Metal Ceramic and Glasses
Designation & Processes
R. Lindeke
ME 2105
Taxonomy of Metals
Metal Alloys
Ferrous
Steels
Steels
<1.4wt%C
<1.4
wt% C
Nonferrous
Cast Irons
Cast
Irons
3-4.5
wt%C
3-4.5 wt% C
Cu
Al
1600
d
1200
L
g
austenite
g+L
a800
ferrite
600
400
0
(Fe)
L+Fe3C
1148°C
4.30
1000
727°C
Eutectoid:
0.76
1
2
Eutectic:
g+Fe3C
4
( Binary Alloy Phase Diagrams, 2nd ed.,
Vol. 1, T.B. Massalski (Ed.-in-Chief),
ASM International, Materials Park, OH,
1990.)
Fe3C
cementite
a+Fe3C
3
Ti
microstructure:
ferrite, graphite
cementite
T(°C)
1400
Mg
5
6
Co , wt% C
6.7
Alloy Taxonomy – (FerrousFocus!)
Steels
High Alloy
Low Alloy
low carbon Med carbon
<0.25 wt% C 0.25-0.6wt% C
high carbon
0.6-1.4wt% C
heat
plain
treatable
Cr,V
Cr, Ni
Additions none
none
none
Ni, Mo
Mo
Example 1010 4310
1040
4340 1095
Hardenability 0
+
+
++
++
TS
0
+
++
+
EL
+
+
0
Name
plain
Uses
auto
struc.
sheet
HSLA
bridges
towers
press.
vessels
plain
crank
shafts
bolts
hammers
blades
pistons
gears
wear
applic.
wear
applic.
tool
Cr, V,
Mo, W
4190
+++
++
-drills
saws
dies
increasing strength, cost, decreasing ductility
Based on data provided in Tables 11.1(b), 11.2(b), 11.3, and 11.4, Callister 7e.
austenitic
stainless
Cr, Ni, Mo
304
0
0
++
high T
applic.
turbines
furnaces
V. corros.
resistant
-LOW-CARBON STEEL
<0.25%C
•Unresponsive to heat treatment
•Consist of ferrite and pearlite
•Relatively low strength
•Relatively ductile and tough
•Weldable and machinable
•Economical amongst all steel
-High Strength Low Alloy Steel
-Alloying up to 10%
-Increase corrosion properties
-Higher strength
SAE – Society of Automotive engineers
AISI- American Iron and Steel Institute
ASTM- American Society for Testing
and Materials
UNS- Unified Numbering System
MEDIUM CARBON STEELS – 0.25-0.6 wt%C
•Heat treated by austenizing, quenching, and then tempering to improve their mechanical
properties. Most often utilized in tempered condition with tempered martensite microsture.
•Low hardenability  can be heat treated only in very thin sections and with rapid quenching
High Carbon steels: 0.60-1.4 wt%C – hardest, strongest, least ductile
Always used in hardened/tempered condition – wear and indentation resistant
Tool/die steels contain high Carbon and Chromium, Vanadium, tungsten and molybdenum
 They contain primary Carbides
Stainless Steel
Corrosion resistant
 Cr of at least 11
wt%
Three classes
-Martensitic – heat
treated (Q&T), Magnetic
-Ferritic – not heat
treated, Magnetic
-Austenitic – heat
treatable (PH), Nonmagnetic & most
corrosion resistant
CAST IRONS – Carbon > 2.14 wt. %C , usually 3-4.5wt%C
Complete Melting 1150 oC-1300 oC
Silicon > 1%, slower cooling rates during solidification
Gray, White, Nodular, malleable
Types of Cast Iron
Gray iron
•
•
•
•
•
graphite flakes
weak & brittle under tension
stronger under compression
excellent vibrational dampening
wear resistant
Ductile iron
•
•
•
add Mg or Ce
graphite in nodules not flakes
matrix often pearlite - better ductility
Types of Cast Iron
White iron
• <1wt% Si so harder but
brittle
• more cementite
Malleable iron
• heat treat at 800-900ºC
• graphite in rosettes
• more ductile
Production of Cast Iron
Nonferrous Alloys
• Cu Alloys
• Al Alloys
-lower r: 2.7g/cm3
Brass: Zn is subst. impurity
(costume jewelry, coins,
-Cu, Mg, Si, Mn, Zn additions
corrosion resistant)
-solid sol. or precip.
Bronze : Sn, Al, Si, Ni are
strengthened (struct.
subst. impurity
aircraft parts
(bushings, landing
& packaging)
gear)
• Mg Alloys
NonFerrous
Cu-Be:
-very low r: 1.7g/cm3
Alloys
precip. hardened
-ignites easily
for strength
-aircraft, missiles
• Ti Alloys
• Refractory metals
-lower r: 4.5g/cm3
vs 7.9 for steel
-reactive at high T
-space applic.
• Noble metals
-Ag, Au, Pt
-oxid./corr. resistant
-high melting T
-Nb, Mo, W, Ta
Copper Alloys
Aluminum
Alloys
Specifics:
Additions to Al and Cu alloy Designations:
Magnesium Alloys
Titanium Alloys
Metal Fabrication
• How do we fabricate metals?
– Blacksmith - hammer (forged)
– Molding - cast
• Forming Operations
– Rough stock formed to final shape
Hot working
• T high enough for
recrystallization
• Larger deformations
vs.
Cold working
• well below Tm
• work hardening
• smaller deformations
Metal Fabrication Methods - I
FORMING
CASTING
JOINING
• Forging (Hammering; Stamping) • Rolling (Hot or Cold Rolling)
(wrenches, crankshafts)
(I-beams, rails, sheet & plate)
force
die
A o blank
often at
Ad
elev. T
roll
Ao
Ad
roll
• Drawing
• Extrusion
force
(rods, wire, tubing)
die
Ao
Ad
(rods, tubing)
Ao
tensile
force
die
die must be well lubricated & clean
force
container
ram
billet
container
die holder
extrusion
die
ductile metals, e.g. Cu, Al (hot)
Ad
Metal Fabrication Methods - II
FORMING
CASTING
JOINING
• Casting- mold is filled with liquid metal
– metal melted in furnace, perhaps alloying
elements added. Then cast in a mold
– most common, cheapest method
– gives good reproduction of shapes
– weaker products, internal defects
– good option for brittle materials or microstructures
that are cooling rate sensitive
Metal Fabrication Methods - II
FORMING
CASTING
• Sand Casting
(large parts, e.g.,
auto engine blocks)
Sand
• Die Casting
(high volume, low T alloys)
Sand
molten metal
• Investment Casting
(low volume, complex shapes
e.g., jewelry, turbine blades)
plaster
die formed
around wax
prototype
JOINING
• Continuous Casting
(simple slab shapes)
molten
solidified
wax
Schematic of the Investment Casting
Process:
Typical Cast Microstructure:
Composition of 356 Cast
Aluminum:
(SAE 356)
Si 6.5 - 7.5
Fe 0.2
Cu 0.2
Mn 0.1
Mg 0.25 - 0.45
Cr 0.05
Ni 0.05
Zn 0.35
Pb 0.05
Ti 0.25
Sn 0.05
Al Balance
Metal Fabrication Methods - III
FORMING
CASTING
• Powder Metallurgy
(materials w/low ductility)
JOINING
• Welding
(when one large part is
impractical)
pressure
filler metal (melted)
base metal (melted)
fused base metal
heat
area
contact
densify
unaffected
piece 1
heat affected zone
unaffected (Iron Castings
piece 2
Handbook, C.F.
• Heat affected zone:
point contact
at low T
densification
by diffusion at
higher T
(region in which the
microstructure has been
changed).
Walton and T.J.
Opar (Ed.), 1981.)
Schematic of Powder Metallurgy Processes, Use
for Metals and Ceramics
Taxonomy of Ceramics
Glasses
Clay Refractories
products
-optical
-whiteware -bricks for
high T
-composite -bricks
(furnaces)
reinforce
-containers/
household
Abrasives Cements
Advanced
ceramics
-sandpaper -composites engine
-cutting
-structural
-rotors
-polishing
-valves
-bearings
• Properties:
-sensors
-- Tm for glass is moderate, but large for other ceramics.
-- minimal 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.
Application: Refractories
• Need a material to use in high temperature furnaces.
• Consider the Silica (SiO2) - Alumina (Al2O3) system.
• Phase diagram shows:
mullite, alumina, and crystobalite as candidate refractories.
2200
T(°C)
3Al2O3-2SiO2
Liquid
(L)
2000
1800
alumina + L
mullite
+L
crystobalite
+L
1600
1400
mullite
mullite
+ crystobalite
0
20
alumina
+
mullite
40
60
80
100
Composition (wt% alumina)
(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: Die Blanks
• Die blanks:
-- Need wear resistant properties!
die
Ao
die
Courtesy Martin Deakins, GE
Superabrasives, Worthington,
OH. Used with permission.
Ad
tensile
force
Adapted from Fig. 11.8 (d),
Callister 7e.
• Die surface:
-- 4 mm polycrystalline diamond
particles that are sintered onto 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.
Application: Cutting Tools
• Tools:
-- for grinding glass, tungsten,
carbide, ceramics
-- for cutting Si wafers
-- for oil drilling
• 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.
oil drill bits
blades
coated single
crystal diamonds
polycrystalline
diamonds in a resin
matrix.
Photos courtesy Martin Deakins,
GE Superabrasives, Worthington,
OH. Used with permission.
Application: Sensors
• Example: Oxygen sensor ZrO2
• Principle: Make diffusion of ions
Ca 2+
fast for rapid response.
• Approach:
Add Ca impurity to ZrO2:
A Ca 2+ impurity
removes a Zr 4+ and a
O2- ion.
-- increases O2- vacancies
-- increases O2- diffusion rate
• Operation:
-- voltage difference
produced when
O2- ions diffuse
from the external
surface of the sensor
to the reference gas.
sensor
gas with an
unknown, higher
oxygen content
O2diffusion
-
reference
gas at fixed
oxygen content
+
voltage difference
produced!
Alternative Energy – Titania Nano-Tubes
"This is an amazing material architecture for
water photolysis," says Craig Grimes, professor
of electrical engineering and materials science
and engineering. Referring to some recent finds
of his research group (G. K. Mor, K. Shankar,
M. Paulose, O. K. Varghese, C. A. Grimes,
Enhanced Photocleavage of Water Using Titania
Nanotube-Arrays, Nano Letters, vol. 5, pp. 191195.2005 ), "Basically we are talking about
taking sunlight and putting water on top of this
material, and the sunlight turns the water into
hydrogen and oxygen. With the highly-ordered
titanium nanotube arrays, under UV
illumination you have a photoconversion
efficiency of 13.1%. Which means, in a nutshell,
you get a lot of hydrogen out of the system per
photon you put in. If we could successfully shift
its bandgap into the visible spectrum we would
have a commercially practical means of
generating hydrogen by solar energy.
Figure 11.2 Cookware made of a glass-ceramic provides good
mechanical and thermal properties. The casserole dish can withstand
the thermal shock of simultaneous high temperature (the torch flame)
and low temperature (the block of ice). (Courtesy of Corning Glass
Works.)
Ceramic Fabrication Methods-I
PARTICULATE
FORMING
GLASS
FORMING
CEMENTATION
• Pressing:
plates, dishes, cheap glasses
Gob
Parison
mold
Pressing
operation
--mold is steel with
graphite lining
• Fiber drawing:
Compressed
air
• Blowing:
suspended
Parison
Finishing
mold
(adapted from C.J. Phillips, Glass: The Miracle Maker, Pittman Publishing Ltd., London.)
wind up
Sheet Glass Forming
• Sheet forming – continuous draw
– originally sheet glass was made by “floating”
glass on a pool of mercury – or tin
Modern Plate/Sheet Glass making:
Image from Prof. JS Colton, Ga. Institute of Technology
Ceramic Fabrication Methods-IIA
GLASS
FORMING
PARTICULATE
FORMING
CEMENTATION
• Milling and screening: desired particle size
• Mixing particles & water: produces a "slip"
• Form a "green" component
Ao
container
--Hydroplastic forming:
force
extrude the slip (e.g., into a pipe)
--Slip casting:
pour slip
into mold
absorb water
into mold
“green
ceramic”
pour slip
into mold
solid component
• Dry and fire the component
bille
t
container
ram
drain
mold
hollow component
die holder
extrusion
Ad
die
“green
ceramic”
(from W.D. Kingery,
Introduction to
Ceramics, John
Wiley and Sons,
Inc., 1960.)
Commercial Clay Compositions
A mixture of components is used
(50%) 1. Clay mineral
(25%) 2. Filler – e.g. quartz (finely ground)
(25%) 3. Fluxing agent (Feldspar) – binds it
together after sintering
aluminosilicates + K+, Na+, Ca+
Features of a Slip
Shear
• Clay is inexpensive
• Adding water to clay
-- allows material to shear easily
along weak van der Waals bonds
-- enables extrusion & slip casting
charge
neutral
• Structure of Kaolinite Clay:
weak van
der Waals
bonding
4+
charge
neutral
(adapted from W.E. Hauth, "Crystal Chemistry of
Ceramics", American Ceramic Society Bulletin,
Vol. 30 (4), 1951, p. 140.)
Si
3+
Al
OH
2O
Shear
Drying and Firing
• Drying: layer size and spacing decrease.
(from W.D. Kingery,
Introduction to
Ceramics, John Wiley
and Sons, Inc., 1960.)
wet slip
partially dry
“green” ceramic
Drying too fast causes sample to warp or crack due to non-uniform shrinkage
• Firing:
--T raised to (900-1400°C)
--vitrification: liquid glass forms from clay and flows between
SiO2 particles. Flux melts at lower T.
Si02 particle
(quartz)
micrograph of
porcelain
glass formed
around
the particle
70mm
(From H.G. Brinkies,
Swinburne University of
Technology, Hawthorn
Campus, Hawthorn, Victoria,
Australia.)
Ceramic Fabrication Methods-IIB
GLASS
PARTICULATE
CEMENTATION
FORMING
FORMING
Sintering: useful for both clay and non-clay compositions.
• Procedure:
-- produce ceramic and/or glass particles by grinding
-- place particles in mold
-- press at elevated T to reduce pore size.
• Aluminum oxide powder:
-- sintered at 1700°C
for 6 minutes.
(from W.D. Kingery, H.K. Bowen, and D.R.
Uhlmann, Introduction to Ceramics, 2nd ed.,
John Wiley and Sons, Inc., 1976, p. 483.)
15 mm
Powder Pressing
Sintering - powder touches - forms neck &
gradually neck thickens
– add processing aids to help form neck
– little or no plastic deformation
Uniaxial compression - compacted in single direction
Isostatic (hydrostatic) compression - pressure applied by
fluid - powder in flexible envelope
Hot pressing - pressure + heat (HIP combines both)
Ceramic Fabrication Methods-III
GLASS
PARTICULATE
CEMENTATION
FORMING
FORMING
• Produced in extremely large quantities.
• Portland cement:
-- mix clay and lime bearing materials
-- calcinate (heat to 1400°C)
-- 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.
Applications: Advanced Ceramics
Heat Engines
• Advantages:
– Run at higher temperature
– Excellent wear &
corrosion resistance
– Low frictional losses
– Ability to operate without
a cooling system
– Low density
• Disadvantages:
– Brittle
– Too easy to have voidsweaken the engine
– Difficult to machine
• Possible parts – engine block, piston coatings, jet engines
Ex: Si3N4, SiC, & ZrO2
Applications: Advanced Ceramics
• Ceramic Armor
– Al2O3, B4C, SiC & TiB2
– Extremely hard materials
• shatter the incoming projectile
• energy absorbent material underneath
Applications: Advanced Ceramics
Electronic Packaging
• Chosen to securely hold microelectronics &
provide heat transfer
• Must match the thermal expansion coefficient of
the microelectronic chip & the electronic
packaging material. Additional requirements
include:
– good heat transfer coefficient
– poor electrical conductivity
• Materials currently used include:
• Boron nitride (BN)
• Silicon Carbide (SiC)
• Aluminum nitride (AlN)
– thermal conductivity 10x that for Alumina
– good expansion match with Si