What are the mechanical properties?
yield strength, creep, stiffness, impact, ductility, and fatigue strength
What are the physical properties?
conductivity, temperature, thermal, and environmental
What type of atoms make up a metal?
mostly made of metallic elements
What are typical mechanical properties for a metal?
high electrical conductivity, ductile, strong, shiny
Are metals typically amorphous or crystalline?
crystsalline
Are metals typically single crystal or multi-grained?
multigrain
Do metals have high or low electrical and thermal conductivity?
high
What is a ceramic?
compounds of metallic and non metallic elements
What are typical mechanical properties for a ceramic?
corrosion resistant, low thermal conductivity, brittle, capable of being used at high temperatures
Are ceramics typically amorphous or crystalline?
both
Are crystalline ceramics typically single crystal or multi-grained?
multigrain
Do ceramics have high or low electrical and thermal conductivity?
low
What is a polymer
larger molecules made from smaller molecules in a process called polymerization
What are typical mechanical properties for polymers?
transparent, low electrical and thermal conductivity, and low density
What are typical mechanical properties for thermosets?
low density, brittle, and low electrical conductivity
Are thermosets, thermoplastics, and elastomers typically amorphous or crystalline?
thermosets- amorphous
thermoplastics/elastomers- amorphous or crystalline
Do polymers have high or low electrical and thermal conductivity?
low
What is a composite material?
materials formed mechanically from 2 or more materials
What is a semiconductor
an intermediate between metals and ceramics
How can the electrical properties of a semiconductor be altered?
they can be changed by altering the concentration of minute amounts of impurity atoms
Are semiconductors typically amorphous or crystalline?
cyrstalline
Are crystalline semiconductors typically single crystal or multi-grained?
mostly single crystals
Give some common examples of each material type...
metals, ceramics, polymers, composites, and semiconductors
metals-steel, cast iron, brass, bronze, aluminum alloys
ceramics-alumina, MgO, silica, silicon nitride (brick/glass)
polymers-C, O, N, H, Si, F (furniture/paints/adhesives)
composites- tires, fiberglass, concrete
semiconductors-silicon, germanium (electoronics/detectors)
What is a grain structure?
Found in crystalline materials. It is the portion of a material which has a particular arrangement and a boundary.
What is a mechanical property?
It describes how a material responds to an applied force. It affects how a material can be used and produced.
physical properties are everything else
What is an ionic bond?
Electrons are given/taken to creat full shells.
For compounds with not pure elements.
What is a covalent bond?
Sharing electrons to get 8 valence electrons
What is a metallic bond?
Only occurs in metals when valence electrons are shared.
(a sea of negative electrons)
What are the typical electrical properties for a material with an ionic bond?
good electrical conductors and insulators
What are the typical electrical properties for a material with a covalent bond?
they arent very good electrical conductors
What are the typical electrical properties for a material with a metallic bond?
high electrical and thermal conductors
Are the bond strengths for secondary bonds higher or lower than those for primary bonds?
lower
As the bond strength increases would you expect the melting point to increase or decrease?
increase
As the bond strength increases would you expect the stiffness of a material to increase or decrease?
increase
What is a thermoplastic polymer?
Molecules that are not rigidly linked together but have good ductility and formability
What is a thermoset polymer?
molecules that are rigidly linked together, stronger and more brittle
What is an elastomer polymer?
(rubbers) - are extremely kinked up and partially linked together so that they can be stretched and still recover their original shape.
Which has higher ductility-a thermoset or thermoplastic polymer? Why?
Thermoplastics because the secondary bonding between chains is weaker.
How are ceramic and polymer crystal structures different from metallic crystal structures?
Ceramic and polymer crystal structures are amorphous, while metallic crystals are generally crystalline
When a metallic element and oxygen are combined to form a ceramic what is the ceramic called?
silica - crystalline and amoprhous
How are ceramic crystal structures named?
They are named after a common compound (atom per lattice site)
What is an interstitial?
a defect (an extra atom inserted at the lattice site that is not normal)
Are there any pure elements?
NO!
What is a substitutional solid solution?
when the solute (minor element) replaces the solvent (major element) in a crystal.
What is an interstitial solid solution?
When solute atoms are located in the spaces between the solvent atoms.
What is the solvent-rich phase called in a solid?
matrix
What is the solute-rich phase called in a solid?
precipitate
Rank the following in terms of increasing ductility?
o HCP
metal
o BCC metal
o FCC metal
least ductile to most
HCP, BCC, FCC
List four ways that a metal could be strengthened.
1. solid solution stregnthening
2. plastic defomation
3. grain-size strengthening
4. Precipitaion strengthening
What is the mechanism by which the strengthening occurs
grain boundaries
Plastic deformation of a metal increases the strength of the metal. How does this occur?
Because plastic deformation distorts the material until its max yield strength and causes it to have less ductility and more strength.
How are thermoplastic polymers strengthened? Describe the mechanism!
They are reinforced with fibers by aligning the chains to get them stronger and more brittle
Typically as the strength of a metal increases what happens to the ductility?
ductility increases
Practice math problems
ok!