Corrosion features

Undermining of Mg particles that may take place in a very severe corrosion process has been shown not to influence reaction (1.79) or (1.80) (Song et al, 1997b) either. Therefore, the hydrogen evolution phenomenon in an aqueous solution is one of the most fundamental and important corrosion features of Mg and its alloys. 

As heterogeneous and homogeneous reactions are taken into account some complex changes in the solution and at the surface of the electrodes can occur. It is why the basic modelling mnst be completed by the analysis of the corrosion feature. 

The rich literature on the corrosion of Ni-Cr-Mo alloys in GCR helium is briefly reviewed. Then, we report our preliminary results on the exposure tests of Haynes 230 in GCR representative conditions and we compare resistance of this material to the corrosion features of some reference Ni-Cr-Mo alloys. 

One of the earliest NDT applications for laser-based profilometry systems was for the inspection of marine boiler tubes. Under funding from the U.S. Navy", several systems were developed that were capable of rapidly and accurately mapping the inside surface of 25 mm and 50 mm diameter boiler tubing. Features such as internal pitting and corrosion can be located and quantitatively assessed using computer-graphic analysis. The system employs an... 

Localized erosion-corrosion caused by turbulence or impinging flow at certain points of the surface. In the majority of cases of impingement attack, a geometrical feature of the system results in turbulence at one or more parts of the surface. 

Process Feature Size Equipment Remote handling Corrosion resistance... 

Atmospheric corrosion is electrochemical ia nature and depends on the flow of current between anodic and cathodic areas. The resulting attack is generally localized to particular features of the metallurgical stmcture. Features that contribute to differences ia potential iaclude the iatermetaUic particles and the electrode potentials of the matrix. The electrode potentials of some soHd solutions and iatermetaUic particles are shown ia Table 26. Iron and sUicon impurities ia commercially pure aluminum form iatermetaUic coastitueat particles that are cathodic to alumiaum. Because the oxide film over these coastitueats may be weak, they can promote electrochemical attack of the surrounding aluminum matrix. The superior resistance to corrosion of high purity aluminum is attributed to the small number of these constituents. 

If a need is met by a variety of products, then the price should reflect the price of these competitive products and any unique or advantageous features of the product being priced. For example, some plastic parts for automotive appHcations can be priced higher than corresponding metal parts because of lighter weight, corrosion resistance, or other features. 

Finally, pitting may be viewed as a special form of concentration cell corrosion. Most alloys that are susceptible to crevice corrosion also pit. However, many metals may pit but not show crevice attack. Further, although sharing many common features with concentration cell corrosion, pitting is sufficiently different to warrant a separate categorization. 

Attack by strong acids tends to produce intense localized wastage. Weak acids cause more general corrosion. However, numerous exceptions to these general rules exist. Fortunately, corrosion damage caused by acids has many unique features that allow easy recognition in most cases. 

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