Corrosion, biological

Biological Corrosion The metabohc activity of microorganisms can either directly or indirectly cause deterioration of a metal by corrosion processes. Such activity can (1) produce a corrosive environment, (2) create electrolytic-concentration cells on the metal surface, (3) alter the resistance of surface films, (4) have an influence on the rate of anodic or cathodic reaction, and (5) alter the environment composition. 

Several instances of serious biological corrosion occurred when... 

Two basic mechanisms cause biological corrosion. Biologically produced substances may actively or passively cause attack. Each mechanism either accelerates preexisting corrosion or establishes a new form of metal loss. Often the distinction between active and passive attack is vague. 

Localized biological corrosion of stainless steels. There are three general sets of conditions under which localized biological corrosion of austenitic stainless steel occurs (Figure 6.29). These conditions should be examined for metals that show active-passive corrosion behavior. Microbiological corrosion in austenitic steel weldments has been documented. (Wahid)61, (Krysiak)14... 

S Biological corrosion. Damp masonry surfaces allow the growth of micro-organisms such as bacteria, moulds, mosses, algae and lichens (Figure 6.11). With an efficient metabolism the separation of the products of metabolism can result in the deposition of salts. If walls are not treated the effect is an uninhabitable building. 

Destruction of carbonates by organisms also involves translocation of material from the site of biological corrosion or abrasion, and its redistribution in the environment. Carbonate particles which are mechanically removed by gastropods and echinoderms are transported through their digestive tracts and distributed via faecal pellets. Sponges remove the chips of car-... 

Today, a variety of and large amount of synthetic polymeric materials are produced and are supporting our comfortable daily life as well as modern high technologies. The major reasons for their success are their strength, durability, resistance to chemical and biological corrosion and low production cost. On the one hand these properties have created various fields of applications, but on the other have given rise to the problem of waste polymers. 

The review of inhibited paint coatings would be incomplete without mentioning coatings with Cl that inhibit biological corrosion. Microbiologically influenced corrosion is the deterioration of a metal by a corrosion process that occurs either directly or indirectly as a result of the activity of living organisms [85]. 

---