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Electroetching is a metal etching process [1] that involves the use of a solution of an electrolyte, an anode, and a cathode. The metal piece to be etched is connected to the positive pole of a source of direct electric current. A piece of the same metal is connected to the negative pole of the direct current source and is called the cathode. [2]
Sometimes, pulse electroplating can be performed in a heated electroplating bath to increase the deposition rate, since the rate of most chemical reactions increases exponentially with temperature per the Arrhenius law. The anode-to-cathode gap is related to the current distribution between anode and cathode.
cathode made of platinum or stainless steel (needle), anode nickel-plated or gold-plated copper or brass or polished steel, duration 10 s, distance between cathode and anode 3 mm . [20] An electrolyte of 100 g of litharge dissolved in 0.5 l of water can also be used in which 100 g of NaOH is dissolved.
During the aqueous deposition process, gas is being formed at both electrodes. Hydrogen gas is being formed at the cathode, and oxygen gas at the anode. For a given amount of charge transfer, exactly twice as much hydrogen is generated compared to oxygen on a molecular basis. This has some significant effects on the coating process.
The cathode efficiency depends on the process and varies between 90 and 97%. Due to this mismatch, during the plating the nickel concentration in the solution and the pH will slowly rise. [6] The process takes minutes to hours depending on the current density and the intended thickness of the plating. [7]
Excluding the continuous strip plating industry, copper is the second most commonly-plated metal after nickel. [6] Copper electroplating offers a number of advantages over other plating processes, including low metal cost, high-conductivity and high-ductility bright finish, and high plating efficiency.
In electrowinning, an electrical current is passed from an inert anode through a leach solution containing the dissolved metal ions so that the metal is recovered as it is reduced and deposited in an electroplating process onto the cathode. In electrorefining, the anode consists of the impure metal (e.g., copper) to be refined. The impure ...
The driving force for the cathodic protection current is the difference in electrode potential between the anode and the cathode. [9] During the initial phase of high current, the potential of the steel surface is polarized (pushed) more negative protecting the steel which hydroxide ion generation at the steel surface and ionic migration ...