Material science

star goldstar goldstar goldstar goldstar greyFemaleMale
34 Questions - Developed by: Gustav Söderkvist - Developed on: - 1.334 taken

  • 1
    Diffusion involves:
    Migration of species to reduce differences in concentration.
    A mechanism which causes differences in concentration.
    Crack growth during fatigue.
    A mechanism which causes thermal expansion of the material during heating.
  • 2
    When Prince Ruperts drops fracture:
    The drops bounce back because these droplets do not break.
    They shatter into many pieces because of a lot of stored energy.
    The fracture only occurs in the thinnest section.
    The fracture starts from the thickest section because it is brittle.
  • 3
    The glass used in mobile phones is treated:
    In a molten salt bath at high temperature to put the surfaces in compression.
    With a special coating to allow the electric signals to pass through.
    With special amorphous layers in order to reduce the reflectivity of the screen.
    By gluing a polymer coating on one side to avoid scratching.
  • 4
    Which statement is correct?
    Mechanical forming is the main processing method for ceramics.
    Impact toughness of ceramics is high.
    Ceramics are normally very ductile.
    Ceramics are strongly bonded.
  • 5
    Is a heat treatment process to reduce toughness.
    Is a process used to assemble composites.
    Is a heat treatment process to improve ductility.
    Is a heat treatment process to make polymers stronger.
  • 6
    Aluminium cans are produced by:
    Deep drawing
  • 7
    If a material is deformed plastically, the yield stress will:
    None of the above, the material will break
    Not change
  • 8
    The ability of a material to absorb energy in the plastic range is called:
    Fatigue strength
  • 9
    Most commercial glasses consist of:
  • 10
    Elastic deformation:
    Is determined by the stiffness of the bonds.
    Occurs by movement of dislocations.
    Does not occur in ceramics because they are brittle.
    Increases with decreasing yield strength.
  • 11
    Which statement is correct?
    Upon impact, the materials toughness has to be overcome before plastic deformation and fracture begins.
    Ductility is the ability to deform plastically.
    Both ductility and strength determine the fatigue strength of a material.
    Toughness is a measure of the load a material can withstand.
  • 12
    The glass transition temperature is the temperature where:
    The refractory index of glass is changed.
    A polymer is changed from a rubbery to a rigid state.
    Glass changes from solid to liquid and is therefore critical for the processing of glassware.
    Some eyeglasses can change from dark to normal.
  • 13
    The wheels for Koenigsegg cars are made from:
    Mg alloys
    Al alloys
    CFRP (carbon-fiber)
  • 14
    Fracture toughness determines:
    The critical crack size when fracture will occur.
    The combination of critical stress and crack size.
    The critical stress when fracture will occur.
    None of the above.
  • 15
    Brittle fracture is more dangerous than ductile fracture because:
    No warning sign
    Crack propagates at very high speeds
    No need for extra stress during crack propagation
  • 16
    What is correct about atomic bondings?
    Bonds with strong ionic character develops between atoms with hogh electronegativity.
    A fully ionic character of a bond (100% ionic) can only develop between two metals.
    At equilibrium the potential energy of the bond is zero and the net force is equal to the stiffness of the bond.
    Atoms with covalent bonds share electrons.
  • 17
    The following influences deterioration of polymers:
  • 18
    Creep is:
    Deformation at increasing deformation rate at low temperature.
    Deformation at constant temperature and constant deformation rate.
    Deformation at elevated temperatures at constant load.
    Deformation at elevated temperature at increasing load.
  • 19
    Magnesium is currently receiving enormous interest for development and use in automotive components. One challenge with magnesium is the limitation in creep strength for "under bonnet" applications.
    This is because:
    Magnesium burns readily in air/oxygen.
    Magnesium often contains internal cracks and flaws above a critical size, reducing the stress required for failure.
    Magnesium has a hexagonal crystal structure which is unstable at higher temperature.
    Magnesium undergoes significant time-dependent deformation when subjected to a constant load at moderate temperatures.
  • 20
    Which statement is correct?
    Pure metals are always stronger than alloys.
    Strength increased when the distance between particles is reduced.
    Particles do not affect the strength of a material.
    Strength is increased when the dislocation density is reduced.
  • 21
    According to Hooke's law, if you hang by a tree branch and note how much it bends, then hanging with twice the weight produces:
    The same bend if the branch doesn't break
    4 times the bend
    Half the bend
    Twice the bend
  • 22
    A crystal point defect known as a substitutional occurs when:
    The atom occupies a position in the crystal structure not normally occupies by an atom.
    Two atoms are coincident.
    The atom leaves vacant the position it would normally occupy.
    Another sort of atom occupies a position that is normally occupied by an atom of a given crystal structure.
  • 23
    The structure and characteristics of a polymer is determined by:
    The arrangement of the molecules
    Molecular weight
    The shape of the molecules
    All of these together
  • 24
    When you bend a tree branch by hanging on its end, the top side of the branch is under:
    Neither tension or compression
    Both in tension and compression
  • 25
    Tungsten is stiffer than Copper and Copper is stiffer than Lead. (Tungsten has a higher Young's modulus than Copper and Copper has a higher Young's modulus than Lead).
    What statement is correct?
    Tungsten, Copper and Lead are all metals and therefore have the same thermal expansion.
    Lead has a lower thermal expansion than Copper.
    Tungsten has a lower thermal expansion than Copper.
    Copper has a higher melting point than Tungsten.
  • 26
    The crystal plane in the figure has Miller indices:
    The crystal plane in the figure has Miller indices:
  • 27
    Toilets are made by:
    Glass blowing
    Slip casting
    3D printing
  • 28
    Mechanical forming operations are often conducted at elevated temperature because:
    It prevents friction between the metal and the tool during forming by increasing the temperature in the metal and the tool.
    Metals are softer at higher temperatures.
    The products that are formed at higher temperature are stronger than those formed at low temperature.
    Alloys fracture if they are formed at room temperature,
  • 29
    The tensile strength is the point where:
    None of the above
    The material fractures
    Dislocations start to move
    Necking begins
  • 30
    Ductility of a metal can be increased by:
    Heat treatment
    Increasing the amount of work hardening
    Adding ceramic fibres (ie. making a fibre-reinforced composite)
    None of the above
  • 31
    If the surface crack causing fracture in a brittle material is made twice as deep, the fracture strength will:
    Decrease by a factor of 2
    Decrease by a factor of √2
    Not change
    Decrease by a factor of 4
  • 32
    Ceramics are:
    Covalently bonded
    Generally brittle because of limited slip systems for dislocation motion
    Always non-crystalline compounds between non-metallic and metallic elements.
    Often manufactured into components by extrusion
  • 33
    The common way to protect nails from corrosion is:
    Anodise it
    Galvanise it
    Paint it
    Do nothing - aluminium doesn't corrode
  • 34
    In which of the following applications is fatigue a critical design parameter?
    A plane
    A cup
    A lap-top computer
    A liquid nitrogen containment vessel

Comments page 0 of 0
Click here to add a comment
There are currently 0 comments to display.