentare • 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

13. 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

14. 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.

15. 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.

16. 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

17. 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.

18. 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.

19. 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-A • example : 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.

20. 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 compound 10 indicates the no of carbon atoms in carbonyl chloride

21. APPLICATION OF SYNTHETIC POLYMER Polypropylene the polymer we are using from morning to night

22. 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 offers • 1.High Strength • 2.Light Weight • 3.Design Flexibility • Tensile Properties • Stiffness • Impact Resistance • Transfer Load to Reinforcement • Temperature Resistance • Chemical Resistance

23. APPLICATION OF COMPOSITE MATERIALS • Carbonfiber 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.

24. CERAMICS Ceramic 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 Ceramics are Strong solid inert materials. They withstand chemical erosion due to Acid and Caustic. These can withstand high temperature of about 1000 °C to1600°C. TYPES OF CERAMICS 1.Whitewares clays 2.RefaracotoriesHave high Silicon or Aluminium oxide content. 3.Abrasives. Natural garnet, diamond, Silicon carbide.

25. 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.

26. GLASSES Glass 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 Mixture of soda ash ,limestone, sand and broken glass in dry condition. send to furnace and heat to 1600°C Molding. Annealing. shaping. Marketing .

27. 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.

28. CATALYST Catalyst is substance which alters the rate of reaction without itself undergoing any chemical change in the reaction Acid catalyzed reaction usually catalysed by acids Ex:H2SO4,HCl, AlCl3, HF,BF3 etc. Operational Difficulties Corrosive and toxic. difficult to handle. effluent disposal. product separation. Solid Acid catalyst • Zeolitesaluminosilicate • Heteropolyacids H3PW12O40 • Sulfated zirconia So4-2 /Zr02 • Mixed oxides Al2O3 ,ZnO

29. Zeolite • Zeolites are micro porous crystalline aluminosilicates with Si & Al • Tetrahedral Framework . Calcination Tetrapropyl ammonium bromide

30. Acidity arises from Framework aluminium

31. SHAPE SELECTIVITY IN ZEOLITES Reactant selectivity Reactant molecules are to large to diffuse through the Zeolite pore Product selectivity Product are bulky to diffuse out of the pore . They are converted into less bulky group. Restricted Transition state Selectivity Reaction involving transition state would require more space than available in the cavities or pores.