pitting potential

pitting potential

[′pid·iŋ pə‚ten·chəl]
(metallurgy)
The electrochemical potential in a given environment above which, but not below, a corrosion pit initiates in a metal surface.
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As can be seen for the uncoated 2524-T3 aluminum alloy, the pitting potential, [E.sub.pitting], and corrosion potential, [E.sub.corr], are nearly the same and a small increase of the potential E above [E.sub.corr] will lead to the initiation or acceleration of pitting with a large increase of the anodic current density j [12, 13].
It was observed that pitting potential decreased with increase in Zn content up to 3%, addition of copper increased pitting potential dramatically up to 5%, and Mg did not affect the pitting potential.
This type of attack occurs only on materials that work at a potential (corrosion potential, [E.sub.corr]) higher than a certain critical value, which is known as the pitting potential ([E.sub.pit]) and depends on the composition of the metallic material.
Pitting potential was measured to address concerns about snow melting agents containing chlorine causing pitting corrosion on the outer surface of exhaust system parts.
Method of measuring the pitting potential for stainless steels by potentiodynamic control in sodium chloride solution.
The values of the corrosion parameters such as cathodic ([[beta].sub.c]) and anodic ([[beta].sub.a]) Tafel slope, corrosion potential ([E.sub.Corr]), corrosion current density ([j.sub.Corr]), pitting potential ([E.sub.Pit]), pitting current density ([j.sub.Pit]), protection potential (EProt), polarization resistance (Rp), and corrosion rate ([R.sub.Corr]) obtained for the API X70 steel electrodes from the CPP curves shown in Figure 6 are listed in Table 2.
For the anodic polarization curves, the CoAW exhibited a typical passive region up to the pitting potential in the pH = 6.75 AS solution compared the other two solutions.
Because of the protective oxide films the titanium implant surface exhibits anodic pitting potential that are very high ([much greater than] 1V) compared to other biomaterials used (iron, steel, cobalt-chromium alloys etc).
Appreciable amount of pitting was observed for matrix and composites beyond pitting potential due to the breakdown of passive oxide layer.
These samples also exhibit a well-articulated pitting potential that is shifted to slightly more positive potentials in the presence of Al[O.sub.2.sup.-].
From the perspective of the Catholic church and others who oppose abortion, though, the research presents a serious moral problem: One major source of stem cells -- fortunately not the only source -- is human embryos, pitting potential cures for terrible afflictions against respect for human life.
In Figure 12, it becomes more difficult to identify the pitting potential as the annealing temperature increases.