Types of corrosion examples
Corrosion is the deterioration of a material due to chemical interaction with its environment. It is a natural process in which metals convert their structure into a more chemically stable form, such as oxides, hydroxides or sulfides. The consequences of corrosion are all too common. Familiar examples include rusting of automotive body panels and pipes and many tools. Corrosion is usually a negative phenomenon, as it is associated with the mechanical failure of an object. Metal atoms are removed from a structural element until it fails, or oxides build up inside a pipe until it plugs. All metals and alloys are subject to corrosion. Even noble metals, such as gold, are subject to corrosive attack in some environments.
During metal corrosion, the areas over which anodic and cathodic reactions occur can vary greatly. Corrosion can occur in different forms and grow at different rates. This results in various forms of corrosion, such as uniform attack, pitting and crevice corrosion. The problem is that there are many forms of corrosion and each is caused by different reasons and undergoes different mechanisms. In addition, each form of corrosion has its own special mechanism, which can be quite complex in some cases. This is especially problematic when two or more types of corrosion occur simultaneously.
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Corrosion can lead to partial or total destruction of metal. In industry, it can lead to fractures, leaks in tanks and reduced mechanical strength of the affected machinery. As is logical, direct and indirect losses can be very significant.
Most corrosion processes involve electrochemical reduction-oxidation reactions, although the types of corrosion will depend on the environmental conditions as well as the characteristics of the material itself. The most common classification is as follows:
Occurs when there is bonding between dissimilar metals, either physically or electrically. The material with the lowest electrochemical potential is the one that suffers the corrosion. The larger the contact area between the anode and the cathode, the faster the piece corrodes.
Also called pitting occurs in passivated materials. As oxidizing agents accumulate and the pH of the medium increases, the passivation layer deteriorates, generating the corrosive process in localized areas.
Corrosion
The best known type of corrosion and also the easiest to detect and predict. It is unusual-though not unheard of-for general corrosion to produce disastrous failures. For that reason, generalized corrosion is seen more as an aesthetic issue than a serious problem. Widespread corrosion occurs relatively uniformly over the surface of a metal. When calculating the service pressure, the gradual recession of the component’s wall thickness must be taken into account.
In a marine or other corrosive environment, the surface of carbon or low alloy steel begins to degrade, allowing the formation of an iron oxide layer that eventually thickens, until it peels off and a new layer begins.
When the protective oxide layer (or passive oxide layer) on the surface of the material degrades, the metal becomes prone to losing electrons. This causes the iron in the metal to become a solution at the more anodic bottom of the crack, diffuse to the top and oxidize resulting in iron oxide or rust. The concentration of the iron chloride solution in a crack may increase and acidify as the crack deepens. These changes result in accelerated crack growth, perforation of the pipe walls, and leakage.
Types of atmospheric corrosion
To avoid surface corrosion, the correct for the profiled spring, flat spring, flat spring or material laser part or the correct Surface treatment should be used to be voted.
Contact corrosion is caused by the electrochemical reaction of two dissimilar metallic materials or other electron-conducting solids. It can occur when metals of different noble quality are in close contact through a conductive liquid, for example, when one of them is touched. Spring shaped outside stainless steel with a galvanized steel. The nobler metal promotes corrosion. A prerequisite for this process is a corrosive medium between the two metals, e.g. conductive water.