Classification of Materials
Metals
Ceramics
Polymers
Composites
Classes of Materials
• Metals
–
–
–
–
–
Iron and Steels
Aluminum and Alloys
Copper and Alloys
Nickel and Alloys
Titanium and Alloys
• Ceramics and
Glasses
–
–
–
–
–
–
Alumina
Magnesia
Silica
Silicon Carbide
Silicon Nitride
Cement and
Concrete
• Polymers
–
–
–
–
–
–
–
–
–
–
PE
PMMA
Nylon (PA)
PS
PU
PVC
PET
PEEK
EP
NR
• Composites
– GFRP
– CFRP
Classes of Property
Economic
Price and availability
Recyclability
General Physical
Density
Mechanical
Modulus
Yield and tensile strength
Hardness
Fracture toughness
Fatigue strength
Creep strength
Damping
Thermal
Thermal conductivity
Specific heat
Thermal expansion coefficient
Electrical and Magnetic
Resistivity
Dielectric constant
Magnetic permeability
Environmental Interaction
Oxidation
Corrosion
Wear
Production
Ease of Manufacture
Joining
Finishing
Aesthetic
Color
Texture
Feel
Metals
• Metals are typically split into ferrous (iron
containing) and non-ferrous
• Most widely used metals are alloys except
for aluminum and precious metals
• Metals are in general are good thermal
and electrical conductors. Many metals
are relatively strong and ductile at room
temperature, and many maintain good
strength even at high temperature.
Iron
Iron was the third of the prehistoric
materials ages (stone, bronze, iron).
Iron began to be used once furnaces
could be made hot enough to melt iron.
Iron quickly became the metal of
choice because of its abundance in the
earth’s crust.
Iron however has two major problems:
1) Corrosion
2) Brittleness
These problems are partially overcome
by alloying iron to make steel
Steel
Steel is an alloy consisting mostly of iron,
with a carbon content between 0.02% and
1.7 or 2.04% by weight (C:1000–
10,8.67Fe), depending on grade. Carbon is
the most cost-effective alloying material for
iron, but various other alloying elements are
used such as manganese and tungsten.[1]
Carbon and other elements act as a
hardening agent, preventing dislocations in
the iron atom crystal lattice from sliding past
one another. Varying the amount of alloying
elements and form of their presence in the
steel (solute elements, precipitated phase)
controls qualities such as the hardness,
ductility, and tensile strength of the resulting
steel. Steel with increased carbon content
can be made harder and stronger than iron,
but is also more brittle. The maximum
solubility of carbon in iron (in austenite
region) is 2.14% by weight, occurring at
1149 °C; higher concentrations of carbon or
lower temperatures will produce cementite.
Alloys with higher carbon content than this
are known as cast iron because of their
lower melting point.[1]
Steel
Aluminum (Aluminium)
•
•
Aluminium or aluminum is a silvery and ductile member of the poor metal group of chemical
elements. It has the symbol Al; its atomic number is 13.
Aluminium is found primarily in bauxite ore and is remarkable for its ability to resist corrosion
(due to the phenomenon of passivation) and its light weight. Structural components made
from aluminium and its alloys are vital to the aerospace industry and very important in other
areas of transportation and building.
Although aluminium is the most
abundant metallic element in Earth's
crust (believed to be 7.5% to 8.1%), it
is very rare in its free form, occurring in
oxygen-deficient environments such as
volcanic mud, and it was once
considered a precious metal more
valuable than gold. Napoleon III,
Emperor of France, is reputed to have
given a banquet where the most
honoured guests were given aluminium
utensils, while the other guests had to
make do with gold ones.
20th century metallurgists developed
improved processes for extraction.
Aluminum
SuperAlloys
•
•
A superalloy, or high-performance alloy,
is an alloy able to withstand extreme
temperatures that would destroy
conventional metals like steel and
aluminum. Superalloys exhibit excellent
mechanical strength and creep resistance at
high temperatures, good surface stability,
and corrosion and oxidation resistance.
Superalloys typically have an austenitic
face-centered cubic crystal structure. A
superalloy's base alloying element is usually
nickel, cobalt, or nickel-iron. Superalloy
development has relied heavily on both
chemical and process innovations and has
been driven primarily by the aerospace and
power industries. Typical applications are in
the aerospace industry, eg. for turbine
blades for jet engines.
Examples of superalloys are Hastelloy,
Inconel, Haynes alloys, Incoloy, MP98T,
TMS alloys, and CMSX single crystal alloys.
Variety of ceramic applications
• Furnace linings, heat sinks, capacitors,
fuel cells, magnets (hard and soft),
superconductors, windows, optical
fibers, nuclear fuel, artificial hip joints,
cutting tools, turbine blades, bearings
What is a Ceramic?
• Solid compounds formed by heat or heat
and pressure that contain
– At least one metal and one non-metal or one
non-metal elemental solid (NMES) [MgO,
Al2O3, YBa2Cu3O7]
– At least two NMES [SiC]
– At least two NMES and a non-metal
My name is Bond…..
• In ceramics bonding is a mixture of ionic
and covalent
• If ionic bonding dominates crystal
structures occur that are typically based
on FCC and HCP
• If covalent bonding dominates rings and
tetrahedral units are often seen
Ceramics: crystalline and glassy
Zinc blende (ZnS)
structure
Continuous random
network oxide glass
Repeat units of some common
polymers
• Poly(ethylene)
CH2CH2
n
• Poly(propylene)
CHCH2
n
CH3
CHCH2
• Poly(styrene)
n
CO
COO(CH2)2O
n
• Poly(ethyleneterephtalate)
Conformation of Polymers
Amorphous thermoplastic
Crosslinked thermoset
Semi-crystalline thermoplastic
Variety of polymer applications
• Packaging materials, building and
construction, consumer products,
electrical equipment, furniture,
adhesives, inks, coatings, optical films,
polarizers, photoresists, conducting
polymers, latex paint, fabrics/textiles,
dielectric materials (capacitors), light
emitting diodes.
Plastics use in BMW 5 Series
PA
PBT+PC
PBT
PMMA
PE
PVC
ABS+PC
PUR
PP
ABS
POM
UP-GF
PPO
OTHERS
Elastomers
(a)
(b)
• Entropy springs
• Lightly crosslinked
• Typically non-linear elastic
(c)
ABS
The nitrile groups from neighbouring chains, being polar, attract each other and
bind the chains together, making ABS stronger than pure polystyrene. The styrene
gives the plastic a shiny, impervious surface. The butadiene, a rubbery substance,
provides resilience even at low temperatures. ABS can be used between −25 and
60 °C.
Production of 1 kg of ABS requires the equivalent of about 2 kg of oil for raw
materials and energy.
ABS is used where weight, strength, surface finish and impact resistance are
required.
Polycarbonate
Although polycarbonate has
high impact-resistance, it has
low scratch-resistance and so a
hard coating is applied to
polycarbonate eye-wear lenses.
The characteristics of
polycarbonate are quite like
those of polymethyl
methacrylate (PMMA; acrylic),
but polycarbonate is stronger
and more expensive. This
polymer is highly transparent to
visible light and has better light
transmission characteristics than
many kinds of glass. CR-39 is a
specific polycarbonate material
— although it is usually referred
to as CR-39 plastic — with good
optical and mechanical
properties, frequently used for
eyeglass lenses.
PC Examples
Polyethylene
Polyethylene is classified into several different categories based mostly
on its density and branching. The mechanical properties of PE depend
significantly on variables such as the extent and type of branching, the
crystal structure, and the molecular weight.
Ultra high molecular weight polyethylene (UHMWPE)
Ultra low molecular weight polyethylene (ULMWPE - PE-WAX)
High molecular weight polyethylene (HMWPE)
High density polyethylene (HDPE)
High density cross-linked polyethylene (HDXLPE)
Cross-linked polyethylene (PEX)
Medium density polyethylene (MDPE)
Low density polyethylene (LDPE)
Linear low density polyethylene (LLDPE)
Very low density polyethylene (VLDPE
Polyethylene is one of the most widely used polymers because of its cost and
versatility.
Spectra® fiber is one of the world’s strongest and lightest fibers.
A bright white polyethylene, it is, pound-for-pound, ten times
stronger than steel, more durable than polyester and has a
specific strength that is 40 percent greater than aramid fiber.
Spectra® fiber is made from ultra-high molecular weight
polyethylene that is used in a patented gel-spinning process.
Polyethylene is a remarkably durable plastic, and scientists at
Spectra Technologies have captured the tremendous natural
strength in the molecular backbone of this everyday plastic to
create one of the world’s strongest and lightest fibers. The gelspinning process and subsequent drawing steps allow Spectra®
fiber to have a much higher melting temperature (150°C or
300°F) than standard polyethylene.
With outstanding toughness and extraordinary visco-elactic
properties, Spectra® fiber can withstand high-load strain-rate
velocities. Light enough to float, it also exhibits high resistance
to chemicals, water, and ultraviolet light. It has excellent
vibration damping, flex fatigue and internal fiber-friction
characteristics, and Spectra® fiber’s low dielectric constant
makes it virtually transparent to radar.
Spectra® fiber is used in numerous high-performance
applications, including police and military ballistic-resistant
vests, helmets and armored vehicles, as well as sailcloth,
fishing lines, marine cordage, lifting slings, and cut-resistant
gloves and apparel. Honeywell also converts Spectra® fiber into
the Spectra Shield® family of specialty composites for armor
and other applications.
Polypropylene
Polypropylene is often used as a stronger alternative to polyethylene.
Synthetic Rubber
Based on Butadiene. Cross-linking is needed to create entropy spring.
Composite Materials
Polymer matrix
composite (PMC)
Carbon fiber
reinforced epoxy
crossply laminate
Metal matrix
composite (MMC)
Silicon carbide
particulate
reinforced
aluminum
Ceramic matrix
composite (CMC)
Silicon carbide
monofilament
reinforced glass
ceramic
After D. Hull and T. W. Clyne, “An introduction to composite materials”, 2nd Edition, Cambridge University
Press, Cambridge, (1996)
Review
• Describe the subject of materials science
and engineering.
Review
• Cite the primary classifications of solid
materials.
Review
• Give distinctive features of each group of
materials.
• Metals
• Polymers
• Ceramics
• Composites
Review
• Cite one material from each group.
• Give some applications of different types
of materials.