CFS Corrosion Resistance & Coatings 2

Question 1

Which coating process involves immersing fasteners in molten zinc at approximately 840°F (449°C)?

Accepted Answer

Hot-dip galvanizing

Answer

Hot-dip galvanizing immerses fasteners in molten zinc at around 840°F to form a thick, alloyed zinc-iron coating.

Question 2

Galvanic corrosion between two dissimilar metals is most severe when the metals are:

Accepted Answer

Far apart on the galvanic series

Answer

The greater the separation between two metals on the galvanic series, the higher the driving voltage and the more severe the galvanic corrosion.

Question 3

Which type of corrosion occurs in the crevice between a fastener head and the mating surface due to oxygen depletion?

Accepted Answer

Crevice corrosion

Answer

Crevice corrosion initiates in confined spaces where oxygen is depleted, creating an aggressive local environment.

Question 4

Dacromet coating is primarily used to avoid which problem associated with electroplated fasteners?

Accepted Answer

Hydrogen embrittlement

Answer

Dacromet is a water-based coating applied at low temperatures that eliminates the hydrogen embrittlement risk inherent in acid pickling and electroplating processes.

Question 5

What is the purpose of a chromate conversion coating applied after zinc electroplating?

Accepted Answer

To passivate the zinc and extend corrosion resistance

Answer

Chromate conversion coatings passivate the zinc surface, sealing microscopic pores and significantly extending corrosion resistance.

(CFS) Certified Fastener Specialist Practice Test

(CFS) Certified Fastener Specialist Practice Test

CFS Corrosion Resistance & Coatings 2