Corrosion Flashcards
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Questions and Answers

Fayed surfaces cause concern in chemical cleaning because of the danger of?

entrapping corrosive materials.

Caustic cleaning products used on aluminum structures have the effect of producing?

corrosion.

Fretting corrosion is most likely to occur?

when two surfaces fit tightly together but can move relative to one another.

The rust or corrosion that occurs with most metals is the result of?

<p>a tendency for them to return to their natural state.</p> Signup and view all the answers

Which of the following are the desired effects of using Alodine on aluminum alloy?

<p>Increased corrosion resistance</p> Signup and view all the answers

Which of the listed conditions is NOT one of the requirements for corrosion to occur?

<p>The presence of a passive oxide film.</p> Signup and view all the answers

The lifting or flaking of the metal at the surface due to delamination of grain boundaries caused by the pressure of corrosion residual product buildup is called?

<p>exfoliation.</p> Signup and view all the answers

A nonelectrolytic chemical treatment for aluminum alloys to increase corrosion resistance and paint-bonding qualities is called?

<p>alodizing.</p> Signup and view all the answers

Which of the following are acceptable to use in cleaning anodized surfaces?

<p>Aluminum wool and fiber bristle brush.</p> Signup and view all the answers

Intergranular corrosion in aluminum alloy parts?

<p>cannot always be detected by surface indications.</p> Signup and view all the answers

Which of the following may not be detectable even by careful visual inspection of the surface of aluminum alloy parts or structures?

<p>Intergranular corrosion.</p> Signup and view all the answers

What may be used to remove corrosion from highly stressed steel surfaces?

<p>Fine-grit aluminum oxide.</p> Signup and view all the answers

A primary cause of intergranular corrosion is?

<p>improper heat treatment.</p> Signup and view all the answers

Corrosion should be removed from magnesium parts with?

<p>stiff, nonmetallic brush.</p> Signup and view all the answers

Why is it important not to rotate the crankshaft after the corrosion preventative mixture has been put into the cylinders on engines prepared for storage?

<p>The seal of corrosion preventative mixture will be broken.</p> Signup and view all the answers

Which of the following is an acceptable first step procedure to help prevent scratching when cleaning a transparent plastic surface?

<p>Flush the surface with clean water.</p> Signup and view all the answers

What should be done to prevent rapid deterioration when oil or grease come in contact with a tire?

<p>Wipe the tire with a dry cloth followed by a washdown and rinse with soap and water.</p> Signup and view all the answers

Galvanic corrosion is likely to be most rapid and severe when?

<p>the surface area of the anodic metal is smaller than the surface area of the cathodic metal.</p> Signup and view all the answers

Corrosion caused by galvanic action is the result of?

<p>contact between two unlike metals.</p> Signup and view all the answers

Which of these materials is the most anodic?

<p>Magnesium</p> Signup and view all the answers

The interior surface of sealed structural steel tubing would be best protected against corrosion by which of the following?

<p>A coating of linseed oil.</p> Signup and view all the answers

Which of these materials is the most cathodic?

<p>Stainless Steel</p> Signup and view all the answers

Of the following, when and/or where is galvanic corrosion most likely to occur?

<p>At the interface of a steel fastener and aluminum alloy inspection plate in the presence of an electrolyte.</p> Signup and view all the answers

One way of obtaining increased resistance to stress corrosion cracking is by?

<p>creating compressive stresses (via shot peening) on the metal surface.</p> Signup and view all the answers

In the corrosion process, which statement is true?

<p>Only No. 2 is true.</p> Signup and view all the answers

Spilled mercury on aluminum?

<p>causes rapid and severe corrosion that is very difficult to control.</p> Signup and view all the answers

Study Notes

Corrosion Fundamentals

  • Fayed surfaces pose a risk in chemical cleaning due to potential entrapment of corrosive materials.
  • Caustic cleaners on aluminum can generate corrosion, leading to material deterioration.
  • Fretting corrosion occurs between tightly fitting surfaces that have relative movement.

Metal Corrosion Types

  • Most metal corrosion stems from a natural tendency to revert to the original state.
  • Desired effects of Alodine treatment on aluminum include a slightly rough surface and improved corrosion resistance.
  • Conditions for corrosion exclude the presence of a passive oxide film, which acts as a protective barrier.

Corrosion Mechanisms

  • Exfoliation refers to the lifting or flaking of metal surfaces due to delamination at grain boundaries from corrosion product buildup.
  • Alodizing is a nonelectrolytic chemical process improving aluminum alloys' corrosion resistance and paint adhesion.

Surface Cleaning and Inspection

  • Acceptable cleaning methods for anodized surfaces include aluminum wool and fiber bristle brushes.
  • Intergranular corrosion in aluminum alloys may not be visible through surface inspection, making detection challenging.

Treatment and Protection Measures

  • Fine-grit aluminum oxide is effective for removing corrosion on highly stressed steel surfaces.
  • Improper heat treatment is a primary catalyst for intergranular corrosion in aluminum alloy components.
  • Magnesium parts should be cleaned with a stiff, nonmetallic brush to avoid further corrosion damage.

Mechanical Components Care

  • Preventive mixtures for corrosion on engine crankshafts should not be rotated post-application to maintain sealing integrity.
  • To protect tires from rapid deterioration due to oil or grease, clean with a dry cloth followed by soap and water rinsing.

Galvanic Corrosion Insights

  • Galvanic corrosion is aggravated when the anodic metal’s surface area is smaller than the cathodic metal’s.
  • Occurs due to contact between dissimilar metals, leading to accelerated deterioration.
  • Magnesium is identified as the most anodic material, while stainless steel ranks as the most cathodic.

Interfaces and Stress Management

  • Galvanic corrosion frequently arises at the junction of steel fasteners and aluminum under electrolytic conditions.
  • Mitigating stress corrosion cracking can be achieved by inducing compressive stresses through techniques like shot peening.

True/False Assessments on Corrosion

  • In the context of corrosion processes, only the second statement regarding the electrochemical series is accurate, as it states the most anodic metals readily yield electrons.
  • Spilled mercury on aluminum leads to rapid, severe corrosion, presenting a management challenge.

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Test your knowledge on various aspects of corrosion with these flashcards. Each card covers key concepts, including causes, effects, and types of corrosion in different materials. Perfect for students and professionals alike looking to deepen their understanding of corrosion.

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