Question

Design an experiment to test the effectiveness of nanostructured coatings to improve the corrosion resistance of metals. What would be the primary performance metric to measure?

• A. Coating hardness
• B. Corrosion rate under controlled environmental conditions
• C. Coating thickness uniformity
• D. Electrical resistance of the coating

Hint:

Performance Metrics. The metric used to evaluate effectiveness should directly measure the property being improved. For corrosion resistance, measure the corrosion rate (e.g., mass loss, penetration depth, corrosion current density).

Answer 1

The Correct Option is B

The goal is to test the effectiveness of coatings in improving *corrosion resistance*.
Therefore, the primary performance metric must directly measure how well the coating prevents or slows down corrosion of the underlying metal.
- Coating hardness (1) relates to wear or scratch resistance.
- Coating thickness uniformity (3) is an important quality factor for the coating application but not the performance metric itself.
- Electrical resistance (4) might play a role in electrochemical corrosion but isn't the direct measure of material degradation.
- Corrosion rate (2), measured under specific controlled corrosive environments (e.
g.
, salt spray, electrochemical tests like polarization resistance or Tafel extrapolation), directly quantifies the material degradation due to corrosion.
Lower corrosion rate indicates better protection by the coating.
This is the most direct and primary metric for evaluating corrosion resistance effectiveness.