Chapter 1 Introduction to Materials Science and Engineering PDF

Chapter 1 Introduction to Materials Science and Engineering  Topic Contents 1. Historical perspective 2. Materials Science and Engineering 3. Classification of Materials  What are Materials? Materials – Substances from which something is composed or made f...

Chapter 1 Introduction to Materials Science and Engineering  Topic Contents 1. Historical perspective 2. Materials Science and Engineering 3. Classification of Materials  What are Materials? Materials – Substances from which something is composed or made from – Development of human civilization has been closely tied to materials which has been produced & used in society  What are Engineering Materials? Engineering Materials – Materials used to produce technical products – Engineered materials with desired properties  Why should we know about it? Cost? Materials in our live – Electronic & Electrical Effective? – Mechanical Fabrication? – Chemical Safety? – Civil & Structural – Infrastructure & Transportation – Aerospace – Military – Telecommunications – Entertainment  Evolution of Materials MATERIALS ENGINEERING MATERIALS Prehistoric Iron age Electric age Stone Bronze (Industrial (Silicon age) age age revolution) Materials Alloy of existing in copper Minimum nature material Nano Designed Stone, processing materials materials wood, Produce better material age age clay properties to those occurring naturally Advance composite Iron, steel. Surface treatment other metals Artificial layered structures Steam engine Prehistoric  Stone age Early in developments of human cultures, before the use of metals Tools & weapons are made by stone  Bronze age Bronze (Cooper + Tin + Zinc) The time in the development of any human culture Before introduction of iron, when most tools & weapons were made from bronze  Iron age Marks the period of development of technology replacing bronze as the basic materials for implements & weapon Last stage of the archaeological sequence Now?  Topic Contents 1. Historical perspective 2. Materials Science and Engineering 3. Classification of Materials  Discipline of Materials Study Materials Science – Study of basic materials knowledge Investigation of the relationship between STRUCTURES and PROPERTIES of materials Materials Engineering – Used of Materials Science knowledge (fundamental) to design and to produce materials with properties that will meet the requirements of society – Structure-Property correlations, designing or engineering the structure of a materials to a pre-determined set of properties  Materials Science and Engineering (MSE) – Combines both basic knowledge & applications – form a bridge between the basic sciences (physics, chemistry, maths) & the various engineering disciplines (electrical, mechanical, chemical, civil & aerospace engineering) – Interdisciplinary nature Material Science Material Engineering Basic knowledge of Applied knowledge of materials materials Resultant knowledge of the structure, properties, processing and performance of engineering materials Material Science and Engineering  The Materials Selection Process 1. Pick Application Determine required Properties Properties: mechanical, electrical, thermal, magnetic, optical, deteriorative. 2. Properties Identify candidate Material(s) Material: structure, composition. 3. Material Identify required Processing Processing: changes structure and overall shape ex: casting, sintering, vapor deposition, doping forming, joining, annealing.  4 components that are involved in design, production & utilization of materials – Processing – Structure – Properties – Performance To succeed in processing materials with a given set of properties, it is necessary to understand the basis set of the properties from the atomic & molecular level, and to understand how small differences in structure can lead to large differences in observed properties  What is Processing? Multiple procedures to produce something pre-determined  What is Structure? Arrangement of its internal components Electron within Subatomic individual atoms & level interaction with their nuclei Organization of atoms Atomic or molecules relatives level to one another Microscopic Direct observation level using microscope tools Macroscopic Viewed by naked eye level  What is Property? Material trait in terms of the kind and magnitude of response to a specific imposed stimulus Properties of solid materials Material: Conductor may be grouped into six Stimulus: Voltage different categories: Response: Electric current Mechanical Electrical Property Stimulus Response Thermal Mechanical Applied load Deformation Magnetic or force Optical Deteriorative. Electrical Electrical Conductivity field Structure, Processing, & Properties Properties depend on structure ex: hardness vs structure of steel (d) 600 Hardness (BHN) 30 mm 500 (c) Data obtained from Figs. 10.30(a) 400 (b) and 10.32 with 4 wt% C composition, (a) and from Fig. 11.14 and associated 4 mm discussion, Callister 7e. 300 Micrographs adapted from (a) Fig. 10.19; (b) Fig. 9.30;(c) Fig. 10.33; 30 mm 30 mm and (d) Fig. 10.21, Callister 7e. 200 100 0.01 0.1 1 10 100 1000 Cooling Rate (ºC/s) Processing can change structure ex: structure vs cooling rate of steel  ELECTRICAL Electrical Resistivity of Copper: 6 Adapted from Fig. 18.8, Callister 7e. (Fig. 18.8 adapted from: J.O. Linde, 5 Ann Physik 5, 219 (1932); and C.A. Wert and R.M. Thomson, Resistivity, r Physics of Solids, 2nd edition, (10-8 Ohm-m) 4 McGraw-Hill Company, New York, 1970.) 3 2 1 0 -200 -100 0 T (°C) Adding “impurity” atoms to Cu increases resistivity. Deforming Cu increases resistivity. Electrical properties, such as electrical conductivity and dielectric constant, the stimulus are an electric field.  THERMAL Space Shuttle Tiles: --Silica fiber insulation Thermal Conductivity offers low heat conduction. of Copper: --It decreases when you add zinc Adapted from chapter- opening photograph, Chapter 19, Callister 7e. (Courtesy of Lockheed 400 Thermal Conductivity Missiles and Space Company, Inc.) 300 (W/m-K) 200 100 0 0 10 20 30 40 Composition (wt% Zinc) Adapted from Fig. 19.4W, Callister 6e. (Courtesy of Thermal properties can Lockheed Aerospace be represented in terms Ceramics Systems, Sunnyvale, CA) of heat capacity and (Note: "W" denotes fig. thermal conductivity. 100 mm is on CD-ROM.)  MAGNETIC: demonstrate the response of a material to the application of a magnetic field. Magnetic Storage: Magnetic Permeability --Recording medium vs. Composition: is magnetized by --Adding 3 atomic % Si recording head. makes Fe a better recording medium! Magnetization Fe+3%Si Fe Magnetic Field Adapted from C.R. Barrett, W.D. Nix, and Fig. 20.23, Callister 7e. A.S. Tetelman, The Principles of (Fig. 20.23 is from J.U. Lemke, MRS Bulletin, Engineering Materials, Fig. 1-7(a), p. 9, Vol. XV, No. 3, p. 31, 1990.) 1973. Electronically reproduced by permission of Pearson Education, Inc., Upper Saddle River, New Jersey.  OPTICAL Transmittance: -- Aluminum oxide may be transparent, translucent, or opaque depending on the material structure. -- such as index of refraction, the stimulus is electromagnetic and light radiation. polycrystal: polycrystal: single crystal low porosity high porosity Adapted from Fig. 1.2, Callister 7e. (Specimen preparation, P.A. Lessing; photo by S. Tanner.)  DETERIORATIVE: relate to the chemical reactivity of material Heat treatment: slows Stress & Saltwater... crack speed in salt water! --causes cracks! crack speed (m/s) 10-8 “as-is” “held at 160ºC for 1 hr before testing” 10-10 Alloy 7178 tested in saturated aqueous NaCl solution at 23ºC increasing load 4 mm --material: 7150-T651 Al "alloy" (Zn,Cu,Mg,Zr) Adapted from chapter-opening photograph, Adapted from Fig. 11.26, Chapter 17, Callister 7e. Callister 7e. (Fig. 11.26 provided courtesy of G.H. (from Marine Corrosion, Causes, and Narayanan and A.G. Miller, Boeing Commercial Prevention, John Wiley and Sons, Inc., 1975.) Airplane Company.)  What is Performance? A measurement of how good a product is.  The four components of the discipline of materials science and engineering and their linear interrelationship. Processing Structure Properties Performance  Car body →What is the right material to use? What features of the structure limit the strength? How can High level of aerodynamic toughness & formability car chassis be formed? What is the strength-to density ratio?  Topic Contents 1. Historical perspective 2. Materials Science and Engineering 3. Classification of Materials Common material classification categories: Engineering Materials Metals Ceramics Polymers Composites Classification of Materials (Metals) METAL (metallic materials) ferrous non-ferrous steel cast iron Metals can be further classified as Ferrous & Non- Ferrous, some examples include; Ferrous Non-Ferrous Steels Aluminium Stainless Steels Copper High Speed Steels Brass Cast Irons Titanium  Properties: – Stiff & strong – Ductile – Resistance to fracture – Good conductors of electricity & heat – Not transparent to visible light – Some metals have magnetic properties (Fe, Co, Ni)  Metal / metallic materials Ferrous materials consist of steel and cast iron Eg. Carbon steel, high alloy steel, stainless steel, tool steel (steel group) Eg. White cast iron, grey cast iron (cast iron group) Nonferrous materials consist of the rest of the metals and alloys Eg. Aluminum, magnesium, titanium & their alloys Materials from each group are further classified and given certain designation according to the ASTM standard Each has their own unique number/code that represent main alloying elements, cast or wrought and in case of plain carbon – amount of carbon. Steel can be classified or grouped according to some common characteristic. The most common classification is by their i. Composition Example : 10xx, 15xx ii. Strength Most common material used in construction of structure such as bridge, building and ships  Designation of Steels: Classification of Plain Carbon Steels 11XX steels are free machining steels that contain extra sulfur 12XX steels contain extra sulfur and phosphorus 15XX steels contain manganese  Designation of Steels: Classification of Alloy Steels the last two digits describe carbon content of a steel, the first two digits identify the family of the steel.  Classification of Alloy Steels “E” is used to indicate steels produced in an electric arc furnace. “H” indicates that hardenability is a special property of the metal. “B” indicates the presence of boron, “L” indicates the presence of lead. Metals in Car Classification of Materials (Ceramics) Compounds between metallic + non-metallic elements oxides, nitrides, carbides (Al2O3, SiO2, SiC, Si3N4, porcelain, cement, glass Properties at room temperature – Stiff & strong – Hard – Extremely brittle – Highly susceptible to fracture – Insulative to heat & electricity – Resistance to high temperature & harsh environment – Can be transparent, translucent, opaque – Some of the oxide ceramics have magnetic bahaviour (Fe3O4)  Ceramics are compounds of metallic and non-metallic elements, examples include: Oxides (alumina – insulation and abrasives, zirconia – dies for metal extrusion and abrasives) Carbides (tungsten-carbide tools) Nitrides (cubic boron nitride, 2nd in hardness to diamond)  Applications Clay – Shaped, dried, and fired inorganic material Examples: Brick, tile, sewer pipe, chimney flue, china, porcelain, etc. Refractory – Designed to provide acceptable mechanical or chemical properties while at high temperatures Example: Space shuttle all-silica insulating tiles  Applications Electrical Resistors – Create desired voltage drops and limit current Thermistors – Application of heat regulates current flow Rectifiers – Allow current to flow in one direction Heating elements for furnaces  Classification of Materials (Polymers) Plastic & rubber materials Organic materials based on C, H & other nonmetallic elements (O, N, Si) Long molecular chain with carbon as a backbone PP, PE, PVC, nylon, PS, PC, silicone rubber Properties – Pliable (easily formed into complex shape) – Inert chemically & unreactive in a large number of environments – Tendency to soften/decompose at modest temperature – Low electrical conductivity – Non magnetic – Mechanically flexible – Poor electrical conductor  POLYMER PLASTICS ELASTOMERS THERMOPLASTICS THERMOSETS Design for polymer Polymer – low density, good thermal & electrical insulation, high resistance to most chemicals and ability to take colors and opacities. But if unreinforced bulk polymer are mechanically weaker, it will has lower elastic moduli & high thermal expansion coefficients. Improvement→Reinforced variety of fibrous materials →Composites (PMC). Advantages : ease of manufacturing & versatility. Can manufacture into complicated shapes in one step with little need for further processing or surface treatment. Versatility : ability to produce accurate component, with excellent surface finish and attractive color, at low cost and high speed Design consideration for polymer Structural part When the parts is to carry load Should remember the strength and stiffness of plastics vary with temperature. Long term properties Eg. Creep behavior Stress raiser  Plastics can be further classified as; ✓ Thermoplastic ✓ Thermoset ✓ Elastomers Thermoplastics Thermosets Elastomers Acrylics Epoxy resins Rubbers Nylons Phenolic Silicones PVC Polyesters Polyurethanes Polyethylene Rubber Plastics Thermoplastic Formed into a desired shape by applying heat and pressure and being cooled May be heated and remolded Thermosetting Formed into a desired shape by applying heat and pressure and being cooled May not be heated and remolded Elastomers Natural or synthetic material Can be stretched 200 percent of their length at room temperature and can return quickly to original length after force is released Vulcanization Chemical process used to form strong bonds between adjacent polymers to produce a tough, strong, hard rubber (automobile tires)  Classification of Materials (Composites) METALS CERAMICS COMPOSITES POLYMERS  Mixture of two or more types of materials A matrix phase + a reinforcing phase Designed to ensure a combination of the best properties of each component material  A composite is a combination of two or more chemically distinct materials whose physical characteristics are superior to its constituents acting independently. Because of their high strength/stiffness to weight ratio they are widely used in the; Aerospace industry Offshore structures Boats Sporting goods  Examples of composites include; ✓Reinforced Plastics ✓Ceramic-matrix ✓Metal-Matrix ✓Laminates Carbon Outer Cylinder Thrust Combustion reinforced Kevlar, skinCylinder Glass panels taffetalinings chamber plastic reinforced chamber &linings for fuselage rocket polyester of plastic jet A380 sails engine hull Distinguishing Characteristics Composed of more then one material Designed to obtain desirable properties from each individual material Design for composite A composite material can be broadly defined as an assembly two or more chemically distinct material, having distinct interface between them and acting to produce desired set of properties Composites – MMC, PMC & CMC. The composite constituent divided into two Matrix Structural constituent / reinforcement Properties / behavior depends on properties, size & distribution, volume fraction & shape of the constituents, & the nature and strength of bond between constituents.  Mostly developed to improve mechanical properties i.e strength, stiffness, creep resistance & toughness. Three type of composite (1) Fiber-Reinforced Composites (2) Particulate Composites (Particle reinforced composite) (3) Layer Composites (Structural composite) Designing with composite A composite materials usually are more expensive on a cost. Important factors when designing with composite materials is that their high strength are obtained only as a result of large elastics strains in the fiber Fatigue behavior at low stress level because fibrous composites may have many crack, which can be growing and propagate through the matrix Layer Composites (Structural composite) – Alternate layers of materials bonded together Particulate Composites (Particle reinforced composite) – Discrete particles of one material surrounded by a matrix of another material Fiber-Reinforced Composites –Composed of continuous or discontinuous fibers embedded in a matrix of another material  Structural composite - Laminar composed of two-dimensional sheets or panels that have a preferred high strength direction such as is found in wood and continuous and aligned fiber-reinforced plastics. One example of a relatively complex structure is modern ski and another example is plywood.  Structural composite - Sandwich Panels: Consist of two strong outer sheets which are called face sheets and may be made of aluminum alloys, fiber reinforced plastics, titanium alloys, steel. Sandwich panels can be used in variety of applications which include roofs, floors, walls of buildings and in aircraft, for wings, fuselage and tailplane skins  Advanced Materials Materials that are utilized in high-tech application (device/product that operates or functions using relatively intricate & sophisticated principles) DVD Players, Microprocessor, Liquid Crystal Display ADVANCED MATERIALS SEMICONDUCTOR BIOMATERIALS MATERIAL OF THE FUTURE SMART NANOENGINEERED MATERIAL MATERIAL  Advanced Materials: Semiconductors SEMICONDUCTORS – Electrical properties intermediate between conductors & insulator – Electrical characteristics are extremely sensitive to the presence of minute concentration of impurity atoms, which concentrations may be controlled over very small spatial region  Micro-Electrical-Mechanical Systems (MEMS) Si wafer for computer chip devices.  Advanced Materials: Biomaterials Components implanted into the human body for replacement of diseased or damaged body parts. Must not produce toxic substances and must be compatible with body tissues. All of above materials – metals, ceramics, polymers, composites and semiconductors – may be used as biomaterials. For example, some of the biomaterials that are utilized in artificial hip replacements.  Requirements – mechanical strength (many cycles) – good lubricity – biocompatibility Adapted from Fig. 22.24, Callister 7e.  Hip Implant Key problems to overcome Ball – fixation agent to hold acetabular cup – cup lubrication material Acetabular – femoral stem – fixing agent (“glue”) Cup and Liner – must avoid any debris in cup Femoral Stem Adapted from chapter-opening photograph, Chapter 22, Callister 7e.  Advanced Materials: Smart materials Materials that are able to sense changes in their environments & then respond to these changes in predetermined manners A smart material can be described as a material that has a useful response to external influences or stimuli. Devices made from Smart Materials ✓ Sensors (detects an input signal) ✓ Actuators (performs a responsive & adaptive function) Types of smart materials ✓ Shape memory alloys ✓ Piezoelectric ceramics ✓ Magnetostrictive materials ✓ Electrorheological/magnetorheological fluids There are many examples of smart materials in everyday use that are not modern developments they include; ✓Metal springs ✓Light bulbs self regulate because as the filament temperature increases their resistance rises ✓Ancient civilisations have long used porous ceramics for self regulating cooling Wine Cooler Other more modern examples of smart materials include; Shape memory polymers and alloys Smart Heat Wireshrink tubing and packaging Smart Automatic actuators – open/close greenhouse windows Link Silicone Actuators, linear, angular and rotary Thermostats for heating control Anthromorphic Allows Smart Fluidsrotary actuation motion – human between like shafts uprobotic to 360 motion 0 Motion Materials Piezoelectric control gel – CD tray opening/closing, camera lenses Ferro fluids – earthquake dampers in buildings, hard disks Chameleon Sensors,Colours musical cards, motors, actuators, clocks Car paints, printing inks, packaging Other more modern examples of smart materials include; Polymorph This is a unique polymer that fuses in hot water and can then be moulded to any form. When solid it has similar properties to nylon Used to make the moulds for the vacuum formed seat and fuel tank of this motorcycle project Other more modern examples of smart materials include; Thermocolour Sheet This is a self adhesive sheet whose colour changes according to the temperature. Used for thermometers, heat warning patches and novelty advertising of products Inactivated Finger Sheet changes placed Sheet on colour sheetaccording to temp Other more modern examples of smart materials include; Phosphorescent Sheet This is a sheet that absorbs light energy and re-emits it as white light for up to eight hours. Used extensively for emergency lighting in the event of a power cut Other more modern examples of smart materials include; Magnetic Sheet This is a flat polymer magnetic sheet as used in fridge magnets. Also available in thin A4 sheets that can be printed on Other more modern examples of smart materials include; Rigid PVC Foam Plastic This is a new generation of sheet material used widely for signs and exhibitions. Thermoforms very well. It is widely used for ‘plug and yoke’ mouldings  Other more modern examples of smart materials include; Lenticular Sheet This sheet is about 1mm thick but gives the illusion that it is nearer to 6mm thick. An object placed on the sheet appears to sink below the surface The camera lens does not capture the effect Other more modern examples of smart materials include; Anodised Effect Card This is almost impossible to tell from the real thing. Ideal for project mock-ups. It is relatively cheap and cuts easily with a scissors or craft knife Other more modern examples of smart materials include; Galvanised Effect Card This is almost identical to the real thing. Ideal for project mock-ups. It is relatively cheap and cuts easily with a scissors or craft knife. Used for packaging of top branded goods Other more modern examples of smart materials include; Quantum Tunnelling Composite (QTC) A QTC in its normal state is a perfect insulator When compressed it becomes a perfect conductor If only lightly compressed its conductivity is proportional to the pressure applied How does it work? In normal physics an electron cannot pass through an insulation barrier. In Quantum physics theory a wave of electrons can pass through an insulator – this is what is happening! Advanced Materials: Nanoenginered materials Dimension