Glossary

Alphabetized glossary of terms associated with MBI Coatings

 A
Abrasive wear is the wear ear due to hard particles or hard protuberances forced against and moving along a solid surface.
 
Adhesive strength is 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.
 
Adhesive Wear is the wear due to localized bonding between contacting solid surfaces leading to material transfer between the two surfaces or the loss from either surface.
 
Adhesion is a binding force that holds together molecules of substances whose surfaces are in contact.  The ability of coatings to attach and remain fixed on the surface without blistering, flaking, cracking or removed.
 
Aluminizing is the formation of aluminum or aluminum alloy coating on metal surfaces by thermal spray or diffusion for the purposes of corrosion protection and oxidation.
 
Amorphous coatings have non-crystalline structures, or devoid of regular structure which makes them tougher with work-hardnening properties.
 
Annealing is a process involving heating and cooling causing softening of a cold-worked structure by re-crystallization of grain growth or both.
 
Apparent hardness is the value obtained by testing a coating or sintered material with standard indentation hardness equipment. Since the reading reflects a composite of a coating and a solid material, it is usually lower than that of an equivalent solid wrought or cast material of the coating. Not to be confused with particle hardness. (See also micro-hardness).
 
Arc Spray or Wire arc spray works by placing an electric arc between two consumable electrodes of a coating material, then using compressed gas to atomize and propel the material to the substrate.
 
ASTM (American Society of Testing Materials) ASTM C633 is used to determine the adhesion or cohesion strength of thermal spray by subjecting it to tension perpendicular to the surface.
 
B
Blasting is a method of cleaning or surface roughening done by forcibly projecting streams of sharp angular abrasives.  Such as with san-blasting, a pressurized stream of particulates (oxides, carbides, metals, sand, etc.) is projected on a surface to clean, prep or abrade.
 
Bond coat is a preliminary (or prime coat) of material that improves adherence of the subsequent spray deposit.
 
Bond strength is the strength of the adhesion between the coating and the substrate. A number of test methods are in use to measure the bond strength of coatings.
 
British thermal unit (Btu) is the quantity of heat required to raise the temperature of one pound of water by one degree Fahrenheit.
 
C
Capillary action is a phenomenon in which water or many other liquids will rise above the normal liquid level in a tiny tube or capillary, due to attraction between molecules of the liquid for each other and the walls of the tube.
 
Carbide is a chemical compound formed between carbon and a metal or metals; examples are tungsten carbide, tantalum carbide, titanium carbide, chromium carbide.
 
Cathodic coatings become the cathode in an electrochemical cell with the substrate (anode). This type of coating protects the substrate from corrosion only by being a complete barrier. If the coating allows the environment to reach the substrate, accelerated corrosion of the substrate will occur.
 
Cavitation damage is the degradation of a solid body resulting from its exposure to cavitation. (This may include loss of material, surface deformation, or changes in properties or appearance).
 
Coating is a protective and/or decorative layer generally applied in an industrial setting to alter properties of a surface in a positive fashion.  Lately, coatings are being called for and applied as part of the original equipment manufacturer (OEM) process.
 
Coating strength is a measure of the cohesive bond within a coating, as opposed to coating-to-substrate bond (adhesive strength).  Also, it is the tensile strength of a coating, usually expressed in kpa (psi).
 
Coating stresses are the stresses in a coating resulting from rapid cooling of molten material or semi-molten particles as they impact the substrate.  Coating stresses are a combination of body and textural stresses.
 
Cohesion is the intermolecular attraction between like-molecules.
 
Composite coating is mixture of two or more materials. Many thermal spray coatings could be considered as composites.
 
Corrosion is the chemical or electrochemical reaction between a material, usually a metal, and its environment that produces a deterioration of the material and its properties.
Corrosion resistance is the ability of a coating to impart and withstand corrosion in a given corrosion system.
 
Curing is the process that is necessary for some coatings to become hard films. Example:  (Enamels cure whil e lacquers do not cure and Thermal spray coatings do not require curing).
 
D
Dielectric shielding is a process in which a nonconductive material, such as a coating is placed between an anode and an adjacent cathode to avoid current flow, wastage or to improve current distribution.
 
Ductility is the ability of a material to deform plastically without fracturing, measured by elongation or reduction of area in a tensile test, by height of cupping in an Erichsen test, or by other means.
 
E
Elasticity is the property of certain materials that enables them to return to their original dimensions after an applied stress.
 
Erosion is the progressive loss of material from a solid surface due to mechanical interaction between that surface and a fluid, a multi-component fluid, or solid particles carried with the fluid.
 
F
Fatigue strength is the maximum stress that can be sustained for a specified number of cycles without failure, the stress being completely reversed within each cycle unless otherwise stated.
 
Fatigue wear is wear of a solid surface caused by fracture arising from material fatigue.
 
Film is a thin, not necessarily visible, layer of material.
 
Flame spraying is a process in which an oxy-fuel gas flame is the source of heat for melting the surfacing material. Compressed gas may be used for atomizing and propelling the surfacing material to the substrate.
 
Flow-coating is a system of applying paint where the paint is allowed to flow over and drain off the work-piece.
Fretting is the surface damage resulting from relative motion between surfaces in contact under pressure.
 
Friction is the reaction force resulting from surface interaction and adhesion during sliding. The friction Coefficient is defined as the friction force divided by the load.
 
Fused coatings are the result of a process in which the coating material is deposited by thermal spraying and then fused by post heat treatment. This can be done by flame, induction heating, furnace or by laser.
 
G
Galvanizing is the process by which steel is coated with a layer of zinc.  The zinc coating provides the steel with greater corrosion resistance.  Common process is hot dip galvanizing a better process is zinc arc spraying.
 
Galvanic corrosion is accelerated corrosion of a metal because of an electrical contact with a more noble metal or nonmetallic conductor in a corrosive electrolyte.
 
Grit blasting is a pressurized stream of hard metal or oxide grit material used to clean and roughen surfaces prior to coating.
 
H
Hard chromium plating is the electrolytic deposition of chromium to form a hard coating with good wear resistance. The structure is micro-cracked.
 
Hardness test is 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.
 
Hard-facing is the application of tough coating materials designed to resist severe wear.
 
High velocity oxy-fuel spraying (HVOF) is a Thermal spray process. The spray powder particles are injected into a high velocity jet formed by the combustion of oxygen and fuel, heated and accelerated to the substrate.
 
Hydrogen blistering is the formation of blisters on or below a metal surface from excessive internal hydrogen pressure. (Hydrogen may be formed during chrome plating, corrosion, etc.).
 
I
Impingement is a process resulting in a continuing succession of impacts between (liquid or solid) particles and a solid surface.
 
Impregnation is a process of filling the pores of a coating with a sealer material such as resin, wax, etc.
 
Insulation is a material of low thermal conductivity (ceramic) used to reduce heat losses.
 
K
Kerosene is the liquid fuel of choice used in some HVOF thermal spray processes.
 
Kilowatt-hour (kWh) is an energy unit defined as 1,000 watts of electricity for one hour (equivalent to 3,413 Btu).  Such units are used in Plasma coating processes.
 
L
Lacquer is a fast-drying usually clear coating that is highly flammable and dries by solvent evaporation only.  It can be reconstituted after drying by adding solvent.
 
Lamellar corrosion is a form of corrosion in which the expanding corrosion products stack up as layers. Similar to exfoliation of high strength aluminum alloys.
 
Lapping is the rubbing two surfaces together, with or without abrasives, for the purpose obtaining extreme dimensional accuracy or superior surface finish.
 
Liquid impingement erosion is the progressive loss of material from a solid surface due to continue exposure to impacts by liquid drops or jets.
 
Load factor is the ratio of the average load in a given period to the maximum load carried during that period.
 
M
Macro-hardness is the hardness of a coating as measured on a macroscopic scale, which shows the coatings bulk properties.
 
Mechanical bonding is usually represented by mechanical interlocking of the deposited particles with the rough heights on the substrate surface produced during grit blasting.
 
Metallizing (See thermal spraying).
 
Micrograph is produced when a section of the coating is taken, polished to show the particulate layers and then photographed through a microscope.
 
Micro-hardness is the hardness of a coating as measured on a microscopic scale. Can show the hardness of individual phases within the coating and avoid the effects of porosity.
 
Micrometer (µm) is formally known as micron.  It is a linear measure equal to one millionth of a meter or .00003937 inch. The symbol for the micrometer is µm.
 
Microstructure is the structure of a prepared surface of a metal as revealed by a microscope at a magnification exceeding 25x.
 
Mil is one thousandth of an inch.
 
Muriatic acid is an archaic term for hydrochloric acid, HCl (acidum salis, marine acid, spirit of salt).
 
N
Nanometer abbreviated "nm", a unit of length equal to one thousandth of a micrometer.
 
Naphtha is a petroleum distillate used mostly by professionals for cleanup and to thin solvent-based coatings. It is known to be a volatile organic compound.
 
Nickel plating is the electro deposition of nickel to form a corrosion barrier or to reclaim a worn part.
 
Noble metal is a metal with a standard electrode potential that is more noble (positive) than that of hydrogen.
 
Non-stick “Plasma-release” coatings
TRACLON (Traction-release polymers embedded into Tungsten carbide, Stainless, Ni-Cr, etc.)
 
O
Orange peel is a surface description of bumpiness or waviness that resembles the skin of an orange. Orange peel finish is often desired to minimize the contact between the surface and the product.
 
Overspray is the spray material that misses the area being targeted and falls upon the surrounding surfaces.
 
Oxidations is the loss of electrons by a constituent of a chemical reaction. (Also refers to the corrosion of metal that is exposed to an oxidizing gas at elevated temperatures).
 
Ozone is a oxidizing allotropic form of the element oxygen. The ozone molecule contains three atoms (O3).
 
P
Particle size is a measure expressed in microns or percent passing through a standard mesh screen.
 
Passivity is a condition in which a piece of metal, because of an impervious covering of oxide or other compound, has a potential much more positive than that at the metal in the active state.
 
Peening is a blasting process using spherical shaped beads or shot for cleaning and/or modifying surface properties.
 
Permeability is a property measured as a rate of passage of a liquid or gas through a coating.
 
Pickling is removing surface oxides from metals by chemical or electrochemical reaction. Treating the surface of iron or steeel with acid to remove scale, rust and dirt, preparatory to further processing such as cold rolling, tinning,  galvanizing, or polishing.
 
Plasma is a gas so hot that all electrons are stripped away from the atoms. As such, the gas has a positive charge and can be confined in a magnetic field. High-temperature plasma is used in controlled fusion experiments.
Plasma spraying is a thermal spraying process in which the coating material is melted with heat from a plasma torch that generates a non-transferred arc. The molten coating material is propelled against the base metal by the hot, ionized gas issuing from the torch.
 
Plasma-release coatings (Non-stick)
TRACLON (Traction-release polymers embedded into Tungsten carbide, Stainless, Ni-Cr, etc.)
 
Plasticity is the property that enables a material to undergo permanent deformation without rupture.
 
Polishing is the abrading of a material surface by means of the action of sanding and rubbing.
 
Polyurethane is a type of coating or resin known for its toughness, flexibility, weather resistance, chemical resistance, and abrasion resistance. The resin or vehicle commonly used to make topcoats.
 
Porosity is a measure of the volume of internal pores, or voids, in ion exchangers and filter media; sometimes expressed as a ratio to the total volume of the medium.
 
Powder coating is a polymeric coating deposited via electrostatic attraction and applied to the surface as a dry, finely ground powder and then heated above its melting point so the powder particles flow together or cure.
 
Powder metallurgy is the art of producing metal powders and utilizing metal powders for production of' massive materials and shaped objects.
 
Preventive maintenance is maintenance performed according to a fixed schedule involving the routine repair and replacement of machine parts and components.
 
Primer is the first coat of (usually) paint applied to a surface.  Formulated to have good bonding and wetting characteristics; may or may not contain inhibiting pigments.
 
Products of combustion are the gases, vapors, and solids resulting form the combustion of fuel.
 
Pull-out occurs when particles are plucked from the coating during machining or grinding. Also occurs during metallographic preparation. It is sometimes confused with porosity.
 
Q
Quality control is all aspects of the control of the spraying process including the surface preparation, spraying, control of thickness deposited and the oxide and porosity levels, surface finish and NDE checks as specified.
 
Quenching is the rapid cooling in the heat treating of metals, the step of cooling metals rapidly in order to obtain desired properties; most commonly accomplished by immersing the metal in oil or water.
 
R
Reactive metal is a metal that readily combines with oxygen at elevated temperatures to form very stable oxides, for example, titanium, zirconium, and beryllium.
 
Recrystallization is the formation of a new strain free grain structure from that existing in cold worked metal, usually accomplished by heating. Also, it is the change from one crystal structure to another, as occurs on heating or cooling through a critical temperature.
 
Refractoryis a ceramic material that can resist great heat and wear.  Therefore it is suitable as a lining thermal barrier coating.  This is not to be confused with refractory metals, such as columbium and tantalum.
 
Residual stresses are the stresses that remain within a body as a result of plastic deformation.
 
Resilience is the ability of a material to absorb energy when deformed elastically and to return it when unloaded. This is usually measured by the modulus of resilience, which is the strain energy per unit volume required to stress the material from, zero stress to the yield stress.
 
Rockwell hardness test is an indentation hardness test using a calibrated machine that utilizes the depth of indentation, under constant load, as a measure of hardness.
 
Rust is a corrosion product consisting primarily of hydrated iron oxide. (A term properly applied only to ferrous alloys.).
 
S
Sacrificial coating is a coating that provides corrosion protection wherein the coating material corrodes in preference to the substrate, thereby protecting the latter from corrosion.
 
Salt fog is an ASTM B-117 test procedure that attempts to simulate the corrosive environment caused by road salt and marine spray.
 
Sampling is the removal of a portion of a material for examination or analysis.
 
Sand blasting (also grit blasting) is the process of surface cleaning and roughening that provides a mechanical "tooth" to aid coating adhesion. Media include aluminum oxide, silicone carbide, crushed hardened steel or even crushed walnut shells. The medium must be chosen and sized according to the substrate or the foreign material on the substrate to be removed.
 
Scale is a deposit of oxide of iron that forms on the surface of steel after heating.
 
Sealant or sealers are materials (polymers) specifically used to for sealing the porosity in coatings.
 
Sealing is a process which, by absorption of a sealer into thermal spray coatings, seals porosity and increases resistance to corrosion of the underlying substrate material.
 
Self-bonding coatings is a name given to thermal spray coatings that are capable of bonding to clean smooth surfaces. Bond and "one-step" coatings are normally in this group.  Such coatings are particularly important where grit blasting or surface roughening processes cannot be performed.
 
Shear strength is the stress required to produce fracture in the plane of cross section, the conditions of loading being such that the directions of force and of resistance are parallel and opposite although their paths are offset a specified minimum amount. The maximum load divided by the original cross-sectional area of a section separated by shear.
 
Shielded is the separation of metallic parts by an electrical nonconductor; insulated by other than an air gap.
 
Shrinkage is a decrease in dimensions of a coating during processing.
 
Shot peening is the bombardment of a component surface with steel or ceramic shot. Produces a residual compressive stress in the surface and improves fatigue and stress corrosion performance.
 
Spalling is the breaking off of the surface of refractory material as a result of internal stresses or the lifting or detachment of a coating from the substrate.
 
Splat is a single thin flattened sprayed particle.
 
Spray-fusing is a process in which the coating material is deposited by flame spraying and then fused into the substrate by the addition of further heat. This can be applied by flame, induction heating or by laser.
 
Stress-relief cracking is also called post-weld heat treatment cracking, stress-relief cracking occurs when susceptible alloys are subjected to thermal stress relief after welding to reduce residual stresses and improve toughness. Stress-relief cracking occurs only in metals that can precipitation-harden during such elevated-temperature exposure; it usually occurs at stress raisers, is intergranular in nature, and is generally observed in the coarse-grained region of thewels heat affected  zone.
 
Stress relieving is a heat treatment carried out in steel to reduce internal stresses.
 
Substrate is the parent or base material to which a coating is applied.
 
Surface Preparation is cleaning and roughening the surface to be sprayed, usually by grit blasting. This is to increase the adhesion of the coating to the substrate.
 
Surfacing is the application of a coating or cladding to a surface to impart a change in its surface properties or behavior.
 
T
Tensile strength is the maximum stress that a material can withstand while being stretched.
 
Tension is the force or load that produces elongation.
 
Thermal barrier coatings are coatings that form an insulating barrier to a heat source to protect the substrate.
 
Thermal shock is a cycle of temperature swings that result in failure of metal due to expansion and contraction.
 
Thermal spraying is a group of processes wherein finely divided metallic or nonmetallic materials are deposited in a molten or semi-molten condition to form a coating. (The coating material may be in the form of powder, ceramic rod, wire, or molten materials.)
 
Thermal degradation is a type of fatigue occurs when metal is subjected to heat.  Because thermal spraying is relatively “cold process” and substrates are kept below 150C (300F), for most applications there is no risk of thermal degradation to the parts being coated.
 
Thermo-chemically formed coatings are painted, dipped or sprayed chromium oxide based coatings consolidated by repeated deposition and curing cycles (about 500oC).
 
Toughness is the ability of a metal to absorb energy and deform plastically before fracturing.
 
TRACLON  coatings  are exclusive to MBI, also known as non-stick “Plasma-release” coatings  (Traction-release polymers embedded into Tungsten carbide, Stainless, Ni-Cr, etc.)
 
Traction control & grip coatings
TRAC-TEC coatings (various hardness, thickness and finish roughness)
 
Transferred arc is a type of a plasma torch in which the plasma jet is emitted from the torch and the current flows from the internal cathode to the internal anode represented by the nozzle of the torch. When the jet is carried to another anode with it being electrically favorable to do so the current will then transfer to the second anode, usually the work piece and the arc is said to be transferred.
 
Tribology is the science and technology concerned with interacting surfaces in relative motion.
 
Turbines are wheels with many blades that is spun when steam pushes the blades. A turbine converts heat energy into mechanical energy.  Turbine surfaces are coated and repaired by thermal spray.
 
U
U-bend specimen is a horseshoe-shaped test piece used to detect the susceptibility of a material to stress corrosion cracking.
 
Undercutting is a step in the sequence of surface preparation involving the removal of substrate material. Undercutting corrosion of a scribed surface during a testing program is also an indication of poor paint performance.
 
Urethane is an important resin in the coatings industry. A true urethane coating is a two-component product that cures when an isocyanate (the catalyst) prompts a chemical reaction that unites the components.
 
Vaporization is the change from liquid or solid phase to the vapor phase.
 
Voids is a term generally applied to paints to describe holidays, holes, and skips in a film. Also used to describe shrinkage in castings and weld.
 
W
Wear is the loss of material from a surface by means of some mechanical action.

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