Corrosion factors affecting

Perhaps the most important stress factor affecting corrosion fatigue is the frequency of the cyclic stress. Since corrosion is an essential component of the failure mechanism and since corrosion processes typically require time for the interaction between the metal and its environment, the corrosion-fatigue life of a metal depends on the frequency of the cyclic stress. Relatively low-stress frequencies permit adequate time for corrosion to occur high-stress frequencies may not allow sufficient time for the corrosion processes necessary for corrosion... 

Horvath, J. and Uhlig, H., Metallurgical Factors Affecting the Critical Potential for Pitting Corrosion of Cr-Fe-Ni Alloys , J. Electrochem. Soc., 114, 201c (1%7)... 

The corrosion of tin-rich white metal bearings is rare and consequently detailed studies of the phenomenon have not been carried out. However, useful contributions to the understanding of the factors affecting bearing corrosion have been made recently . 

The principles and practice of corrosion inhibition have been described in terms of the factors affecting inhibitor performance and selection (principles) and the more important practical situations in which inhibitors are used (practice). For the latter a brief account is given of the nature of the system, the reasons for inhibitor application and the types of inhibitor in use. 

In addition to the chemical requirements, a number of other factors affect the susceptibility of the system to on-load corrosion, particularly operation and design. 

For a hot water environment general guidance can be given for the desirable properties in good enamels. Five factors affecting enamel life are corrosiveness of contact liquor, design, operating conditions, life of sacrificial anode (if any) and the durability of the enamel coat. This implies that... 

FIGURE 38 Lead coffin. Lead coffin (first—third centuries c.E.) from Jerusalem, Israel. Lead, widely used in many ancient civilizations, was one of the first metals to be recovered from its ores. Lead objects date back from as early as the seventh century b.c.e. In Mesopotamia molten lead was used to fasten bolts and shafts into masonry. In Syria it was made into rods used as currency, and in Greece it was cast into coins. During the Roman Empire the use of lead become so widespread that the health hazards caused by lead exposure are suspected to have been one of the factors affecting the fall of the Roman Empire. Since it is very resistant to corrosion, lead was also used by the Romans, for making coffins as the one illustrated. 

The chosen meaningful parameters are the following reaction heat, flammability, explosiveness, toxicity, corrosiveness, chemical interaction, inventory, process temperature and pressure, equipment safety and safe process structure (see Table 5). This does not mean that other factors affecting the inherent safety of a process are meaningless. On the contrary they should be considered more detailed in further design stages. 

The Chemical Inherent Safety Index Ici (Eq.4) contains chemical factors affecting the inherent safety of processes. These factors consist of chemical reactivity, flammability, explosiveness, toxicity and corrosiveness of chemical... 

Most of the factors affecting the rate of corrosion can be understood from a graphical superposition of the current-potential curves for the metal-dissolution and electronation reactions. The principle of the graphical superposition method is straightforward. 

Electroless metal deposition at trace levels in the solution is an important factor affecting silicon wafer cleaning. The deposition rate of most metals at trace levels depends mainly on the metal concentration and some may also depend on the interaction with other species as well. For copper the deposition rate at trace levels in HF solutions is different for n and p types. It depends on illumination for p-Si but not for n-Si. It is also different in HF and BHF solutions. In a HF solution the deposition process is controlled by both the supply of minority carriers and the kinetics of cathodic reactions. Thus, a high deposition rate occurs on p-Si only when both and illumination are present. In the BHF solution, the corrosion process is limited by the supply of electrons for p-Si whereas for n-Si it is limited by the dissolution of silicon because the reaction rate is indepaidmt of concentration and illumination. The amount of copper deposition does not correlate with the corrosion current density, which may be attributed to the chemical reactions associated with hydrogen reduction. More information on trace metal deposition can be found in Chapters 2 and 7. 

Shaw, T. R. In "Atmospheric Factors Affecting the Corrosion of Engineering Metals" ASTM SPP 646, 1978. 

Environmental Factors Affecting Corrosion of Weathering Steel... 

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