Materials Science and Engineering and Atomic structure Flashcards
What are engineering materials?
Materials are inanimate matter useful to the practice of an engineer. Constitute backbone of civilization. Solid liquid or gaseous.
How does the prof define engineering?
Applied science. Engineer considers applicability above theoretical sciences.
What are the four broad groups of engineering materials?
Metals and alloys, ceramics and glasses, organic polymers, composites
What are metals and alloys?
Capable of changing their shape permanently. Good thermal and electrical conductivity. Light reflectivity. Usually allows are used in real workd
What are ceramics and glasses?
Made from a combination of elements from both metals and non metals portions of periodic table. Inorganic substances. Brittle. Good thermal and electrical insulation.
What are organic polymers?
Molecules joined in a chain like fashion. Based on hydrocarbons. Polymeric materials consist of synthetic plastics and natural polymers. Rubber is a natural polymer. Resist corrosion. Deformable, light, resist electrical current.
What are composites?
Combos of other materials. Prove that conjunction between types of materials can be useful. Eg. concrete and fibre reinforced polymers
What are the two types of material classification and their definitions?
Structural : don’t move
Machines : do move (seismic design in civil)
Devices: engineering innovations
What are the types of properties of materials? With 3 examples of each type
Physical: shape, size, density, porosity, structure, specific gravity, any appearance
Mechanical: strength, stiffness, elasticity, plasticity, ductility, creep, see mechanical testing this list is longggg
Thermal: specific heat, thermal capacity, thermal expansion, heat transfer and conductivity, latent heat, thermal fatigue ++
Electrical: resistivity, conductivity, relative capacity and
CORROSION RESISTANCE ALSO CHEMICAL
Chemical: anything on periodic table, anything pH, valency
Magnetic: idk any of these words. Steel is magnetic concrete isn’t this is useful
Optic: useful for tests -> colour, diffraction and luminescence
Technological : hardness weldability (steel) formability castability (concrete)
What are the types of inter atomic bonds under mechanical strain?
- neutral relaxed or strain-free position
- in tension, atoms are further apart and material gets longer
- in compression, atoms closer together and material shortens
How does electron placement affect variation?
When electrons aren’t perfectly placed, there is higher variability in the material. Eg. Wood has high variability therefore not ideal for construction even though it is very strong.
What are some characteristics of ionic bonds?
They are the strongest bonds. They don’t allow for heat and electricity conduction. Ionic compounds are generally crystalline and highly soluble in water. Because of strong electrostatic force they are rigid with high melting and boiling points. Transfer of electrons!
What are some characteristics of covalent bonds?
Sharing creates attraction. Overlapping electron orbitals lower electron energy. They are local and directional. Insoluble in water and good insulators.
What are some characteristics of metallic bonds?
Similar to covalent. Valence electrons aren’t bound so are free to move throughout the metal. Reason why metals are good conductors. Delocalized and non-directional bonds.
What are some characteristics of van der waals bonds?
Weak secondary bonds that are formed when molecules undergo polarization
