Types and Applications of Materials

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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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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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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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

Types and Applications of Materials

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