Materials Engineering Exam 1
properties of metals
- Dense, stiff, and strong but ductile - High resistance to fracture - Good conductors of electricity and heat
properties of composites
-Combine other types of materials -Tailor material properties for specific uses -Properties can differ based on fiber direction
properties of polymers
-Extremely ductile and pliable -Generally inert and unreactive -Soften at modest temperature
properties of ceramics
-Hard, stiff, and strong -Brittle and susceptible to fracture -Good insulators of electricity and heat
There is (are) ___ 2sp^2 hybrid orbital(s) present in each sp^2 hybridized carbon atom
3
define biomaterial
A biomaterial is a nonliving material implanted into the body. A biomaterial must be reliable, safe, and compatible with body tissues and fluids. Ex: Hip and knee replacements, heart valves
define nanomaterials
A nanomaterial has structural elements less than 100 nanometers. The atoms can be arranged to customize material properties. Ex: Carbon nanotubes, graphene, and nanocomposites
Pauli exclusion principle
An atomic orbital may have at most two electrons, each with opposite spin direction
What atomic model does this describe: Electrons are assumed to revolve around the nucleus in discrete orbitals
Bohr Atomic model In the Bohr model, the position of any particular electron is well defined in terms of orbitals.
what primary bonding type does the following describe: The mixing of two or more atomic orbitals
Bond hybridization it occurs when an electron moves to a different orbital and creates equivalent hybrid orbitals.
The _____ for two atoms represents the energy required to separate the two atoms to an infinite separation.
Bonding energy The bonding energy, E0, is the minimum on the net potential energy curve on a graph of the potential energy versus interatomic separation. E0 occurs at an interatomic separation r0.
aluminum oxide is a type of what material
Ceramic Aluminum oxide has a metallic element, aluminum, and nonmetallic element, oxygen.
how would you improve the following stress contribution in a ship sinking: inexperienced welders created weld defects
Improved welding practices and codes Improving welding practices and welding codes reduced the weld defects and discontinuities.
define quantum numbers
In wave mechanics, every electron in an atom is characterized by four parameters called quantum numbers The size, shape, and spatial orientation of an electron
how would you improve the following stress contribution in a ship sinking: cracks propagated through welded steel sheets
Installed riveted straps and strong weld seams Riveted straps and strong weld seams stop cracks from propagating.
how would you improve the following stress contribution in a ship sinking: ductile to brittle transition in cold water
Lowered the steel's ductile-to-brittle transition temperature The ductile-to-brittle transition temperature was lowered by increasing the steel's quality. Correct
high carbon steel is a type of what material
Metal High carbon steel has a metallic material, iron, and a small amount of a nonmetallic material, carbon.
metals definition
Metals are composed of one or more metallic elements (e.g., iron, aluminum, copper, titanium, gold, nickel), and often also nonmetallic elements (e.g., carbon, nitrogen, oxygen) in relatively small amounts.
High Density Polyethylene (HDPE) is a type of what material
Polymer High density polyethylene (HDPE) is a chainlike organic compound of carbon and hydrogen.
polymers definition
Polymers include the familiar plastic and rubber materials. Many of them are organic compounds that are chemically based on carbon, hydrogen, and other nonmetallic elements (i.e., O, N, and Si). Furthermore, they have very large molecular structures, often chainlike in nature, that often have a backbone of carbon atoms. example: polyethylene (PE), nylon, poly(vinyl chloride) (PVC), polycarbonate (PC
define quantum mechanics
Principles and laws that govern atomic and subatomic entities Quantum mechanics involves the study of the behavior of electrons in atoms that could not be explained by classical mechanics.
Improvements in material _____ are needed to control water and air pollution.
Processing Material processing and refinement need to produce less pollution, less impact on the land, and fewer toxic substances.
thermal properties
Relate to changes in temperature or temperature gradients across a material Ex: Thermal expansion and heat capacity
mechanical properties
Relate to deformation in response to an applied load or force Ex: Elastic modulus, strength, and resistance to fracture
deteriorative characteristics
Relate to the chemical reactivity of materials Ex: Corrosion resistance of metals
the third quantum number represents what
Relates to an orbital's energy state when a magnetic field is applied 1 < ml < 1 The magnetic quantum number, ml describes an orbital's change in energy state when a magnetic field is applied and can have values between −1 and 1
how would you improve the following stress contribution in a ship sinking: stress concentrations at corners
Rounded off hatch corners Rounding the hatch corners by welding a curved reinforcement strip reduced the stress concentrations.
what improvements need to be made to solar and nuclear energy to make them usable for transportation?
Solar cells will need a more efficient energy conversion process, lower cost materials, and improved energy storage capacity of batteries. Nuclear energy needs new fuels, better materials for containment structures, and better materials for radioactive waste disposal facilities.
magnetic properties
The responses of a material to the application of a magnetic field Ex: Magnetic susceptibility and magnetization
electrical properties
The stimulus is an applied electric field Ex: Electrical conductivity and dielectric constant
optical properties
The stimulus is electromagnetic or light radiation Ex: Index of refraction and reflectivity
What atomic model does this describe: Electrons have a probability of being at various locations around the nucleus
Wave-mechanical model In the wave-mechanical model, the position of an electron is described by a probability distribution.
Electronegativity
a measure of how (un)willing atoms are to accept electrons
Sodium (Na) is classified as a(n) _____. alkaline earth metal alkali metal transition metal
alkali metal Elements in column 1 (H, Li, Na, K, Rb, Cs, Fr) are considered alkali metals.
All _____ must be compatible with body tissues and fluids.
biomaterials
Bonding energy depends on the atom types involved in the bond and the material's_____.
bonding type Bonding energy depends on the atom types involved in the bond and the bonding type. Some types of bonds have much higher bonding energies than other types of bonds.
Covalent bonding occurs between atoms that are _____ the periodic table.
close together in Atoms that are close together in the periodic table have a similar electronegativity and tend to form covalent bonds.
composites definition
composed of two (or more) individual materials that come from the categories previously discussed—metals, ceramics, and polymers example: fiberglass
Carbon Fiber Reinforced Polymers (CFRP) is a type of what material
composite Carbon fiber-reinforced polymer is a composite of carbon fibers inside a polymer.
ceramics definition
compounds between metallic and nonmetallic elements; they are most frequently oxides, nitrides, and carbides. For example, common ceramic materials include aluminum oxide (or alumina, Al2O3), silicon dioxide (or silica, SiO2), silicon carbide (SiC), silicon nitride (Si3N4)
The free valence electrons in metallic solids cause metallic solids to be good _____ of electricity.
conductors
what primary bonding type does the following describe: Two elements with similar electronegativity share at least one electron each
covalent bonding A covalent bond is formed by two atoms sharing electrons. The shared electrons belong to both atoms.
nanostructure
deals with groups of atoms that form very small particles.
thermal conductivity ___ when you add impurities atoms and grain boundaries
decreases
A covalent bond is _____
directional A covalent bond can only exist in the direction between the atoms that share electrons.
subatomic structure
electrons within atoms.
The _____ of the carbon-12 isotope represents the amount of carbon-12 in relation to the amount of all isotopes of carbon.
fraction of occurrence The fraction of occurrence represents the amount of a particular isotope in relation to the amount of all isotopes of an element.
Valence electrons in metallic bonds are ___
free to move throughout the metallic solid
A metallic atom tends to _____ electrons to have a filled outer electron shell.
give up A metallic atom is electropositive and tends to give up the few valence electrons.
Iodine (I) is classified as a(n) _____.
halogen Elements in column 17 (F, Cl, I, Br, I, At) are classified as halogens.
define semiconductor
have electrical properties that are intermediate between those of electrical conductors (i.e., metals and metal alloys) and insulators (i.e., ceramics and polymers) covalent bonding Ex: Integrated circuits (microchips) for electronics and computers
do subshells with one missing electron have low or high electronegativity
high
Solids at room temperature typically have _____ bonding energies.
high Solids at room temperature typically have high bonding energy. High bonding energy results in a melting temperature much higher than room temperature.
Bond hybridization can occur ____
in some elements Although bond hybridization is most often associated with carbon, it can occur in some other nonmetals and transition metals.
Increasing the bonding energy will _____ the stiffness of a material.
increase Increasing the bonding energy will increase the stiffness of a material. Higher bonding energy means that the bonds between atoms are more difficult to break.
Electronegativity trend on the periodic table
increases from left right
Krypton (Kr) is classified as a(n) _____
inert gas Elements in column 18 (He, Ne, Ar, Kr, Xe, Rn) on the periodic table shown above are called inert gases.
The availability of _____ was key to the automobile's development.
inexpensive steel
silicon is an example of what type of element
intermediate Silicon is classified as intermediate based on chemical and physical properties that are similar to both metals and nonmetals.
do subshells with one electron have low or high electronegativity
low
Understanding the relationships between _____ and material properties allows scientists to create new materials with better properties.
material structure
Ionic bonding occurs between _____.
metals and nonmetals
sulfur is an example of what type of element
nonmetal
A coulombic force of attraction is found in ionic bonding when two ions have _____ charges.
opposite An opposite charge causes an attractive force that results in an ionic bond.
An ion core composed of the atom's nucleus and remaining nonvalence electrons has a _____ charge.
positive
paradigm of materials engineering put the following in order structure, properties, processing, performance
processing > structure > properties > performance A material's structure depends on how the material was processed. Ex: A metal's microstructure depends on the metal's fabrication and processing. A material's properties depend on the structure. Ex: A ceramic's optical properties depend on electronic structure. A material's performance depends on the properties. Ex: The aluminum alloy for an orchard ladder must have adequate strength and stiffness.
A nonmetallic atom tends to _____ electrons to have a filled outer electron shell.
receive A nonmetallic atom is electronegative and tends to receive a small number of valence electrons to fill the outer electron shell.
Developing _____ will reduce the world's dependence on nonrenewable materials.
renewable materials with similar properties Developing renewable materials with similar properties to the nonrenewable materials that are currently used will reduce the world's dependence on nonrenewable materials.
All _____ have electrical properties between an electrical conductor and an electrical insulator.
semi conductors
The development of sophisticated electronic devices was a result of _____.
semiconducting materials
Covalent bonding occurs when two atoms _____ electrons
share
the first quantum number represents what
size n = size of electron orbital
A _____ uses sensors and actuators to change a material's characteristics in response to environmental changes.
smart material
define smart materials
smart material uses a sensor and actuator to adapt to environmental changes. Ex: Smart helicopter rotor blades reduce cockpit noise using sensors and noise-canceling
Bond hybridization in carbon can take the form of _____ hybrid bonds
sp^2 and sp^3
the fourth quantum number represents what
spin orientation ms can equal -1/2 or 1/2
what are the four steps of the material selection process cycle
step 1: in-service conditions step 2: trade off material properties step 3: deterioration of material properties step 4: economical material and fabrication
macrostructure
structural elements that can be seen with the naked eye.
microstructure
structural elements that can only be seen using a microscope.
the second quantum number represents what
subshell shape l = s(0), p(1), d(2), f(3)
A material scientist must consider _____ of a material when choosing a material for a particular application.
the entire life cycle A material scientist must consider the entire life cycle of a material including processing, performance, and recyclability when choosing a material.
What is true of the energy-distance curves near equilibrium for two materials with different thermal expansion coefficients?
the material with the lower thermal expansion coefficient has a steeper slope and more negative value
atomic structure
the organization of atoms that make molecules or crystals.
Ionic bonding occurs when electrons belonging to two different atoms are ____
transferred atoms transfer electrons, either giving or receiving, in ionic bonding to have filled outer electron shells.
Uranium (U) is classified as a(n) _____.
transition metal Uranium (U) is a part of the actinide series at the bottom of the periodic table but is still considered a transition metal.