ASTM G15-04

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:G15–04
Standard Terminology Relating to
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Corrosion and Corrosion Testing
ThisstandardisissuedunderthefixeddesignationG 15;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope anodic polarization—the change of the electrode potential in
the noble (positive) direction due to current flow. (See
1.1 This terminology covers commonly used terms in the
polarization.)
field of corrosion. Related terms may be found in Terminolo-
anodic protection—a technique to reduce the corrosion rate of
gies D16, D 4538, G40, or other ASTM terminology stan-
a metal by polarizing it into its passive region where
dards.AlltermsdefinedbyASTMcommitteesmaybefoundin
dissolution rates are low.
the ASTM Dictionary of Engineering & Technology.
anolyte—the electrolyte adjacent to the anode of an electro-
2. Referenced Documents lytic cell.
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auxiliary electrode—See counter electrode.
2.1 ASTM Standards:
breakdown potential—the least noble potential where pitting
D16 Terminology for Paint, Related Coatings, Materials,
or crevice corrosion, or both, will initiate and propagate.
and Applications
cathode—the electrode of an electrolytic cell at which reduc-
D 4538 Terminology Relating to Protective Coating and
tion is the principal reaction. (Electrons flow toward the
Lining Work for Power
cathode in the external circuit.)
G40 Terminology Relating to Wear and Erosion
cathodic corrosion—corrosionofametalwhenitisacathode.
3. Terminology
(It usually happens to metals because of a rise in pH at the
cathode or as a result of the formation of hydrides.)
AC impedance—See electrochemical impedance.
cathodic inhibitor—a corrosion inhibitor whose primary ac-
active—the negative direction of electrode potential. (Also
tion is to slow the kinetics of the cathodic reaction, produc-
used to describe corrosion and its associated potential range
ing a negative shift in corrosion potential.
when an electrode potential is more negative than an
cathodic polarization—the change of the electrode potential
adjacent depressed corrosion rate [passive] range.)
in the active (negative) direction due to current flow. (See
anion—a negatively charged ion.
polarization.)
anode—the electrode of an electrolytic cell at which oxidation
cathodic protection—a technique to reduce the corrosion rate
is the principal reaction. (Electrons flow away from the
of a metal surface by making it the cathode of an electro-
anode in the external circuit. It is usually the electrode where
chemical cell.
corrosion occurs and metal ions enter solution.)
catholyte—the electrolyte adjacent to the cathode of an
anode corrosion efficiency—the ratio of the actual corrosion
electrolytic cell.
(weight loss) of an anode to the theoretical corrosion (weight
cation—a positively charged ion.
loss) calculated by Faraday’s law from the quantity of
caustic cracking—stress corrosion cracking of metals in
electricity that has passed.
caustic solutions. (See also stress-corrosion cracking.)
anodic inhibitor—a corrosion inhibitor whose primary action
caustic embrittlement—See caustic cracking.
is to slow the kinetics of the anodic reaction, producing a
cavitation—the formation and rapid collapse within a liquid of
positive shift in corrosion potential.
cavities or bubbles that contain vapor or gas or both.
cavitation corrosion—the conjoint action of cavitation-
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erosion and corrosion.
This terminology is under the jurisdiction of ASTM Committee G01 on
Corrosion of Metals and are the direct responsibility of Subcommittee G01.02 on
cavitation damage—the degradation of a solid body resulting
Terminology.
from its exposure to cavitation. (This may include loss of
Current edition approved Jan. 1, 2004. Published January 2004. Originally
material, surface deformation, or changes in properties or
approved in 1971. Last previous edition approved in 2003 as G 15 – 03a.
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appearance.)
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
cavitation-erosion—loss of material from a solid surface due
Standards volume information, refer to the standard’s Document Summary page on
to mechanical action of continuing exposure to cavitation.
the ASTM website.
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G15–04
chemical conversion coating—a protective or decorative depolarization—not a preferred term. (See polarization.)
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