Materials Science and Engineering

Question 1

Definition of Engineering Materials

Answer 1

Engineering Materials are defined as that part of the inanimate matter which is useful to the engineer in the practice of his profession

Question 2

Definition of Materials Science

Answer 2

Materials Science refers to the knowledge of physical sciences arranged as general truth and principle, in particular physics and chemistry

Question 3

What are the four broad groups of engineering materials?

Answer 3

1. Metals and Alloys
2. Ceramics and Glasses
3. Organic Polymers
4. Composites

Question 4

Define Metals and Alloys and give 3 examples

Answer 4

– Metals: characteristic appearance * Capable of changing their shape permanently * Good thermal and electrical conductivity * Reflectivity of light

– Alloys: combination of more than one metal –

Examples: iron, steel, aluminum, copper, silver, gold, brass, bronze, manganese, lead, titanium

Question 5

Define Ceramics and Glasses and give 3 examples

Answer 5

– Made from a combination of elements from both the metals and nonmetals portions of the periodic table – Nonmetallic inorganic substances – Brittle – Good thermal and electrical insulating properties – Examples: bricks, tiles, silica, soda-lime-glass, ferrites and garnets, graphite,

Question 6

Define Organic Polymers and give 3 examples

Answer 6

– Composed of large number of molecules, joined together
in a chain-like fashion
– Majority of engineering polymers are based on
hydrocarbons (molecules that consist of hydrogen and
carbon atoms in various structural arrangements)
– Polymeric engineering materials consist of a large
number of synthetic plastics in addition to many natural
polymers such as wood and rubber
– Relatively inert and light
– High degree of plasticity (deformability)
– Good compatibility with human tissue
– Resist atmospheric and other types of corrosion
– Resistance to electrical current
– Examples: PVC, PVA, polyethylene, epoxy, vinyl ester,
nylon, cotton, leather, aramid

Question 7

Define Composites and give 3 examples

Answer 7

– Combinations of other materials
– This class of engineering materials illustrates that
although many dissimilarities may exist between
different materials, they frequently can be utilized in
conjunction to produce a material with unique properties
and behaviour
– Composites have rapidly become a separate,
recognized class of engineering materials
– Examples: concrete, fibre reinforced polymers (GFRP)

Question 8

What are the three areas of implementation?

Answer 8

Structural, machines and devices

Question 9

Describe structural

Answer 9

• Objects without moving parts
  – Examples: bridges, dams, steel melting furnaces,
  nuclear containment facilities

Question 10

Describe machines

Answer 10

• Involve major parts
  – Examples: lathes, jet engines, electric motors,
  generators

Question 11

Describe devices

Answer 11

• Engineering innovations
  – Examples: transistors, photoelectric cells, ceramic
  magnets, lasers

Question 12

What are the material properties and give 2 examples

Answer 12

Physical: shape, size, finish, color, specific gravity, density,
porosity, structure
* Mechanical: strength, stiffness, elasticity, plasticity, ductility,
creep, brittleness, hardness, toughness, resilience, impact
resistance, fatigue behaviour
* Thermal: specific heat, heat of transformation, thermal
capacity, thermal expansion, heat transfer and thermal
conductivity, thermal stresses, thermal fatigue, thermal shock
capacity, latent heat of fusion
Electrical: resistivity, conductivity, relative capacity or
dielectric constant, dielectric strength, semi-conductivity,
superconductivity, corrosion resistance*
* Chemical: corrosion resistance*, atomic weight, valency,
molecular weight, acidity, alkalinity, atomic number
* Magnetic: hysteresis, reductivity, retentivity, susceptibility,
residual inductance, saturation value