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Chapter 13 - 1 ISSUES TO ADDRESS... How are metal alloys classified and what are their common applications ? Chapter 13: Types and Applications of Metals,

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Presentation on theme: "Chapter 13 - 1 ISSUES TO ADDRESS... How are metal alloys classified and what are their common applications ? Chapter 13: Types and Applications of Metals,"— Presentation transcript:

1 Chapter ISSUES TO ADDRESS... How are metal alloys classified and what are their common applications ? Chapter 13: Types and Applications of Metals, Ceramics, and Polymers How do we classify ceramics? What are some applications of ceramics? What are the various types/classifications of polymers?

2 Chapter Adapted from Fig , Callister & Rethwisch 3e. (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. 13.1, Callister & Rethwisch 3e. Classification of Metal Alloys Metal Alloys Steels FerrousNonferrous Cast Irons <1.4wt%C3-4.5wt%C Steels <1.4 wt% C Cast Irons wt% C Fe 3 C cementite L  austenite  +L+L  +Fe 3 C  ferrite  +Fe 3 C  +  L+Fe 3 C  (Fe) C o, wt% C Eutectic: Eutectoid: °C 1148°C T(°C) microstructure: ferrite, graphite/cementite

3 Chapter Based on data provided in Tables 13.1(b), 13.2(b), 13.3, and 13.4, Callister & Rethwisch 3e. Steels Low Alloy High Alloy low carbon <0.25 wt% C Med carbon wt% C high carbon wt% C Usesauto struc. sheet bridges towers press. vessels crank shafts bolts hammers blades pistons gears wear applic. wear applic. drills saws dies high T applic. turbines furnaces Very corros. resistant Example , 409 Additionsnone Cr,V Ni, Mo none Cr, Ni Mo none Cr, V, Mo, W Cr, Ni, Mo plainHSLAplain heat treatable plaintool stainless Name Hardenability varies TS varies EL increasing strength, cost, decreasing ductility

4 Chapter Refinement of Steel from Ore Iron Ore Coke Limestone 3CO +Fe 2 O 3  2Fe+3CO 2 C+O2O2  CO 2 +C  2CO CaCO 3  CaO+CO 2 CaO + SiO 2 + Al 2 O 3  slag purification reduction of iron ore to metal heat generation Molten iron BLAST FURNACE slag air layers of coke and iron ore gas refractory vessel

5 Chapter Ferrous Alloys Iron-based alloys Nomenclature for steels (AISI/SAE) 10xxPlain Carbon Steels 11xxPlain Carbon Steels (resulfurized for machinability) 15xxMn ( %) 40xxMo (0.20 ~ 0.30%) 43xxNi ( %), Cr ( %), Mo ( %) 44xxMo (0.5%) where xx is wt% C x 100 example: 1060 steel – plain carbon steel with 0.60 wt% C Stainless Steel -- >11% Cr Steels Cast Irons

6 Chapter Cast Irons Ferrous alloys with > 2.1 wt% C –more commonly wt% C Low melting – relatively easy to cast Generally brittle Cementite decomposes to ferrite + graphite Fe 3 C  3 Fe (  ) + C (graphite) –generally a slow process

7 Chapter Fe-C True Equilibrium Diagram Graphite formation promoted by Si > 1 wt% slow cooling Adapted from Fig. 13.2, Callister & Rethwisch 3e. [Fig adapted from Binary Alloy Phase Diagrams, 2nd ed., Vol. 1, T.B. Massalski (Ed.- in-Chief), ASM International, Materials Park, OH, 1990.] L  +L +L  + Graphite Liquid + Graphite (Fe) C, wt% C °C T(°C)  + Graphite °C  Austenite 4.2 wt% C 

8 Chapter Types of Cast Iron Gray iron graphite flakes weak & brittle in tension stronger in compression excellent vibrational dampening wear resistant Ductile iron add Mg and/or Ce graphite as nodules not flakes matrix often pearlite – stronger but less ductile Adapted from Fig. 13.3(a) & (b), Callister & Rethwisch 3e.

9 Chapter Types of Cast Iron (cont.) White iron < 1 wt% Si pearlite + cementite very hard and brittle Malleable iron heat treat white iron at ºC graphite in rosettes reasonably strong and ductile Adapted from Fig. 13.3(c) & (d), Callister & Rethwisch 3e.

10 Chapter Types of Cast Iron (cont.) Compacted graphite iron relatively high thermal conductivity good resistance to thermal shock lower oxidation at elevated temperatures Adapted from Fig. 13.3(e), Callister & Rethwisch 3e.

11 Chapter Production of Cast Irons Adapted from Fig.13.5, Callister & Rethwisch 3e.

12 Chapter Limitations of Ferrous Alloys 1)Relatively high densities 2)Relatively low electrical conductivities 3)Generally poor corrosion resistance

13 Chapter Based on discussion and data provided in Section 13.3, Callister & Rethwisch 3e. Nonferrous Alloys NonFerrous Alloys Al Alloys -low  : 2.7 g/cm 3 -Cu, Mg, Si, Mn, Zn additions -solid sol. or precip. strengthened (struct. aircraft parts & packaging) Mg Alloys -very low  : 1.7g/cm 3 -ignites easily -aircraft, missiles Refractory metals -high melting T’s -Nb, Mo, W, Ta Noble metals -Ag, Au, Pt -oxid./corr. resistant Ti Alloys -relatively low  : 4.5 g/cm 3 vs 7.9 for steel -reactive at high T’s -space applic. Cu Alloys Brass : Zn is subst. impurity (costume jewelry, coins, corrosion resistant) Bronze: Sn, Al, Si, Ni are subst. impurities (bushings, landing gear) Cu-Be: precip. hardened for strength

14 Chapter GlassesClay products RefractoriesAbrasivesCementsAdvanced ceramics -optical -composite reinforce -containers/ household -whiteware -structural -bricks for high T (furnaces) -sandpaper -cutting -polishing -composites -structural -engine rotors valves bearings -sensors Adapted from Fig and discussion in Section , Callister & Rethwisch 3e. Classification of Ceramics Ceramic Materials

15 Chapter tensile force A o A d die Die blanks: -- Need wear resistant properties! Die surface: -- 4  m polycrystalline diamond particles that are sintered onto a cemented tungsten carbide substrate. -- polycrystalline diamond gives uniform hardness in all directions to reduce wear. Adapted from Fig (d), Callister & Rethwisch 3e. Courtesy Martin Deakins, GE Superabrasives, Worthington, OH. Used with permission. Ceramics Application: Die Blanks

16 Chapter Tools: -- for grinding glass, tungsten, carbide, ceramics -- for cutting Si wafers -- for oil drilling blades oil drill bits Single crystal diamonds polycrystalline diamonds in a resin matrix. Photos courtesy Martin Deakins, GE Superabrasives, Worthington, OH. Used with permission. Ceramics Application: Cutting Tools Materials: -- manufactured single crystal or polycrystalline diamonds in a metal or resin matrix. -- polycrystalline diamonds resharpen by microfracturing along cleavage planes.

17 Chapter Example: ZrO 2 as an oxygen sensor Principle: Increase diffusion rate of oxygen to produce rapid response of sensor signal to change in oxygen concentration Ceramics Application: Sensors A substituting Ca 2+ ion removes a Zr 4+ ion and an O 2- ion. Ca 2+ Approach: Add Ca impurity to ZrO 2 : -- increases O 2- vacancies -- increases O 2- diffusion rate reference gas at fixed oxygen content O 2- diffusion gas with an unknown, higher oxygen content - + voltage difference produced! sensor Operation: -- voltage difference produced when O 2- ions diffuse from the external surface through the sensor to the reference gas surface. -- magnitude of voltage difference  partial pressure of oxygen at the external surface

18 Chapter Materials to be used at high temperatures (e.g., in high temperature furnaces). Consider the Silica (SiO 2 ) - Alumina (Al 2 O 3 ) system. Silica refractories - silica rich - small additions of alumina depress melting temperature (phase diagram): Fig , Callister & Rethwisch 3e. (Fig adapted from F.J. Klug and R.H. Doremus, J. Am. Cer. Soc. 70(10), p. 758, 1987.) Refractories Composition (wt% alumina) T(°C) alumina + mullite + L mullite Liquid (L)(L) mullite +crystobalite + L alumina + L 3Al 2 O 3 -2SiO 2

19 Chapter Advanced Ceramics: Materials for Automobile Engines Advantages: –Operate at high temperatures – high efficiencies –Low frictional losses –Operate without a cooling system –Lower weights than current engines Disadvantages: –Ceramic materials are brittle –Difficult to remove internal voids (that weaken structures) –Ceramic parts are difficult to form and machine Potential candidate materials: Si 3 N 4, SiC, & ZrO 2 Possible engine parts: engine block & piston coatings

20 Chapter Advanced Ceramics: Materials for Ceramic Armor Components: -- Outer facing plates -- Backing sheet Properties/Materials: -- Facing plates -- hard and brittle — fracture high-velocity projectile — Al 2 O 3, B 4 C, SiC, TiB 2 -- Backing sheets -- soft and ductile — deform and absorb remaining energy — aluminum, synthetic fiber laminates

21 Chapter Polymer Types – Fibers Fibers - length/diameter >100 Primary use is in textiles. Fiber characteristics: –high tensile strengths –high degrees of crystallinity –structures containing polar groups Formed by spinning – extrude polymer through a spinneret (a die containing many small orifices) – the spun fibers are drawn under tension – leads to highly aligned chains - fibrillar structure

22 Chapter Polymer Types – Miscellaneous Coatings – thin polymer films applied to surfaces – i.e., paints, varnishes –protects from corrosion/degradation –decorative – improves appearance –can provide electrical insulation Adhesives – bonds two solid materials (adherands) – bonding types: 1. Secondary – van der Waals forces 2. Mechanical – penetration into pores/crevices Films – produced by blown film extrusion Foams – gas bubbles incorporated into plastic

23 Chapter Advanced Polymers Molecular weight ca. 4 x 10 6 g/mol Outstanding properties –high impact strength –resistance to wear/abrasion –low coefficient of friction –self-lubricating surface Important applications –bullet-proof vests –golf ball covers –hip implants (acetabular cup) UHMWPE Adapted from chapter- opening photograph, Chapter 22, Callister 7e. Ultrahigh Molecular Weight Polyethylene (UHMWPE)

24 Chapter Advanced Polymers styrene butadiene Thermoplastic Elastomers Styrene-butadiene block copolymer hard component domain soft component domain Fig , Callister & Rethwisch 3e. (Fig adapted from the Science and Engineering of Materials, 5th Ed., D.R. Askeland and P.P. Phule, Thomson Learning, 2006.) Fig (a), Callister & Rethwisch 3e.

25 Chapter Ferrous alloys: steels and cast irons Non-ferrous alloys: -- Cu, Al, Ti, and Mg alloys; refractory alloys; and noble metals. Categories of ceramics: -- glasses -- clay products -- refractories -- cements -- advanced ceramics Summary Polymer applications -- elastomers -- fibers -- coatings-- adhesives -- films-- foams -- advanced polymeric materials

26 Chapter Core Problems: Self-help Problems: ANNOUNCEMENTS Reading:


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