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Corrosion Glossary - V
- Vacuum degassing: a process by which
the amount of carbon in the steel is
reduced by exposing liquid steel to a very low vacuum environment. Carbon combines
in the process with oxygen to form carbon monoxide, which is removed in the
process. The result is a steel that contains lower levels of carbon and thus,
has higher formabiliy.
- Vacuum or low pressure plasma spraying:
plasma spraying carried out in a chamber which has been evacuated to a low partial
pressure of oxygen. It is then usually partially backfilled with argon to avoid
the possibility of forming a glow discharge.
deposition: condensation of thin metal coatings on the cool surface
of work in vacuum.
- Valence: a whole number (positive or
negative) representing the power of one element to combine with another. In
general terms, the valence number represents the number of electrons in an atom
or combined group of atoms which can be easily given up or accepted to react
with or bond to another atom or group of atoms to form a molecule
- Vapor: the gaseous product of evaporation.
- Vapor deposition:
see chemical vapor deposition, physical vapor deposition and sputtering.
- Vapor plating:
deposition of a metal or compound on a heated surface by reduction or decomposition
of a volatile compound at a temperature below the melting points of the deposit
and the base material.
- Vaporization: the change from liquid
or solid phase to the vapor phase.
- Varnish (clearcoat): an
unpigmented binder solvent solution
applied to protect or decorate a surface.
- Vehicle: (Paint) portion of a
coating that includes all liquids
and the binder. The vehicle and the pigment are the two basic components of
- Velocity pressure: the measure of the
kinetic energy of a fluid.
- Vent: an opening in a vessel or other
enclosed space for the removal of gas or vapor.
- Vertical firing: an arrangement of a
burner such that air and fuel are discharged into the furnace in practically
a vertical direction.
- Viable: alive and capable of continued
- Virus: the smallest form of life known
to be capable of producing disease or infection, usually considered to be of
large molecular size. They multiply by assembly of component fragments in living
cells, rather than by cell division, as do most bacteria.
- Viscosity: the resistance of fluids
to flow, due to internal forces and friction between molecules, which increases
as temperature decreases.
- VOC: see Volatile organic compound.
- Void volume: the volume of the spaces
between particles of ion exchanger, filter media, or other granular material;
often expressed as a percentage of the total volume occupied by the material.
- Voids: a term generally applied to paints
to describe holidays, holes, and skips in a film. also used to describe shrinkage
in castings and weld.
- Volatile: capable of vaporization at
a relatively low temperature.
- Volatile matter: those products given
off by a material as gas or vapor, determined by definite prescribed methods.
- Volatile organic compound (VOC): organic
chemicals and petrochemicals that emit vapors while evaporating. In paints,
VOC generally refers to the solvent portion of the paint which, when it evaporates,
results in the formation of paint film on the substrate to which it was applied.
- Volatile solids: matter which remains
as a residue after evaporation at 105 or 180oC, but which is lost
after ignition at 600oC. Includes most forms of organic matter.
- Voltaic pile: (historical)
a series combination of cells or battery.
- Volume solids: solid ingredients as
a percentage of total ingredients. The volume of pigment plus
binder divided by the total volume,
expressed as a percent. High-volume solids mean a thicker dry film with improved
- Volumetric: referring to measurement
by volume rather than weight.