COMPOSITE MATERIALS

WHY COMPOSITES?
• ADVANTAGES OVER TRADITIONAL
MATERIALS
• CORROSION RESISTANCE
• HIGH STRENGTH TO WEIGHT RATIO
• LOW MAINTENANCE
• EXTENDED SERVICE LIFE
• DESIGN FLEXIBILITY
 COMPOSITES DEFINITION
• A combination of two or more materials (reinforcement,
resin, filler, etc.), differing in form or composition on a
macroscale. The constituents retain their identities, i.e..,
they do not dissolve or merge into each other, although they
act in concert. Normally, the components can be physically
identified and exhibit an interface between each other.
• A judicious combination of two or more materials that
produces a synergistic effect. A material system composed
of two or more physically distinct phases whose
combination produces aggregate properties that are different
from those of its constituents
COMPOSITION / PHASE
A composite material consists of two phases:
• Primary
– Forms the matrix within which the secondary phase is
imbedded
– Any of three basic material types:
– polymers, metals, or ceramics
• Secondary
– Referred to as the imbedded phase or called the
reinforcing agent
– Serves to strengthen the composite.
– (fibers, particles, etc.)
– Can be one of the three basic materials or an element
such as carbon or boron
 CLASSIFICATION OF COMPOSITE
MATERIAL
• Metal Matrix Composites (MMCs)
– Include mixtures of ceramics and metals, such
as cemented carbides and other cermets, as
well as aluminum or magnesium reinforced by
strong, high stiffness fibers
• Ceramic Matrix Composites (CMCs)
– Least common composite matrix. Aluminum
oxide and silicon carbide are materials that can
be imbedded with fibers for improved
properties, especially in high temperature
applications
• Polymer Matrix Composites (PMCs)
– Thermosetting resins are the most widely used
polymers in PMCs. Epoxy and polyester are
commonly mixed with fiber reinforcement
 METAL MATRIX COMPOSITES
Matrix material – Provides the bulk form of the part or product
serves several – Holds the imbedded phase in place
functions in the
composite – Shares the load with the secondary phase
Common reinforcing phase includes
– Particles of ceramic (commonly called cermets)
– Fibers of various materials, including other metals,
ceramics, carbon, and boron
• FRMMC – combine the high tensile strength and
modulus of elasticity of a fiber with metals of low
density, thus achieving good strength-to-weight and
modulus-to-weight ratios in the resulting composite
material.
METAL MATRIX COMPOSITES REINFORCEMENTS

❑ Cemented carbides are composed of one or more Carbide

compounds bonded in a metallic matrix Common cemented
carbides are based on:
• Tungsten carbide (WC) • Chromium carbide (Cr3C2)
• Titanium carbide (TiC) • Tantalum carbide (TaC)
❑ Carbide ceramics constitute the principal ingredient in
cemented carbides, typically ranging in content from 80%
to 95% of total weight.
❑ Principle metallic binders are:
▪ Cobalt – used for WC
▪ Nickel - used TiC and Cr3C2
 METAL MATRIX COMPOSITES PRODUCTS

• Cutting tools are the most common application of cemented

carbides based on tungsten carbide
• Titanium carbide cermets are used principally for high
temperature applications.
– Nickel is the preferred binder; its oxidation resistance at
high temperature is superior to that of cobalt.
– Used as a cutting tool material for machining steels.
 CERAMIC MATRIX COMPOSITES
❑ Ceramic matrix composites (CMCs) are a special type of
composite material in which both the reinforcement (refractory
fibers) and matrix material are ceramics. In some cases, the same
kind of ceramic is used for both parts of the structure, and
additional secondary fibers may also be included.
Advantage Disadvantage
• High stiffness • Low toughness and bulk
• Hardness tensile strength
• Hot hardness • Susceptibility to thermal
• Compressive strength cracking
• Relatively low density
❑ Ceramic matrix composites represent an attempt to retain the
desirable properties of ceramics while compensating for their
weakness.
❑ Ceramic materials used as matrices includes:
*Alumina, *Boron carbide, *Boron nitride, *Silicon carbide, *Silicon
nitride, *Titanium carbide

Fabrication flow process for SiCw /SiC ceramic composites

Chemical Vapor Infltration Process
CERAMIC MATRIX COMPOSITES PRODUCTS
 POLYMER MATRIX COMPOSITES

Fiber Reinforced Polymer (FRP) Composites

are defined as:

“A matrix of polymeric material that is

reinforced by fibers or other reinforcing
material”
 COMPOSITES MARKETS
• TRANSPORTATION
• CONSTRUCTION
• MARINE
• CORROSION-RESISTANT
• CONSUMER
• ELECTRICAL/ELECTRONIC
• APPLIANCES/BUSINESS
• AIRCRAFT/DEFENSE
 Infrastructure Benefits
• HIGH STRENGTH/WEIGHT RATIO
• ORIENTATED STRENGTH
• DESIGN FLEXIBILITY
• LIGHTWEIGHT
• CORROSION RESISTANCE
• LOW MAINTENANCE/LONG-TERM DURABILITY
• LARGE PART SIZE POSSIBLE
• TAILORED AESTHETIC APPEARANCE
• DIMENSIONAL STABILITY
• LOW THERMAL CONDUCTIVITY
• LOW INSTALLED COSTS
 FRP COMPOSITE CONSTITUENTS

• RESINS (POLYMERS)

• REINFORCEMENTS

• FILLERS

• ADDITIVES
 MATERIALS: RESINS
• PRIMARY FUNCTION:
“TO TRANSFER STRESS BETWEEN REINFORCING
FIBERS AND TO PROTECT THEM FROM
MECHANICAL AND ENVIRONMENTAL DAMAGE”

• TYPES:
– THERMOSET
– THERMOPLASTIC
FRP Composite Applications
 Reinforcements
• Three main types of fibers
– Fiberglass
– Carbon fiber or Graphite
– Organic fibers, aramids (kevlar)
• Tubes, tanks, wind turbine blades and rockets
 RESINS
• THERMOSET
– POLYESTER
– VINYL ESTER
– EPOXY
– PHENOLIC
– POLYURETHANE
 RESINS cont..

• THERMOPLASTIC
– ACETAL
– ACRYRONITRILE BUTADIENE STYRENE
(ABS)
– NYLON
– POLYETHYLENE (PE)
– POLYPROPYLENE (PP)
– POLYETHYLENE TEREPHTHALATE (PET)
 RESINS cont..
• THERMOSET ADVANTAGES
– THERMAL STABILITY
– CHEMICAL RESISTANCE
– REDUCED CREEP AND STRESS RELAXATION
– LOW VISCOSITY- EXCELLENT FOR FIBER
ORIENTATION
– COMMON MATERIAL WITH FABRICATORS
 RESINS cont..
• THERMOPLASTIC ADVANTAGES
– ROOM TEMPERATURE MATERIAL STORAGE
– RAPID, LOW COST FORMING
– REFORMABLE
– FORMING PRESSURES AND TEMPERATURES
 POLYESTERS
• LOW COST
• EXTREME PROCESSING VERSATILITY
• LONG HISTORY OF PERFORMANCE
• MAJOR USES:
– Transportation
– Construction
– Marine
 VINYL ESTER
• SIMILAR TO POLYESTER

• EXCELLENT MECHANICAL & FATIGUE

PROPERTIES

• EXCELLENT CHEMICAL RESISTANCE

• MAJOR USES:
– Corrosion Applications - Pipes, Tanks, &
Ducts
 EPOXY
• EXCELLENT MECHANICAL PROPERTIES
• GOOD FATIGUE RESISTANCE
• LOW SHRINKAGE
• GOOD HEAT AND CHEMICAL RESISTANCE
• MAJOR USES:
– FRP Strengthening Systems
– FRP Rebars
– FRP Stay-in-Place Forms
 PHENOLICS
• EXCELLENT FIRE RETARDANCE
• LOW SMOKE & TOXICITY EMISSIONS
• HIGH STRENGTH AT HIGH TEMPERATURES
• MAJOR USES:
– Mass Transit - Fire Resistance & High
Temperature
– Ducting
 POLYURETHANE
• TOUGH

• GOOD IMPACT RESISTANCE

• GOOD SURFACE QUALITY

• MAJOR USES:
– Bumper Beams, Automotive Panels
 SUMMARY: POLYMERS
• WIDE VARIETY AVAILABLE
• SELECTION BASED ON:
– PHYSICAL AND MECHANICAL PROPERTIES
OF PRODUCT
– FABRICATION PROCESS REQUIREMENTS
 FIBER REINFORCEMENTS

• PRIMARY FUNCTION:
“CARRY LOAD ALONG THE LENGTH OF THE
FIBER, PROVIDES STRENGTH AND OR STIFFNESS
IN ONE DIRECTION”

• CAN BE ORIENTED TO PROVIDE PROPERTIES IN

DIRECTIONS OF PRIMARY LOADS
 REINFORCEMENTS
• NATURAL

• MAN-MADE

• MANY VARIETIES COMMERCIALLY

AVAILABLE
 MAN-MADE FIBERS
• ARAMID
• BORON
• CARBON/GRAPHITE
• GLASS
• NYLON
• POLYESTER
• POLYETHYLENE
• POLYPROPYLENE
 FIBER PROPERTIES
DENSITY (g/cm3)
Steel 8

Alum 2.76

E-Glass 1.99

S-Glass 1.99

Carbon 1.59

Aramid 1.38

0 2 4 6 8 10
 FIBER REINFORCEMENT
• GLASS (E-GLASS)
– MOST COMMON FIBER USED
– HIGH STRENGTH
– GOOD WATER RESISTANCE
– GOOD ELECTRIC INSULATING PROPERTIES
– LOW STIFFNESS
 FIBER REINFORCEMENT cont..
• ARAMID (KEVLAR)
– SUPERIOR RESISTANCE TO DAMAGE
– (ENERGY ABSORBER)
– GOOD IN TENSION APPLICATIONS (CABLES,
TENDONS)
– MODERATE STIFFNESS
– MORE EXPENSIVE THAN GLASS
 FIBER REINFORCEMENT cont..
• CARBON
– GOOD MODULUS AT HIGH TEMPERATURES
– EXCELLENT STIFFNESS
– MORE EXPENSIVE THAN GLASS
– BRITTLE
– LOW ELECTRIC INSULATING PROPERTIES
 FIBER ORIENTATION
• ANISOTROPIC
• UNIDIRECTIONAL
• BIAS - TAILORED DIRECTION
– 0O - flexural strengthening
– 90O - column wraps
– + /- 45O - shear strengthening
• ANGLE VARIES BY APPLICATION
 REINFORCEMENTS
SUMMARY
• TAILORING MECHANICAL PROPERTIES
– TYPE OF FIBER
– PERCENTAGE OF FIBER
– ORIENTATION OF FIBER
 DESIGN VARIABLES
FOR COMPOSITES
• TYPE OF FIBER
• PERCENTAGE OF FIBER or FIBER VOLUME
• ORIENTATION OF FIBER
– 0o, 90o, +45o, -45o
• TYPE OF POLYMER (RESIN)
• COST
• VOLUME OF PRODUCT - MANUFACTURING
METHOD
 DESIGN VARIABLES
FOR COMPOSITES

• PHYSICAL:
– tensile strength
– compression strength
– stiffness
– weight, etc.
• ENVIRONMENTAL:
– Fire
– UV
– Corrosion Resistance
 TAILORING COMPOSITE
PROPERTIES
• MAJOR FEATURE
• PLACE MATERIALS WHERE NEEDED -
ORIENTED STRENGTH
– LONGITUDINAL
– TRANSVERSE
– or between
• STRENGTH
• STIFFNESS
• FIRE RETARDANCY