Corrosion control

In fact, however, these reactions do not occur by direct interactions of the metal with oxygen or water but rather by two electrode processes occurring simultaneously on the surface of the metal, i.e. 

These equations imply that the rate of corrosion will depend on the presence of water, the concentration of oxygen and the pH and composition of the aqueous 

Many surfaces will be homogeneous, i.e. metals or alloys in a uniform environment, and the anodic and cathodic reactions wilt occur randomly over the whole surface, although maybe at particular sites, e.g. lattice imperfections. Since metals are good electronic conductors, however, this need not be the only situation where corrosion occurs. For example, where two metals are in contact or one metal is in contact with two quite different environments, e.g. a teg of a North Sea oil platform passing through the sea water into the sea bed, there may be well defined anodic and cathodic areas and electrons pass through the metal from one to the other. Indeed, it will be seen that such situations often lead to the worst corrosion problems and are a major cause of component failure. 

On the other hand, although electrons may move around the metal, the metal cannot accumulate a net charge and hence the currents for the anodic and cathodic processes must be equal and the metal will take up a potential where the current for reaction (9.3) is the same as for reactions (9.4) and/or (9.5). 

---

The Institute has many-year experience of investigations and developments in the field of NDT. These are, mainly, developments which allowed creation of a series of eddy current flaw detectors for various applications. The Institute has traditionally studied the physico-mechanical properties of materials, their stressed-strained state, fracture mechanics and developed on this basis the procedures and instruments which measure the properties and predict the behaviour of materials. Quite important are also developments of technologies and equipment for control of thickness and adhesion of thin protective coatings on various bases, corrosion control of underground pipelines by indirect method, acoustic emission control of hydrogen and corrosion cracking in structural materials, etc. 

COLORANTS FORFOOD,DRUGS,COSTffiTICS AND TffiDICALDEVICES] (Vol 6) -corrosion of [CORROSION AND CORROSION CONTROL] (Vol 7)... 

---