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?

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

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

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

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

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

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 

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.

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.

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.

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

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

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

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

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

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.

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

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

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

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

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

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

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)

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.

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

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