Materials Engineering Flashcards
6 cards from real BE/B Eng Bachelor of Engineering practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Materials Engineering flashcards as text
What is the purpose of anodizing aluminum?
Answer: To grow a thick, hard oxide layer on the surface for improved corrosion and wear resistance
Anodizing electrochemically grows a controlled, thick aluminum oxide (Al₂O₃) layer on the aluminum surface, greatly improving corrosion resistance, hardness, and the ability to absorb dye.
What is a shape memory alloy (SMA)?
Answer: A material that returns to a pre-defined shape when heated after being deformed
SMAs (e.g., Nitinol) exploit a reversible martensitic phase transformation: deformed at low temperature, they recover their original shape when heated above the transformation temperature.
In fracture mechanics, what does the stress intensity factor (K) characterize?
Answer: The magnitude of stress at the tip of a crack in a material
The stress intensity factor K quantifies the stress field singularity at a crack tip; when K exceeds the material's fracture toughness (K_IC), unstable crack propagation occurs.
What distinguishes amorphous materials from crystalline materials?
Answer: Amorphous materials lack long-range atomic order; crystalline materials have periodic atomic arrangement
Crystalline materials (e.g., metals, most ceramics) have atoms arranged in a repeating lattice structure, while amorphous materials (e.g., glass, most polymers) have random, disordered atomic arrangement.
What is the purpose of a sacrificial anode in cathodic protection?
Answer: To corrode preferentially in place of the protected metal structure
A sacrificial anode (e.g., zinc or magnesium) is more anodic than the protected structure; it corrodes instead, supplying electrons that make the structure cathodic and immune to corrosion.
In polymer science, what is the degree of polymerization?
Answer: The number of repeating monomer units in a polymer chain
The degree of polymerization (DP) is the average number of monomer repeat units per polymer chain, directly related to molecular weight and influencing mechanical and thermal properties.