Corrosion Terminology Glossary

Corrosion Terminology - A's

abrasion resistance —the ability of a material to resist being worn away and to maintain its original appearance and structure when subjected to rubbing, scraping, or wear. abrasive —a solid substance that, owing to its hardness, toughness, size, shape, consistency, ..

Corrosion Terminology - B's

back fill —material placed in a hole to fill the space around the anodes, vent pipe, and buried components of a cathodic protection system. Barcol hardness —a hardness value obtained by measuring the resistance of rubbers, plastics, or coatings to indentation ...

Corrosion Terminology - C's

calcareous coating —a layer consisting of calcium carbonate and other salts deposited on the surface.When the surface is cathodically polarized as in cathodic protection, this layer is the result of the increased pH adjacent to the protected surface. calcareous ...

Corrosion Terminology - D's

DC decoupling device —a device used in electrical circuits that allows the flow of alternating current in both directions and stops or substantially reduces the flow of direct current. deactivation —the process of prior removal of the active corrosive constituents, ...

Corrosion Terminology - E's

elastic deformation —changes of dimensions of a material upon the application of a stress within the elastic range. Following the release of an elastic stress, the material returns to its original dimensions without any permanent deformation. elasticity —the ...

Corrosion Terminology - F's

fatigue —the process of progressive localized permanent structural change occurring in a material subjected to fluctuating stresses less than the ultimate tensile strength of the material that may culminate in cracks or complete fracture after a sufficient number of ...

Corrosion Terminology - G's

galvanic anode —a metal that provides sacrificial protection to another metal that is more noble when electrically coupled in an electrolyte. This type of anode is the electron source in one type of cathodic protection. galvanic corrosion —accelerated corrosion ...

Corrosion Terminology - H's

half-cell — (1) the single oxidation or reduction half reactions in the complete electro-chemical cell. (The potential of a half-cell can only be calculated from the thermodynamic properties of its components.) [thermodynamic use] (2) commonly used in the field to ...

Corrosion Terminology - I's

immunity —a state of resistance to corrosion of a metal in which the metal itself is more thermodynamically stable than its possible corrosion products. (In practical situations, immunity is assumed when the equilibrium concentration of corrosion products is negligible ...

Corrosion Terminology - K's

knife-line attack —intergranular corrosion of an alloy along an arrow band adjoining or in contact with a weld.

Corrosion Terminology - L's

lamellar corrosion —see exfoliation corrosion . Langelier Saturation Index —a number calculated from total dissolved solids, calcium concentration, total alkalinity, pH, and solution temperature that shows the tendency of a water solution to precipitate or ...

Corrosion Terminology - M's

macro cell corrosion —corrosion of a metal embedded in porous media (e.g., concrete or soil) caused by concentration or galvanic cells that exist on a scale at least as large as the smallest major dimension of the corroding item (e.g., the diameter of a bar or pipe). ...

Corrosion Terminology - N's

natural drainage —current drainage from an underground or submerged metallic structure to a more negative(more anodic) structure, such as the negative bus of a trolley substation. near-white metal blast cleaned surface —an abrasive blast cleaned steel surface ...

Corrosion Terminology - O's

occluded cell —an electro-chemical cell created at a localized site on a metal surface that has been partially obstructed from the bulk environment. opacity —the degree of obstruction to the transmission of visible light or to which a material obscures a substrate. ...

Corrosion Terminology - P's

paint —a pigmented liquid or resin applied to a substrate as a thin layer that is converted to a solid film after application. (It is commonly used for decoration or protection.) paint system —see coating system . parting —see dealloying . parting ...

Corrosion Terminology - Q's

quenched and tempered —quench hardened and then tempered.

Corrosion Terminology - R's

redox potential —see oxidation-reduction potential . reduction —gain of electrons by a constituent of a chemical reaction. reference electrode —an electrode having a stable and reproducible potential, which is used in the measurement of other electrode ...

Corrosion Terminology - S's

sacking —scrubbing a mixture of a cement mortar over the concrete surface using a cement sack, gunnysack, or sponge rubber float. sacrificial anode —see galvanic anode . sacrificial pigment —a pigment that provides cathodic protection to the substrate ...

Corrosion Terminology - T's

tackcoat —athin wet coat applied to the surface that is allowed to dry just until it istacky before application of a thicker wet coat. (Use of a tack coat allowsapplication of thicker coats without sags or runs.) Tafelplot —aplot of the relationship between ...

Corrosion Terminology - U's

ultimate tensile strength —the maximum stress that a material can sustain without failing from tensile overload. ultrahigh-pressure water jetting —water jetting performed at pressures above 210 MPa (30,000 psig). under film corrosion —see filiform corrosion ...

Corrosion Terminology - V's

vehicle —the liquid portion of a formulated coating material. Vickershardness —hardnessvalue, measured in accordance with ISO 6507-1 or Test Method E92, obtainedusing a diamond pyramid indenter and one of a variety of possible appliedloads. void — (1) ...

Corrosion Terminology - W's

wash primer —a thin, inhibiting, or passivating primer, usually formulated with chromate or phosphate pigment in a synthetic resin (e.g., polyvinyl butyral) binder. water cleaning —use of pressurized water discharged from a nozzle to remove unwanted matter from ...

Corrosion Terminology - X,Y,Z's

yield point —the stress on a material at which the first significant permanent or plastic deformation occurs without an increase in stress. In some materials,particularly annealed low-carbon steels, there is a well-defined yield point from the straight line defining ...