Tribology: The science and technology concerned with interacting surfaces in relative motion
Coating: The act of building a deposit on a substrate
The spray deposit
Thermal Spraying: A group of processes in which finely divided metallic or nonmetallic surfacing materials are deposited in a molten or semi-molten state onto a substrate to form a deposit
Thermal Barrier Coatings: A group of ceramic coatings, including Yttria Stabilized Zirconia (YSZ) and Magnesium/Zirconate, used to protect the substrate in extreme heat environments. The heat rejection properties of TBCs excel in applications to an excess of 3000 °F. TBCs have been used successfully on piston tops, valves, exhaust systems, etc.
Splat: A single sprayed particle that resembles a thin, flattened drop of liquid, under magnification.
Metallic bond: The principal bond that holds metals together and is formed between base metals and filler metals in all processes
Mechanical bond: The adherence of a thermal spray deposit to a roughened surface by the mechanism of interlocking particles
Gradated coating: A thermal spray deposit composed of mixed materials in successive layers that progressively change in composition from the constituent material lot to the surface of the sprayed deposit
Composite coating: A coating consisting of two or more dissimilar spray materials which may or may not be layered
Plasma spraying: A thermal spray process in which a non transferred arc is used as the source of heat that ionizes a gas which, in turn, melts and propels the coating material to the work piece
Abrasion: To wear away by friction.
Wear: To damage, erode or consume by long, hard use
Spalling: The flaking or separation of a sprayed coating
Abradable seals: A seal made from mating two soft metal, or metal containing soft graphite, surfaces together using friction and pressure
Grit blasting: The preparation of a substrate for the thermal spray process by blasting with sharp irregular shaped grains to produce a pitted surface
Bond strength: The force required to pull a coating free of a substrate, usually expressed in kPa (psi)
Anode: The electrode maintained at a positive electrical potential
Cathode: The electrode maintained at a negative electric potential
Arc: A luminous discharge of electrical current crossing the gap between two electrodes
Plasma: An electrically neutral, highly ionized gas composed of electrons, ions, and neutral particles
Deposition rate: The weight of material deposited in a unit of time
Feed rate: A nonstandard term for spray rate
Powder: Material manufactured into finely divided particles. When blended for thermal spraying, powder falls within a specific mesh range, usually finer than 120 mesh (125 microns)
