Friday, November 25, 2011

Corrosion


Corrosion removal deals with the taking away of mass from the surface of materials
by their environment and other forms of environmental attack that weaken or
otherwise degrade material properties. The complex nature of corrosion suggests
that the designer who is seriously concerned about corrosion review a good readable
text such as Corrosion Engineering by Fontana and Greene [44.1].
Included in this chapter are many corrosion data for selected environments and
materials. It is always hazardous to select one material in preference to another
based only on published data because of inconsistencies in measuring corrosion,
lack of completeness in documenting environments, variations in test methods, and
possible publishing errors. These data do not generally indicate how small variations
in temperature or corrosive concentrations might drastically increase or decrease
corrosion rates. Furthermore, they do not account for the influence of other associated
materials or how combinations of attack mechanisms may drastically alter a
given material's behavior. Stray electric currents should be considered along with
the various attack mechanisms included in this chapter. Brevity has required simplification
and the exclusion of some phenomena and data which may be important in
some applications.
The data included in this chapter are but a fraction of those available. Corrosion
Guide by Rabald [44.2] can be a valuable resource because of its extensive coverage
of environments and materials.
Again, all corrosion data included in this chapter or published elsewhere
should be used only as a guide for weeding out unsuitable materials or selecting
potentially acceptable candidates. Verification of suitability should be based on
actual experience or laboratory experimentation. The inclusion or exclusion of
data in this chapter should not be interpreted as an endorsement or rejection of
any material.

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