core 4 - p1 Flashcards
(20 cards)
What are the four main categories of materials?
Metals, Non-Metals, Composites, and Smart Materials.
List five general properties of metals.
High melting points, good conductors of electricity and heat, high density, malleable, ductile.
How do the atomic structures of pure metals differ from alloys?
Pure metals have a regular crystal lattice with layers that slide easily, making them soft. Alloys have distorted layers due to mixed atoms, making them harder and stronger.
Why are alloys often preferred over pure metals in engineering?
Pure metals are low in strength and too ductile/malleable. Alloys improve strength and hardness through controlled additions of other elements.
What distinguishes ferrous metals from non-ferrous metals?
Ferrous metals contain iron (e.g., steel, cast iron) and are magnetic, prone to corrosion. Non-ferrous metals lack iron (e.g., aluminum, copper), are non-magnetic, and corrosion-resistant.
Name three types of iron and their key characteristics.
Pig iron: Impure, from blast furnaces.
Cast iron: Re-melted pig iron, brittle with high carbon (2-6%).
Wrought iron: Refined with slag, fibrous and ductile.
What chemical reactions occur in a blast furnace during iron extraction?
- CO 2 + C → 2CO
- C + O 2 → CO 2
- 3CO+Fe 2 O 3 → 2Fe + 3CO 2
- CaCO 3 → CaO + CO 2 , then CaO + SiO 2 → CaSiO 3 (slag).
What are three common forms of metal supply?
Square bar, round bar, sheet steel, I-beam, hollow square (any three).
How does carbon content affect steel properties?
-Mild steel (≤0.3% C): Ductile, used in construction.
-Medium carbon (0.3-0.6% C): Stronger, for gears.
-High carbon (>0.6% C): Hard but brittle, for cutting tools.
What impurities weaken steel, and how are they countered?
Sulfur and phosphorus. Countered by adding alloys like manganese.
omplete the table for ferrous alloys:
Ferrous Alloy Composition Applications
Low carbon steel 0.1-0.3% C, 99.7-99.9% Fe Wire, girders, nuts/bolts
Stainless steel Fe, Cr, Ni Kitchen equipment, medical tools
Cast iron 2-6% C, 94-98% Fe Machine bases, pipes
Define tensile strength and compressive strength.
-Tensile: Maximum stress a material withstands while being stretched.
-Compressive: Maximum stress a material withstands under crushing loads.
What is the difference between elasticity and plasticity?
Elasticity allows a material to return to its original shape after deformation. Plasticity causes permanent deformation beyond the yield point.
How is hardness measured? Name three tests.
Brinell, Rockwell, and Vickers tests. They measure resistance to indentation.
What does the Charpy impact test measure?
A material’s toughness (energy absorbed during fracture) using a notched specimen struck by a pendulum.
Distinguish between thermoplastics and thermosets.
Thermoplastics: Soften when heated, recyclable (e.g., PVC).
Thermosets: Harden permanently when cured, non-recyclable (e.g., epoxy).
What is Young’s modulus?
A measure of stiffness, calculated as
Stress / Strain. Indicates resistance to elastic deformation.
What is the significance of the stress-strain curve’s yield point?
What is the significance of the stress-strain curve’s yield point?
Define corrosion resistance and two methods to enhance it.
Ability to resist degradation from oxidation. Methods: Alloying (e.g., stainless steel) or coatings (e.g., galvanizing).
What is the purpose of sintering?
To fuse powdered materials (e.g., metals, ceramics) under heat/pressure without melting, improving strength and conductivity.
