PCS PCS Corrosion Science and Prevention

Question 1

In electrochemical corrosion, what four components must be present simultaneously for the corrosion cell to function?

Accepted Answer

Anode, cathode, electrolyte, and metallic path

Answer

Oxygen, water, iron, and carbon dioxide

Answer

Primer, topcoat, substrate, and electrolyte

Answer

UV light, moisture, salt, and metal

Question 2

Which form of corrosion occurs when two dissimilar metals are in electrical contact in the presence of an electrolyte?

Accepted Answer

Galvanic corrosion

Answer

Crevice corrosion

Answer

Stress corrosion cracking

Answer

Erosion corrosion

Question 3

What type of corrosion occurs in low-oxygen areas such as lap joints, gaskets, and under deposits?

Accepted Answer

Crevice corrosion

Answer

Galvanic corrosion

Answer

Uniform corrosion

Answer

Intergranular corrosion

Question 4

Zinc-rich primers provide corrosion protection to steel primarily through which mechanism?

Accepted Answer

Cathodic (sacrificial) protection by acting as the anode

Answer

Barrier protection by sealing the surface

Answer

Passivation of the steel surface

Answer

UV absorption to prevent photodegradation

Question 5

What is the primary cause of osmotic blistering in coatings applied over steel in immersion service?

Accepted Answer

Water-soluble salts trapped under the coating film

Answer

UV degradation of the resin

Answer

Insufficient film thickness

Answer

Excessive surface roughness

Question 6

Which test method is used in the field to detect soluble salt contamination on a prepared steel surface before coating?

Accepted Answer

Bresle patch method (ISO 8502-6)

Answer

Pull-off adhesion test (ASTM D4541)

Answer

Cross-hatch tape test (ASTM D3359)

Answer

Roughness comparator (ASTM D4417)