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8/3/2019 Types and Applications of Materials
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Types and Applications of Materials
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Classification of EngineeringMaterials
Metallic Ferrous alloys
Irons and steels, etc.
Non-ferrous alloys Aluminum, copper, magnesium, etc.
Non-metallic
Ceramic
Glasses, glass ceramics, graphite, diamond, etc.
Polymeric Thermoplastic plastics, thermoset plastics, elastomers, etc.
Composite (combination of two or more types)
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Metal Alloys
Ferrous
A mixture of two or more metals, one of themetals being iron
MagneticLittle resistance to corrosion
Non-Ferrous
No iron
Not magnetic
More resistant to corrosion than ferrousalloys
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Common Metallic Materials Iron/Steel
Aluminum
Copper
Titanium Nickel
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Ferrous Alloys
Mainly composed of iron Important as engineering construction
materials
Their widespread use is accounted forby three factors: Iron-containing compounds areabundant
Produced using economicaltechniques
Extremely versatile
Susceptible to corrosion
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Some Ferrous AlloysName Properties Uses
Mild SteelTough, high tensilestrength, ductile.
Girders, plates, nutsand bolts, general
purpose.
High Speed Steel
Can be hardened and
tempered.
Cutting tools for lathes.
Stainless SteelCorrosion resistant Kitchen draining boards.
Pipes, cutlery, aircraft.
High Tensile SteelVery strong and very
tough.
Gears, shafts, engine
parts.
High Carbon SteelThe hardest of the
carbon steels. Tough,malleable.
Chisels, hammers,drills, files, lathe tools.
Medium Carbon Steel
Stronger and harder
than mild steels.
Metal ropes, wire,
garden tools, springs.
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Ferrous Alloys -> Steels Iron-carbon alloys
The mechanical properties are sensitive to carboncontent
May be classified according to carbon concentration
Low-carbon
Medium-carbon
High-carbon
Subclasses also exist according to concentration of
other alloying elements Plain carbon steels contain only residual concentration
of impurities other than carbon and a little manganese
Alloy steels have more alloying elements in specific
concentrations.
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Ferrous Alloys -> Steels-> Low-carbon Steels
Make up the greatest quantities of produced steel
Generally contain less than 0.25 wt%
Relatively soft and weak, outstanding ductility and
toughness Machinable and weldable, lowest production cost
of all steels
Typical applications include auto body
components, I-beams and sheets used in bridgesand tin cans
Typically yield strength: 275 MPa (40,000 psi),
Tensile strength: between 415 and 550 MPa
(60,000 and 80,000 psi),
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Ferrous Alloys -> Steels-> Low-carbon Steels -> HSLA Steels
High-strength, low-alloy (HSLA)
Contain other alloying elements such as copperand nickel in combined concentrations as high as10 wt%
Higher strength and corrosion resistance thanplain low-carbon steels
May be strengthened by heat treatment
Tensile strengths in excess of 480 MPa (70,000psi)
Ductile, formable and machinable
Used where structural strength is critical
Bridges, towers, support columns, pressure
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Ferrous Alloys -> Steels-> Medium-Carbon Steels
Have carbon concentrations between 0.25 and0.60 wt%
Plain medium-carbon steels have lowhardenabilities
Can be successfully heat treated only in very thinsections
Additions of chromium, nickel, and molybdenum
improve the capacity of these alloys to be heattreated
These heat-treated alloys are stronger than the low-carbon steels, but at a sacrifice of ductility and
toughness
Used in railwa wheels and tracks ears and
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Ferrous Alloys -> Steels-> High-Carbon Steels
Have carbon contents between 0.60 and 1.4 wt%
Are the hardest, strongest, and yet least ductile ofthe carbon steels
Wear-resistant and hold a sharp cutting edge
Used in cutting tools and dies for forming andshaping materials, as well as in knives, razors,hacksaw blades, springs, and high-strength wire.
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Ferrous Alloys -> Steels-> Stainless Steels
Highly resistant to corrosion
Predominant alloying element is chromium
Concentration of at least 11 wt% Cr required
Corrosion resistance may also be enhanced bynickel and molybdenum additions.
Divided intro three classes
Martensitic
Ferritic Austenitic
Used in gas turbines, steam boilers, aircraft andmissiles
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Ferrous Alloys -> Cast Irons Generically contain carbon above 2.14 wt%
In practice, most cast irons contain between 3.0 and4.5 wt% C and other alloying elements
Become completely liquid at temperatures
between approximately 1150 and 1300C (2100and 2350 F)
Considerably lower than for steels
Easily melted and amenable to casting
The most common cast iron types are gray,nodular, white, and malleable
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Ferrous Alloys -> Cast Irons
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Ferrous Alloys -> Cast Irons -> GrayIron
The carbon and silicon contents of gray cast ironsvary between 2.5 and 4.0 wt% and 1.0 and 3.0wt%, respectively.
Graphite exists in the form of flakes, giving a
fractured gray surface, hence its name
Weak and brittle in tension; strong, ductile incompression
Effective in damping vibrational energy High resistance to wear
Used in base structures and heavy equipmentfrequently exposed to vibration
Least expensive of all metallic materials
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Ferrous Alloys -> Cast Irons-> Ductile or Nodular Iron
Gray iron with a small amount of magnesiumand/or cerium added before casting
Has a different microstructure and mechanicalproperties than gray iron
Graphite forms in nodules instead of flakes,hence the name
Castings are stronger and much more ductile
than gray iron Tensile strength: between 380-480 Mpa (55,000
and 70,000 psi), and
Ductility from 10 to 20 %EL
Used in valves, pump bodies, gears and machine
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Ferrous Alloys -> Cast Irons-> White Iron and Malleable Iron
White iron derives its name from the whiteappearance of the fracture surface of low-silicon(
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Ferrous Alloys -> Cast Irons-> White Iron and Malleable Iron
Malleable iron is made by heating white ironbetween 800-900C (1470 and 1650F) for aprolonged time in a neutral atmosphere
Its microstructure is similar to nodular iron
Relatively high strength and appreciable ductilityand malleability
Used in connecting rods, transmission gears,
flanges, valve parts and pipe fittings
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Non-ferrous Alloys Are alloys that do not contain iron
Not magnetic, more resistant to corrosion thanferrous alloys
Preferred when the limitations of ferrous alloys(high density, low conductivity, susceptibility tocorrosion) are undesirable
Classified either according to the base metal or
according to some specific characteristic. These groups include alloys containing copper,
aluminum, magnesium and titanium, therefractory metals, the superalloys, the noble
metals and the miscellaneous alloy
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Non-ferrous Alloys Alloys that are so brittle that forming/shaping by
appreciable deformation is not possible ordinarilyare cast alloys
Those that are amenable to mechanical
deformation are termed wrought alloys
Heat treatable designates an alloy whose
mechanical strength is improved by precipitationhardening or a martensitic transformation, both ofwhich involve specific heat-treating procedures
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Some Non-Ferrous Metals and Alloys
Name Properties Uses
AluminiumSoft, malleable, conductive
, corrosion resistant.Aircraft, boats, window
frames, saucepans,pistons and cranks.
Aluminium alloysMalleable and ductile Aircraft and vehicle parts.
CopperTough, ductile, high
electrical conductor, canwork hard or cold
Wire, cables, pipes,cylinders, PCBs, roofs
BrassVery corrosive, harder than
copper, good conductor
Castings, ornaments,
valves, forgings.
LeadHeaviest common metal,soft, malleable, corrosion
resistant
Protection against X-Raymachines. Paints, roof
coverings.
Zinc
Corrosion resistant, easily
worked
Steel galvanized iron
roofing, tanks, buckets,rust-proof paints
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Non-ferrous Alloys -> Copper
Alloys Have been utilized in a variety of applications
since antiquity
Unalloyed copper is soft and ductile and difficultto machine; also, it has an almost unlimited
capacity to be cold worked
It is highly resistant to corrosion in diverseenvironments including the ambient atmosphere
Most copper alloys cannot be hardened orstrengthened by heat-treating procedures
Cold working and/or solid-solution alloying must beutilized
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Non-ferrous Alloys -> Copper Alloys-> Brasses
The most common copper alloys with zinc as asubstitutional impurity and the predominantalloying element
Some of the common brasses are yellow, naval,
and cartridge brass, muntz metal, and gildingmetal.
Used in jewelry, cartridge casings, musicalinstruments, electronic packaging, and coins
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Non-ferrous Alloys -> Copper Alloys-> Bronzes
Alloys of copper and several other elements,including tin, aluminum, silicon, and nickel
Somewhat stronger than brasses, yet still have ahigh degree of corrosion resistance
Generally utilized when, in addition to corrosionresistance, good tensile properties are required
The most common precipitation hardenablecopper alloys are the beryllium coppers
Tensile strengths as high as 1400 Mpa (200,000psi)
May be cast, hot worked, or cold worked
Used in springs, surgical and dental instruments
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Non-ferrous Alloys-> Aluminum and its Alloys
Characterized by a relatively low density (2.7g/cm3 as compared to 7.9 g/cm3 for steel)
High electrical and thermal conductivities
Resistanct to corrosion in some commonenvironments
The chief limitation of aluminum is its low meltingtemperature [660C (1220F)]
Mechanical strength of aluminum may beenhanced by cold work and by alloying
Principal alloying elements include copper,magnesium, silicon, manganese, and zinc
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Non-ferrous Alloys-> Aluminum and its Alloys
Generally, aluminum alloys are classified aseither castor wrought
Composition for both types is designated by afour-digit number that indicates principal
impurities and purity level For cast alloys, a decimal point is located between
last two digits
After these digits is a hyphen and basic temperdesignationa letter and possibly a one- tothree-digit number which indicates themechanical/heat treatment of the alloy
Used in beverage cans, bus bodies and
automotive parts
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Non-ferrous Alloys-> Magnesium and its Alloys
Has the lowest density of all structural metals(1.7 g/cm3)
Used where light weight is important (e.g. aircraft)
Moderately low melting temperature [651C(1204F)]
Relatively unstable and especially susceptible tocorrosion in marine environments.
Corrosion resistance is good in normalatmosphere
Fine magnesium powder ignites easily whenheated in air
Aluminum, zinc, manganese are major alloying
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Non-ferrous Alloys-> Titanium and its Alloys
Relatively new engineering materials thatpossess an extraordinary combination ofproperties
Pure titanium has low density (4.5 g/cm3), high
melting point [1668C], elastic modulus of 107GPa (15.5 106 psi)
Tensile strengths as high as 1400MPa (200,000psi) attainable
Highly ductile and easily forged and machined
The major limitation of titanium is its chemicalreactivity with other materials at elevated
temperatures
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Non-ferrous Alloys-> Refractory Metals
Refractory metals have extremely high meltingtemperatures
In this group are niobium, molybdenum, tungsten,tantalum
MT between 2468C for niobium and 3410C, thehighest melting temperature of any metal, fortungsten
Interatomic bonding in these metals is extremelystrong
Large elastic moduli and high strengths andhardnesses
Varied applications
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Non-ferrous Alloys-> Superalloys
Have superlative combinations of properties These materials are classified according to the
predominant metal in the alloy, which may becobalt, nickel, or iron
Other alloying elements include the refractorymetals (Nb,Mo,W, Ta), chromium, and titanium
Used in aircraft turbine components
Mechanical integrity under these conditions iscritical
Also used in nuclear reactors and petrochemicalequipment
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Non-ferrous Alloys-> Noble Metals
The noble or precious metals are a group of eightelements that have some physical characteristics incommon
Expensive, superior or notable (noble) in properties,i.e. characteristically soft, ductile, and oxidationresistant
The noble metals are silver, gold, platinum, palladium,rhodium, ruthenium, iridium, and osmium First 3 are most common and are used extensively in
jewelry Sterling silver has approximately 7.5 wt% Cu
Alloys of both silver and gold are employed as dentalrestoration materials
Some integrated circuit electrical contacts are of gold.
Platinum used laborator e ui ment in
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-> Miscellaneous NonferrousMaterials
Nickel and its alloys are highly resistant tocorrosion in many environments
Monel, a nickel-based alloy containingapproximately 65 wt% Ni and 28 wt% Cu (the
balance iron), has very high strength and isextremely corrosion resistant
It is used in pumps and valves
Nickel is one of the principal alloying elements in
stainless steels, and one of the majorconstituents in the superalloys
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-> Miscellaneous NonferrousMaterials
Lead, tin, and their alloys find some use asengineering materials
Mechanically soft and weak, low melting temps,resistant to many corrosion environments, have
recrystallization temps below room temperature
Lead-tin alloys are used in solders
Lead and alloys are used in x-ray shields and
storage batteries Tin is used in food containers (cans)
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-> Miscellaneous NonferrousMaterials
Unalloyed zinc also is a relatively soft metalhaving a low melting temperature
It is reactive in a number of common environmentsand, therefore, susceptible to corrosion
Galvanized steel is plain carbon steel with a thinzinc layer
Zinc preferentially corrodes and protects the steel
Galvanized steel is used in sheet metal, fences,screws
Zinc alloys are used in padlocks, car parts andoffice supplies
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-> Miscellaneous NonferrousMaterials
Zirconium is relatively abundant in the earthscrust
Zirconium and its alloys are ductile and arecomparable to those of titanium alloys and the
austenitic stainless steels
The primary asset of these alloys is resistance tocorrosion in many corrosive media, includingsuperheated water.
Zirconium is transparent to thermal neutrons
Used in heat exchangers, reactor vessels, andpiping systems
Also used in incendiary ordnance and in sealing
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Ceramics
Hard Strong
Low conductivity
Brittle Can be dense or lightweight depending on
method of formation
More resistant to high temperatures and harsh
environments
Cl ifi ti f C i
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Classification of Ceramic
Materials
Structural clay products Whitewares
Refractories
Glasses Abrasives
Cements
Advanced Ceramics
Structural
Electrical
Coatings
Chemical
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Ceramics -> Glasses
Are noncrystal-line silicates containing otheroxides, notably CaO, Na2O, K2O, and Al2O3
The two prime assets of these materials are theiroptical transparency and the relative ease with
which they may be fabricated
Used in containers, windows, lenses, andfiberglass
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Ceramics -> Glasses -> Glass-ceramics
Made by devitrification from most inorganicglasses
Have a low coefficient of thermal expansion
High mechanical strengths and thermal
conductivities Some glass-ceramics are optically transparent;
others opaque
The most attractive attribute of this class of
materials is the ease with which they may befabricated Conventional glass-forming techniques may be
used conveniently in the mass production of nearlypore-free ware
Glassceramics are manufactured commercially
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Ceramics -> Clay Products
One of the most widely used ceramic rawmaterials is clay.
Found naturally in great abundance, it is often usedas mined without any upgrading of quality
Another reason for its popularity lies in the easewith which clay products may be formed
When mixed in the proper proportions, clay andwater form a plastic mass that is very amenable to
shaping The formed piece is dried to remove some of the
moisture, after which it is fired at an elevatedtemperature to improve its mechanical strength
Two classifications: structural clay products and
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Ceramics -> Clay Products
Structural clay products include building bricks,tiles, and sewer pipesapplications in whichstructural integrity is important
The whiteware ceramics become white after the
high-temperature firing. Included in this group are porcelain, pottery,
tableware, china, and plumbing fixtures (sanitaryware).
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Ceramics -> Refractories
Can withstand high temperatures without meltingor decomposing
Remain unreactive and inert when exposed tosevere environments and provide thermal
insulation
Used in furnace linings for metal refining,
metallurgical heat treatment, and powergeneration
For many commercial materials, the rawingredients consist of both large (or grog)particles and fine particles
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Ceramics -> Refractories
Porosity is one microstructural variable thatmust be controlled to produce a suitablerefractory brick
Strength, load-bearing capacity, andresistance to attack by corrosive materialsall increase with porosity reduction.
At the same time, thermal insulation
characteristics and resistance to thermalshock are diminished
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Ceramics -> Abrasives
Used to wear, grind, or cut away other material The prime requisite for this group of materials is
hardness or wear resistance
In addition, a high degree of toughness is essential
Refractoriness is also desirable due to hightemperatures
Diamonds (natural and synthetic) are utilized as
abrasives More common ceramic abrasives include silicon
carbide, tungsten carbide, aluminum oxide andsilica sand
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Ceramics -> Abrasives
Abrasives can be bonded to grinding wheels,coated or used as loose grains.
In the first case, the abrasive particles arebonded to a wheel by means of a glassy ceramic
or an organic resin.
Coated abrasives are coated on some type ofpaper or cloth material; sandpaper is probably themost familiar example.
Grinding, lapping, and polishing wheels oftenemploy loose abrasive grains that are delivered insome type of oil- or water-based vehicle.
Diamonds, corundum, silicon carbide, and rouge
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Ceramics -> Cements
When mixed with water, these materials form apaste that subsequently sets and hardens.
This trait is especially useful in that solidstructures having just about any shape may be
formed
Some of these materials act as a bonding phasethat chemically binds particulate aggregates intoa single structure
The role of the cement is similar to the glassybonding phase when clay products and somerefractory bricks are fired
The process by which cement hardens is not one
of drying, but rather, of hydration
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Ceramics -> Cements
Of this group of materials, portland cement isconsumed in the largest tonnages.
Produced by grinding mixing clay and lime-bearingminerals in the proper proportionsthen heating the
mixture to about 1400C (2550F) in a rotary kiln This process, sometimes called calcination,
produces physical and chemical changes in the rawmaterials
The result is then ground into a very fine powder towhich is added a small amount of gypsum to retardthe setting process
Portland cement is termed a hydraulic cement
because its hardness develops by chemical
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Ceramics -> Diamond
Diamond is the hardest known material and has avery low electrical conductivity due to its crystalnature and bonds
Unusually high thermal conductivity
Optically transparent in the visible and infraredregions of the electromagnetic spectrum
High index of refraction
Used as gem stones and to grind or cut softermaterials
The surfaces of drills, knives, and other toolshave been coated with diamond films to increase
surface hardness
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Ceramics -> Graphite
Has excellent lubricative properties High strength ,good chemical stability at elevated
temperatures and in nonoxidizing atmospheres
High thermal conductivity, low coefficient ofthermal expansion
High resistance to thermal shock, high adsorptionof gases, and good machinability
Commonly used as heating elements for electricfurnaces, high temperature refractories andinsulations, rocket nozzles, electrical contactsand electrodes in batteries
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Polymers
The word polymer literally means "manyparts.
Polymers contain many chemically bondedparts
Two industrially important polymeric materialsare plastics and elastomers (rubbers).
Less dense than metals or ceramics
Resist atmospheric and other forms ofcorrosion
Good compatibility with human tissue
High resistance to conduction of electricity
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Polymers
Are classified into the following types: Plastics
Elastomers (or rubbers)
Fibers
Coatings
Adhesives
Foams
Flms
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Polymers -> Plastics
Polyethylene, polypropylene, polyvinyl chloride,polystyrene, and the fluorocarbons, epoxies,phenolics, and polyesters may all be classified asplastics
Have a wide variety of combinations of properties May be either thermoplastic or thermosetting;
Some plastics are very rigid and brittle; others areflexible, exhibiting both elastic and plasticdeformations when stressed, with considerabledeformation before fracture
Utilized as coatings on nonstick cookware, in
bearings and bushings, and for high-temperature
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Polymers -> Elastomers
The properties of elastomers depend on thedegree of vulcanization and on whether anyreinforcement is used