ISSUES TO ADDRESS...• How are metal alloys classified and how are they used?

• How do we classify ceramics?

• What are some applications for ceramics?

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CHAPTER 13: TYPES AND APPLICATONS OF MATERIALS

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Adapted from Fig. 9.21,Callister 6e. (Fig. 9.21 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

Fe3C

cementite

Metal Alloys

Steels

Ferrous Nonferrous

Cast Irons Cu Al Mg Ti<1.4wt%C 3-4.5wt%C

1600

1400

1200

1000

800

600

4000 1 2 3 4 5 6 6.7

L

austenite

+L

+Fe3C

ferrite+Fe3C

+

L+Fe3C

(Fe) Co, wt% C

Eutectic:

Eutectoid:0.77

4.30

727°C

1148°C

T(°C)

Steels<1.4wt%C

Cast Irons3-4.5wt%C

microstructure: ferrite, graphite cementite

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Low Alloy High Alloy

low carbon <0.25wt%C

med carbon 0.25-0.6wt%C

high carbon 0.6-1.4wt%C

Uses auto 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 V. corros. resistant

Example 1010 4310 1040 4340 1095 4190 304

Additions noneCr,V Ni, Mo

noneCr, Ni Mo

noneCr, V, Mo, W

Cr, Ni, Mo

plain HSLA plainheat

treatableplain tool

austentitic stainless

Name

Hardenability 0 + + ++ ++ +++ 0TS - 0 + ++ + ++ 0EL + + 0 - - -- ++

increasing strength, cost, decreasing ductilityBased on data provided in Tables 11.1(b), 11.2(b), 11.3, and 11.4, Callister 6e.

STEELS

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NonFerrous Alloys

• Cu AlloysBrass: Zn is subst. impurity (costume jewelry, coins, corrosion resistant)Bronze: Sn, Al, Si, Ni are subst. impurity (bushings, landing gear)Cu-Be: precip. hardened for strength

• Al Alloys-lower : 2.7g/cm3 -Cu, Mg, Si, Mn, Zn additions -solid sol. or precip. strengthened (struct.

aircraft parts & packaging)

• Mg Alloys-very low : 1.7g/cm3 -ignites easily -aircraft, missles

• Refractory metals-high melting T -Nb, Mo, W, Ta• Noble metals

-Ag, Au, Pt -oxid./corr. resistant

• Ti Alloys-lower : 4.5g/cm3

vs 7.9 for steel -reactive at high T -space applic.

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

NONFERROUS ALLOYS

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• Properties: --Tmelt 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.

Glasses Clay products

Refractories Abrasives Cements Advanced ceramics

-optical -composite reinforce -containers/ -household

-whiteware -bricks

-bricks for high T (furnaces)

-sandpaper -cutting -polishing

-composites -structural

engine -rotors -valves -bearings

-sensors

Adapted from Fig. 13.1 and discussion in Section 13.2-6, Callister 6e.

TAXONOMY OF CERAMICS

• Need a material to use in high temperature furnaces.• Consider Silica (SiO2) - Alumina (Al2O3) system.• Phase diagram shows: mullite, alumina, and crystobalite (made up of SiO2) tetrahedra as candidate refractories.

6Composition (wt% alumina)

T(°C)

1400

1600

1800

2000

2200

20 40 60 80 1000

alumina +

mullite

mullite + L

mulliteLiquid

(L)

mullite + crystobalite

crystobalite + L

alumina + L

3Al2O3-2SiO2

Adapted from Fig. 12.27, Callister 6e. (Fig. 12.27 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

tensile force

AoAddie

die

• Die blanks: --Need wear resistant properties!

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• 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

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• Tools: --for grinding glass, tungsten, carbide, ceramics --for cutting Si wafers --for oil drilling

bladesoil 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 singlecrystal diamonds

polycrystallinediamonds in a resinmatrix.

Photos courtesy Martin Deakins,GE Superabrasives, Worthington,OH. Used with permission.

APPLICATION: CUTTING TOOLS

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• Ex: Oxygen sensor: ZrO2

• Principle: Make diffusion of ions fast for rapid response.• Approach: Add Ca impurity to:

--increase O2- vacancies

--increase O2- diffusion

• Operation: --voltage difference produced when

O2- ions diffuse between external and references gases.

A Ca2+ impurity removes a Zr4+ and a

O2- ion.

Ca2+

reference gas at fixed oxygen content

O2- diffusion

gas with an unknown, higher oxygen content

-+voltage difference produced!

sensor

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

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SUMMARY

Reading:

Core Problems:

Self-help Problems:

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