What is wet corrosion and galvanic corrosion?

Answer 1

The dry corrosion is the corrosion of the metal that takes place in the absence of conducting(aqueous) medium. The reaction between metal and oxygen (atmosphere) at elevated temperatures in perfectly dry conditions is an example of dry corrosion.

Answer 2

Wet corrosion is caused when an area on metal is allowed to collect water, such as a rain gutter that is too clogged to allow the water to flow out. Sooner or later the water causes the metal to start to deteriorate through rust.

Answer 3

Galvanic corrosion is an electrochemicalprocess in which one metal corrodespreferentially when in electrical contact with a different type of metal and both metals are immersed in anelectrolyte.

When two or more different sorts of metal come into contact in the presence of an electrolyte a galvanic coupleis set up as different metals have different electrode potentials. The electrolyte provides a means forion migration whereby metallic ions can move from the anode to the cathode. This leads to the anodic metal corroding more quickly than it otherwise would; the corrosion of the cathodic metal is retarded even to the point of stopping. The presence of electrolyte and a conducting path between the metals may cause corrosion where otherwise neither metal alone would have corroded.

WET CORROSION:The main features of corrosion of a divalent metal M in an aqueous solution containing oxygen are presented schematically in Figure 2.1. The corrosion process consists of an anodic and a cathodic reaction. In the anodic reaction (oxidation) the metal is dissolved and transferred to the solution as ions M2+. The cathodic reaction in the example is reduction of oxygen. It is seen that the process makes an electrical circuit without any accumulation of charges. The electrons released by the anodic reaction are conducted through the metal to the cathodic area where they are consumed in the cathodic reaction. A necessary condition for such a corrosion process is that the environment is a conducting liquid (an electrolyte) that is in contact with the metal. The electrical circuit is closed by ion conduction through the electrolyte. In accordance with the conditions this dissolution process is called wet corrosion, and the mechanism is typically electrochemical.

Answer 4

wet corrosion mean the direct attack of liquid phase, for example condensed humidity or acid or alkali, on metal. it's the common form of corrosion.

dry corrosion is a form of corrosion, high temperature oxydation, that occur at elevated temperature without a liquid phase.

Answer 5

Dry corrosion refers to the oxidation that occurs when oxygen in the air reacts with metal without the presence of a liquid. Its effects are not as detrimental as wet corrosion but it still causes some damage to the metal.

Answer 6

at high temperature ,dry air and prescence of electrochemical cell

Answer 7

Wet corrosion is more destructive than dry corrosion.

Answer 8

if the corrosion product goes into solution or evolved as a gas , the corrosion reaction go on unchecked