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C O U R S E L E C T U R E The Six Categories of Engineering Materials Notes taken on January 8, 2016 by Edward Tanguay |
six categories of engineering materials
nearly all materials used for modern applications come from these six categories
adjacent atoms share electrons in a non-directional way
electrons that provide the metallic bonding are reflecting any proton light rays from the environment
gives us the characteristic shiny luster
can conduct electricity, since bonding electrons are mobile
metal is providing the conductivity
polymer sheathing that is providing the safety and insulation
electron sharing between adjacent atoms
good structural integrity
carbon-to-hydrogen bonding
electrons are being shared by the two adjacent atoms
electrons are thus spoken for, good insulator
electron sharing from one atom to another
involves the electrostatic attraction between oppositely charged ions
atoms that have lost one or more electrons (known as cations) and atoms that have gained one or more electrons (known as anions)
from a metallic cation to a negative anion, very often oxygen
the magnitude of the electrostatic force of interaction between two point charges is directly proportional to the scalar multiplication of the magnitudes of charges and inversely proportional to the square of the distance between them
common ceramic coffee mug
electrons are spoken for, therefore electrical insulating
first three categories are based on the three different kind of electron bonding: metallic, covalent, and ionic
the key distinction between the ceramic and glass
glass: random atomic arrangement of ions
ceramic: crystalline formation
because of the nature of the ionic bonding
silicon ions and oxygen ions, a common silicate material
the ductility of a polymer
ductility: when a solid material stretches under tensile stress
like the plastic spatula
from microscopic glass fibers
a few microns in diameter
microscopic and submicroscopic
can control the conductivity in a very powerful way