Both components are immersed in a solution called electrolyte that contains one or more dissolved metal salts, as well as other ions that allow the flow of electricity. A direct current power supply generates an electrical potential at the anode and cathode. At the cathode, the metal ions dissolved in the electrolyte solution are reduced at the interface between the solution and the cathode and disappear from the solution. This creates an imbalance of cations in the solution. This excess of cations combines with the metal atoms of the cathode, forming the salt that dissolves, leaving the remaining metal exposed, and on the other hand replenishing the precipitated ions. The cathode is a sink of metal cations and a generator of anions while the opposite happens at the anode, it is a sink of anions and generator of cations. The amount of both is regulated by the dissociation constant and the equilibrium laws, which means that the speed at which the anode dissolves is equal to the speed at which the cathode is coated. Although an electric current circulates, it is not constituted by electrons that travel between the electrodes in the anions, but rather an electron, or several, from the cathode will reduce a metal cation that will be deposited. This will produce an imbalance in the solution, causing some electrolyte molecules to dissociate. If it is far from the anode it will recombine again, but if it is close it will react by delivering an electron, or several, to it and generating a soluble salt that will be released.

Finally, indicate that this technique should not be confused with electrophoresis, this is based on the movement towards an anode or cathode of molecules or particles suspended in a solution, not of ions like electrodeposition.

The use of metallic electrodeposition is very common in jewelry made with cheap metals to which a coating of a very thin film of gold, silver, etc. is given, to increase its value, improve its appearance or to protect it from the negative effects of the environment, mainly the oxygen that produces its rapid corrosion.

The coins of Argentina, from the Series "Trees of the Argentine Republic" are made of steel electroplated with Copper ($1), Brass ($2), and Nickel ($5), except for the $10 coin which is made of Alpaca, in the same way the coins of Uruguay belonging to the Series "Native Fauna of Uruguay" are made of steel electroplated with Brass.

We can also observe that "electronic cards") generally come coated with a gold film of a few microns, to maintain good contact and conductivity with the circuit devices.

The Hull cell is a type of test cell used to qualitatively check the condition of a galvanic bath. Optimization for current density range, optimization of additive concentration, recognition of impurity effects and indication of macro-launch power capability is enabled.[4]​ The Hull cell replicates the plating bath on a laboratory scale.[5]​ It is filled with a sample of the metallization solution, an appropriate anode which is connected to a rectifier. The "work" is replaced by a Hull cell test panel that is coated to show the "health" of the bathroom.

The Hull cell is a trapezoidal container containing 267 ml of solution. This shape allows the test panel to be placed at an angle with respect to the anode. As a result, the deposit is plated at different current densities that can be measured with a hull cell ruler. The volume of the solution allows for quantitative optimization of the additive concentration: 1 gram addition to 267 ml is equivalent to 0.5 oz/gal in the coating tank. [9].

Contenido

El ánodo y el cátodo de la celda conectados a un suministro externo de corriente continua - una batería "Batería (electricidad)") o, más comúnmente, un rectificador. Ambos estarán sumergidos en un baño por una solución de sales del elemento químico que utilizamos para recubrir el objeto.

El cátodo, artículo a recubrir, estará conectado al terminal negativo. Mientras que el ánodo, conectado al terminal positivo, estará compuesto de dicho material para ir aportando iones a la solución a medida que se oxida sustituyendo a los que se están consumiendo en la reacción electroquímica.

Realizando un balance general se puede considerar que cuando se enciende la fuente de alimentación externa, el metal del ánodo se oxida a partir de un estado de valencia cero para formar cationes con carga positiva. Estos cationes asociar con los aniones de la solución. Los cationes se reduce en el cátodo depositándose en el estado metálico, valencia cero. Por ejemplo, en una solución ácida, el cobre se oxida en el ánodo a Cu perdiendo dos electrones. El Cu asociado con el anión SO en la solución forman el sulfato de cobre. En el cátodo, el Cu se reduce a cobre metálico al obtener dos electrones. El resultado es la transferencia efectiva de cobre de la fuente de ánodo a una película que recubre el cátodo.

El recubrimiento más común es un metal puro, no una aleación. Sin embargo, algunas aleaciones pueden ser electrodepositada, en particular el latón y soldadura.

Muchos baños galvánicos incluyen cianuros de otros metales (por ejemplo, cianuro de potasio), además de cianuros del metal a depositar. Estos cianuros libres facilitar la corrosión del ánodo, ayudan a mantener un nivel constante de iones metálicos y contribuir a la conductividad.

Además, productos químicos no metálicos tales como carbonatos y fosfatos se pueden añadir para aumentar la conductividad.

En la operación hay que tener en cuenta que una geometría compleja dará un espesor de recubrimiento irregular, aumentando este en esquinas del objeto por ejemplo. Estos contratiempos se pueden solucionar utilizando múltiples ánodos o un ánodo que imite la forma del objeto a procesar.

Cuando no se desea el recubrimiento en ciertas áreas del sustrato, se aplican barreras para evitar que el baño entrar en contacto con el sustrato. Barreras típicas son cinta, papel de aluminio, lacas y ceras. [ 3 ].

Un factor muy importante es la corriente que utiliza el sistema para llevar a cabo la operación, será determinante para las propiedades del recubrimiento, ya que establece la adherencia de la capa tanto como su calidad y velocidad de deposición, esta última es directamente proporcional al voltaje. Lo más común es usar corriente continua en pulsos, ciclos de 8-15 segundos activado el sistema para dejar 1-3 segundos de inactividad.

Strike

Initially, a special electroplating deposit called "bump" or "flash" can be used to form a very thin coating (typically less than 0.1 micrometers thick) with high quality and good adhesion to the substrate. This serves as a basis for subsequent deposition processes. A strike uses a high current density and a bath with a low ion concentration. This process is slow, so once the desired thickness is obtained, more efficient deposition processes are used.

This method is used for coating dissimilar poorly compatible metals. If a deposit-type plate is desirable on a metal to improve corrosion resistance, but this metal has inherently poor adhesion to the substrate, a strike compatible with both is first deposited. An example of this situation is the poor adhesion of electrolytic nickel on zinc alloys, in which case a copper etch is used, which has good adhesion to both. [2].

Electroplating brush

A closely related process is electroplating brushing. Localized areas or entire objects are worked with a brush saturated with the coating solution. The brush, usually a stainless steel body wrapped with a textile material that serves to both contain the plating solution and prevent direct contact with the element being treated, is connected to the positive pole of a low-voltage direct current source, and the coating element connected to the negative. The operator gaps the brush in metallizing solution and then applies it to the element, moving the brush continuously to achieve uniform distribution of the coating material. Electroplating brush has several advantages over tanks, including portability, the ability to coat items that for some reason cannot be introduced into the coating tank (one application is the coating of portions of very large decorative support columns used in building restoration), low or no masking requirements, and a comparatively smaller volume of solution required. The disadvantages compared to the tank are that it requires greater operator involvement (the coating tank can often be worked with a minimum of attention), and the inability to achieve a large coating thickness.

Deposition without electric current

Typically, an electrolytic cell, consisting of two electrodes, electrolyte, and external current source, is used for electrodeposition. In contrast, an electrolytic deposition process uses only one electrode and no external source of electrical current. However, the solution for the electrolytic process needs to contain a reducing agent so that the electrode reaction has the form:

In principle, any water-based reducer can be used, although the redox potential of the half-cell reducer must be high enough to overcome the energy barriers inherent in liquid chemistry. Electroless nickel plating uses hypophosphite as a reducer, while plating of other metals such as silver, gold and copper typically use low molecular weight aldehydes.

An important advantage of this approach over electroplating is the lack of need for power sources or electroplating baths, reducing production cost. The technique can also various plate shapes and type of surface. The film is more uniform. Alloys can be deposited and additives added to the film such as Teflon. The disadvantage is that depending on the material the galvanizing process is generally slower and this type of thick metal plates cannot be created. As a consequence of these characteristics, electroless deposition is quite common in the decorative arts. Although it is gaining ground in industrial applications, one of which, for example, is hard drives.

Cleaning

Cleanliness is essential to the success of electroplating, since molecular layers of oil can prevent the coating from adhering. ASTM B322 is a standard guide for cleaning metals before electroplating. Cleaning processes include: solvent cleaning, hot cleaning with alkaline detergent, electro-cleaning, and acid treatment, etc. The most common industrial test for cleaning is the waterbreak test, in which the surface is thoroughly rinsed and held vertically. Hydrophobic contaminants such as oils cause water to bead and break down, allowing water to drain quickly. Perfectly clean metal surfaces are hydrophilic and will hold a continuous sheet of water that will not count up or drain off. ASTM F22 describes a version of this test. This test does not detect hydrophilic contaminants, but the electrodeposition process can easily displace these since the solutions are water-based. Surfactants such as soap reduce the sensitivity of the test and should be rinsed carefully.

Both components are immersed in a solution called electrolyte that contains one or more dissolved metal salts, as well as other ions that allow the flow of electricity. A direct current power supply generates an electrical potential at the anode and cathode. At the cathode, the metal ions dissolved in the electrolyte solution are reduced at the interface between the solution and the cathode and disappear from the solution. This creates an imbalance of cations in the solution. This excess of cations combines with the metal atoms of the cathode, forming the salt that dissolves, leaving the remaining metal exposed, and on the other hand replenishing the precipitated ions. The cathode is a sink of metal cations and a generator of anions while the opposite happens at the anode, it is a sink of anions and generator of cations. The amount of both is regulated by the dissociation constant and the equilibrium laws, which means that the speed at which the anode dissolves is equal to the speed at which the cathode is coated. Although an electric current circulates, it is not constituted by electrons that travel between the electrodes in the anions, but rather an electron, or several, from the cathode will reduce a metal cation that will be deposited. This will produce an imbalance in the solution, causing some electrolyte molecules to dissociate. If it is far from the anode it will recombine again, but if it is close it will react by delivering an electron, or several, to it and generating a soluble salt that will be released.

Finally, indicate that this technique should not be confused with electrophoresis, this is based on the movement towards an anode or cathode of molecules or particles suspended in a solution, not of ions like electrodeposition.

The use of metallic electrodeposition is very common in jewelry made with cheap metals to which a coating of a very thin film of gold, silver, etc. is given, to increase its value, improve its appearance or to protect it from the negative effects of the environment, mainly the oxygen that produces its rapid corrosion.

The coins of Argentina, from the Series "Trees of the Argentine Republic" are made of steel electroplated with Copper ($1), Brass ($2), and Nickel ($5), except for the $10 coin which is made of Alpaca, in the same way the coins of Uruguay belonging to the Series "Native Fauna of Uruguay" are made of steel electroplated with Brass.

We can also observe that "electronic cards") generally come coated with a gold film of a few microns, to maintain good contact and conductivity with the circuit devices.

The Hull cell is a type of test cell used to qualitatively check the condition of a galvanic bath. Optimization for current density range, optimization of additive concentration, recognition of impurity effects and indication of macro-launch power capability is enabled.[4]​ The Hull cell replicates the plating bath on a laboratory scale.[5]​ It is filled with a sample of the metallization solution, an appropriate anode which is connected to a rectifier. The "work" is replaced by a Hull cell test panel that is coated to show the "health" of the bathroom.

The Hull cell is a trapezoidal container containing 267 ml of solution. This shape allows the test panel to be placed at an angle with respect to the anode. As a result, the deposit is plated at different current densities that can be measured with a hull cell ruler. The volume of the solution allows for quantitative optimization of the additive concentration: 1 gram addition to 267 ml is equivalent to 0.5 oz/gal in the coating tank. [9].