03 Corrosion of Metals and Alloys Flashcards
Uniform Corrosion
Most common form of corrosion. Characterized by a chemical or electrochemical reaction that proceeds uniformly over the entire exposed surface.
Uniform Corrosion
Represents the greatest destruction of metal on a tonnage basis.
Crevice Corrosion
Metal deterioration that happens in tight spaces where a stagnant liquid gets trapped.
Galvanic Corrosion
Exists between two dissimilar metals with potential difference in a conductive solution.
Galvanic Corrosion
One metal (the cathode) is protected, whilst the other (the anode) is corroded. The rate of attack on the anode is accelerated, compared to the rate when the metal is uncoupled.
less
Galvanic corrosion is a serious threat because it accelerates the deterioration of the ____________ resistant metal.
Pitting Corrosion
A highly localized form of attack that eats away at the metal, creating small holes or cavities.
Pitting Corrosion
One of the most destructive and insidious forms of corrosion; as it can penetrate deep into the metal, leading to sudden and unexpected failures even when overall material loss seems minimal.
Titanium
Which material has the highest pitting resistance?
Intergranular Corrosion
Metals are made up of tiny crystals called grains. The boundaries where these grains meet are susceptible to __________________.
Intergranular Corrosion
Due to chemical composition difference at the grain boundaries from the bulk of the grain, this happens.
Selective Leaching
This type of corrosion targets alloys, which are mixtures of different metals.
Selective Leaching
During _______________, one specific component of the alloy is preferentially dissolved and removed from the surface by the corrosive environment.
Erosion-Corrosion
Occurs when a metal surface is repeatedly exposed to a fluid with abrasive particles. The repeated impact of the particles can cause loss of material that leads to pits, grooves, or cavities.
Stress Cracking Corrosion
Occurs when a metal is exposed to a corrosive environment under tensile stress. This combination can cause cracking or other forms of material failure.
Hydrogen Damage
Degradation that occurs when hydrogen penetrates the surface of a metal. Can lead to various forms of damage like embrittlement, blistering, and cracking.
Wet Corrosion
This occurs in the presence of a liquid containing ions (electrolyte).
High-Temperature Corrosion
This occurs at elevated temperatures above 400Β°C (750ΒΊF) from gases, solid or molten salts, or molten metals.
Wet Corrosion
Chemical process: ________________
High-Temperature Corrosion
Follows thermodynamic laws and electrochemistry kinetics: _____________________
Wet Corrosion
The kinetics are influence by various factors such as temperature, pH, and presence of impurities.
High-Temperature Corrosion
This type is not primarily electrochemical in nature, but involves chemical attacks from gases, solid or molten salts, or molten metals at elevated temperatures.
Tafel Equation
The _________________ is commonly used to describe corrosion kinetics, relating the current density to factors like activation energy and overpotential.
diffusion rates and electrolyte resistance
In High-Temperature Corrosion, the kinetics are influenced by factors such as _____________ and _____________.