ISSUES TO ADDRESS... How are metal alloys classified and how are they used? How do we classify ceramics? What are some applications for ceramics? 1 CHAPTER 13: TYPES AND APPLICATONS OF MATERIALS

2 Adapted from Fig. 9.21,Callister 6e. (Fig adapted from Binary Alloy Phase Diagrams, 2nd ed., Vol. 1, T.B. Massalski (Ed.-in-Chief), ASM International, Materials Park, OH, 1990.) Adapted from Fig. 11.1, Callister 6e. TAXONOMY OF METALS

3 Based on data provided in Tables 11.1(b), 11.2(b), 11.3, and 11.4, Callister 6e. STEELS

4 Based on discussion and data provided in Section 11.3, Callister 6e. NONFERROUS ALLOYS

5 Properties: --T melt for glass is moderate, but large for other ceramics. --Small toughness, ductility; large moduli & creep resist. Applications: --High T, wear resistant, novel uses from charge neutrality. Fabrication --some glasses can be easily formed --other ceramics can not be formed or cast. Adapted from Fig and discussion in Section , Callister 6e. TAXONOMY OF CERAMICS

Need a material to use in high temperature furnaces. Consider Silica (SiO 2 ) - Alumina (Al 2 O 3 ) system. Phase diagram shows: mullite, alumina, and crystobalite (made up of SiO 2 ) tetrahedra as candidate refractories. 6 Adapted from Fig , Callister 6e. (Fig is adapted from F.J. Klug and R.H. Doremus, "Alumina Silica Phase Diagram in the Mullite Region", J. American Ceramic Society 70(10), p. 758, 1987.) APPLICATION: REFRACTORIES

Die blanks: --Need wear resistant properties! 7 Die surface: --4  m polycrystalline diamond particles that are sintered on to a cemented tungsten carbide substrate. --polycrystalline diamond helps control fracture and gives uniform hardness in all directions. Courtesy Martin Deakins, GE Superabrasives, Worthington, OH. Used with permission. Adapted from Fig. 11.7, Callister 6e. Courtesy Martin Deakins, GE Superabrasives, Worthington, OH. Used with permission. APPLICATION: DIE BLANKS

8 Tools: --for grinding glass, tungsten, carbide, ceramics --for cutting Si wafers --for oil drilling blades oil drill bits Solutions: --manufactured single crystal or polycrystalline diamonds in a metal or resin matrix. --optional coatings (e.g., Ti to help diamonds bond to a Co matrix via alloying) --polycrystalline diamonds resharpen by microfracturing along crystalline planes. coated single crystal diamonds polycrystalline diamonds in a resin matrix. Photos courtesy Martin Deakins, GE Superabrasives, Worthington, OH. Used with permission. APPLICATION: CUTTING TOOLS

9 Ex: Oxygen sensor: ZrO 2 Principle: Make diffusion of ions fast for rapid response. Approach: Add Ca impurity to: --increase O 2- vacancies --increase O 2- diffusion Operation: -- voltage difference produced when O 2- ions diffuse between external and references gases. APPLICATION: SENSORS

Steels: increase TS, hardness (and cost) by adding -C (low alloy steels) -Cr, V, Ni, Mo, W (high alloy steels) -Ductility usually decreases w/ additions Nonferrous: -Cu, Al, Ti, Mg Refractory, and noble metals Basic categories of ceramics: -Glasses -Clay products -Refactories -Cements -Advanced ceramics 10 SUMMARY

ISSUES TO ADDRESS... What are the common fabrication techniques for metals? How do the properties vary throughout a piece of metal that has been quenched? How can properties be modified by a post heat treatment? How is the processing of ceramics different than for metals? 1 CHAPTER 14: SYNTHESIS, FABRICATION, AND PROCESSING OF MATERIALS

2 REFINEMENT OF STEEL FROM ORE

3 Forging (wrenches, crankshafts) FORMING Drawing (rods, wire, tubing) often at elev. T Rolling (I-beams, rails) Extrusion (rods, tubing) Adapted from Fig. 11.7, Callister 6e. METAL FABRICATION METHODS- I

7 Hot working -- recrystallization --less energy to deform --oxidation: poor finish --lower strength Cold working -- recrystallization --less energy to deform --oxidation: poor finish --lower strength Cold worked microstructures --generally are very anisotropic! --Forged--Fracture resistant! Reprinted w/ permission from R.W. Hertzberg, "Deformation and Fracture Mechanics of Engineering Materials", (4th ed.), John Wiley and Sons, Inc., (a) Fig. 10.5, p. 410 (micrograph courtesy of G. Vander Voort, Car Tech Corp.); (b) Fig. 10.6(b), p. 411 (Orig. source: J.F. Peck and D.A. Thomas, Trans. Metall. Soc. AIME, 1961, p. 1240); (c) Fig , p. 415 (Orig. source: A.J. McEvily, Jr. and R.H. Bush, Trans. ASM 55, 1962, p. 654.) (a) (b)(c) --Swaged FORMING TEMPERATURE

plaster die formed around wax prototype 5 CASTING Sand Casting (large parts, e.g., auto engine blocks) Investment Casting (low volume, complex shapes e.g., jewelry, turbine blades) Die Casting (high volume, low T alloys) Continuous Casting (simple slab shapes) METAL FABRICATION METHODS- II

6 JOINING Powder Processing (materials w/low ductility) Welding (when one large part is impractical) Heat affected zone: (region in which the microstructure has been changed). Adapted from Fig. 11.8, Callister 6e. (Fig from Iron Castings Handbook, C.F. Walton and T.J. Opar (Ed.), 1981.) METAL FABRICATION METHODS- III

7 Annealing: Heat to T anneal, then cool slowly. Based on discussion in Section 11.7, Callister 6e. THERMAL PROCESSING OF METALS

8 Ability to form martensite Jominy end quench test to measure hardenability. Hardness versus distance from the quenched end. Adapted from Fig , Callister 6e. (Fig adapted from A.G. Guy, Essentials of Materials Science, McGraw-Hill Book Company, New York, 1978.) Adapted from Fig , Callister 6e. HARDENABILITY--STEELS

9 The cooling rate varies with position. Adapted from Fig , Callister 6e. (Fig adapted from H. Boyer (Ed.) Atlas of Isothermal Transformation and Cooling Transformation Diagrams, American Society for Metals, 1977, p. 376.) WHY HARDNESS CHANGES W/POSITION

13 Jominy end quench results, C = 0.4wt%C "Alloy Steels" (4140, 4340, 5140, 8640) --contain Ni, Cr, Mo (0.2 to 2wt%) --these elements shift the "nose". --martensite is easier to form. Adapted from Fig , Callister 6e. (Fig adapted from figure furnished courtesy Republic Steel Corporation.) HARDENABILITY VS ALLOY CONTENT

11 Effect of quenching medium: Medium air oil water Severity of Quench small moderate large Hardness small moderate large Effect of geometry: When surface-to-volume ratio increases: --cooling rate increases --hardness increases Position center surface Cooling rate small large Hardness small large QUENCHING MEDIUM & GEOMETRY

12 Ex: Round bar, 1040 steel, water quenched, 2" diam. Adapted from Fig , Callister 6e. PREDICTING HARDNESS PROFILES

13 Pressing: GLASS FORMING Blowing: Fiber drawing: Adapted from Fig. 13.7, Callister, 6e. (Fig is adapted from C.J. Phillips, Glass: The Miracle Maker, Pittman Publishing Ltd., London.) CERAMIC FABRICATION METHODS-I

14 Quartz is crystalline SiO 2 : Basic Unit: Glass is amorphous Amorphous structure occurs by adding impurities (Na +,Mg 2+,Ca 2+, Al 3+ ) Impurities: interfere with formation of crystalline structure. (soda glass) Adapted from Fig , Callister, 6e. GLASS STRUCTURE

15 Specific volume (1  ) vs Temperature (T): Glasses: --do not crystallize --spec. vol. varies smoothly with T --Glass transition temp, T g Crystalline materials: --crystallize at melting temp, T m --have abrupt change in spec. vol. at T m Viscosity: --relates shear stress & velocity gradient: --has units of (Pa-s) Adapted from Fig. 13.5, Callister, 6e. GLASS PROPERTIES

16 Viscosity decreases with T Impurities lower T deform Adapted from Fig. 13.6, Callister, 6e. (Fig is from E.B. Shand, Engineering Glass, Modern Materials, Vol. 6, Academic Press, New York, 1968, p. 262.) GLASS VISCOSITY VS T AND IMPURITIES

17 Annealing: --removes internal stress caused by uneven cooling. Tempering: --puts surface of glass part into compression --suppresses growth of cracks from surface scratches. --sequence: --Result: surface crack growth is suppressed. HEAT TREATING GLASS

Milling and screening: desired particle size PARTICULATE FORMING Mixing particles & water: produces a "slip" --Hydroplastic forming: extrude the slip (e.g., into a pipe) 18 Form a "green" component hollow component Dry and Fire the component --Slip casting: solid component Adapted from Fig. 11.7, Callister 6e. Adapted from Fig , Callister 6e. (Fig is from W.D. Kingery, Introduction to Ceramics, John Wiley and Sons, Inc., 1960.) CERAMIC FABRICATION METHODS-IIA

13 Clay is inexpensive Adding water to clay --allows material to shear easily along weak van der Waals bonds --enables extrusion --enables slip casting Structure of Kaolinite Clay: Adapted from Fig , Callister 6e. (Fig is adapted from W.E. Hauth, "Crystal Chemistry of Ceramics", American Ceramic Society Bulletin, Vol. 30 (4), 1951, p. 140.) FEATURES OF A SLIP

20 Firing : --T raised to ( C) --vitrification: glass forms from clay and flows between SiO 2 particles. Drying : layer size and spacing decrease. Adapted from Fig , Callister 6e. (Fig is from W.D. Kingery, Introduction to Ceramics, John Wiley and Sons, Inc., 1960.) Adapted from Fig , Callister 6e. (Fig is courtesy H.G. Brinkies, Swinburne University of Technology, Hawthorn Campus, Hawthorn, Victoria, Australia.) DRYING AND FIRING

Sintering: useful for both clay and non-clay compositions. Procedure: --grind to produce ceramic and/or glass particles --inject into mold --press at elevated T to reduce pore size. Aluminum oxide powder: --sintered at 1700C for 6 minutes. PARTICULATE FORMING 21 Adapted from Fig , Callister 6e. (Fig is from W.D. Kingery, H.K. Bowen, and D.R. Uhlmann, Introduction to Ceramics, 2nd ed., John Wiley and Sons, Inc., 1976, p. 483.) CERAMIC FABRICATION METHODS-IIB

CEMENTATION Produced in extremely large quantities. Portland cement: --mix clay and lime bearing materials --calcinate (heat to 1400C) --primary constituents: tri-calcium silicate di-calcium silicate Adding water --produces a paste which hardens --hardening occurs due to hydration (chemical reactions with the water). Forming: done usually minutes after hydration begins. 22 CERAMIC FABRICATION METHODS-III

23 Fabrication techniques for metals - Forming, casting, joining Hardenability - Increases with alloy content Fabrication techniques for ceramics - Glass forming (impurities affect forming temp.) - Particulate forming (needed if ductility is limited) - Cementation (large volume, room T process) Heat treating: used to - Alleviate residual stress from cooling - Produce fracture-resistant components by putting surface in compression SUMMARY

ISSUES TO ADDRESS... What are the classes and types of composites ? 1 Why are composites used instead of metals, ceramics, or polymers? How do we estimate composite stiffness & strength? What are some typical applications? CHAPTER 15: COMPOSITE MATERIALS

2 Composites: --Multiphase material w/significant proportions of ea. phase. Matrix: --The continuous phase --Purpose is to: transfer stress to other phases protect phases from environment --Classification: MMC, CMC, PMC Dispersed phase: --Purpose: enhance matrix properties. MMC: increase  y, TS, creep resist. CMC: increase Kc PMC: increase E,  y, TS, creep resist. --Classification: Particle, fiber, structural metalceramicpolymer Reprinted with permission from D. Hull and T.W. Clyne, An Introduction to Composite Materials, 2nd ed., Cambridge University Press, New York, 1996, Fig. 3.6, p. 47. TERMINOLOGY/CLASSIFICATION

3 Particle-reinforced Examples: Adapted from Fig , Callister 6e. (Fig is copyright United States Steel Corporation, 1971.) Adapted from Fig. 16.4, Callister 6e. (Fig is courtesy Carboloy Systems, Department, General Electric Company.) Adapted from Fig. 16.5, Callister 6e. (Fig is courtesy Goodyear Tire and Rubber Company.) COMPOSITE SURVEY: Particle-I

4 Elastic modulus, E c, of composites: -- two approaches. Application to other properties: -- Electrical conductivity,  e : Replace E by  e. -- Thermal conductivity, k: Replace E by k. Particle-reinforced Adapted from Fig. 16.3, Callister 6e. (Fig is from R.H. Krock, ASTM Proc, Vol. 63, 1963.) COMPOSITE SURVEY: Particle-II

5 Aligned Continuous fibers Fiber-reinforced Examples: From W. Funk and E. Blank, “Creep deformation of Ni3Al-Mo in-situ composites", Metall. Trans. A Vol. 19(4), pp , Used with permission. --Metal:  '(Ni 3 Al)-  (Mo) by eutectic solidification. --Glass w/SiC fibers formed by glass slurry E glass = 76GPa; E SiC = 400GPa. From F.L. Matthews and R.L. Rawlings, Composite Materials; Engineering and Science, Reprint ed., CRC Press, Boca Raton, FL, (a) Fig. 4.22, p. 145 (photo by P. Davies); (b) Fig , p. 349 (micrograph by H.S. Kim, P.S. Rodgers, and R.D. Rawlings). Used with permission of CRC Press, Boca Raton, FL. (a) (b) COMPOSITE SURVEY: Fiber-I

6 Discontinuous, random 2D fibers Fiber-reinforced Example: Carbon-Carbon --process: fiber/pitch, then burn out at up to 2500C. --uses: disk brakes, gas turbine exhaust flaps, nose cones. Other variations: --Discontinuous, random 3D --Discontinuous, 1D Adapted from F.L. Matthews and R.L. Rawlings, Composite Materials; Engineering and Science, Reprint ed., CRC Press, Boca Raton, FL, (a) Fig. 4.24(a), p. 151; (b) Fig. 4.2(b) p Reproduced with permission of CRC Press, Boca Raton, FL. (b) (a) COMPOSITE SURVEY: Fiber-II

7 Critical fiber length for effective stiffening & strengthening: Fiber-reinforced fiber diameter shear strength of fiber-matrix interface fiber strength in tension Ex: For fiberglass, fiber length > 15mm needed Why? Longer fibers carry stress more efficiently! Shorter, thicker fiber:Longer, thinner fiber: Poorer fiber efficiency Better fiber efficiency Adapted from Fig. 16.7, Callister 6e. COMPOSITE SURVEY: Fiber-III

Estimate of E c and TS: --valid when -- Elastic modulus in fiber direction: --TS in fiber direction: efficiency factor: --aligned 1D: K = 1 (anisotropic) --random 2D: K = 3/8 (2D isotropy) --random 3D: K = 1/5 (3D isotropy) 8 Fiber-reinforced (aligned 1D) Values from Table 16.3, Callister 6e. (Source for Table 16.3 is H. Krenchel, Fibre Reinforcement, Copenhagen: Akademisk Forlag, 1964.) COMPOSITE SURVEY: Fiber-IV

9 Structural Stacked and bonded fiber-reinforced sheets -- stacking sequence: e.g., 0/90 -- benefit: balanced, in-plane stiffness Sandwich panels -- low density, honeycomb core -- benefit: small weight, large bending stiffness Adapted from Fig , Callister 6e. Adapted from Fig , Callister 6e. (Fig is from Engineered Materials Handbook, Vol. 1, Composites, ASM International, Materials Park, OH, COMPOSITE SURVEY: Structural

10 CMCs: Increased toughness PMCs: Increased E/  MMCs: Increased creep resistance Adapted from T.G. Nieh, "Creep rupture of a silicon-carbide reinforced aluminum composite", Metall. Trans. A Vol. 15(1), pp , Used with permission. COMPOSITE BENEFITS

11 Composites are classified according to: -- the matrix material (CMC, MMC, PMC) -- the reinforcement geometry (particles, fibers, layers). Composites enhance matrix properties: -- MMC: enhance  y, TS, creep performance -- CMC: enhance K c -- PMC: enhance E,  y, TS, creep performance Particulate-reinforced : -- Elastic modulus can be estimated. -- Properties are isotropic. Fiber-reinforced : -- Elastic modulus and TS can be estimated along fiber dir. -- Properties can be isotropic or anisotropic. Structural : -- Based on build-up of sandwiches in layered form. SUMMARY

ISSUES TO ADDRESS... What happens when light shines on a material ? 1 Why do materials have characteristic colors? Optical applications: --luminescence --photoconductivity --solar cell --optical communications fibers Why are some materials transparent and other not? CHAPTER 19: OPTICAL PROPERTIES

2 Incident light is either reflected, absorbed, or transmitted: Optical classification of materials: Adapted from Fig , Callister 6e. (Fig is by J. Telford, with specimen preparation by P.A. Lessing.) LIGHT INTERACTION WITH SOLIDS

3 Absorption of photons by electron transition: Metals have a fine succession of energy states. Near-surface electrons absorb visible light. Adapted from Fig. 21.4(a), Callister 6e. OPTICAL PROPERTIES OF METALS: ABSORPTION

4 Electron transition emits a photon. Reflectivity = I R /I o is between 0.90 and Reflected light is same frequency as incident. Metals appear reflective (shiny)! Adapted from Fig. 21.4(b), Callister 6e. OPTICAL PROPERTIES OF METALS: REFLECTION re-emitted photon from material surface

5 Absorption by electron transition occurs if h > E gap If E gap < 1.8eV, full absorption; color is black (Si, GaAs) If E gap > 3.1eV, no absorption; colorless (diamond) If E gap in between, partial absorption; material has a color. Adapted from Fig. 21.5(a), Callister 6e. SELECTED ABSORPTION: NONMETALS incident photon energy h

6 Color determined by sum of frequencies of --transmitted light, --re-emitted light from electron transitions. Ex: Cadmium Sulfide (CdS) -- E gap = 2.4eV, -- absorbs higher energy visible light (blue, violet), -- Red/yellow/orange is transmitted and gives it color. Ex: Ruby = Sapphire (Al 2 O 3 ) + (0.5 to 2) at% Cr 2 O 3 -- Sapphire is colorless (i.e., E gap > 3.1eV) -- adding Cr 2 O 3 : alters the band gap blue light is absorbed yellow/green is absorbed red is transmitted Result: Ruby is deep red in color. Adapted from Fig. 21.9, Callister 6e. (Fig adapted from "The Optical Properties of Materials" by A. Javan, Scientific American, 1967.) COLOR OF NONMETALS

7 Transmitted light distorts electron clouds. Result 1: Light is slower in a material vs vacuum. Index of refraction (n) = speed of light in a vacuum speed of light in a material Material Lead glass Silica glass Soda-lime glass Quartz Plexiglas Polypropylene n Adding large, heavy ions (e.g., lead can decrease the speed of light. --Light can be "bent" Result 2: Intensity of transmitted light decreases with distance traveled (thick pieces less transparent!) Selected values from Table 21.1, Callister 6e. TRANSMITTED LIGHT: REFRACTION

8 Process: Ex: fluorescent lamps Adapted from Fig. 21.5(a), Callister 6e. APPLICATION: LUMINESCENCE incident radiation emitted light

9 Description: Ex: Photodetector (Cadmium sulfide) APPLICATION: PHOTOCONDUCTIVITY

10 p-n junction: Operation: --incident photon produces hole-elec. pair. --typically 0.5V potential. --current increases w/light intensity. Solar powered weather station: polycrystalline Si Los Alamos High School weather station (photo courtesy P.M. Anderson) APPLICATION: SOLAR CELL

11 Design with stepped index of refraction (n): Design with parabolic index of refraction Parabolic = less broadening = improvement! Adapted from Fig , Callister 6e. (Fig adapted from S.R. Nagel, IEEE Communications Magazine, Vol. 25, No. 4, p. 34, 1987.) Adapted from Fig , Callister 6e. (Fig adapted from S.R. Nagel, IEEE Communications Magazine, Vol. 25, No. 4, p. 34, 1987.) APPLICATION: FIBER OPTICS

12 When light (radiation) shines on a material, it may be: --reflected, absorbed and/or transmitted. Optical classification: --transparent, translucent, opaque Metals: --fine succession of energy states causes absorption and reflection. Non-Metals: --may have full (E gap 3.1eV), or partial absorption (1.8eV < E gap = 3.1eV). --color is determined by light wavelengths that are transmitted or re-emitted from electron transitions. --color may be changed by adding impurities which change the band gap magnitude (e.g., Ruby) Refraction: --speed of transmitted light varies among materials. SUMMARY