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. Abrasive Blasting. See preferred term Blasting. 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. 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 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. Arc 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. 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. 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 (psi). Coating Stress. The stresses in a coating resulting from rapid cooling of molten material or semimolten particles as they impact the substrate. Coating stresses are a combination of body and textural stresses. 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. Electric Bonding. A nonstandard term for surfacing. 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. 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. 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. Fused Spray Deposit. A self-fluxing spray deposit which is subsequently heated to coalescence within itself and with the substrate. 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. 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. 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. 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. 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. Physical Bond. See preferred term Metallic Bond. 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 Injection. Feeding of a powder through a powder port into a thermal spray flame. 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. 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. 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. Screen. One of a set of sieves, designated by the size of the openings, used to classify and sort powder to particle size. 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. Self-Fluxing Alloys. Surfacing materials that "wet" the substrate and coalesce when heated to their melting point, without the addition of an externally applied flux. These alloys contain boron or silicon, or both, as fluxing agents. 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 Distance. The distance maintained between the thermal spraying gun nozzle tip and the surface of the workpiece during spraying. 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.
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