composites pdf upes
TRANSCRIPT
-
8/7/2019 Composites PDF UPES
1/9
Vikas Misra
AP (SG)
UPES,Dehradun
-
8/7/2019 Composites PDF UPES
2/9
CompositesComposite material is combination of two or more
chemically unlike materials with distinct boundariesbetween them.
Such materials have their own specificproperties & are usually different from theirindividual material properties.
The properties such as strength, resistance toheat or some other property of composites aremuch better than the properties of individual
materials from which they are made.
-
8/7/2019 Composites PDF UPES
3/9
.
Composites include the following :
Multiphase metal alloys
Ceramics
Polymers
Some common composites are Pearlitic steel,wood,RCC, automobile tyres
Composites materials can be divided into 3
main classes :-Fibre Reinforced materials
Laminated Materials
Disperse Materials
-
8/7/2019 Composites PDF UPES
4/9
.
Fibre Reinforced materials: Here fibres of
High strength materials are introduced intothe soft & ductile matrix.
The strength of soft & ductile matrix getsincreased by high strength fibres
the resulting composite material will havehigh stiffness, high Specific strength( UTS/density),elevated temp strength & high fracturetoughness.
Fibres mainly bear the load & the matrixtransfers & distributes the external load to
the fibres.
-
8/7/2019 Composites PDF UPES
5/9
.
.Also matrix protects the fibres from externalactions & imparts certain Physico chemicalproperties such as resistance to corrosion &oxidation, electrical & thermal conductivity etc.
The properties of composite materials atelevated temp may get affected by thereactions occurring between the matrix &fibres, this may result in dissolution or softening
of fibres & may also form brittle layer atinterfaces.
Fibres can be metals or nonmetals.
-
8/7/2019 Composites PDF UPES
6/9
.
The common metallic fibres used incomposite materials are of Boron, Be,Mo,T,SS,& non metallic fibres are of C,Glass, Silica,alumina, silicon carbide & Aramide.
Aramide is an aromatic polymaide fibre with a
very rigid molecular structure & is marked undertrade name KEVLAR.
Matrix can also be metallic or non metallic,
common metallic matrices are of Al,Cu,Titaniumalloys & nonmetallic matrices are of unsaturatedpolyesters & epoxy resins.
-
8/7/2019 Composites PDF UPES
7/9
.
Fibre reinforced composites have hugediversified applications. Like helmets, car &
jeep bodies, bikes, vehicle tyres, aircraft partssteel rods etc.
Laminated Materials : Here the composite
material consists of two or more layers ofunlike components. Like Laminated Plywood, Alclad aluminum alloy, copper clad Stainlesssteel .
Thermostatic controls consisting of a bimetallicstrip of copper & Ni used to control temperaturesin ovens & furnaces is also a composite material
of this type.
-
8/7/2019 Composites PDF UPES
8/9
.
The properties of these composites & fibrereinforced composites are highly sensitive to
direction of loading w.r.t. the direction oflamillae or fibres.
Disperse Materials : Here the particles of one
material are distributed as a mechanicalmixture into the other (Base).
This is the same as dispersion hardening of
strengthening. Common example of suchcomposites are Sintered Aluminum powder,thoriated tungsten, dispersed Nickel.
-
8/7/2019 Composites PDF UPES
9/9
.
Large number of methods are available forproduction of composite materials,
Important One are Unidirectionalsolidification, infiltration of molten metal,plasma spraying, electroplating, diffusion
bonding, P/M.