Property Classifications
mechanical |
stiffness, strength, toughness |
electrical |
electrical conductivity, dielectric constant |
thermal |
heat capacity, thermal conductivity |
magnetic |
response to magnetic field |
optical |
index of refraction, reflectivity |
deteriorative |
chemical reactivity |
Design, Production, and Utilization
proccessing |
structure |
properties |
performance |
Material performance is a function of its properties, properties are a function of structure, and structure is the result of processing.
Materials Selection Process
in-service conditions |
what compromises have to be made? |
deterioration during operation |
is mechanical strength lost in operating environment? |
economics |
what will final product cost? |
Solid Material Classifications
metals |
composed of metallic elements, nonlocalized electrons |
orderly, dense, stiff, strong, ductile, resist fracture, good electrical/thermal conductors, opaque, luster, magnetic properties |
ceramics |
compound of metallic and nonmetallic elements |
stiff, strong, hard, brittlemess, susceptible to fracture, insulative to electricity and heat, resistant to harsh environment, variable optical and magnetic characteristics |
polymers |
large molecular structure |
not strong, not stiff, low density, ductile, pliable, chemically inert, soften/decompose at moderate temperautre, low electrical conductivity, nonmagnetic |
composite |
composed of two or more materials |
depends on materials combined |
Advanced Materials
semiconductors |
intermediate electrical properties |
biomaterials |
nontoxic and biocompatible |
smart materials |
sensor, actuator respond to changes in environment |
nanomaterials |
less than 100 nanometers in size |
Smart Materials and Systems
shape-memory alloy |
pieoelectric ceramics |
magnetostrictive materials |
electroheological and magntorheological fluids |
Smart materials are able to sense environmental changes and respond to them in a predetermined manner. They are composed of a sensor (detects signal) and an actuator (performs predetermined function).
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