Classification of Materials
Materials with conductivity between metals and insulators are called…
A) Elastomers
B) Refractories
C) Composites
D) Semiconductors
Semiconductors
(D)
Cast iron differs from steel mainly because it has…
A) Less than 0.1% carbon
B) About 2–4% carbon
C) No iron
D) Mostly chromium
B) About 2–4% carbon
Young's modulus measures a material's…
A) Hardness
B) Elastic stiffness
C) Toughness
D) Melting point
B) Elastic stiffness
High-speed machining cutting inserts are commonly made of…
A) Brass
B) Cast iron
C) Polycarbonate
D) Cemented tungsten carbide
D) Cemented tungsten carbide
Annealing a metal means…
A) Heating and slow cooling to soften it and relieve stress
B) Quenching it in water
C) Adding sulfur
D) Coating it with zinc
A) Heating and slow cooling to soften it and relieve stress
Which pair contains only ceramics?
A) Nylon and Teflon
B) Brass and bronze
C) Zirconia and silicon nitride
D) Epoxy and Kevlar
C) Zirconia and silicon nitride
The main alloying element in duralumin (a strong aluminium alloy) is…
A) Copper
B) Zinc
C) Tin
D) Lead
A) Copper
Toughness is best defined as…
A) Resistance to scratching
B) Stiffness
C) Energy absorbed before fracture
D) Density
C) Energy absorbed before fracture
In a hip implant, the cup liner is often made of…
A) Ultra-high-molecular-weight polyethylene
B) Soda-lime glass
C) Brass
D) Cast iron
A) Ultra-high-molecular-weight polyethylene
Sintering is…
A) Pouring molten metal
B) Weaving fibers
C) Cutting a crystal
D) Heating compacted powder below its melting point so particles bond
D) Heating compacted powder below its melting point so particles bond
Concrete is best classified as a…
A) Pure ceramic crystal
B) Thermoset polymer
C) Particulate composite
D) Metallic alloy
C) Particulate composite
Borosilicate glass (Pyrex) resists thermal shock thanks to added…
A) Lead oxide
B) Soda
C) Boron oxide
D) Iron
C) Boron oxide
Creep is…
A) Slow time-dependent deformation under constant load, often at high temperature
B) Sudden fracture
C) Corrosion in seawater
D) Loss of magnetism
A) Slow time-dependent deformation under constant load, often at high temperature
For a light, stiff beam, which property ratio matters most?
A) Strength / cost
B) Hardness / density
C) Specific stiffness (modulus / density)
D) Melting point / modulus
C) Specific stiffness (modulus / density)
Increasing the crystallinity of a polymer generally…
A) Lowers density
B) Makes it transparent
C) Increases density and strength
D) Turns it into a thermoset
C) Increases density and strength
Why are ceramics usually much harder than polymers?
A) Strong ionic/covalent bonds, versus weak bonds between polymer chains
B) They contain free electrons
C) They are always crystalline metals
D) They have longer chains
A) Strong ionic/covalent bonds, versus weak bonds between polymer chains
Type 304 stainless steel typically contains about…
A) 18% Cr and 8% Ni
B) 5% Cr and 20% Ni
C) 18% Cu and 8% Zn
D) 30% C and 2% Cr
A) 18% Cr and 8% Ni
Below its glass transition temperature (Tg), a polymer becomes…
A) Rubbery
B) Liquid
C) Soft
D) Rigid and glassy
D) Rigid and glassy
A ship propeller in seawater needs corrosion and cavitation resistance. Choose…
A) Plain carbon steel
B) Nickel-aluminium bronze
C) Pure aluminium
D) Polyethylene
B) Nickel-aluminium bronze
Reducing grain size in a metal generally…
A) Lowers yield strength
B) Makes it amorphous
C) Raises yield strength (Hall–Petch)
D) Removes carbon
C) Raises yield strength (Hall–Petch)
Glass-ceramics differ from ordinary glass because they contain…
A) No silica
B) A controlled crystalline phase
C) Polymer fibers
D) Free electrons
B) A controlled crystalline phase
Nylon 6,6 is made from…
A) Ethylene
B) Styrene and butadiene
C) Phenol and formaldehyde
D) Hexamethylenediamine and adipic acid
D) Hexamethylenediamine and adipic acid
Which statement about the ductile-to-brittle transition is correct?
A) Copper becomes brittle in liquid nitrogen
B) BCC steels can become brittle at low temperature
C) Glass becomes ductile when cold
D) Aluminium shatters at 0 °C
B) BCC steels can become brittle at low temperature
A tank for liquid nitrogen (−196 °C) should use…
A) Ferritic carbon steel
B) Austenitic stainless steel
C) PVC
D) Cast iron
B) Austenitic stainless steel
Precipitation hardening strengthens an alloy because
A) It removes all carbon
B) Fine particles block dislocation movement
C) It makes the alloy amorphous
D) It lowers the density
B) Fine particles block dislocation movement