Thermal Spray Glossary

Thermal Spray Glossary A-C

A

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.
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.


B

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.
 



C

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.