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Cathodic arc deposition or Arc-PVD is a physical vapor deposition technique in which an electric arc is used to vaporize material from a cathode target. The vaporized material then condenses on a substrate, forming a thin film. The technique can be used to deposit metallic, ceramic, and composite films.
High zinc improves the bath's efficiency (plating speed), while lower levels improve the bath's ability to throw into low current densities. Typically, the Zn metal level varies between 20 and 50 g/L (2.7-6.7 oz/gal). The pH varies between 4.8 and 5.8 units. The following chart illustrates a typical all potassium chloride bath composition:
The coating temperature has an effect on the bath conductivity and deposited film conductivity, which increases as temperature increases. Temperature also has an effect on the viscosity of the deposited film, which in turn affects the ability of the deposited film to release the gas bubbles being formed.
The Hull cell is a type of test cell used to semi-quantitatively check the condition of an electroplating bath. It measures useable current density range, optimization of additive concentration, recognition of impurity effects, and indication of macro throwing power capability. [14] The Hull cell replicates the plating bath on a lab scale.
The part to be coated is immersed in a bath of electrolyte which usually consists of a dilute alkaline solution such as KOH. It is electrically connected, so as to become one of the electrodes in the electrochemical cell, with the other "counter-electrode" typically being made from an inert material such as stainless steel, and often consisting of the wall of the bath itself.
The unshaded bars indicate the location on the chart of those steels when in acidic/stagnant water ( like in the bilge ), where crevice-corrosion happens. Notice how the *same* steel has much different galvanic-series location, depending on the electrolyte it's in, making prevention of corrosion .. more difficult.
Cathodic stripping voltammetry is a voltammetric method for quantitative determination of specific ionic species. [6] It is similar to the trace analysis method anodic stripping voltammetry , except that for the plating step, the potential is held at an oxidizing potential, and the oxidized species are stripped from the electrode by sweeping ...
The main advantage of electroforming is that it accurately replicates the external shape of the mandrel. Generally, machining a cavity accurately is more challenging than machining a convex shape; however, the opposite holds true for electroforming because the mandrel's exterior can be accurately machined and then used to electroform a precision cavity.