This glossary is intended to foster development of a shared vocabulary
within the rapidly evolving field of cold
gas-dynamic spray. Defining this terminology is an important and
controversial challenge that we hope will lead
to a future standard representing industry
consensus.
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Gas-Dynamic Spray Process Glossary are
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abradable coating.
A sacrificial layer of material applied to a
substrate, usually to enable a shape-conforming
seal.
abrasion.
The rubbing or scraping of the surface layer.
abrasive.
A natural or manufactured substance used to
grind, wear down, rub away, smooth, scour,
clean, or polish.
abrasive blasting.
A method of cleaning or roughening a surface by
a forcibly projected stream of abrasive
particles.
abrasive wear.
The surface condition resulting from active
contact with an abrasive.
adhesive strength. A nonstandard term when used
for bond
strength.
agglomerated powder.
A substance of clusters of finely divided
particles. See also
conglomerated powder and
flocculated powder.
aggregate,
n. A mass of particles held together by mechanical forces.
air classification.
The separation of powder into particle size
fractions by means of an air stream of
controlled velocity.
aligned
porosity. A localized array of porosity oriented in a line.
alloy.
A substance with metallic properties and composed of two or more chemical
elements of which at least one is a metal.
alloy
powder.
Powder prepared from a homogeneous molten alloy or from the
solidification product of such an alloy. See
also powder blend.
amorphous.
Non-crystalline, or devoid of regular structure.
apparent density.
The weight of a unit volume of solid, which
might not be homogeneous.
apparent hardness.
The indicated solidity and firmness of a solid,
which might not be homogenous.
asperity.
A small-scale topographical surface irregularity
such as a peak, protuberance.
atomization.
The dispersion of a material into fine particles
by a rapidly moving gas, liquid stream, or by
mechanical dispersion.
atomized powder.
A powder produced by the dispersion of a molten
material into fine particles by a rapidly moving
gas, liquid stream, or by mechanical dispersion.
automatic spraying.
Spraying with equipment requiring only
occasional or no observation and no manual
adjustments during its operation. See also
manual
spraying,
mechanized spraying,
robotic
spraying, and
semiautomatic spraying.
axial injection.
Introduction of a material along an axis
parallel or coincident with the axis of the
spray jet.
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babbitt metal.
Nonferrous bearing alloys consisting mainly of
various amounts of copper, antimony, tin, and
lead.
backing.
A material or device placed against the back
side of a substrate to facilitate the spray
process or support the substrate.
bead.
See spray deposit bead.
binder.
A
cementing medium used in producing composite or
agglomerated powders.
blast helmet.
Personal protective device enclosing the
person's head in a loose-fitting hard shell,
directing fresh air to the wearer, and
protecting the head and neck from flying
particles generated by abrasive blasting.
blast hood.
Personal protective device enclosing the
person's head and neck in a loose-fitting
covering, and protecting the head and neck from
flying particles generated by abrasive blasting.
blasting.
See abrasive blasting.
blended powder.
Thoroughly intermingled powder containing
materials of substantially similar chemical
composition. See also
mixed
powder.
block
sequence. A combined longitudinal and cross-sectional sequence for a continuous
multiple-pass spray deposit in which separated
increments are completely or partially sprayed
before intervening increments are sprayed. See
also cascade sequence,
continuous sequence,
and cross-sectional sequence.
bond.
See
covalent bond, ionic bond,
mechanical bond, and metallic bond.
bond coat. A
coating layer applied to a substrate to improve
the adherence or performance of subsequent
layers.
bonding force.
The attractive force holding atoms together. See
also covalent bond, ionic bond,
and metallic bond.
bond specimen.
The test specimen on which a spray deposit has
been applied to determine the bond strength and
spray deposit strength.
bond strength.
The force per unit area required to separate a
spray deposit from the substrate.
bottle. A nonstandard term when used for
gas
cylinder.
bow shock.
A flow discontinuity in the spray
feedstock-laden spray jet caused by deceleration
and deflection of the gas flow ahead of the
substrate. See also
compressed layer and
free jet.
brittleness.
The tendency of a material to fracture without
first undergoing significant plastic
deformation.
buildup.
A surfacing variation in which surfacing material is deposited to achieve
the required dimensions. See also buttering,
cladding, and hardfacing.
buildup sequence. A nonstandard term for
cross-sectional sequence.
buttering.
A surfacing variation depositing surfacing metal on one or more surfaces
to provide metallurgically compatible metal for
a joint. See also buildup, cladding,
and hardfacing.
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carrier gas.
A gas conveying powder in the spray process from
the powder feeder through the surfacing gun. See
also
spray feedstock driving gas.
cascade sequence.
A combined longitudinal and cross sectional
sequence in which spray deposits are made in
overlapping layers. See also
block
sequence,
continuous sequence, and
cross-sectional sequence.
cathodic protection.
A technique to reduce the corrosion rate of a
metal by making it the cathode of an
electrochemical cell.
cavitation erosion.
The progressive loss of material from a solid
surface due to the collapse of bubbles or
cavities within a liquid containing a gas,
vapor, or a mixture of the two.
ceramic.
A class of inorganic nonmetallic materials
subjected to high temperatures during
manufacture.
cermet powders.
A blended or composite powder of metal and
ceramic constituents.
cladding.
A surfacing variation depositing or applying surfacing material, usually
to improve corrosion or heat resistance. See
also buildup, buttering, and
hardfacing.
coating. A nonstandard term when used for
spray
deposit or
thermal
spray deposit.
coating density. A nonstandard term when used for spray deposit
density ratio.
coating strength. A nonstandard term when used
for spray
deposit strength.
cold gas-dynamic spray (CGSP).
A solid-state spraying process using a
supersonic jet of compressed gas to accelerate
near-room-temperature spray feedstock particles
through a nozzle at very high velocities towards
a substrate where they plastically deform and
consolidate on impact. See
high-pressure cold gas-dynamic spray,
low-pressure cold gas-dynamic spray and
pulsed
cold gas-dynamic spray.
cold spray.
See cold
gas-dynamic spray. See also
high-pressure cold gas-dynamic spray,
low-pressure cold gas-dynamic spray and
pulsed
cold gas-dynamic spray.
composite.
A material consisting of two or more discrete
materials with each material retaining its
physicochemical identity.
composite powder.
See
powder composite.
composite spray deposit.
A spray deposit made with two or more dissimilar
surfacing materials, which may be formed in
layers.
compressed layer.
A high-pressure high-density gas layer formed
between the substrate surface and the bow shock
creating a resistance to flow. See also
bow shock and free jet.
compressed layer temperature.
See flow
stagnation temperature.
conformal spray deposit.
A spray deposit covering and fitting the shape
of the substrate.
conglomerated powder.
A substance of particles of different materials.
See also
agglomerated powder and
flocculated powder.
continuous sequence. A longitudinal sequence in which each spray deposit pass is made
continuously from one end of the substrate to
the other. See also block sequence,
cascade sequence, and
cross-sectional sequence.
continuous spray deposit.
A spray deposit made without interruption.
convergent-divergent nozzle.
See de
Laval nozzle.
corrosion.
Chemical or electrochemical reaction between a
material and its environment which results in
deterioration in the properties of the material.
cosmetic spray deposit bead.
A spray deposit bead used to enhance appearance.
cosmetic spray deposit pass.
A spray deposit pass resulting in a cosmetic
spray deposit bead.
covalent
bond.
A primary bond arising from the reduction in energy associated with
overlapping half-filled orbitals of two atoms.
See also
bonding force, ionic bond,
mechanical bond, and
metallic
bond.
cover bead.
A spray deposit bead resulting from a cover
pass.
cover pass.
A spray deposit pass or passes resulting in the
exposed layer of a multipass spray deposit on
the side from which spraying was done.
crack.
A fracture type discontinuity characterized by a sharp tip and high ratio
of length and width to opening displacement.
crater.
Substrate surface discontinuity caused by
mechanical impact such as a particle impacting
at less than the critical velocity.
critical spray angle.
The orientation of spray jet impingement at
which the angle of incidence is sufficient to
facilitate spray deposition.
critical spray velocity.
The temperature-dependant (particle and
substrate) spray velocity above which there is a
transition from erosion to coating formation.
cross-sectional sequence.
The order in which the passes of a multiple-pass
spray process are deposited.
See also block sequence, cascade sequence, and
continuous sequence.
crushed powder.
Powder formed from a solid which is crushed to
the appropriate size for spraying. See also
milled
powder.
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debond.
An interface separation of a coating from a
substrate. See also
delamination.
defect.
A discontinuity or discontinuities that by
nature or accumulated effect render a part or
product unable to meet minimum applicable
acceptance standards or specifications. The term
designates rejectability. See also
discontinuity and
flaw.
degreasing.
The removal of grease and oil from a surface.
delamination.
The separation of a coating into constituent
layers. See also
debond.
de Laval nozzle.
A nozzle which converges to a throat and then
diverges to allow gas expansion and produce gas
acceleration.
delay time. A nonstandard term when used for
deposition delay.
demixing.
The act of segregating a powder mixture,
sometimes due to overmixing. See also
segregation.
deposit. A nonstandard term when used for
spray
deposit.
deposition.
The process of applying a sprayed material to a
substrate.
deposition delay.
The time interval from initiation of surface
treatment by the flow of particles to the
beginning of particle attachment to the
substrate.
deposition efficiency.
See
spraying deposition efficiency.
deposition rate.
The weight of material deposited in a unit of
time. Usually expressed as kilograms per hour
(kg/h) or pounds per hour [lb/h].
deposition sequence. A nonstandard term when
used for
spray deposit pass sequence.
deposit sequence. A nonstandard term when used
for spray
deposit pass sequence.
discontinuity.
An interruption of the typical structure of a
material, such as a lack of homogeneity in its
mechanical, metallurgical, or physical
characteristics. A discontinuity is not
necessarily a defect. See also
defect
and flaw.
dovetailing.
A method of surface preparation involving
angular undercutting to interlock the spray
deposit. See also
groove roughening, knurling, rotary roughening, and
rough
threading.
driving gas. See
spray
feedstock driving gas.
ductility.
The ability of a material to deform plastically
without fracturing.
duplex coating.
A coating consisting of two layers of two
dissimilar materials.
dust.
Fine dry pulverized particles. See also
particle
and
powder.
dynamic spray. A nonstandard term when used for
cold
gas-dynamic spray.
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edge loss.
Spray deposit lost as overspray beyond the edge
of the substrate.
elasticity.
The property of certain materials enabling them
to return to their original dimensions after an
applied stress.
electromagnetic pulse spray.
A solid-state spraying process using
electromagnetic force to propel spray feedstock
particles through a nozzle at very high
velocities towards a substrate where the
particles plastically deform and consolidate on
impact. See also
cold
gas-dynamic spray.
embrittlement.
The severe loss of ductility, toughness, or
both, of a material usually a metal or alloy.
erosion.
Removal of material from a surface due to
mechanical interaction between the surface and a
fluid, a multicomponent fluid, or impinging
liquid or solid particles.
erosion-corrosion.
Associated action involving corrosion and
erosion in the presence of a corrosive
substance.
etch.
To erode a material surface by chemical,
electrochemical, or mechanical means to
highlight microstructure or create a pattern.
exfoliation.
Corrosion proceeding laterally from the sites of
initiation along planes parallel to the surface,
generally at grain boundaries or coating
interfaces, forming corrosion products that
force metal or coating away from the body of the
material, giving rise to a layered appearance.
exhaust booth.
A system of individual units functioning
collectively to gather expended spray gases and
airborne materials while simultaneously flushing
and renewing the air in the working environment.
See also
spray chamber and
spraying
booth.
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fatigue.
A cumulative effect causing a material to fail
after repeated applications of stress none of
which exceeds the ultimate tensile strength.
fatigue strength.
The maximum cyclic stress a material can
withstand for a specified number cycles before
failure occurs.
fatigue wear.
Wear of a solid surface caused by fracture
arising from fatigue in the material.
feeder. See
powder feeder.
feed hopper.
A container used for holding and metering spray
feedstock for delivery to the spray device. See
also
powder feeder.
feed hopper pressure.
See
stagnation pressure.
feed rate.
The rate at which material passes through the
spray device in a given length of time.
feedstock. A nonstandard term when used for
spray
feedstock.
field spray deposit.
A spray deposit made at a location other than a
shop or the place of substrate fabrication.
fill bead. A nonstandard term when used for
intermediate spray deposit bead.
fill pass. A nonstandard term when used for
intermediate spray deposit pass.
filler.
A material added to a product to increase its
bulk, weight, viscosity, opacity, strength, or
simply to dilute it for economy.
filler bead. A nonstandard term when used for
intermediate spray deposit bead.
filler pass. A nonstandard term when used for
intermediate spray deposit pass.
fines.
The portion of a powder composed of particles
which are smaller than the specified size.
finish allowance.
The amount of excess coating left on the surface
for subsequent machining.
fixture.
A device for holding workpieces in proper
relation to each other.
flaw.
An undesirable discontinuity. See also
defect
and discontinuity.
flocculated powder.
Small lumps or loose clusters of loosely
aggregated particles. See also
agglomerated powder and
conglomerated powder.
flow rate.
The time required for a material of standard
weight or volume to flow through an orifice
according to a specific procedure.
flow stagnation temperature.
Temperature of the fluid flow at the compressed
layer. See also
room
stagnation temperature and
stagnation temperature.
fluidized bed.
A contained mass of finely divided solids
behaving like a fluid when brought into
suspension by a moving gas or liquid.
free jet.
The jet of spray feedstock-laden carrier gas
from the exit of the nozzle to the bow shock.
See also
bow shock and
compressed layer.
fretting wear.
Material loss resulting from a small amplitude
oscillatory motion between two solid surfaces in
contact.
fused and crushed powder.
Powder formed from a fused solid mass
subsequently crushed to the appropriate size for
spraying.
fused coatings.
A process in which the coating material is
deposited by spraying and then fused by post
heat treatment. This can be done by flame,
furnace, induction, laser, or resistance
heating.
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galvanic corrosion.
Accelerated corrosion of a metal because of an
electrical contact with a more noble metal or
nonmetallic conductor in a corrosive
electrolyte.
gas-dynamic spraying.
See cold
gas-dynamic spraying.
gas flow rate.
The flow rate of gas, typically in liters per
minute (lpm) [standard cubic feet per minute (scfm)],
through the spraying torch.
graded coating.
A sprayed deposit composed of mixed materials in
successive layers, progressively changing in
composition from the material immediately
adjacent to the substrate to that at the surface
of the sprayed deposit.
gradient coating. A nonstandard term when used
for
graded coating.
graduated coating. A nonstandard term when used
for
graded coating.
grain.
An individual crystal in a polycrystalline
material.
grain boundary.
A narrow zone corresponding to the transition
from one crystallographic orientation to
another, thus separating one grain from another.
granular powder.
A finely divided material having approximately
equidimensional but nonspherical, irregular
shaped powders.
grit.
Crushed ferrous or non-metallic abrasive
material in various mesh sizes used in abrasive
blasting to clean and/or roughen surfaces.
grit blasting.
A process using a pressurized stream of grit to
clean and roughen surfaces.
groove
roughening. A method of surface preparation in which grooves are made and the
original surface is roughened and spread. See
also dovetailing, knurling, rotary roughening, and
rough
threading.
gun. A nonstandard term when used for
surfacing gun.
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hardfacing.
The application of a cladding or coating of
material designed to resist wear. See also
buildup, buttering, and
cladding.
hardness test.
A test designed to assess the resistance to
penetration from a load. The surface is indented
under a defined load and the depth or area of
penetration is measured. See also
macrohardness and
microhardness.
hard surfacing. A nonstandard term for hardfacing.
helmet.
See
blast helmet.
heterogeneity.
The quality or state of being heterogeneous.
heterogeneous.
Made up of parts or elements, not unified,
compatible, or proportionate. See also
homogeneous.
high pressure.
In cold gas-dynamic spray typically taken to
mean the range of 2.5 MPa to 4 MPa [350 psi to
600 psi].
high-pressure cold gas-dynamic spray (CGSP-H).
A cold gas-dynamic spray process variation
employing high-pressure carrier gas and spray
feedstock injection before the nozzle throat.
See also
low-pressure cold gas-dynamic spray and
pulsed
cold gas-dynamic spray.
homogeneity.
The quality or state of being homogeneous.
homogeneous.
Of uniform structure or composition throughout.
See also
heterogeneous.
hood. A nonstandard term when used for blast hood.
hydrogen embrittlement.
Hydrogen-induced cracking or severe loss of
ductility caused by the presence of hydrogen in
the metal matrix.
hydrophilic.
Tending to absorb water.
hydrophobic.
Tending to repel water or lacking affinity for
water.
hypersonic.
Having a Mach number of greater than 5.0. Some
energy of the object goes into exciting the
chemical bonds of the fluid. See also
subsonic
and
supersonic.
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impingement.
A continuing succession of impacts between a
liquid or solid particles and a solid surface.
impingement angle. A nonstandard term when used
for spray
angle.
impingement corrosion.
A form of erosion-corrosion generally associated
with the impingement of a high velocity, flowing
liquid containing air bubbles against a solid
surface.
impingement zone. A nonstandard term when used
for
compressed layer.
impregnation.
A process of filling the pores of a material
with sealant.
impurity.
An unwanted minor constituent or one of an
unacceptable concentration level. See also
inclusion.
incident particles.
Those particles transferring most of their
potential energy to the substrate. See also
reflected
particles.
inclusion.
Entrapped
foreign solid material or a physical
discontinuity within a material.
induction time.
See
deposition delay.
inert gas.
A stable gas that does not support combustion
and does not form reaction products with other
materials. Included are helium, argon, and
sometimes nitrogen.
injection angle. See
spray
feedstock injection angle.
interconnected porosity.
A network of pores in and extending to the
surface of a coating.
intergranular corrosion.
Corrosion occurring preferentially at grain
boundaries.
intermediate spray deposit bead.
The spray deposit resulting from an intermediate
spray deposit pass.
intermediate spray deposit pass.
A spray deposit pass within a cross-sectional
sequence lying between the first spray coating
pass or layer and the cover pass or layer.
internal energy.
The sum of an objects kinetic and potential
energies. See also
kinetic energy and potential
energy.
internal oxidation.
The formation of isolated particles of corrosion
products beneath the surface of the metal or
coating as a result of preferential oxidation of
certain alloy constituents.
ionic bond.
A primary bond arising from the electrostatic
attraction between two oppositely charged ions.
See also
bonding force,
covalent
bond,
mechanical bond, and
metallic
bond.
irregular powder.
Finely divided particles lacking symmetry. See
also nodular powder.
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jet.
A forceful stream of fluid discharged from a
narrow opening or a nozzle.
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kinetic energy.
The energy a substance possesses by virtue of
its velocity of motion. See also
internal
energy and
potential
energy.
kinetic spray. A nonstandard term when used for
the cold
gas-dynamic spray process.
knurling. A method of surface preparation in which the surface is upset with a
knurling tool. See
also
dovetailing, groove roughening, rotary roughening, and
rough
threading.
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page
laval
nozzle.
See de
Laval nozzle.
layer.
A stratum
of spray deposit consisting of one or more spray
deposit beads.
linear discontinuity.
A discontinuity with a length substantially
greater than its width.
localized corrosion.
Corrosion at discrete sites, for example,
pitting, crevice corrosion, and stress corrosion
cracking.
low pressure.
In cold gas-dynamic spray typically taken to
mean the range of 0.5 MPa to 1 MPa [70 psi to
145 psi]
low-pressure cold gas-dynamic spray (CGSP-L).
A cold gas-dynamic spray process variation
employing low-pressure carrier gas and spray
feedstock injection after the nozzle throat. See
also
high-pressure
cold gas-dynamic spray and
pulsed cold gas-dynamic spray.
lubricant.
Any substance interposed between two surfaces
for the purpose of reducing the friction or wear
between them.
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Mach number.
The speed of an object relative to a fluid
medium divided by the speed of sound in the
medium. See also
hypersonic,
subsonic,
and supersonic.
macrograph.
A graphic reproduction of the image of an object
as seen by the naked eye.
macrohardness.
The result of a hardness test performed on a
macroscopic scale to show the bulk property of a
material. See also
microhardness.
manual spraying.
A spraying operation with the surfacing gun held
and manipulated by hand. Accessory equipment,
such as part motion devices may be used. See
also
automatic spraying,
mechanized spraying,
robotic
spraying and
semiautomatic spraying.
mask.
A material or device used to conceal or screen
from a process.
matrix.
The continuous phase of a material or coating in
which separate particles of another constituent
are embedded.
maximum substrate velocity.
The substrate velocity above which substrate
activation is insufficient to facilitate
particle attachment. See also
substrate
velocity.
mean particle size. The equivalent average spherical particle size.
See also
particle size.
mechanical bond.
The adherence by interlocking such as a spray
deposit to a roughened surface. See also
bonding
force,
covalent bond, ionic bond,
and
metallic bond.
mechanized spraying.
An operation with equipment requiring manual
adjustment by an operator in response to visual
observation, with the surfacing gun held by a
mechanical device. See also
automatic
spraying,
manual
spraying,
robotic spraying, and
semiautomatic spraying.
mesh size. The
designated openings in a sieve or screen. See
also
minus sieve and
plus
sieve.
|
US Sieve Size
|
Tyler Equivalent
|
Opening
|
|
mm
|
in
|
|
No. 120
|
115 Mesh
|
0.125
|
0.0049
|
|
No. 140
|
150 Mesh
|
0.105
|
0.0041
|
|
No. 170
|
170 Mesh
|
0.088
|
0.0035
|
|
No. 200
|
200 Mesh
|
0.074
|
0.0029
|
|
No. 230
|
250 Mesh
|
0.063
|
0.0025
|
|
No. 270
|
270 Mesh
|
0.053
|
0.0021
|
|
No. 325
|
325 Mesh
|
0.044
|
0.0017
|
|
No. 400
|
400 Mesh
|
0.037
|
0.0015
|
metal.
An opaque, lustrous, elemental chemical substance that is a good
conductor of heat and electricity, usually
malleable, ductile, and more dense than other
elemental substances.
metallic bond.
The primary bond holding metals together arising
from the increased spacing of valence electrons
when an aggregate of metal atoms are in close
proximity. See also
bonding
force,
covalent bond, ionic bond,
and
mechanical bond.
metallizing. A nonstandard term when used for
spraying or the application of a metal spray
deposit.
metal-matrix composite.
A material with nonmetallic reinforcement
incorporated in the metallic matrix. The
reinforcement may constitute from 10% to 60% of
the material. Example reinforcements include
graphite, silicon carbide, and refractory
metals.
micrograph.
A graphic reproduction of the image of an object
formed by a microscope.
microhardness.
The result of a hardness test performed on a
microscopic scale to determine the property of
individual phases within a material and avoid
the effects of porosity. See also
macrohardness.
microinch.
One millionth of an inch (0.000001 in) [.0000254
mm].
micrometer (µm).
One millionth of a meter (0.001 mm) [0.0003937
in].
micron.
See micrometer.
microtrack.
A device for measuring powder particle size
distributions.
mil.
One thousandth of an inch (0.001 in) [0.0254
mm].
milled powder.
Powder or powder mixtures having received the
mechanical treatment, such as by ball milling,
to alter the size or shape of the individual
particles or to coat one component of the
mixture with another. See also
crushed
powder.
minus sieve.
The portion of a powder sample passing through a
standard sieve of specified mesh size. See also
plus
sieve.
mixed powder.
Thoroughly intermingled powder of different
materials. See also
blended powder.
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nanostructured powder.
Particles displaying grains or phases whose
average size is less than 200 nm.
nodular powder.
Finely divided particles having a regular shape.
See also
irregular powder.
nozzle.
See spray nozzle.
nozzle
accumulation.
Filler metal or surfacing material deposited on the inner surface and on
the exit end of the nozzle.
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orifice. The portion of the nozzle containing the
throat.
orifice
throat length.
The length of the constricting orifice.
overspray. The
portion of the spray feedstock not deposited on
the substrate.
oxidation.
Loss of electrons by a constituent of a chemical
reaction, or the corrosion of a metal exposed to
an oxidizing gas at elevated temperatures.
oxidizing.
An environment or material promoting oxidation.
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particle.
The smallest discrete portion of a powder. See
also dust
and
powder.
particle shape.
The appearance of any particle. Common shapes
include spherical, rounded, angular, acicular,
dendritic, irregular, porous, fragmented,
blocky, rod, flake, nodular, or plate.
particle size.
The controlling lineal dimension of an
individual particle as determined by analysis
with sieves or other suitable means. See also
mean particle size.
particle size distribution.
The percentage by weight or by number of each
particle size in the powder sample.
particle volume concentration.
The ratio of particle volume to carrier gas
volume in the surfacing spray. Usually expressed
in m3/m3.
pass.
See
spraying pass.
pass sequence.
See cross-sectional sequence.
passivation.
The process in metal corrosion by which metals
become passive.
passive.
The state of a metal surface characterized by
low corrosion rates in a potential region
strongly oxidizing for the metal.
peening,
blasting. Blasting process using shot or spherical shaped beads, for
cleaning and/or modifying surface properties.
peening,
mechanical.
The mechanical working of metals using impact blows.
permeability.
The rate of passage of a liquid or gas through a
solid material.
pitting.
Small localized cavities caused by corrosion,
wear, or other mechanically assisted degradation
of a surface.
plastic deformation.
The permanent distortion of solid materials
under applied stresses straining the material
beyond its elastic limit.
plus sieve.
The portion of a powder sample retained on a
sieve of specified mesh size. See also
minus
sieve.
polishing.
The smoothing of a material surface by means of
the action of abrasive particles attached
usually to a fabric cloth.
pore.
A small opening, void, or channel within a
solid. See also
pull-out.
pore size.
The largest dimension of a pore.
porosity.
The presence of pores, usually expressed as a
percentage by volume.
potential energy.
The stored energy a substance possesses because
of its position or arrangement of its parts. See
also
internal energy and
kinetic
energy.
powder.
A material manufactured into finely divided
particles. See
spray
feedstock. See also
dust
and
particle.
powder alloy.
A powder prepared from a homogeneous molten
mixture of elements. See also
powder
blend and
powder composite.
powder blend.
A powder mixture of two or more alloy powders.
See also
powder alloy and powder
composite.
powder composite.
A powder in which each particle consists of two
or more distinct materials joined together as by
chemical cladding, mechanical agglomeration, or
by spray drying. See also
powder
alloy and
powder
blend.
powder constituent.
The various components of the powder mixture.
powder feeder.
A mechanical device designed to introduce a
controlled flow of powder to the spray device.
See also
feed hopper.
powder injection angle.
See spray
feedstock injection angle.
powder port.
See spray
feedstock port.
pre-alloyed powder.
A powder composed of two or more elements
alloyed in the powder manufacturing process and
in which the particles are of the same nominal
composition throughout.
preheat.
The heat applied to the substrate to remove
moisture, minimize thermal shock effects,
improve deposition efficiency, or enhance bond
strength.
procedure.
The detailed elements of a process or method used to produce a specific
result.
process. A grouping of basic operational elements.
protective atmosphere.
A gas or vacuum envelope present during joining, thermal cutting, or
thermal spraying, used to prevent or reduce the
formation of oxides and other detrimental
surface substances, and to facilitate their
removal.
pull-out.
A surface discontinuity where particles are
forcibly extracted from the coating surface
during finishing. See also
pore.
pulsed cold gas-dynamic spray (CGSP-P).
A cold gas-dynamic spray process variation
employing a shutter to generate high-pressure
carrier gas shock waves to propel spray
feedstock through a nozzle. See also
high-pressure
cold gas-dynamic spray and
low-pressure cold gas-dynamic spray.
purge. The introduction of a gas to remove contaminants from a system.
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rate of
deposition.
See deposition rate.
reducing
atmosphere.
A type of protective atmosphere dissociating metal oxides at elevated
temperatures.
reflected particles.
Those particles not reaching the critical
velocity of the spray feedstock or are deflected
to a spray path less than the critical spray
angle. See also
incident
particles.
residual
stress.
Stress present in a material free of external forces or thermal
gradients.
robotic spraying.
A spraying operation with equipment moving along
a controlled path using controlled parameters
with no manual intervention once a cycle is
initiated. See also
automatic spraying, manual spraying, mechanized
spraying, and semiautomatic spraying.
room stagnation temperature.
The ambient temperature of the spray chamber.
See also
flow stagnation temperature and
stagnation temperature.
rotary
roughening. A method of surface preparation in which a revolving tool is pressed
against the surface being prepared, while either
the work or the tool, or both, move. See also
dovetailing,
groove
roughening, knurling, and
rough
threading.
rough
threading. A method of surface roughening consisting of cutting threads with the
sides and tops of the threads jagged and torn.
See also
dovetailing, groove
roughening, knurling, and
rotary
roughening.
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sacrificial coating.
A coating providing corrosion protection wherein
the coating material corrodes in preference to
the substrate.
sand.
A granular material resulting from the
disintegration or crushing of rocks or minerals.
sandblasting.
Abrasive blasting with sand.
scale.
Loosely adherent layers of corrosion products
resulting from surface oxidation.
scoring.
A severe form of wear characterized by the
formation of extensive grooves and scratches in
the direction of sliding.
scratching.
The mechanical removal, displacement, or both,
of material from a surface by the action of
abrasive particles or protuberances sliding
across the surface.
seal coat.
Material applied to infiltrate and close the
pores of a spray deposit.
sealant.
A preparation of resin or wax type materials for
sealing the porosity in coatings.
sealer.
See sealant.
sealing.
A process which increases the resistance to
corrosion of the underlying substrate material.
segregation,
powder. Separation of powder particles by size, shape, or
composition. See also
demixing.
semiautomatic spraying.
A spraying operation performed manually with
equipment controlling one or more of the process
conditions. See also
automatic
spraying,
manual
spraying,
mechanized spraying, and
robotic
spraying.
shadow mask.
A spraying technique in which an area is
partially shielded during spraying thus
permitting a feathering of the spray deposit at
the coating edge. A common technique is to raise
the mask above the substrate.
shielding gas.
A gas used to produce a protective atmosphere.
shock wave.
A propagation disturbance within a solid,
liquid, or gas medium across which there is a
finite decrease in velocity and large and abrupt
rise in pressure, temperature, and density of
the flow. See also
bow shock.
shot peening.
The bombardment of a component surface with
steel or ceramic shot to produce a residual
compressive stress in the surface and improve
fatigue and stress corrosion performance.
shrinkage.
A decrease in dimensions of a coating during
processing.
shrinkage stress. A nonstandard term when used for residual
stress.
sieve classification.
Portion of a powder sample passing through a
standard sieve of a specified number and
retained by some finer sieve of a specified
number.
size analysis.
Analysis of the size of the particles being
deposited by spraying processes.
size distribution.
The distribution of sizes within a size
analysis. The distribution may be normal or
skewed in some way due to the powder
manufacturing process.
smoothing
bead. A spray deposit bead made to correct an undesirable spray deposit
surface contour. See also cosmetic spray
deposit bead.
smoothing
pass.
A spray deposit pass resulting in a smoothing bead. See also cosmetic
spray deposit pass.
solid-state spraying.
A group of spray processes applying surfacing
materials without melting. See also
cold
gas-dynamic spray and
electromagnetic powder spray.
spalling.
The chipping, fragmentation, or separation of a
surface.
splat.
A single thin flattened sprayed particle.
spray.
A jet of vapor or finely divided liquid.
spray,
v. The act of spraying.
spray angle.
The angle of particle impingement on the
substrate. See also
critical spray angle.
spray booth. A nonstandard term when used for
spraying
booth.
spray chamber.
An enclosed space in which the spraying process
is confined. See also
exhaust
booth and
spraying booth.
spray chamber temperature.
See room
stagnation temperature.
spray deposit.
The substrate coating or layer of surfacing
material applied to a substrate.
spray deposit bead.
A spray deposit resulting from a spraying pass.
spray deposit density ratio.
The ratio, usually expressed as a percentage, of
the determined density to the theoretical
density of the coating material. See also
determined density and
theoretical coating.
spray
deposit interface.
The boundary between the spray deposit and the substrate.
spray deposit pass sequence.
The order in which the surfacing gun is
manipulated relative to the substrate to apply
the desired spray deposit.
See block sequence,
cascade sequence,
continuous sequence, and cross-sectional
sequence.
spray deposit strength.
A measure, usually expressed in kPa (psi), of
the cohesive bonding within a spray deposit. See
also
adhesive strength.
spray distance.
The distance maintained between the surfacing
gun nozzle tip and the substrate surface.
spray feedstock.
Any consumable form of spray material used in
the application of a coating.
spray feedstock driving gas.
A pressurized gas applied to the spray feedstock
to facilitate its flow into the surfacing gun.
spray feedstock injection angle.
The angular measurement between the carrier gas
axis and the axis of spray feedstock
introduction.
spray feedstock port.
The aperture through which powder is introduced
into the spraying apparatus.
spray force.
The axial force developed by a spray jet.
spray forming.
The fabrication of free standing shapes by the
deposition of material onto a substrate.
spray gun. A nonstandard term when used for
surfacing
gun.
spray nozzle.
Portion of the spray device through which the
spray is shaped and projected.
spray surfacing.
A group of surfacing processes applying material
to a substrate by spraying. See also
solid-state spraying and
thermal
spraying.
sprayer.
One who
performs semiautomatic spraying. See also
spraying
operator.
spraying
booth.
An exhaust booth where spray surfacing is performed. See also
exhaust
booth and
spray chamber.
spraying deposition efficiency.
The ratio, usually expressed in percent, of the
weight of spray deposit to the weight of the
material sprayed.
spraying induction time. A nonstandard term when
used for
deposition delay.
spraying
operator. One who operates automatic, mechanized, or robotic spray surfacing
equipment. See also
sprayer.
spraying
pass.
A single progression of the surfacing gun across the substrate surface
resulting in a spray deposit bead or layer.
spraying pass sequence. A nonstandard term when
used for
spray deposit pass sequence.
spraying sequence.
The order in which layers of materials are
applied in a planned relationship such as
overlapped, superimposed, or at various angles.
See also
spray deposit pass sequence.
stagnation point.
The point at which the fluid flow comes to rest
and kinetic energy is converted into internal
energy.
stagnation pressure.
The pressure a gas would exhibit if brought to
zero velocity by an isentropic process.
Generally used to refer to the fluid pressure in
the pre-chamber.
stagnation temperature.
Temperature of the fluid flow at the stagnation
point. See also
flow
stagnation temperature and
room
stagnation temperature.
stand-off distance. A nonstandard term when used
for spray
distance.
strain.
A measure of the extent to which a body is
deformed when it is subjected to a stress.
stress.
The force per unit area on body tending to cause
it to deform. It is a measure of the internal
forces in a body between particles of the
material of which it consists as they resist
separation, compression, or sliding.
stress corrosion cracking.
A cracking process requiring the simultaneous
action of a corrosive and sustained tensile
stress.
subsonic.
Having a Mach number of less than 1.0. See also
supersonic and
hypersonic.
substrate.
The parent or base material to which the coating
is applied.
substrate activation.
Cleaning and roughening of the substrate surface
due to particle impingement.
substrate velocity.
The speed of the substrate relative to a
stationary spray nozzle. See also
maximum
substrate velocity.
supersonic.
Having a Mach number of greater than 1.0. High
supersonic speeds are those between 3 and 5. See
also
subsonic and
hypersonic.
surface preparation.
Cleaning and roughening of the surface to be
sprayed to improve the adhesion of the coating
to the substrate.
surface
roughening. A group of methods for producing irregularities on a surface. See also
dovetailing, groove roughening,
knurling,
rotary roughening, and rough
threading.
surface topography.
The geometrical detail of a surface, relating
particularly to microscopic variations in
height.
surface void.
A void which is located at the surface of a
coating.
surfacing.
The application by welding, brazing, or spray
surfacing of a layer, or layers, of material to
a surface to obtain desired properties or
dimensions, as opposed to making a joint. See
also
buildup,
buttering, cladding, and
hardfacing.
surfacing gun.
A device used to apply energy to spray feedstock
and direct the resulting surfacing spray towards
a substrate.
surfacing
material.
The material applied to a base metal or substrate during surfacing. See
also
surfacing metal.
surfacing
metal.
The metal or alloy applied to a base metal or substrate during surfacing.
See also
surfacing material.
surfacing spray.
The jet of surfacing material and any
corresponding carrier fluid.
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tensile strength.
A measure of the resistance a material offers to
tensile stress. It is defined as the stress
required to break the material, and expressed as
the force per unit cross sectional area.
tensile stress.
Axial forces per unit area applied to a body
tending to extend it.
theoretical density.
The density of a solid homogeneous piece of
material.
thermal barrier coating.
A coating forming an insulating barrier to a
heat source to protect the substrate.
thermal spray deposit.
A spray deposit created with a thermal spray
process.
thermal spraying (THSP).
A group of processes in which finely divided
metallic or nonmetallic surfacing materials are
deposited in a molten or semimolten condition on
a substrate to form a thermal spray deposit. The
surfacing material may be in the form of powder,
rod, cord, or wire.
throat.
The point or region in the fluid flow passage
having the minimum cross-sectional area.
tribology.
The science and technology concerned with
interacting surfaces in relative motion.
two-phase flow.
A flow consisting of two different phases of
material, for example of both gas and solid
phases.
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undercoat.
A deposited coat of material acting as a
substrate for a subsequent spray deposit.
undercutting.
A surface preparation step involving the removal
of substrate material.
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vacuum cold spray. A nonstandard term when used
to describe execution of the cold gas-dynamic
spray process in a vacuum environment.
vapor.
The gaseous form of substances normally present
in a solid or liquid state.
venturi.
A region in a fluid flow passage where flow is
constricted to increase the velocity of fluid.
This region encompasses the tapering
constriction, the throat, and the diverging
section before the nozzle tube.
virgin material.
A material not subjected to any processing other
than its original manufacture.
void.
A shrinkage cavity produced during spraying or
solidification.
void content.
The volume percentage of voids.
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wear.
Loss of material from a surface by means of some
mechanical action. See also
abrasive
wear,
cavitation erosion,
erosion,
fatigue wear, fretting wear,
and
scoring.
workpiece.
An assembly, component, member, or part being altered by a manufacturing
process.
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