SENIOR CORROSION TECHNOLOGIST EXAM
2026 FINAL EXAM PAPER COMPLETE
QUESTIONS AND SOLUTIONS
◉ Under what circumstances may crevice corrosion occur? Answer:
Metal to metal crevices
metal to nonmetal crevices
under deposits of debris of corrosion products
◉ metal ion or oxygen concentration cell corrosion can occur in
both____ Answer: Metal to metal crevices
and metal to nonmetal crevices
◉ Crevice corrosion occurs most commonly on passive film
protected metals such as? Answer: Aluminum and Al alloys
stainless steels and Ni based alloys
Titanium and Ti alloys
zirconium and Zi alloys
copper alloys
◉ Methods to control crevice corrosion are: Answer: Material
selection
,design
CP
◉ What are the design methods used to control crevice corrosion?
Answer: Using butt-welded joints instead of lap-welded or bolted
joints
sealing of lap joints where they can't be avoided
avoiding skip welds
providing complete drainage
avoiding materials that can hold moisture in contact with the
substrate
providing surface that can be kept clean easily and kept free of
debris
◉ What is the definition of filiform corrosion? Answer: A special
form of oxygen cell corrosion occurring beneath organic or metallic
coatings on materials
◉ What is the mechanism of filiform corrosion? Answer: It is driven
by the potential difference between the advancing head of the attack
and the area behind the head of the advancing attack.
◉ Filiform corrosion can occur under semipermeable coatings on
what metals and alloys? Answer: Steel, Zinc, Aluminum, and
,magnesium alloys exposed to a humidity greater than 60% relative
humidity
◉ how do you control filiform corrosion? Answer: Proper cleaning
and preparation of the metallic surface, and then applying the
coating only to a thoroughly cleaned and dried surface
◉ Galvanic corrosion Answer: A form of corrosion which occurs
because of the potential difference between metals.
◉ What affects galvanic corrosion rates? Answer: Potential
difference between the metals or alloys
Specific nature of the environment
polarization behavior of the coupled metals
spatial affects, such as area, distance, and cell geometry
resistivity of the electrolyte
◉ In galvanic corrosion the more active metal becomes the anode or
cathode? Answer: Anode
◉ In galvanic corrosion the less active metal becomes the anode or
cathode? Answer: Cathode
, ◉ What are electrode potentials sensitive to? Answer: Electrode
composition
electrolyte composition
temp
degree of agitation
presence of depolarizers, inhibitors, or both
surface condition of electrodes
metallurgical condition of the electrodes
◉ What two environmental ways can galvanic corrosion occur?
Answer: Either immersion or atmospheric
◉ If neither the anode nor cathode polarizes significantly what
happens? Answer: The amount of current flow will be large, and the
resulting galvanic corrosion will also be large.
◉ how can you estimate the performance of specific metals and
alloys in galvanic corrosion? Answer: Their position on the galvanic
series
◉ What ways can be used to control galvanic attack? Answer: Design
material selection
electrical isolation
2026 FINAL EXAM PAPER COMPLETE
QUESTIONS AND SOLUTIONS
◉ Under what circumstances may crevice corrosion occur? Answer:
Metal to metal crevices
metal to nonmetal crevices
under deposits of debris of corrosion products
◉ metal ion or oxygen concentration cell corrosion can occur in
both____ Answer: Metal to metal crevices
and metal to nonmetal crevices
◉ Crevice corrosion occurs most commonly on passive film
protected metals such as? Answer: Aluminum and Al alloys
stainless steels and Ni based alloys
Titanium and Ti alloys
zirconium and Zi alloys
copper alloys
◉ Methods to control crevice corrosion are: Answer: Material
selection
,design
CP
◉ What are the design methods used to control crevice corrosion?
Answer: Using butt-welded joints instead of lap-welded or bolted
joints
sealing of lap joints where they can't be avoided
avoiding skip welds
providing complete drainage
avoiding materials that can hold moisture in contact with the
substrate
providing surface that can be kept clean easily and kept free of
debris
◉ What is the definition of filiform corrosion? Answer: A special
form of oxygen cell corrosion occurring beneath organic or metallic
coatings on materials
◉ What is the mechanism of filiform corrosion? Answer: It is driven
by the potential difference between the advancing head of the attack
and the area behind the head of the advancing attack.
◉ Filiform corrosion can occur under semipermeable coatings on
what metals and alloys? Answer: Steel, Zinc, Aluminum, and
,magnesium alloys exposed to a humidity greater than 60% relative
humidity
◉ how do you control filiform corrosion? Answer: Proper cleaning
and preparation of the metallic surface, and then applying the
coating only to a thoroughly cleaned and dried surface
◉ Galvanic corrosion Answer: A form of corrosion which occurs
because of the potential difference between metals.
◉ What affects galvanic corrosion rates? Answer: Potential
difference between the metals or alloys
Specific nature of the environment
polarization behavior of the coupled metals
spatial affects, such as area, distance, and cell geometry
resistivity of the electrolyte
◉ In galvanic corrosion the more active metal becomes the anode or
cathode? Answer: Anode
◉ In galvanic corrosion the less active metal becomes the anode or
cathode? Answer: Cathode
, ◉ What are electrode potentials sensitive to? Answer: Electrode
composition
electrolyte composition
temp
degree of agitation
presence of depolarizers, inhibitors, or both
surface condition of electrodes
metallurgical condition of the electrodes
◉ What two environmental ways can galvanic corrosion occur?
Answer: Either immersion or atmospheric
◉ If neither the anode nor cathode polarizes significantly what
happens? Answer: The amount of current flow will be large, and the
resulting galvanic corrosion will also be large.
◉ how can you estimate the performance of specific metals and
alloys in galvanic corrosion? Answer: Their position on the galvanic
series
◉ What ways can be used to control galvanic attack? Answer: Design
material selection
electrical isolation
