Materials world

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Materials world
high toughness dislocation plasticity suffers
from modest hardness and lower melting point!
brittle materials toughness
strength variability major concerns!
low density, high flexibility lacks high
temperature applications!
Composites A special material class combining
properties of metallic, ceramic and polymeric
materials. Three distinct composite classes
MMC, CMC and PMC.
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Ceramics How to define?
Origin of word Ceramic Keramikos (burnt stuff)
In general, Ceramics are broadly defined as a
class of inorganic nonmetallic materials having
ionic/covalent bonding and typically processed
/ used at high temperature
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Classification
Properties depend on use of high quality fine
powders process parameters
Mostly silicate based materials
Used in technical applications requiring good
mechanical and functional properties
Lower cost mostly used for low key
applications!
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High temperature applications
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Ceramics low density materials
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structural ceramics-strength toughness
New materials
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Fracture of solids stress concentration
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Ductile and brittle fracture
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Important loading geometries
mode I
mode II
mode III
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Why metals are tough?
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Application of ceramics
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Structural applications of zirconia
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Use of zirconia in steel industries
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More applications of zirconia
PSZ used as valve guides for a turbocharger
Stabilised zirconia used as valve seats
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Structural applications of carbide ceramics
Silicon Carbide Mechanical seals, gas turbine
components, wear and corrosion resistant parts,
.
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Industrial applications of silicon nitride
turbocharger rotors
ball bearings
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Commercial uses of silicon nitride ceramics
Silicon nitride Aerospace and automotive
engine components, heaters, ignitors, gas turbine
parts, ..
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Commercial applications NHK springs
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More uses of structural ceramics
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Al2O3-SiC composites cutting tools
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IC engine ball bearings
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Materials resistant to projectiles