Causes and Prevention of Material Failure

What is the primary chemical reaction involved in iron corrosion?

• Formation of iron chloride

• Formation of iron oxide

• Formation of iron sulfide

• Formation of iron nitrate

What happens when a local anodic or cathodic point forms a corrosion cell in the surrounding surface?

• Uniform corrosion

• Pitting corrosion

• Galvanic corrosion

• Crevice corrosion

What can cause pitting corrosion by damaging or breaking the oxide film or protective coating?

• Chloride ions

• Oxygen

• Hydrogen

• Nitrogen

What is galvanic corrosion?

• Corrosion that occurs when a single metal is exposed to air

• Corrosion that occurs when two different metals are immersed in a common electrolyte

• Corrosion that occurs due to high temperatures

• Corrosion that occurs in the absence of moisture

Which of the following is an example of an electrolyte?

• Pure water

• Salt water

• Dry air

• Sand

What is the effect of galvanic corrosion on the cathode?

• It corrodes faster

• It remains protected

• It becomes more active

• It changes color

Which of the following is NOT a factor in galvanic corrosion?

• Type of metals

• Presence of an electrolyte

• Temperature of the environment

• Electrical contact between metals

What causes intergranular corrosion (IGC)?

• Presence of impurities at the grain boundaries

• High temperature exposure

• Mechanical stress

• Lack of oxygen

What can cause the enrichment or depletion of an alloying element at the grain boundaries?

• Mechanical polishing

• Chemical reactions

• Heat treatment

• Impurities

How is chemical corrosion characterized?

• Formation of rust

• Oxidation of a metal with an acid to form oxides

• Melting of metal

• Freezing of metal