metal ceramic and glasses designation & processes r. lindeke me 2105
TRANSCRIPT
( Binary Alloy Phase Diagrams, 2nd ed.,Vol. 1, T.B. Massalski (Ed.-in-Chief), ASM International, Materials Park, OH, 1990.)
Taxonomy of MetalsMetal Alloys
Steels
Ferrous Nonferrous
Cast Irons Cu Al Mg Ti<1.4wt%C 3-4.5wt%CSteels
<1.4 wt% CCast Irons3-4.5 wt% C
Fe3C
cementite
1600
1400
1200
1000
800
600
4000 1 2 3 4 5 6 6.7
L
austenite
+L
+Fe3Cferrite
+Fe3C
+
L+Fe3C
(Fe) Co , wt% C
Eutectic:
Eutectoid:0.76
4.30
727°C
1148°C
T(°C) microstructure: ferrite, graphite cementite
Based on data provided in Tables 11.1(b), 11.2(b), 11.3, and 11.4, Callister 7e.
Steels
Low Alloy High Alloy
low carbon <0.25 wt% C
Med carbon0.25-0.6 wt% C
high carbon 0.6-1.4 wt% 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
austenitic stainless
Name
Hardenability 0 + + ++ ++ +++ 0TS - 0 + ++ + ++ 0EL + + 0 - - -- ++
increasing strength, cost, decreasing ductility
-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 engineersAISI- American Iron and Steel InstituteASTM- American Society for Testing and MaterialsUNS- 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 ductileAlways used in hardened/tempered condition – wear and indentation resistantTool/die steels contain high Carbon and Chromium, Vanadium, tungsten and molybdenum They contain primary Carbides
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), Non-magnetic & most corrosion resistant
Stainless Steel
CAST IRONS – Carbon > 2.14 wt. %C , usually 3-4.5wt%CComplete Melting 1150 oC-1300 oC
Gray, White, Nodular, malleable
Silicon > 1%, slower cooling rates during solidification
Types of Cast IronGray 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 IronWhite iron• <1wt% Si so harder but
brittle• more cementite
Malleable iron• heat treat at 800-900ºC• graphite in rosettes• more ductile
Nonferrous Alloys
NonFerrous Alloys
• 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, missiles
• 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.
• 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
Metal Fabrication
• How do we fabricate metals?– Blacksmith - hammer (forged)– Molding - cast
• Forming Operations – Rough stock formed to final shape
Hot working vs. Cold working• T high enough for • well below Tm
recrystallization • work hardening
• Larger deformations • smaller deformations
FORMING
roll
AoAd
roll
• Rolling (Hot or Cold Rolling) (I-beams, rails, sheet & plate)
Ao Ad
force
dieblank
force
• Forging (Hammering; Stamping) (wrenches, crankshafts)
often atelev. T
Metal Fabrication Methods - I
ram billet
container
containerforce
die holder
die
Ao
Adextrusion
• Extrusion (rods, tubing)
ductile metals, e.g. Cu, Al (hot)
tensile force
AoAddie
die
• Drawing (rods, wire, tubing)
die must be well lubricated & clean
CASTING JOINING
FORMING CASTING JOINING
Metal Fabrication Methods - II
• 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
plasterdie formedaround waxprototype
• Sand Casting (large parts, e.g., auto engine blocks)
• Investment Casting (low volume, complex shapes e.g., jewelry, turbine blades)
Metal Fabrication Methods - II
wax
• Die Casting (high volume, low T alloys)
• Continuous Casting (simple slab shapes)
molten
solidified
FORMING CASTING JOINING
Sand Sand
molten metal
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
CASTING JOINING
Metal Fabrication Methods - III
• Powder Metallurgy (materials w/low ductility)
pressure
heat
point contact at low T
densification by diffusion at higher T
area contact
densify
• Welding (when one large part is impractical)
• Heat affected zone: (region in which the microstructure has been changed).
(Iron Castings Handbook, C.F. Walton and T.J. Opar (Ed.), 1981.)
piece 1 piece 2
fused base metal
filler metal (melted)base metal (melted)
unaffectedunaffectedheat affected zone
FORMING
• Properties: -- 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.
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
Taxonomy of Ceramics
• 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.
(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
Composition (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
tensile force
AoAddie
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 helps control fracture and gives uniform hardness in all directions.
Courtesy Martin Deakins, GE Superabrasives, Worthington, OH. Used with permission.
Adapted from Fig. 11.8 (d), Callister 7e. Courtesy Martin Deakins, GE
Superabrasives, Worthington, OH. Used with permission.
Application: Die Blanks
• Tools: -- for grinding glass, tungsten, carbide, ceramics -- for cutting Si wafers -- for oil drilling
bladesoil drill bits• Solutions:
coated singlecrystal diamonds
polycrystallinediamonds in a resinmatrix.
Photos courtesy Martin Deakins,GE Superabrasives, Worthington,OH. Used with permission.
Application: Cutting Tools
-- 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.
• Example: Oxygen sensor ZrO2
• Principle: Make diffusion of ions fast for rapid response.
Application: Sensors
A Ca2+ impurity
removes a Zr4+ and a
O2- ion.
Ca2+
• Approach: Add Ca impurity to ZrO2:
-- increases O2- vacancies
-- increases O2- diffusion rate
reference gas at fixed oxygen content
O2-
diffusion
gas with an unknown, higher oxygen content
-+voltage difference produced!
sensor• Operation: -- voltage difference produced when
O2- ions diffuse from the external surface of the sensor to the reference gas.
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. 191-195.2005 ), "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.)
• Pressing:
GLASSFORMING
(adapted from C.J. Phillips, Glass: The Miracle Maker, Pittman Publishing Ltd., London.)
Ceramic Fabrication Methods-I
Gob
Parison mold
Pressing operation
• Blowing:
suspended Parison
Finishing mold
Compressed air
plates, dishes, cheap glasses
--mold is steel with graphite lining
• Fiber drawing:
wind up
PARTICULATEFORMING
CEMENTATION
Sheet Glass Forming
• Sheet forming – continuous draw– originally sheet glass was made by “floating”
glass on a pool of mercury – or tin
• Milling and screening: desired particle size• Mixing particles & water: produces a "slip"• Form a "green" component
• Dry and fire the component
ram billet
container
containerforce
die holder
die
Ao
Adextrusion--Hydroplastic forming: extrude the slip (e.g., into a pipe)
Ceramic Fabrication Methods-IIA
solid component
--Slip casting:
(from W.D. Kingery, Introduction to Ceramics, John Wiley and Sons, Inc., 1960.)hollow component
pour slip into mold
drain mold
“green ceramic”
pour slip into mold
absorb water into mold “green
ceramic”
GLASSFORMING
PARTICULATEFORMING
CEMENTATION
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+
• Clay is inexpensive• Adding water to clay -- allows material to shear easily along weak van der Waals bonds -- enables extrusion & slip casting
• Structure of Kaolinite Clay:
(adapted from W.E. Hauth, "Crystal Chemistry of Ceramics", American Ceramic Society Bulletin, Vol. 30 (4), 1951, p. 140.)
Features of a Slip
weak van der Waals bonding
charge neutral
charge neutral
Si4+
Al3+
-OHO2-
Shear
Shear
• Drying: layer size and spacing decrease.
(from W.D. Kingery, Introduction to Ceramics, John Wiley and Sons, Inc., 1960.)
Drying and Firing
Drying too fast causes sample to warp or crack due to non-uniform shrinkagewet slip partially dry “green” ceramic
• Firing: --T raised to (900-1400°C) --vitrification: liquid glass forms from clay and flows between SiO2 particles. Flux melts at lower T.
(From H.G. Brinkies, Swinburne University of Technology, Hawthorn Campus, Hawthorn, Victoria, Australia.)
Si02 particle
(quartz)
glass formed around the particle
micrograph of porcelain
70 m
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.)
Ceramic Fabrication Methods-IIB
15 m
GLASSFORMING
PARTICULATEFORMING
CEMENTATION
Powder PressingSintering - 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)
• 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.
Ceramic Fabrication Methods-IIIGLASS
FORMING PARTICULATE
FORMINGCEMENTATION
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 voids-
weaken 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