Glossary

Abrasive Blasting

See preferred term Blasting.

Abrasive

Material such as sand, crushed chilled cast iron, crushed steel grit, aluminum oxide, silicon carbide, flint, garnet, of crushed slag used for cleaning or surface roughening.

Absorb.

To take in and engulf wholly.

Absorptive Lens (eye protection).

A filter lens designed to attenuate the effects of glare and reflected and stray light. See Filter Plate.

Acoustical Room

A soundproof enclosure, containing thermal spraying and sometimes related auxiliary equipment. Its design and construction prevent any unacceptable process noises from interfering with normal work in the environment surrounding the enclosure.

Adhesion

A binding force that holds together molecules of substances whose surfaces are in contact or near proximity.

Adhesive Strength

The magnitude of attractive forces, generally physical in character, between a coating and substrate. Two principle interactions that contribute to the adhesion are van der Waals forces and permanent dipole bonds.

Adsorb

To take in on the surface.

Air Cap

A device for forming, shaping and directing an air flow pattern for the atomization of wire or ceramic rod.

Air Cooler

See preferred term Workpiece Cooler.

Air Feed

A thermal spraying process variation in which an air stream carries the powdered surfacing material through the gun and into the heat source.

Air Filter

Mechanism for cleaning air of contaminants such as water, oil, and solid matter.

Alumina

A chemical compound (aluminum oxide);a ceramic used in powder or rod form in thermal spraying operations. May also be a blasting medium.

Anchoring

A supplemental method of locking the thermal spray deposit to the substrate by screw heads, studs, or similar means.

Anode

The electrode maintained at a positive electrical potential. In typical plasma thermal spraying gun designs, this is the front electrode, constructed as a hollow nozzle and usually fabricated from copper. In electric arc thermal spraying guns, one feed wire is the positive electrode.

Apparent Density Ratio

The ratio of the measured density of an object to the absolute density of a perfectly solid material of the same composition, usually expressed as a percentage.

Apparent Density Ratio

The ratio of the measured density of an object to the absolute density of a perfectly solid material of the same composition, usually expressed as a percentage.

Arc

A luminous discharge of electrical current crossing the gap between two electrodes.

Arc Chamber

The confined space within the plasma thermal spraying gun enclosing the anode and cathode, in which the arc is struck.

Arc Chamber

The confined space within the plasma thermal spraying gun enclosing the anode and cathode, in which the arc is struck.

Arc Force

The axial force developed by an arc plasma.

Arc Gas

The gas introduced into the arc chamber and ionized by the arc to form a plasma.

Are Gas

Primary. See preferred term Primary Gas.

Arc Gas

Secondary. See preferred term Secondary Gas. Arc Plasma. A gas that has been heated by an electric arc to at least a partially ionized condition, enabling it to conduct an electric current.

Arc Spraying (ASP)

A thermal spraying process using an arc between two consumable electrodes of surfacing materials as a heat source and a compressed gas to atomize and propel the surfacing material to the substrate.

Atomization

(1) The division of molten material at the end of the wire or rod into fine particles. (2) The process used in the manufacture of powder.

Auxiliary Cooler

A device used to direct compressed air to prevent overheating of the thermal spraying deposit or the substrate.

Backfire

The momentary recession of the flame into the spray gun, followed by immediate reappearance or complete extinction of the flame.

Base Material

See preferred term Substrate

Base Metal

See preferred term Substrate

Berry Formation.

See preferred term Nozzle Accumulation.

Blasting

A method of cleaning or surface roughening by a forcibly projected stream of sharp angular abrasive.

Body Stress

Residual stresses within an individual sprayed particle.

Bond

See Mechanical Bond and Metallic Bond.

Bond Cap (Bond Bar)

The test specimen on which a spray coating is applied for the purpose of determining adhesive-cohesive strength.

Bond Coat

A preliminary (or prime coat) of material that improves adherence of the subsequent spray deposit.

Bonding Force

The force that holds two atoms together; it results from a decrease in energy as two atoms are brought closer to one another.

Bond Line

The interface between a thermal spraying deposit and substrate, or between adhesive and adherent in an adhesive bonded joint.

Bond Strength

The force required to pull a coating free of a substrate, usually expressed in kPa (psi).

British Thermal Unit (BTU)

A unit of measure for heat (equal to 1055 J).

Buildup

A surfacing variation in which surfacing metal is deposited to achieve the required dimensions.

Burnoff Rate

A nonstandard term for melting rate.

Cap

See preferred term Nozzle or Air Cap.

Carbide

A chemical compound formed between carbon and a metal or metals; examples are tungsten carbide, tantalum carbide, titanium carbide, chromium carbide.

Carburizing Flame

A nonstandard term for reducing flame.

Carburizing Flame

A nonstandard term for reducing flame.

Carrier Gas

The gas used to carry powdered material from the powder feeder or hopper to the gun.

Cast

The twist warp or curvature of a metal wire.

Cathode

The electrode maintained at a negative electric potential. In a plasma gun it is usually the rear electrode, conically shaped, and fabricated from tungsten or thoriated tungsten.

Ceramic Rod Flame Spray Gun

A flame spraying device wherein an oxyfuel gas flame provides the beat, and the surfacing material to be sprayed is in ceramic rod form.

Ceramic Rod Flame Spraying

A thermal spraying process variation in which the material to be sprayed is in ceramic rod form. See Flame Spraying (FLSP).

Ceramic Rod Speed

The length of ceramic rod sprayed in a unit of time.

Cermet

A physical mixture of ceramics and metals; examples are alumina plus nickel and zirconia plus nickel.

Cladding

A surfacing variation that deposits or applies surfacing material, usually to improve corrosion or heat resistance.

Clad Metal

A laminar composite consisting of a metal, with a metal of different chemical composition applied to one or two sides.

Clad Powder

See preferred term Powder Clad.

Clad Powder

See preferred term Powder Clad.

Closed Loop Control

A method to continuously monitor and control thermal spray parameters to assure repeatability of the process and coatings.

Coalesce

To grow or come together; fuse; unite.

Coating

(1) The act of building a deposit on a substrate, (2) the spray deposit.

Coating Density

A nonstandard term for spray deposit density ratio.

Coating Strength

(1) A measure of the cohesive bond within a coating, as opposed to coating-to-substrate bond (adhesive strength), (2) the tensile strength of a coating, usually expressed in kPa

Coating Stress

The stresses in a coating resulting from rapid cooling of molten material or semimolten particles as they impact the substrate.

Coefficient of Thermal Expansion

The ratio of the change in length per degree rise in temperature to the length at a standard temperature such as 200C (680F).

Cohesive Strength

See Coating Strength.

Collaring

Adding a shoulder to a shaft or similar component as a protective confining wall for the thermal spray deposit.

Combination Aftercooler/Dryer

A deliquescent desiccant dryer with an integral aftercooler.

Companion Panel

A small tab coated concurrently with the workpiece, used for inspection.

Composite Coating

A coating consisting of two or more dissimilar spray materials which may or may not be layered.

Composite Powder

See preferred term Powder Composite.

Compressed Air Mask

A force feed type of face mask with a suitable regulator worn by the thermal spraying operator to provide a fresh air supply.

Cone.

The conical part of an oxyfuel gas flame next to the orifice of the tip.

Contact Tube

A device which transfers current to a continuous electrode.

Control Console

The instrumented unit from which the gun is operated and operating variables are monitored and controlled.

Controlled Atmosphere Chamber

An enclosure or cabinet either filled with an inert gas or evacuated to below atmospheric pressure in which thermal spraying can be performed to minimize, or prevent, oxidation of the coating or substrate.

Cooler

See preferred term Workpiece Cooler.

Cord

A plastic tube tilled with powder, and extruded to form a compact, flexible layer level wound wire-like "cord."

Cospray

Thermal spraying of two or more dissimilar materials through a single gun using multiple powder injection ports.

Critical Resolved Shearing Stress

The shearing stress on the slip plane necessary to produce slip (threshold value).

Cubicle

See preferred term Acoustical Room.

Cylinder

See Gas Cylinder.

Cylinder Manifold

A multiple header for interconnection of gas or fluid sources with distribution points.

Defect

A discontinuity or discontinuities that by nature or accumulated effect (for example, total crack length) render a part or product unable to meet minimum applicable acceptance standards or specifications. See also Discontinuity and Haw.

Degrease

To remove oil or grease from the surface of the workpiece. See Solvent Degreasing.

Deliquescent

The process of melting or becoming liquid by absorbing moisture from the air.

Deliquescent Desiccant Dryer

A pressure vessel containing a collection chamber and a drying desiccant. It has no moving parts, and normally produces a IOOC (500F) dewpoint or lower. Density. The mass or quantity of matter of a substance per unit volume, expressed as grams per cubic centimeter, or pounds per cubic inch.

Density Ratio

See Apparent Density Ratio.

Deposit.

A nonstandard term for thermal spraying deposit.

Deposition Efficiency

The ratio, usually expressed in percent, of the weight of spray deposit to the weight of the material sprayed

Deposition Rate

The weight of material deposited in a unit of time.

Desiccant

A chemical used to attract and remove moisture from air or gas.

Detonation Flame Spraying

A thermal spraying process variation in which the controlled explosion of a mixture of fuel gas and oxygen is utilized to melt and propel the material to the workpiece.

Dewpoint.

Temperature at which moisture will condense from humid vapors into a liquid state.

Discontinuity

An interruption of the typical structure of a coating, such as a lack of homogeneity in the mechanical, metallurgical, or physical characteristics of the material. A discontinuity is not necessarily a defect. See also Defect and Flaw.

Dovetailing

A method of surface roughening involving angular undercutting to interlock the spray deposit.

Dwell Time

The length of time the spray material is exposed to the heat zone which produces and sustains a molten condition.

Ear Protection

OSHA or other safety agency approved devices for the reduction of sound audible to the outer ear.

Edge Effect

Loosening of the adhesional bond between the spray deposit and the substrate at the workpiece edges.

Edge Loss

Spray deposit lost as overspray resulting from spraying near the edge of the workpiece.

Elastic Modulus

The ratio of stress, within the proportional limit, to the corresponding strain

*Electric Arc Spraying

A nonstandard term for arc spraying.

Electrode

A component for the electrical circuit through which current is conducted to the arc. See Anode and Cathode.

Enclosure

See preferred term Acoustical Room.

Endothermic Compounds

Beads and tablets which absorb moisture from the air and are consumed in the process.The action is termed deliquescence. Beads used are inorganic with absorption capability to reduce dewpoints 5.5'C (42'F) at an inlet temperature of 38'C (IOO'F), and -2.8'C (27'F) -at an inlet temperature of 21 'C (70'F).Beads or tablets utilized are of two types: potassium carbonate and sodium chloride.

*Exhaust Booth.

A mechanically ventilated, seniienclosed area in which air flow across the work area is used to remove fumes, gases, and solid particles.

Face Shield (eye protection)

A device positioned in front of the eyes and over all or a portion of the face to protect the eyes and face. See also Hand Shield and Helmet.

Feed Rate

A nonstandard term for spray rate.

Filter Glass

A nonstandard term for filter plate.

Filter Lens (eye protection)

A round filter plate.

Filter Plate (eye protection)

An optical material that protects the eyes against excessive ultraviolet, infrared, and visible radiation.

Fines

A material finer than a particular mesti size under consideration.

Flame Spraying (FLSP)

A thermal spraying process in which an oxyfuel gas flame is the source of heat for melting the surfacing material. Compressed gas may or may not be used for atomizing and propelling the surfacing material to the substrate.

Flashback

A recession of the flame into or back of the mixing chamber of the thermal spraying gun.

Flashback Arrester

A device to limit damage from a flashback by preventing propagation of the flame front beyond the location of the arrester.

Flaw

An undesirable discontinuity. See Defect.

Flow Meter

A device for indicating the rate of gas flow in a system.

Fretting

Surface damage resulting from relative motion between surfaces in contact under pressure.

Fuel Gases

Gases such as acetylene, natural gas, hydrogen, propane, stabilized methylacetylene propadiene, and other fuels, and hydrocarbons, usually used with oxygen for heating.

Furnace Fusing

T'he melting together of the spray deposit and the substrate which results in coalescence. The furnace offers the advantages of controlled heating, cooling, and protective atmosphere.

Fusion

The melting together of filler metal and metal (substrate), which results in coalescence.

Fusion Temperature

In thermal spraying, during the fusing of self-fluxing coatings, the narrow temperature range within which the coating surface exhibits a glassy or highly reflective appearance.

Galvanic Corrosion.

Corrosion causedby spontaneous current between two dissimilar conductors in an electrolyte or between two dissimilar conductors in dissimilar electrolytes. If the two dissimiIar metals are in contact, the reaction is referred to as couple action.

Gas Cylinder

A portable container used for transportation and storage of a compressed gas.

Gas Pocket

A nonstandard term for porosity.

Gas Regulator

A device for controlling the delivery of gas at some substantially constant pressure.

Gradated Coating

A thermal spraying deposit composed of mixed materials in successive layers which progressively change in composition from the constituent material lot the, substrate to the surface of the sprayed deposit. Also referred to as graduated or graded coating

Gravity Feed

A process by which powder is fed into a thermal spraying gun by gravity,

Grit

See preferred term Abrasive.

Grit Blasting

See preferred term Blasting.

Grit Size

The particle size and distribution of abrasive blasting grains. Usually expressed by Society of Automotive Engineers numbers, such as SAE G25.

Groove and Rotary Roughening

A method of surface roughening in which grooves are made and the original surface is roughened and spread.

Gun

A nonstandard term for thermal spraying gun.

Gun Extension

The extension tube attached in front of the thermal spraying gun to permit spraying within confined areas or deep recesses

Hand Shield

A protective device for shielding the eyes, face, and neck. A hand shield is equipped with a filter plate and is designed to be held by hand.

Hardfacing

A surfacing variation in which surfacing metal is deposited to reduce wear.

Helmet

A device designed to be worn on the head to protect eyes, face, and neck from arc radiation, radiated heat, spatter, or other harmful matter.

HVOF/HVAF (High Velocity Oxygen Fuel/High Velocity Air Fuel)

A high velocity flame spray process

Inert Gas

A gas which does not normally combine chemically with the substrate or the deposit. Typical examples are argon and helium

Injection Angle

Angle at which powder is injected into flame. Powder injected at 0 is injected perpendicular to the flame. Positive angles indicate injection in direction of flame; negative angles in direction against flame.

Eye Protection

Proper helmets, face masks, or goggles which are required to be used to protect the eyes from ultraviolet and infrared radiation during thermal spraying operations.

Interface

The contact surface between the spray deposit and the substrate.

Interpass Temperature

In multiple pass thermal spraying, the temperature (minimum or maximum as specified) of the deposited spray coating before a subsequent pass is started

Ion

An atom or group of atoms forming a molecule that carries a positive or negative charge as a result of having lost or gained one or more electrons.

Ionic Bond

A primary bond arising from the electrostatic attraction between two oppositely charged ions.

Jet pulverizer

A machine that comminutes metal pieces, ores, or agglomerates.

Jig

Mechanism or fixture for holding a part and/or guiding the tool during machining, spraying or assembly operation.

Joint

The location where two or more members meet, are to be met, or have been fastened together.

Joint clearnance

The distance between the faying surfaces of a joing.

Joint design

Joint deometry, including the required dimensions of the welded/brazed/bonded joint.

Joint geometry

The shape and dimensions of a joint in cross section.

Journal

The part of a shaft or axle that rotates or oscillates relative to a radial bearing. A journal is part of a larger unit, such as a crankshaft. It is preferred that the term "shaft" be kept for the whole unit.

Keying

A nonstandard term for mechanical bond.

Knurling

See Groove and Rotary Roughening, Threading and Knurling.

Lamella

A thin layer, as in the overlayed particles in a thermal spray deposit.

Lamination

See preferred term Lamella.

Lens

See Filter Lens.

Locked-up Stress

A nonstandard term for residual stress.

Low Pressure Plasma Spray

See preferred term Vacuum Plasma Deposition.

Manifold

See Cylinder Manifold.

Mask

A device for protecting a substrate surface from the effects of blasting or adherence of a spray deposit.

Matrix

The major continuous substance of a thermal spraying coating as opposed to inclusions or particles of materials having dissimilar characteristics.

Mechanical Bond

The adherence of a thermal spraying deposit to a roughened surface by the mechanism of particle interlocking.

Melting Rate

The weight or length of spray wire or rod melted in a unit of time.

Metallic Bond

The principal bond that holds metals together and is formed between base metals and filler metals in all processes. This is a primary bond arising from the increased spatial extension of the valence electron wave functions when an aggregate of metal atoms is brought close together. See also Bonding Force, and Ionic Bond.

Metallizing

See preferred term Thermal Spraying.

Metallurgical Bond

A nonstandard term for metallic bond.

Metallurgical Bond

A nonstandard term for metallic bond.

Molten Metal Flame Spraying

A thermal spraying process variation in which the metallic material to be sprayed is in the molten condition. See Flame Spraying (FLSP).

Neat

Unadulterated.

Neutral Flame

An oxyfuel gas flame in which the portion used is neither oxidizing nor reducing. See also Oxidizing Flame and Reducing Flame.

Nontransferred Arc

An arc established between the electrode and the constricting nozzle. The workpiece is not in the electrical circuit

Nozzle

(1) A device which directs shielding media, (2) a device that atomizes air in an arc spray gun, (3) the anode in a plasma gun, (4) the gas burning jet in a rod or wire flame spray gun.

Nozzle Accumulation

Surfacing material deposited on the inner surface and on the exit end of the nozzle.

Open Circuit Voltage

The potential difference applied between the anode and cathode prior to initiating the arc.

Overspray

The excess spray material that is not deposited on the part being sprayed.

Oxide

A chemical compound, the combination of oxygen with a metal forming a ceramic; examples - aluminum oxide, zirconium oxide.

Oxidizing Flame

An oxyfuel gas flame having an oxidizing effect (excess oxygen).

Oxyfuel Gas Spraying

A nonstandard term for flame spraying.

Parameter

A measurable factor relating to several variables; loosely used to mean a spraying variable, spraying condition, spray rate, spray distance, angle, gas pressure, gas flow, etc.

Parent Metal

A nonstandard term for substrate. Metal. A nonstandard term for substrate. rent Metal. A nonstandard term for substrate.

Particle Size

The average diameter of a given powder or grit granule.

Particle Size Distribution

Classification of powdered materials as determined by various testing methods defining the particle sizes and quantities in a given sample.

Particle Size Range

See preferred term Particle Size Distribution.

Pass

A single progression of the thermal spray device across the surface of the substrate.

Pistol

See preferred term Thermal Spraying Gun.

Plasma

See Arc Plasma.

Plasma Forming Gas

See preferred term Arc Gas. Plasma Metallizing. A nonstandard term for plasma spraying.

Plasma Spraying (PSP)

A thermal spraying process in which a nontransferred arc is utilized as the source of heat that ionizes a gas which melts and propels the coating material to the workpiece.

Plenum Chamber

The space between the inside wall of constricting nozzle and the electrode.

Porosity

Cavity type discontinuities within a sprayed coating (voids).

Postflow Time

The time interval between plasma arc shutdown and electrode cooling, to inhibit oxidation of electrodes.

Postheating

The application of heat to an assembly after a thermal spraying operation.

Powder

Material manufactured into finely divided particles. When explicitly blended for thermal spraying, powder falls within a specific mesh range, usually finer than 120 mesh (125 microns). Fine powder is usually defined as having particles smaller than 325 mesh (44 microns).

Powder Alloy

Powder prepared from a homogeneous molten mixture of elements, and sometimes entrapped carbides or metal oxides. All of the particles have approximately the same composition.

Powder Blend

A heterogeneous mixture of two or more alloy powders.

Powder Clad (Wire Clad)

Powder or wire wherein one alloy is encapsulated in another; a composite.

Powder Composite

Two or more independent materials, combined to form a single integrated unit. May be either chemically clad or mechanically agglomerated.

Powder Feeder

A device for conveying powdered materials to thermal spraying equipment.

Powder Feed Gas

See preferred term Carrier Gas.

Powder Feed Rate

The quantity of powder introduced into the hot, gaseous stream per unit of time.

Powder Fame Spraying

A thermal spraying process variation in which the material to be sprayed is in powder form; all oxyfuel gas processes. See Flame Spraying (FLSP).

Powder Metallizing

A nonstandard term for powder flame spraying.

Powder Port

Internal or external orifice through which powder is injected into flame or plasma.

Prenow Time

The time interval between start of shielding gas flow and arc or gas ignition.

Preheat

The heat applied to the base metal or substrate immediately before spraying.

Preheat Temperature

A specified temperature that the substrate is required to attain immediately before material deposition.

Primary Gas

The major constituent of the arc gas fed to the gun to produce the plasma; usually argon or nitrogen.

Procedure

The detailed elements of a process or method used to produce a specific result.

Protective Atmosphere

A gas envelope or vacuum surrounding the part to be thermally sprayed, with the gas composition controlled with respect to chemical composition; dewpoint, pressure, flow rate, etc. Examples are inert gases, combusted fuel gases, hydrogen and vacuum

Protective Barriers

Curtains or portable fireproof canvas shields, sometimes required to enclose work areas, when there is a possibility of the spray stream being misdirected, or where the glare of the arc or flame could injure unprotected eyes.

Protective Clothing

Leather or metal coated articles designed to prevent burns from ultraviolet radiation or misdirected particles.

Quench Rate

The speed at which a sprayed particle cools upon striking the surface of the substrate.

Rate of Deposition

See Deposition Rate.

Reducing Flame

A gas flame having a reducing effect (excess fuel gas).

Refrigerated Dryer

The application of a refrigeration cycle to physically lower the dewpoint.

Regenerative Dryer

A double column apparatus containing a drying medium for moisture absorption, which is automatically regenerated.

Regulator

See Gas Regulator

Relative Density

See preferred term Apparent Density Ratio.

Residual Stress

Stress remaining in a structure or member as a result of thermal or mechanical treatment or both. See Coating Stress.

Resonance Time

See preferred term Dwell Time.

Root Mean Square (RMS)

A method of defining the average roughness of a surface. It is the square root of the sum of all individual measurements divided by the number of measurements.

Rotary Roughening

A method of surface roughening in which are revolving roughening tool is pressed against the surface being prepared, while either the work or the tool, or both, move.

Rough Threading

Rough Threading. A method of surface roughening which consists of cutting threads with the sides and tops of the threads jagged and torn.

Saturated Air

To reach 690 kPa (100 psi) air at 100% humidity, it is necessary to compress approximately 0.23 ml (8 ft.') of free air, with its inherent moisture, into 0.028 ml (one cubic foot), since atmospheric humidity is usually more than 12.5% at ambient. All undried compresed air systems at 690 kPa (100psi) and ambient temperatures are at 100% relative humidity.

Seal Coat

Material applied to infiltrate and close the pores of a thermal spraying deposit. Secondary Gas. The minor or second constituent of the arc gas fed to the gun to produce plasma.

Self-Bonding Materials

Those materials that exhibit the characteristics of forming a metallurgical bond with the substrate in the as-sprayed condition.

Shadow Mask

A protective device that partially shields an area of the work, thus permitting some overspray to produce a feathering at the coating edge.

Shear Stress

The stress on the slip plane produced by external loads tending to slide adjacent planes with respect to each other in the direction parallel to the planes.

Shielding Gas

Protective gas used to prevent or minimize atmospheric contamination. See also Protective Atmosphere

Shrinkage Stress

A nonstandard term for residual stress.

Sieve

See preferred term Screen

Sieve Analysis

A method of determining particle size distribution, usually expressed as the weight percentage retained upon each of a series of standard screens of decreasing mesh size. See also Particle Size Distribution.

Slick Up

Point at which a self-fluxing alloy begins to shine during the fusing operation

Solvent Degreasing

The removal of oil, grease, and other soluble contaminants from the surface of the workpiece by immersion in suitable cleaners

Spalling

The flaking or separation of a sprayed coating

Splat

A single thin flattened sprayed particle.

Splat Cooling

Extremely rapid, high rate of cooling, the effects of which can be observed in thermal spraying deposits leading to the formation of metastable phases and an amorphous microstructure.

Spray

A moving mass of dispersed liquid droplets or heat softened particles.

Spray Angle

The angle of particle impingement, measured from the surface of the substrate to the axis of the spraying nozzle

Spray Booth

See preferred term Exhaust Booth.

Spray Deposit

See thermal spraying deposit

Spray Deposit Density Ratio

The ratio of the density of the spray deposit to the theoretical density of the surfacing material. Usually expressed as percent of theoretical density.

Spray Dry

A method for making thermal spray powder, especially ceramic powder, by spraying a slurry into a heated chamber and drying it to powder.

Spray Rate

The rate at which surfacing material passes through the gun.

Spraying Sequence

The order in which different layers of similar or different materials are applied in a planned relationship, such as overlapped, superimposed, or at given angles

Stabilizing Gas

The arc gas, ionized to form the plasma, is usually introduced into the arc chamber tangentially. The relatively cold gas chills the outer surface of the arc stream, tending to constrict the plasma, raise its temperature, and force it out of the anode (nozzle) in a steady, relatively unfluctuating stream.

Statistical Process Control (SPC)

To enhance, optimize and control coating properties influenced by parameter interaction.

Step Mounting

The intentional overlapping of several workpieces in order that one protects or masks its neighbor during the blasting or spraying process.

Sublime

To volatilize from the solid state to a gas.

Substrate

Any material to which a thermal spraying deposit is applied.

Superfines

Extra small, minute powder particles, usually less than five microns in size

Superheat

The difference between the higher actual temperature at the evaporator outlet and the lower theoretical temperature of the refrigerant at pressure

Surface Feet Per Minute (SFPM)

Linear velocity of the thermal spray gun as it traverses the length of the workpiece. Also, the circumferential velocity of the substrate.

Surface Preparation

The operations necessary to produce a desired or specified surface condition.

Surface Roughening

A group of methods for producing irregularities on a surface. See also Dovetailing, Groove and Rotary Roughening, Rotary Roughening, Rough Threading, and Threading and Knurling.

Surfacing

The application by thermal spraying of a layer or layers of material to a surface to obtain desired properties or dimensions, as opposed to making a joint.

Surfacing Material

The material that is applied to a substrate during surfacing

Surfacing Metal

The metal that is applied to a substrate during surfacing.

Textural Stress

The accumulated stress within an entire coating

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 spray deposit. The surfacing material may be in the form of powder, rod, cord, or wire. See also Arc Spraying, Flame Spraying, and Plasma Spraying.

Thermal Spraying Deposit

The coating or layer of surfacing material applied by a thermal spraying process

Thermal Spraying Gun

A device for heating and directing the flow of a surfacing material.

Thermal Stress

Stress resulting from nonuniform temperature distribution

Threading and Knurling

A method of surface roughening in which spiral threads are prepared, followed by upsetting with a knurling tool.

Tons of Refrigeration

A rate of heat exchange equal to 12,000 BTU/h.

Torch

A device used for fusing sprayed coatings; it mixes and controls the flow of gases.

Torch Fusing

The use of a torch to heat and melt a fusable spraying deposit to produce coalescense

Transferred Arc

An arc established between the plasma torch and the workpiece. The workpiece is part of the electrical circuit. Can be reversed to preheat and clean a substrate surface.

Travel Angle

The angle that the gun makes with a reference line perpendicular to the axis of the deposit in the plane of its axis. This angle can be used to define the position of thermal spraying torches and thermal spraying guns.

Traverse Speed

The linear velocity at which the thermal spraying gun traverses across the workpiece during the spraying operation

Undercoat

A deposited coat of material which acts as a substrate for a subsequent thermal spraying deposit. See Bond Coat

Undercutting

A step in the sequence of surface preparation involving the removal of substrate material.

Vacuum Plasma Deposition (VPD)

A thermal spraying process variation utilizing a plasma gun confined to a solid enclosure.The enclosure is evacuated and the spraying performed under low pressure, usually below 10 Toff. Also Vacuum Plasma Spray, Low Pressure Plasma Spray (LPPS).

van der Waals Force

A secondary force arising from the fluctuating dipole nature of an atom with all occupied electron shells filled.

Water Wash

The forcing of exhaust air and fumes from a spraying booth through water so that the vented air is free of thermal sprayed particles or fumes.

Wire Feed Speed

The rate of speed at which the wire is consumed

Wire Flame Spraying

A thermal spraying process variation in which the surfacing material is in wire form. See Flame Spraying (FLSP).

Wire Metallizing

See preferred term Wire Flame Spraying

Wire Straightener

A device used for controlling the cast of coiled wire to enable it to be easily fed into the gun.

Workpiece

The object or surface to be coated. See preferred term substrate

Workpiece Cooler

See Auxiliary Cooler.

X-ray

Electromagnetic radiation (photon), of shorter wavelength than ultraviolet radiation. Produced by bombardment of atoms by high quantum energy particles. Radiation wavelength is from 10-11 to 10-9 m.

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