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Abrasive Blasting
A process for cleaning or finishing by means of an abrasive directed at high velocity against the work piece.
Activation
Elimination of a passive condition on a surface.
Activity (Ion)
The ion concentration corrected for deviations from ideal behavior. Concentration multiplied by activity coefficient.
Addition Agent
A material added in small quantities to a plating solution to modify its characteristics. It is usually added to a plating solution for the purpose of modifying the characteristics of the deposit.
Adhesion
The attractive force that exists between an electrodeposited coating and its substrate that can be measured as the force required to separate the electrodeposited coating and its substrate.
Amorphous
Noncrystalline, or devoid of regular grain structure.
Ampere
The current that will deposit a metallic coating at the rate of 0.0011180 g per sec. current flowing at the rate of 1 coulomb per sec.
Angstrom Unit (A)
10-6 cm.
Anion
A negatively charged ion.
Anode
The electrode in electrolysis, at which negative ions are discharged, positive ions are formed, or other oxidizing reactions occur.
Anode Efficiency
Current efficiency of a specified anodic process.
Anode Film
(1) The layer of solution in contact with the anode that differs in composition from that of the bulk of the solution. (2). The outer layer of the anode itself consisting of oxidation or reaction products of the anode metal.
Anode Polarization
See Polarization.
Anodic Coating
A protective, decorative, or functional coating, formed by conversion of the surface of a metal in an electrolytic oxidation process(plating).
Anodizing
An electrolytic oxidation process in which the surface of a metal, when anodic, is converted to a coating having desirable protective, decorative, or functional properties.
Anolyte
The portion of electrolyte in the vicinity of the anode; in a divided cell, the portion of electrolyte on the anode side of the diaphragm.
Anti-Pitting Agent
An addition agent for the specific purpose of preventing gas pits in a deposit.
Automatic Machine (or Conveyor)
A machine for mechanically processing parts through treatment cycles,
such as cleaning, anodizing, or plating.
Automatic Plating
(1) Full. - Plating in which the cathodes are automatically conveyed through successive cleaning and plating tanks. (2) Semi. - Plating in which the cathodes are conveyed automatically through only one plating tank.
B
Back EMF (Electromotive Force)
The potential set up in an electrolytic cell that opposes the flow of current, caused by such factors as concentration polarization and electrode films. See EMF.
Barrel Burnishing
The smoothing of surfaces by means of tumbling the work in rotating barrels in the presence of metallic or ceramic shot, and in the absence of abrasive. In ball burnishing, the shot consists of hardened steel balls.
Barrel Finishing (or Tumbling)
Bulk processing in a barrel, in either the
presence or absence of abrasives or burnishing shot, for the purpose of improving the surface finish.
Barrel Plating (or Cleaning)
Plating or cleaning in which the work is
processed in bulk in a rotating container.
Base Metal
A metal that readily oxidizes or dissolves to
form ions. The opposite of noble metal.
Basis Metal (or Material)
Material upon which coatings are deposited.
Bipolar Electrode
An electrode that is not directly connected to
the power supply but is so placed in the
solution between the anode and the cathode so that the part nearest the anode becomes cathodic and the part nearest the cathode becomes anodic.
Blue Dip
A solution, once widely used, containing a
mercury compound used to deposit mercury upon a metal by immersion, usually prior to silver plating.
Bright Dip (Nonelectrolytic)
A solution used to produce a bright surface on a metal.
Bright Plating
A process that produces an electrodeposit having a high degree of specular reflectance in the as-plated condition.
Bright Plating Range
The range of current densities within which a
given plating solution produces a bright plate.
Bright-Throwing Power
The measure of the ability of a plating solution
or a specified set of plating conditions to deposit uniformly bright electroplate upon an
irregularly shaped cathode.
Brightener
An addition agent that leads to the formation of a bright plate, or that improves the brightness of the deposit.
Brush Plating
A method of plating in which the plating solution is applied with a pad or brush, within which is an anode and which is moved over the cathode (part) to be plated.
Buffer
A compound or mixture that, when contained in a solution, causes the solution to resist change in pH. Each buffer has a characteristic limited range of pH over which it is effective.
Buffing
The smoothing of a surface by means of a rotating flexible wheel to the surface of which fine, abrasive particles are applied in liquid suspension, paste, or grease stick form.
Building Up
Electroplating for the purpose of increasing the dimensions of an article.
Burnishing
The smoothing of surfaces by rubbing, accomplished chiefly by the movement rather than the removal of the surface layer.
Burnt Deposit
A rough, non-coherent or otherwise unsatisfactory deposit produced by the application of an excessive current density and usually containing oxides or other inclusions.
Bus (Bus Bar)
A rigid conducting section, for carrying current to the anode and cathode bars.
Butler Finish
A finish composed of fine, uniformly distributed parallel lines, having a characteristic luster usually produced with rotating wire brushes or cloth wheels with applied abrasives.
C
Calomel Half Cell (Calomel Electrode)
An electrode in contact with a solution of Potassium chloride of specified concentration that is saturated with mercurious chloride (calomel).
Cataphoresis
See Electrophoresis.
Cathode
The electrode in an electrolysis at which positive ions are discharged, negative ions are formed, or other reducing actions occur.
Cathode Efficiency
The current efficiency of a specified cathodic process.
Cathode Film
The layer of solution in contact with the cathode that differs in composition from that of the bulk of the solution.
Cathodic polarization
See polarization
Catholyte
The portion of the electrolyte in the vicinity of the cathode; in a divided cell
the portion on the cathode side of the diaphragm.
Cation
A positively-charged ion.
Chelate Compound
A Compound in which the metal is contained as an integral part of a ring structure and is not readily ionized.
Chelating Agent
A compound capable of forming a chelate compound with a metal ion. See Chelate Compound.
Chemical Polishing
The improvement in smoothness of a metal by simple immersion in a suitable solution. See Bright Dip (Nonelectrolytic).
Cleaning
The removal of grease or other foreign material
from a surface.
Alkaline Cleaning
Cleaning by means of alkaline solutions.
Anodic or Reverse Cleaning
Electrolytic cleaning in which the work is the anode.
Cathodic or Direct Cleaning
Electrolytic cleaning in which the work is the cathode.
Diphase Cleaning
Cleaning by means of a solution that contains a solvent layer and an aqueous layer. Cleaning is effected both by solvent and emulsifying action.
Direct Current Cleaning
See Cathodic or Direct Cleaning
Electrolytic Cleansing
Alkaline cleaning in which a current is passed through the solution, the work being one of the electrodes.
Immersion
see Soak Cleaning
Reverse Current Cleaning
See Anodic or Reverse Cleaning
Soak Cleaning
Cleaning by immersion without the use of current, usually in an alkaline solution.
Solvent Cleaning
Cleaning by means of organic solvents.
Spray Cleaning
Cleaning my means of spraying.
Ultrasonic Cleaning
Cleaning by any chemical means aided by ultrasonic energy.
Colloidal Particle
An electrically-charged particle, generally smaller in size than 200 m? dispersed in
a second continuous phase.
Coloring
(1) The production of desired colors on metal surfaces by appropriate chemical or
electrolytical action. (2) Light buffing of metal surfaces for the purpose of producing a high luster. Caged "Color buffing."
Complex Ion
An ion composed of two or more ions or radicals, both of which are capable of independent existence, for example cuprocyanide (Cu(CN)2)-.
Complexing Agent
A compound that will combine with metallic ions to form complex ions. See Complex Ion.
Composite Plate
An electrodeposit consisting of two or more layers of metal deposited successively.
Concentration Polarization
That part of the total polarization that is caused by changes in the activity of
the potential-determining components of the electrolyte.
Conductance
The capacity of a medium, usually expressed in mhos, for transmitting electric current. The reciprocal of resistance.
Conducting Salt
A salt added to the solution in order to increase its conductivity.
Conductivity - Specific Conductance
The current transferred across unit area per unit potential gradient. In the metric
system, K = amperes per sq cm divided by volts per cm. The reciprocal of resistivity.
Contact Plating
Deposition of a metal by the use of an internal source of current by immersion of the work in a solution in an contact with another metal.
Contact Potential
The potential difference at the junction of two dissimilar substances.
Conversion Coating
A coating produced by chemical or electrochemical treatment of a metal solution
that gives a superficial layer containing a compound of the metal, for example chromate coatings on zinc and cadmium, oxide coating on steel.
Corrosion
(1) Gradual solution or oxidation of a metal.
(2) Solution of anode metal by the electrochemical action in the plating cell.
Coulomb
The quantity of electricity that is transmitted through an electric circuit in 1 second when the current in the circuit is 1 amp. The quantity of electricity that will deposit 0.0011180 g of silver.
Coulometer
An electrolytic cell arranged to measure the quantity of electricity by the chemical reaction produced in accordance with Faraday's law.
Covering Power
The ability of a plating solution under a set of specified plating conditions to deposit metal on the surfaces of recesses or deep holes. (To be distinguished from throwing power.)
Critical Current Density
A current density above which a new and sometimes undesirable reaction occurs.
Current Density (cd)
Current per unit area.
Current Efficiency
The proportion, usually expressed as a percentage, of the current that is effective in carrying out a specified process in accordance with Faraday's Law.
Cutting Down
Polishing or buffing for the purpose of roughness or irregularities.
D
Deburring
The removal of burrs, sharp edges or fins by mechanical, chemical, or electrochemical means.
Decomposition Potential
The minimum potential, exclusive of IR drop, at which an electrochemical process can take place at an appreciable rate.
Degreasing
The removal of grease and oils from a surface.
Solvent Degreasing
Degreasing by immersion in a liquid organic solvent.
Vapor Degreasing
Degreasing by solvent vapors condensing on the parts being cleaned.
Deionization
The removal of ions from a solution by ion exchange.
Depolarization
A decrease in the polarization of an electrode at a specified current density.
Depolarizer
A substance or a means that produces depolarization.
Detergent
A surface active agent that possess the ability to clean soiled surfaces.
Anionic Detergent
A detergent that produces aggregates of negatively-charged ions with colloidal
properties.
Cationic Detergent
A detergent that produces aggregates of positively-charged ions with colloidal
properties.
Nonionic Detergent
A detergent that produces aggregates of electrically-neutral molecules with colloidal properties.
Diaphragm
A porous or permeable membrane separating anode and cathode compartments of an electrolytic cell from each other or from an intermediate compartment.
Diffusion Coating
An alloy coating produced by applying heat to one or more coatings deposited on a basis metal
Dispersing Agent
A substance that increases the stability of a suspension by retarding the flocculation of such particles.
Divided Cell
A cell containing a diaphragm or other means for physically separating the anolyte from the catholyte.
Double Salt
A compound of two salts that crystallize together in a definite proportion.
Drag-in
The water or solution that adheres to the objects introduced into a bath.
Drag-Out
The solution that adheres to the objects removed from a bath.
Dummy (or Dummy Cathode)
A cathode in a plating solution that is not to be made use of after plating. Often used for removal or decomposition of impurities.
E
Electrochemical Equivalent
The weight of an element, compound, radical, or ion involved in a specified electrochemical reaction during the passage of unit quantity of electricity, such as a Faraday, ampere-hour, or coulomb.
Electrochemistry
The branch of science and technology which deals with transformations between chemical and electrical energy.
Electrode
A conductor through which current enters or leaves an electrolytic cell, at which there is a charge from conduction by electrons to conduction by charged particles of matter, or vice versa.
Electrodeposition
The process of depositing a substance upon an electrode by electrolysis. See Electroforming, Electroplating, Electrorefining, and Electrowinning.
Electrode Potential
The difference in potential between an electrode and the immediately adjacent
electrolyte referred to some standard electrode potential as zero.
Dynamic E.P.
The electrode potential measured when current is passing between the electrode and the electrolyte.
Equilibrium E.P.
A static electrode potential when the electrode and the electrolyte are in equilibrium with
respect to a specified electrochemical reaction.
Static E.P.
The electrode potential measured when no net current is flowing between the electrode and the electrolyte.
Standard E.P.
An equilibrium electrode potential for an electrode in contact with an electrolyte in
which all of the components of a specified chemical reaction are in their standard
states. The standard state for an ionic constituent is unit ion activity.
Electroforming
The production or reproduction of articles by electrodeposition upon a mandrel or mold that is subsequently separated from the deposit.
Electrogalvanizing
Electrodeposition of zinc coatings.
Electroless Plating
Deposition of a metallic coating by a controlled chemical reduction that is catalyzed by the metal or alloy being deposited.
Electrolyte
(I) A conducting medium in which the flow of current is accompanied by a movement of matter. Most often an aqueous solution of acids, bases, or salts, but includes many other media, such as fused salts, ionized gases, some solids, etc.
(2) A substance that is capable of forming a conducting liquid medium when dissolved or melted.
Electrolysis
Production of chemical changes by the passage of current through an electrolyte.
Electrolytic Cell
A unit apparatus in which electrochemical reactions are produced by applying electrical energy, or which supplies electrical energy as a result of chemical reactions and which includes two or more electrodes and one or more electrolytes contained in a suitable vessel.
Electromotive Series
A table that lists in order the standard electrode potentials of specified chemical
reactions.
Electrophoresis
The movement of colloidal particles produced by the application of an electric potential.
Electroplating
The electrodeposition of an adherent metallic coating upon an electrode for the purpose of securing a surface with properties or dimensions different from those of the basis metal.
Electropolishing
The improvement in surface finish of a metal effected by making it anodic in an
appropriate solution.
Electrorefining
The process of anodically dissolving a metal from an impure anode and depositing it cathodically in a purer form.
Electrotyping
The production of printing plates by electroforming.
Electrowinning
The production of metals by electrolysis with insoluble anodes in solutions derived from ores or other materials.
Embrittlement, Hydrogen
See Hydrogen Embrittlement.
EMF (Electromotive Force)
An electrical potential.
Emulsion
A suspension of small droplets of one liquid in another in which it is insoluble. For the formation of a stable emulsion, an emulsifying agent must usually be present.
Emulsifying Agent
A substance that increases the stability of an emulsion.
Energy Efficiency
The product of the current efficiency and the voltage efficiency for a specified
electrochemical process.
Equivalent Conductivity
In an electrolyte, the conductivity of the solution divided by the number of equivalents of conducting solute per unit volume, that is, the conductivity divided by the normality of the solution.
Etch, (n)
A roughened surface produced by a chemical or electrochemical means.
Etch. (v)
To dissolve unevenly (or uniformly) a part of the surface of a metal.
F
Faraday
The number of coulombs (96,490) required for in an electrochemical reaction involving one chemical equivalent.
Filter Aid
An inert, insoluble material, more or less finely divided, used as a filter medium or to assist in filtration by preventing excessive packing of the filter cake.
Flash (or Flash Plate)
A thin electrodeposit, less than 0.1 mil. See Strike.
Flocculate
To aggregate into larger particles, to increase in size to the point where precipitation
occurs.
Formula Weight
The weight, in grams, pounds, or other units, obtained by adding the atomic weights of all elemental constituents in a chemical formula.
Free Cyanide:
(1) True The actual concentration of cyanide radical, or equivalent alkali cyanide, not combined in complex ions with metals in solution.
(2) Calculated. - The concentration of cyanide, or alkali cyanide, present in solution in excess of that calculated as necessary to form a specified complex ion with a metal or metals present in solution.
(3) Analytical free cyanide content of a solution, as determined by a specified analytical method.
Note - The true value of free-cyanide is rarely known with certainty and is therefore usually only dealt with in discussions of theory. The calculated or analytical value is usually used in practice.
G
Galvanic Call
An electrolytic cell capable of producing electrical energy by electrochemical action.
Galvanic Series
A list of metals and alloys arranged according to their relative Potentials in a given
environment. See Electromotive Series.
Galvanizing
Application of a coating of zinc.
Gassing
The evolution of gasses from one or more of the electrodes during electrolysis
Glass Electrode
A half cell in which the potential measurements are made through a glass membrane.
Grinding
The removal of metal by means of a rotating rigid wheel containing abrasive.
Grit Blasting
Abrasive blasting with small irregular pieces of steel or malleable cast iron.
H
Half Cell
An electrode immersed in a suitable electrolyte. It may be designed to yield a known constant potential, in which case unknown potentials may be measured against it for example the calomel half cell.
Hard Chromium
Chromium plated for engineering rather than decorative applications. Not necessarily harder than the latter.
Haring Cell
A rectangular box of nonconducting material, with principal and auxiliary electrodes so arranged as to permit estimation of throwing power of electrode polarizations and potentials between them.
High Lights
Those portions of a metal article most exposed to buffing or operations, and, hence, having the highest luster.
Hull Cell
A trapezoidal box of nonconducting material with electrodes arranged to permit observation of cathodic or anodic effects over a wide range of current densities.
Hydrogen Embrittlement
Embrittlement of a metal or alloy caused by absorption of hydrogen during a pickling, cleaning, or plating process.
Hydrogen Overvoltage
Overvoltage associated with the liberation of hydrogen.
Hydrophilic
(1) Tending to absorb water.
(2) Tending to concentrate in the aqueous phase.
Hydrophobic
(1) Tending to repel water.
(2) Lacking affinity for water.
I
Immersion Plate
A metallic deposit produced by a displacement reaction in which one metal displaces another from solution, for example: Fe + Cu++ --> Cu + Fe++
Indicator (pH)
A substance that changes color when the pH of the medium is changed. In the case of most useful indicators, the pH range within which the color changes is narrow.
Inert Anode
An anode that is insoluble in the electrolyte under the conditions prevailing in the
electrolysis.
Inhibitor
A substance used to reduce the rate of a chemical or electrochemical reaction, commonly corrosion or pickling.
Interfacial Tension
The contractile force of an interface between two phases. See Surface Tension.
Ion
An electrified portion of matter of atomic or molecular dimensions.
Ion Exchange
An exchange of ions between a solution and a solid. In practice, most commonly effected by ion exchange resins.
IR Drop
The voltage across a resistance in accordance with Ohm's Law: E = IR where: E = potential (voltage), I = current, and R = resistance.
J
K
Karat
A twenty-fourth part by weight; thus 18-karat gold is 18/24 pure.
L
Lapping
Rubbing two surfaces together, with or without abrasives, for the purpose of obtaining extreme dimensional accuracy or superior surface finish.
Leveling Action
The ability of a plating solution to produce a surface smoother than that of the substrate.
Limiting Current Density:
(1) Cathodic: The maximum current density at which satisfactory deposits can be
obtained.
(2) Anodic: - The maximum current density at which the anode behaves normally,
without excessive polarization.
M
Mat Finish (Matte Finish)
A dull finish.
Matrix
A form used as a cathode in electroforming; a mold or mandrel.
Metal Distribution Ratio
The ratio of the thicknesses of metal upon two specified areas of a cathode. See Throwing Power.
Metallizing
(1) The application of an electrically conductive metallic layer to the surface of
nonconductors.
(2) The application of metallic coatings by nonelectrolytic procedures such as
spraying of molten metal and deposition from the vapor phase.
Microinch
One millionth of an inch, 0.000001 in; = 0.001 mil.
Micron (?
One millionth of a meter, 0.001 mm.
Microthrowing Power
The ability of a plating solution or a specified set of plating conditions to deposit metal in pores or scratches.
Mil
One thousandth of an inch, 0.001 in. = 25.4 ?
Mill Scale
The heavy oxide layer formed during hot fabrication or heat treatment of metals.
Motor-Generator (MG Set)
A machine that consists of one or more motors mechanically coupled to one or
more generators. In plating, such a machine in which the generator delivers DC of
appropriate amperage and voltage.
N
Noble Metal
A metal that does not readily tend to furnish ions, and therefore does not dissolve readily, nor easily enter into such reactions as oxidations, etc. The opposite of base metal.
Note - Since there is no agreement over the sign of electrode potentials the words noble and base are often preferred because they are unambiguous.
Nodule
A rounded projection formed on a cathode electrodeposition.
O
Orange Peel
A finish resembling the dimpled appearance of an orange peel.
Overvoltage
The irreversible excess of potential required for an electrochemical reaction to proceed actively at a specified electrode, over and above the reversible potential characteristics of that reaction.
Oxidation
A reaction in which electrons are removed from a reactant. Sometimes, more specifically the combination of a reactant with oxygen.
Oxidizing Agent
A compound that causes oxidation, thereby itself becoming reduced.
P
pH
The cologarithm (negative logarithm) of the hydrogen ion activity, less precisely,
concentration, of a medium, as determined by indicators or electrometric means.
Passivity
The condition of a metal that retards its normal reaction in a specified environment and associated with the assumption of a potential more noble than its normal potential.
Peeling
The detachment or partial detachment of an electrodeposited coating from a basis metal or undercoat.
Periodic Reverse Plating
A method of plating in which the current is reversed periodically. The cycles are usually no longer than a few minutes and may be much less.
Pickle
An acid solution used to remove oxides or other compounds from the surface of a metal by chemical or electrochemical action.
Pickling
The removal of oxides or other compounds from a metal surface by means of a pickle.
Pit
A small depression or cavity produced in a metal surface during electrodeposition or by corrosion.
Plastisol
A mixture of resins, plasticizers, and other minor additives, such as pigments, etc., that can be converted to a continuous film by the application of heat. Distinct from baking enamels, etc., in that substantially all the original mixture becomes a part of the film; them is no significant evaporation of solvent. The films am usually much thicker than obtainable from coatings which depend on the evaporation of a volatile solvent.
Plating Range
The current density range over which a satisfactory electroplate can be deposited.
Polarization
The change in the potential of an electrode during electrolysis, such that the potential of an anode always becomes more noble and that of a cathode becomes less noble than their respective static potentials. Equal to the difference between the static potential and the dynamic potential.
Polarizer
A substance or a means that produces or increases polarization.
Polishing
The smoothing of a metal surface by means of the action of abrasive particles attached by adhesive to the surface of wheels or endless belts usually driven at a high speed.
Primary Current Distribution
The distribution of the current over the surface of an electrode in an the absence of polarization.
R
Rack, Plating
A frame for suspending and carrying current to articles during plating and related operations.
Rectification
The conversion of alternating into direct current.
Rectifier
A device that converts alternating into direct current by virtue of a characteristic permitting appreciable flow of current in only one direction.
Reducing Agent
A compound that causes reduction, thereby itself becoming oxidized.
Reduction
A reaction in which electrons are added to a reactant. More specifically, the addition of hydrogen or the abstraction of oxygen. Such a reaction takes place, for example, at the cathode in electrolysis.
Relieving
The removal of material from selected portions of a colored metal surface by mechanical means, to achieve a multi-colored effect.
Resist, n
(1) A material applied to a part of a cathode or plating rack to render the surface
nonconductive.
(2) A material applied to a part of the surface of an article to prevent reaction
of metal from that area during chemical or electrochemical processes.
Ripple (DC)
Regular modulations in the DC output wave of a rectifier unit, or a motor-generator set, originating from the harmonics of the AC input system in the case of a rectifier, or from the harmonics of the induced voltage of a motor. Generator set.
Robber
See Thief.
s
Sacrificial Protection
The form of corrosion protection wherein one metal corrodes in preference to
another, thereby protecting the latter from corrosion.
Sand Blasting
Abrasive blasting with sand.
Saponification
The alkaline hydrolysis of fats whereby a soap is formed; more generally, the hydrolysis of an ester by an alkali with the formation of an alcohol and a salt of the acid portion.
Satin Finish - A surface finish that behaves as a diffuse reflector and which is lustrous but not mirrorlike.
Scale
An adherent oxide coating that is thicker than the superficial film referred to as tarnish.
Sealing of Anodic Coating
A process which, by absorption, chemical reaction, or other mechanism, increases the resistance of an anodic coating to staining and corrosion, improves the durability of colors produced in the coating, or imparts other desirable properties.
Sequestering Agent
A sequestering agent forms soluble complex ions with, or sequesters, a simple ion, thereby suppressing the activity of that ion. Thus, in water treatment the effects of hardness can be suppressed by adding agents to sequester calcium and magnesium. See Chelating Agent.
Shield, (n) A nonconducting medium for altering the current distribution on an anode or cathode.
Shield, (v) To alter the normal current distribution on an anode or cathode by the interposition of a nonconductor.
Slurry
A of suspension of solids in water.
Spotting out
The delayed appearance of spots and blemishes on plated or finished surfaces.
Stalagmometer
An apparatus for determining surface tension. The mass of a drop of a liquid is measured by weighing a known number of drops or by counting the number of drops obtained from a given volume of the liquid.
Stop-Off
See Resist.
Stopping Off
The application of a resist to any part of an electrode - cathode, anode, or rack.
Stray current
Current through paths other than the intended circuit, such as through heating coils or the tank.
Strike:
(1) (n) A thin film of metal to be followed by other
coatings.
(2) (n) A solution used to deposit a strike.
(3) (v). - To plate for a short time, usually at a high initial current density.
Strip
(1) (v) To remove a coating from the basis metal or undercoat.
Strip
(1) (n) A process or solution used for the removal of a coating from a basis metal or an undercoat
Substrate
See Basis Metal (or Material).
Superimposed AC
A form of current in which an alternating current component is superimposed on the direct plating current.
Surface Active Agent (Surfactant)
A soluble or colloidal substance having the property of affecting markedly the surface energy of solutions even when present in very low concentration.
Surface Tension
That property, due to molecular forces, that exists in the surface film of all liquids and tends to prevent the liquid from spreading.
T
Tank Voltage
The total voltage between the anode and cathode of a plating bath or electrolytic cell during electrolysis. It is equal to the sum of:
(1) the equilibrium reaction potential,
(2) the IR drop, and
(3) the electrode potentials.
Tarnish
The dulling, staining, or discoloration of metals due to superficial corrosion. The film so formed.
Thief
An auxiliary cathode so placed as to divert to itself some current from portions of the work which would otherwise receive too high a current density.
Throwing Power
The improvement of the coating (usually metal) distribution over the primary current distribution on an electrode (usually cathode) in a given solution, under specified conditions. The term may also be used for anodic processes for which the definition is analogous.
Total Cyanide
The total content of cyanide expressed as the radical CN-, or alkali cyanide whether present as simple or complex ions. The sum of both the combined and free cyanide content of a solution.
Transference (or Transport, or Migration)
The movement of ions through the electrolyte associated with the passage of the electric current.
Transference Number (Transport Number)
The proportion of the total current carried by the ions of a given kind.
Trees
Branched or irregular projections formed on a cathode during electrodeposition especially at edges and other high current density areas.
Tripoli
Friable and dustlike silica used as an abrasive.
Tumbling
See Barrel Finishing.
V
Voltage Efficiency
The ratio, usually expressed as a percentage, of the equilibrium reaction potential in a given electrochemical process to the bath voltage.
W
Water Break
The appearance of a discontinuous film of water on a surface signifying non-uniform wetting and usually associated with a surface contamination.
Wet Blasting
A process for cleaning or finishing by means of a slurry or abrasive in water directed at high velocity against the work pieces.
Wetting Agent
A substance that reduces the surface tension of a liquid, thereby causing it to spread more readily on a solid surface.
Whiskers
Metallic filamentary growths, often microscopic, sometimes formed during electrodeposition and sometimes spontaneously during storage or service, after finishing.
Work (Plating)
The material being plated or otherwise finished. |
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