Podcast
Questions and Answers
What is a primary characteristic of dry or chemical corrosion?
What is a primary characteristic of dry or chemical corrosion?
- Occurs primarily in the presence of moisture
- Only affects metallic surfaces in liquids
- Is solely caused by temperature fluctuations
- Involves the direct attack of atmospheric gases (correct)
Which type of corrosion results from the direct action of oxygen on a metal surface without moisture?
Which type of corrosion results from the direct action of oxygen on a metal surface without moisture?
- Corrosion by halogens
- Wet corrosion
- Oxidation corrosion (correct)
- Liquid metal corrosion
What is a significant financial impact attributed to corrosion worldwide?
What is a significant financial impact attributed to corrosion worldwide?
- $5 billion per annum
- $2 to $2.5 billion per annum (correct)
- $1 billion per annum
- $10 billion per annum
What phenomenon converts metal into its corresponding metal oxide during oxidation corrosion?
What phenomenon converts metal into its corresponding metal oxide during oxidation corrosion?
Which of the following factors is NOT primarily associated with the losses incurred due to corrosion?
Which of the following factors is NOT primarily associated with the losses incurred due to corrosion?
What is the primary cause of corrosion?
What is the primary cause of corrosion?
Which of the following is an example of corrosion?
Which of the following is an example of corrosion?
What can be a direct consequence of localized corrosion?
What can be a direct consequence of localized corrosion?
Which type of engineering specifically addresses the issue of corrosion?
Which type of engineering specifically addresses the issue of corrosion?
Which of the following does NOT describe a consequence of corrosion?
Which of the following does NOT describe a consequence of corrosion?
What is a visible sign of copper corrosion when exposed to damp air containing CO2?
What is a visible sign of copper corrosion when exposed to damp air containing CO2?
What is a potential hazard caused by the consequences of corrosion?
What is a potential hazard caused by the consequences of corrosion?
How does corrosion impact the value of goods?
How does corrosion impact the value of goods?
What characterizes the areas of anodic and cathodic regions in the oxide film?
What characterizes the areas of anodic and cathodic regions in the oxide film?
What is formed at the anode during corrosion of iron?
What is formed at the anode during corrosion of iron?
What is the end product of the reaction between Fe2+ ions and OH- ions?
What is the end product of the reaction between Fe2+ ions and OH- ions?
Under what condition does electrochemical corrosion primarily occur?
Under what condition does electrochemical corrosion primarily occur?
What happens to ferrous hydroxide (Fe(OH)2) if sufficient oxygen is available?
What happens to ferrous hydroxide (Fe(OH)2) if sufficient oxygen is available?
Which type of corrosion requires moisture to be present?
Which type of corrosion requires moisture to be present?
What is the main difference between chemical and electrochemical corrosion?
What is the main difference between chemical and electrochemical corrosion?
What is the final product when ferrous hydroxide is fully oxidized?
What is the final product when ferrous hydroxide is fully oxidized?
What is the primary driving force behind galvanic corrosion?
What is the primary driving force behind galvanic corrosion?
Which combination of conditions is necessary for galvanic corrosion to occur?
Which combination of conditions is necessary for galvanic corrosion to occur?
When zinc and copper are connected, which metal acts as the anode in galvanic corrosion?
When zinc and copper are connected, which metal acts as the anode in galvanic corrosion?
What happens if there is a plastic washer between two metals in a galvanic corrosion scenario?
What happens if there is a plastic washer between two metals in a galvanic corrosion scenario?
In a galvanic series, the term 'electrode potential' refers to which of the following?
In a galvanic series, the term 'electrode potential' refers to which of the following?
Which of the following is not a condition required for galvanic corrosion?
Which of the following is not a condition required for galvanic corrosion?
Which example best illustrates galvanic corrosion?
Which example best illustrates galvanic corrosion?
What effect does moisture have in the context of galvanic corrosion?
What effect does moisture have in the context of galvanic corrosion?
What characterizes pitting corrosion?
What characterizes pitting corrosion?
In the context of waterline corrosion, which area of the metal is most anodic?
In the context of waterline corrosion, which area of the metal is most anodic?
Which metals are more susceptible to corrosion due to their position in the galvanic series?
Which metals are more susceptible to corrosion due to their position in the galvanic series?
What primarily causes differential aeration corrosion in submerged metals?
What primarily causes differential aeration corrosion in submerged metals?
What happens to the protective film on a metal surface that leads to pitting corrosion?
What happens to the protective film on a metal surface that leads to pitting corrosion?
Which type of environment increases the risk of pitting corrosion?
Which type of environment increases the risk of pitting corrosion?
What is the effect of increasing reduction potential on a metal's tendency to corrode?
What is the effect of increasing reduction potential on a metal's tendency to corrode?
Which of the following metals is considered a noble metal with high reduction potential?
Which of the following metals is considered a noble metal with high reduction potential?
Study Notes
Definition of Corrosion
- Corrosion is the deterioration and destruction of materials caused by environmental reactions, usually starting at the surface.
- It converts refined metals into stable forms such as oxides, hydroxides, or sulfides.
- Corrosion engineering focuses on prevention and control strategies.
Examples of Corrosion
- Rusting of iron results in the formation of reddish Fe3O4 powder.
- Copper exposed to moist air with CO2 develops a green film of basic carbonate [CuCO3 + Cu(OH)2].
Consequences of Corrosion
- Reduction in metal thickness can lead to structural failures.
- Localized metal loss can create crack-like structures, severely weakening materials.
- Structural failures pose hazards to public safety, affecting bridges, vehicles, and aircraft.
- Time lost and increased costs in maintaining industrial equipment due to corrosion.
- Aesthetic deterioration reduces the value of goods.
- Corrosion can cause contamination of fluids, prompting safety and health concerns.
- Pipe perforation can lead to environmental contamination and costly damages.
- Loss of important surface properties affects functionality and performance of components.
- Estimated global annual losses due to corrosion range between 2to2 to 2to2.5 billion.
Types of Corrosion
Dry or Chemical Corrosion
- Occurs due to direct atmospheric gas attacks in the absence of moisture.
- Involves gases like oxygen, halogens, and sulfur oxides.
Oxidation Corrosion
- Direct interaction of oxygen with metal surfaces leads to metal oxide formation through chemisorption.
Electrochemical Corrosion
- Takes place in wet conditions, involving electrolytes.
Galvanic or Bimetallic Corrosion
- Occurs when dissimilar metals in contact undergo corrosion due to differences in their electrochemical series.
- Example: Zinc acts as an anode when connected to copper, often used in pipelines, marine hardware, etc.
Requirements for Galvanic Corrosion
- Presence of two metals with differing corrosion potentials.
- Direct metal-to-metal electrical contact.
- A conductive electrolyte must bridge the two metals to facilitate corrosion.
Pitting Corrosion
- Characterized by local, intense attacks leading to pinholes and cavities.
- Often results from protective film breakdown due to mechanical wear or environmental stress.
Waterline Corrosion
- Significant corrosion occurs beneath the waterline due to differential aeration; areas above are well-oxygenated and act as cathodes while submerged areas become anodic.
Factors Influencing Corrosion
- Metals with low reduction potentials are more reactive and susceptible to corrosion (e.g., Li, Na, Mg, Zn).
- Noble metals, such as Ag, Au, and Pt, have high reduction potentials, making them less prone to corrosion.
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Description
This quiz explores the causes, examples, and consequences of corrosion, an important topic in materials engineering. Learn how corrosion affects various metals and the strategies used for its prevention and control. Test your knowledge on the ramifications of metal deterioration on safety and structural integrity.
