Theories of corrosion
Forms of corrosion
Protection methods
Coating methods
General
100
Electrochemical theory of corrosion
What is the most successful theory of corrosion?
100
In which corrosion occurs on entire surface of the metal.
What is uniform corrosion?
100
Making the metallic structure to act as cathode by connecting to a more active metal.
What is sacrificial anodic protection?
100
It is the most common organic coating.
What is a paint?
100
Due to formation of passive chromium oxide film.
What is the reason for high corrosion resistance of stainless steel?
200
Oxidation resistance is related to the ratio of volume of metal oxide to volume of metal.
What is Pilling-Bedworth rule?
200
That occurs through formation of cells due to difference in the concentration of oxygen.
What is differential aeration corrosion?
200
providing passivation potential to protect the metals.
What is the anodic protection method?
200
Coating of metallic structure with zinc metal.
What is galvanizing?
200
Because they are noble metals.
What is reason for high corrosion resistance of Pt and Au?
300
Because multiple cathodic reactions are possible in aerated acid solutions.
What is the reason for high corrosion rate in aerated acid solutions?
300
corrosion influenced by the activities of microorganisms.
What is microbiological corrosion?
300
Al2O3 layer is produced on the surface.
What happens when aluminium is exposed to oxidising environment?
300
Plating of a metal without the use of electrical energy.
What is electroless plating?
300
It consists of oxides/hydroxides of iron.
What is the composition of rust?
400
Either at cathodic areas or at the junction of anodic and cathodic areas.
What is the area at which corrosion product is deposited in electrochemical corrosion?
400
zinc is anode and copper is cathode.
What are anode and cathode and the galvanic corrosion of zinc/copper pair?
400
Scrap iron, iron silica blend, graphite, platinum, etc.
What are the examples of anodes used in anodic protection?
400
Anodic coatings and cathodic coatings.
What are the two types of metallic coatings?
400
Iron nail fitted in wooden door is less accessible to oxygen.
What is the reason for corrosion of iron nail fitted to wooden door?
500
That occurs in the absence of an electrolyte.
What is chemical/dry corrosion?
500
Pitting corrosion.
What is the most localized form of corrosion that results in holes on the surface?
500
Substance that controls the corrosion by controlling cathodic reaction.
What is a cathodic inhibitor?
500
Surface preparation, optimum pH, temperature, contact time, energy density, etc.
What are the factors influencing electroplating?
500
moisture and oxygen.
What are the essential substances required for corrosion of iron in atmosphere?
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