دانشگاه صنعتی اميركبير

1. دانشگاه صنعتی اميركبير دانشکده مهندسی پزشکی خواص مواد مهندسي مقدمه

2. مواد مهندسي • فلزات • پليمرها • سراميک‌ها • کامپوزيت‌ها

3. سير تکامل مواد در تاريخ

4. مفهوم ماده پيشرفته • مواد متداول جستجو و انتخاب ماده دارای خواص مورد نياز • مواد پيشرفته شناخت دقيق ماهيت ماده موجود، دستکاري ساختار و بهبود يا ايجاد خواص مورد نظر

5. خواص ماده پاسخ‌ها محرک‌ها گرما نیرو میدان الکتریکی نور ميدان مغناطیسی محيط شيميايي و.... خواص حرارتی خواص مکانیکی خواص الکتریکی خواص نوری خواص مغناطیسی خواص شيميايي و.... ماده پيوند‌هاي شيميايي، ساختار بلوري، نقص‌‌ها ساختار

7. Chapter 1 - Introduction • What is materials science? Involves investigating the relationships that exist between the structures and properties of materials. Why should we know about it? • On the basis of structure-property correlations, involves designing or engineering the structure of a material to produce a predetermined set of properties. • Materials drive our society • Stone Age • Bronze Age • Iron Age • Now? • Silicon Age? • Polymer Age?

8. Brief Historical Overview • Paleolithic (40,000 to 100,000 yrs ago): Stone tools and clay pots • Mesolithic (10,000 to 40,000 yrs ago): Extensive use of stone tools and clay, • stone statues, ochre (pigment) • Copper Age (5,000 to 10,000 yrs ago): Copper ornaments, earthenware, • metal smelting • Bronze Age (3,000 to 5,000 yrs ago): Bronze (Cu/Sn), glass, iron smelting • Iron Age (1000 – 3000 yrs ago): Carburized Iron, improved forging, porcelain • Steel and concrete (100 – 1000 yrs ago) • Polymers (beginning early 1900s) • Silicon (60s – ) • The present: Age of biomaterials and nanomaterials?

9. What determines the name for an age (stone age, bronze age, etc.)? • The type of material that is new to that era and is widely used to construct items. • What are some examples of polymers in nature? • Silk, wool, cotton, starch, rubber, DNA, RNA, etc. • Why are polymers so widely used in the automobile and aircraft industries? • They are light and reduce the overall weight of the object.

10. The structure of a material usually relates to the arrangement of its internal components. • Subatomic structure involves electrons within the individual atoms and interactions with their nuclei. • On an atomic level, structure encompasses the organization of atoms or molecules relative to one another. • Microscopic structure contains large groups of atoms that are normally agglomerated together and subject to direct observation using some type of microscope. • Macroscopic structure meaning structural elements that may be viewed with naked eye.

11. Example – Hip Implant • With age or certain illnesses joints deteriorate. Particularly those with large loads (such as hip). Adapted from Fig. 22.25, Callister 7e.

12. Example – Hip Implant • Requirements • mechanical strength (many cycles) • good lubricity • biocompatibility Adapted from Fig. 22.24, Callister 7e.

13. Example – Hip Implant Adapted from Fig. 22.26, Callister 7e.

14. Hip Implant Ball • Key problems to overcome • fixation agent to hold acetabular cup • cup lubrication material • femoral stem – fixing agent (“glue”) • must avoid any debris in cup Acetabular Cup and Liner Femoral Stem Adapted from chapter-opening photograph, Chapter 22, Callister 7e.

15. Example – Develop New Types of Polymers • Commodity plastics – large volume ca. $0.50 / lb Ex. Polyethylene Polypropylene Polystyrene etc. • Engineering Resins – small volume > $1.00 / lb Ex. Polycarbonate Nylon Polysulfone etc.Can polypropylene be “upgraded” to properties (and price) near those of engineering resins?

16. Structure, Processing, & Properties (d) 30mm (c) (b) (a) 4mm 30mm 30mm • Properties depend on structure ex: hardness vs structure of steel 6 00 5 00 Data obtained from Figs. 10.30(a) and 10.32 with 4 wt% C composition, and from Fig. 11.14 and associated discussion, Callister 7e. Micrographs adapted from (a) Fig. 10.19; (b) Fig. 9.30;(c) Fig. 10.33; and (d) Fig. 10.21, Callister 7e. 4 00 Hardness (BHN) 3 00 2 00 100 0.01 0.1 1 10 100 1000 Cooling Rate (ºC/s) • Processing can change structure ex: structure vs cooling rate of steel

17. Types of Materials • Metals: • Strong, ductile • high thermal & electrical conductivity • opaque, reflective. • Polymers/plastics: Covalent bonding  sharing of e’s • Soft, ductile, low strength, low density • thermal & electrical insulators • Optically translucent or transparent. • Ceramics: ionic bonding (refractory) – compounds of metallic & non-metallic elements (oxides, carbides, nitrides, sulfides) • Brittle, glassy, elastic • non-conducting (insulators)

18. Engineering Materials: Controlling Processing - Structure - Properties – Performance • Realistic engineering materials: Trade-off between • properties (what do we need or want?) • deterioration (how long will it last?) • cost (what’s the biggest bang for the buck?) • Resources depletion (how to find new reserves, develop new environmentally-friendly materials, and increase recycling)

19. The Materials Selection Process 1. Pick your 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.

20. Four components involved in the science and engineering of materials, and their interrelationship: Processing===>Structure===>Properties===> Performance

21. Property is a material trait in terms of the kind and magnitude of response to a specified imposed stimulus. 1.Mechanical properties: deformation to an applied load or force; examples include elastic modulus and strength. 2.For electrical properties, such as electrical conductivity and dielectric constant, the stimulus is an electric field. 3.The thermal behavior can be represented in terms of heat capacity and thermal conductivity. 4.Magnetic properties demonstrate the response of a material to the application of a magnetic field. 5.For optical properties, the stimulus is electromagnetic or light radiation; index of refraction and reflectivity are representative optical properties. 6.Deteriorative characteristics indicate the chemical reactivity of materials.

23. 6 5 Cu + 3.32 at%Ni 4 Cu + 2.16 at%Ni Resistivity, r deformed Cu + 1.12 at%Ni 3 (10-8 Ohm-m) 2 Cu + 1.12 at%Ni 1 “Pure” Cu 0 -200 -100 0 T (°C) ELECTRICAL • Electrical Resistivity of Copper: Adapted from Fig. 18.8, Callister 7e. (Fig. 18.8 adapted from: J.O. Linde, Ann Physik5, 219 (1932); and C.A. Wert and R.M. Thomson, Physics of Solids, 2nd edition, McGraw-Hill Company, New York, 1970.) • Adding “impurity” atoms to Cu increases resistivity. • Deforming Cu increases resistivity.

24. 400 300 (W/m-K) 200 Thermal Conductivity 100 0 0 10 20 30 40 Composition (wt% Zinc) 100mm THERMAL • Space Shuttle Tiles: --Silica fiber insulation offers low heat conduction. • Thermal Conductivity of Copper: --It decreases when you add zinc! Adapted from chapter-opening photograph, Chapter 19, Callister 7e. (Courtesy of Lockheed Missiles and Space Company, Inc.) Adapted from Fig. 19.4W, Callister 6e. (Courtesy of Lockheed Aerospace Ceramics Systems, Sunnyvale, CA) (Note: "W" denotes fig. is on CD-ROM.) Adapted from Fig. 19.4, Callister 7e. (Fig. 19.4 is adapted from Metals Handbook: Properties and Selection: Nonferrous alloys and Pure Metals, Vol. 2, 9th ed., H. Baker, (Managing Editor), American Society for Metals, 1979, p. 315.)

25. Fe+3%Si Fe Magnetization Magnetic Field MAGNETIC • Magnetic Storage: --Recording medium is magnetized by recording head. • Magnetic Permeability vs. Composition: --Adding 3 atomic % Si makes Fe a better recording medium! Adapted from C.R. Barrett, W.D. Nix, and A.S. Tetelman, The Principles of Engineering Materials, Fig. 1-7(a), p. 9, Electronically reproduced by permission of Pearson Education, Inc., Upper Saddle River, New Jersey. Fig. 20.23, Callister 7e. (Fig. 20.23 is from J.U. Lemke, MRS Bulletin, Vol. XV, No. 3, p. 31, 1990.)

26. OPTICAL polycrystal: low porosity polycrystal: high porosity single crystal • Transmittance: --Aluminum oxide may be transparent, translucent, or opaque depending on the material structure. Adapted from Fig. 1.2, Callister 7e. (Specimen preparation, P.A. Lessing; photo by S. Tanner.)

27. -8 10 “as-is” “held at 160ºC for 1 hr crack speed (m/s) before testing” -10 10 Alloy 7178 tested in saturated aqueous NaCl solution at 23ºC increasing load 4mm --material: 7150-T651 Al "alloy" (Zn,Cu,Mg,Zr) Adapted from Fig. 11.26, Callister 7e. (Fig. 11.26 provided courtesy of G.H. Narayanan and A.G. Miller, Boeing Commercial Airplane Company.) DETERIORATIVE • Stress & Saltwater... --causes cracks! • Heat treatment: slows crack speed in salt water! Adapted from Fig. 11.20(b), R.W. Hertzberg, "Deformation and Fracture Mechanics of Engineering Materials" (4th ed.), p. 505, John Wiley and Sons, 1996. (Original source: Markus O. Speidel, Brown Boveri Co.) Adapted from chapter-opening photograph, Chapter 17, Callister 7e. (from Marine Corrosion, Causes, and Prevention, John Wiley and Sons, Inc., 1975.)

28. SUMMARY Course Goals: • Use the right material for the job. • Understand the relation between properties, structure, and processing. • Recognize new design opportunities offered by materials selection.

29. BASIS OF MATERIAL CLASSIFICATIONS • 􀂄Chemical Makeup • 􀂄Atomic Bonding • 􀂄Atomic Arrangement • 􀂄Characteristic Physical Properties • 􀂄Characteristic Mechanical Properties