Terminology, corrosion

For assistance in understanding corrosion terminology, please refer to ASTM G 15, Terminology Relating to Corrosion and Corrosion Testing. 

The classification given in Table 1.2 is based on the various forms that corrosion may take, but the terminology used in describing corrosion phenomena frequently places emphasis on the environment or cause of attack rather than the form of attack. Thus the broad classification of corrosion reactions into wet or dry is now generally accepted, and the nature of the process is frequently made more specific by the use of an adjective that indicates type or environment, e.g. concentration—cell corrosion, crevice corrosion, bimetallic corrosion and atmospheric corrosion. 

The terminology suggested can be illustrated by reference to the corrosion behaviour of iron ... 

Although it is realised that this classification and terminology has certain limitations, it represents a preliminary attempt to provide a more rational classification of corrosion processes than that based on wet and dry . 

The terminology cathodic (sulphide) stress-corrosion cracking is borrowed from Spaehn s review for the reasons previously mentioned. Generally,... 

Terminology The International Standards Organization has recently defined a corrosion inhibitor as a chemical substance which decreases the corrosion rate when present in the corrosion system at a suitable concentration, without significantly changing the concentration of any other corrosive agent. This last point is significant since it excludes chemicals employed for deaeration or pH control from the definition of a corrosion inhibitor. On the other hand, it should be noted that the inhibitor is .. . present in the corrosion system. . . , and thus arsenic when added to brasses to prevent dezin-cihcation may be classified as an inhibitor. 

Where inadequate FW deaeration takes place and oxygen corrosion occurs, the descriptive terminology employed often relates to the particular components involved ... 

The implied capability of these plasma deposits to inhibit corrosion at metal surfaces may be of practical as well as of basic importance. An important consideration in this respect is the rapid rate of deposition for such protective coatings attainable at micro-wave frequencies. Since plasma technology is still in a process of evolution, optimum deposition kinetics cannot yet be stated however, the marked effect of excitation frequency on the deposition of organo-silicones can be documented (10), as in Fig. 3. Here, using terminology and comparative data due to Yasuda et al. (2). it is shown that deposition rates in microwave plasmas exceed those at lower (e.g. radio) frequencies by about an order of magnitude. 

Electrochemical concepts, terminology and symbols are more extensively described in [l.i]. For the field of semiconductor electrochemistry and photoelectrochemical energy conversion see [29] and for corrosion nomenclature [30]. 

There is a specific terminology used for hypothesis tests. One migjit ask, for example, whether the rate of corrosion obtained for an aged steel coupon immersed in seawater is equal to that found in city drinking water. 

Some Basic Terminology, Reactions, and Variables in Aqueous Corrosion... 

Table 1.1 Summary of processes, terminology, and variables associated with aqueous corrosion(a)...

The terminology anodic and cathodic inhibitors is based on these functions. Anodic protection prevents or limits electron flow to the cathode area. Cathodic inhibitors generally reduce the corrosion rate by forming a barrier at the cathode thereby restricting the hydrogen ion or oxygen transport to the cathode surface. Tables 14.6 and 14.7 provide some information on common corrosion inhibitors. Specific corrosion control requirements are usually based on blends of two or more of the listed chemicals perhaps, in addition to chemicals to control scale formation and biological activity. 

Corrosives are the largest class of chemicals used by industry, so it stands to reason that they would frequently be encountered in transportation and at fixed facilities. DOT Class 8 materials are corrosive liquids and solids. There are no DOT subclasses of corrosives. There are, however, two types of corrosive materials found in Class 8 acids and bases. Acids and bases are actually two different types of chemicals that are sometimes used to neutralize each other in a spill. They are grouped together in Class 8 because the corrosive effects are much the same on tissue and metals, if contacted. It should be noted, however, that the correct terminology for an acid is corrosive and for a base is caustic. DOT, however, does not differentiate between the two when placarding and labeling. The DOT definition for a corrosive material is a liquid or solid that causes visible destruction or irreversible alterations in human skin tissue at the site of contact, or a liquid that has a severe corrosion rate on steel or aluminum. This corrosive rate on steel and aluminum is 0.246 inches per year at a test temperature of 131 F. ... 

What, you think the survey is facetious and out of place Let s take a look at a corrosion smorg sbord of terminology in Figure 2. The experiences of a corrosion engineer are represented by the term array. Sampling them at random, it seems to be a jumble. However, it is an overview. 

Corrosive, see Corrosives and Class 8, p.47 Fluid, see Terminology, Fluid, p.238 Internal combustion engine, see Self-... 

Related Terms Coal tar, see Coal, p.44 Corrosive, see Corrosives and Class 8, p.47 Flammable liquid, n.o.s., see Flammable Liquids and Class 3, p.96 Liquid, see Terminology, Liquid, p.241 Organic, see Terminology, Organic, p.244... 

This book concentrates just on wet corrosion. The terminology used mainly corresponds to international standards and glossaries [1.2-1.4], Equivalents to the English terms in other languages are given in References [1.4—1.6]. 

Why deterioration and not corrosion In fact, the definition of corrosion is based on anodic and cathodic reactions. These reactions make sense only when applied to metals. Therefore, corrosion is a terminology that is normally used for metals. 

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