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73-404: The complex was set up in 1987 as a heavy repair center for tanks and armored vehicles. The Derg regime had plans to eventually produce tanks, armored vehicles, aircraft missiles like air-to-air missiles and SCUD missiles at the complex. The Ethiopian government is doing everything to transform the country's economy from its current dependency on rain fed agriculture. Although the country's economy

146-666: A 4-vector . Charge carriers which are free to move constitute a free current density, which are given by expressions such as those in this section. Electric current is a coarse, average quantity that tells what is happening in an entire wire. At position r at time t , the distribution of charge flowing is described by the current density: j ( r , t ) = ρ ( r , t ) v d ( r , t ) {\displaystyle \mathbf {j} (\mathbf {r} ,t)=\rho (\mathbf {r} ,t)\;\mathbf {v} _{\text{d}}(\mathbf {r} ,t)} where A common approximation to

219-412: A chosen cross section . The current density vector is defined as a vector whose magnitude is the electric current per cross-sectional area at a given point in space, its direction being that of the motion of the positive charges at this point. In SI base units , the electric current density is measured in amperes per square metre . Assume that A (SI unit: m ) is a small surface centered at

292-399: A constant metal ion level, and contribute to conductivity. Additionally, non-metal chemicals such as carbonates and phosphates may be added to increase conductivity. When plating is not desired on certain areas of the substrate, stop-offs are applied to prevent the bath from coming in contact with the substrate. Typical stop-offs include tape, foil, lacquers , and waxes . Initially,

365-402: A copper strike is used, which has good adherence to both. The pulse electroplating or pulse electrodeposition (PED) process involves the swift alternating of the electrical potential or current between two different values, resulting in a series of pulses of equal amplitude, duration, and polarity, separated by zero current. By changing the pulse amplitude and width, it is possible to change

438-424: A fast switch. Another common problem of pulse electroplating is that the anode material could get plated and contaminated during the reverse electroplating, especially for a high-cost, inert electrode such as platinum . Other factors that affect the pulse electroplating include temperature, anode-to-cathode gap, and stirring. Sometimes, pulse electroplating can be performed in a heated electroplating bath to increase

511-581: A given point M and orthogonal to the motion of the charges at M . If I A (SI unit: A ) is the electric current flowing through A , then electric current density j at M is given by the limit : j = lim A → 0 I A A = ∂ I ∂ A | A = 0 , {\displaystyle j=\lim _{A\to 0}{\frac {I_{A}}{A}}=\left.{\frac {\partial I}{\partial A}}\right|_{A=0},} with surface A remaining centered at M and orthogonal to

584-453: A physical change is a change in the outward appearance. An example of a mechanical change is a change in tensile strength or surface hardness , which is a required attribute in the tooling industry. Electroplating of acid gold on underlying copper- or nickel-plated circuits reduces contact resistance as well as surface hardness. Copper-plated areas of mild steel act as a mask if case-hardening of such areas are not desired. Tin-plated steel

657-467: A range current densities along its length, which can be measured with a Hull cell ruler. The solution volume allows for a semi-quantitative measurement of additive concentration: 1 gram addition to 267 mL is equivalent to 0.5 oz/gal in the plating tank. Electroplating changes the chemical, physical, and mechanical properties of the workpiece. An example of a chemical change is when nickel plating improves corrosion resistance. An example of

730-407: A sample of the plating solution and an appropriate anode which is connected to a rectifier . The "work" is replaced with a Hull cell test panel that will be plated to show the "health" of the bath. The Hull cell is a trapezoidal container that holds 267 milliliters of a plating bath solution. This shape allows one to place the test panel on an angle to the anode. As a result, the deposit is plated at

803-400: A special plating deposit called a strike or flash may be used to form a very thin (typically less than 0.1 μm thick) plating with high quality and good adherence to the substrate. This serves as a foundation for subsequent plating processes. A strike uses a high current density and a bath with a low ion concentration. The process is slow, so more efficient plating processes are used once

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876-438: Is a current density corresponding to the net movement of electric dipole moments per unit volume, i.e. the polarization P : j P = ∂ P ∂ t {\displaystyle \mathbf {j} _{\mathrm {P} }={\frac {\partial \mathbf {P} }{\partial t}}} Similarly with magnetic materials , circulations of the magnetic dipole moments per unit volume, i.e.

949-468: Is a process for producing a metal coating on a solid substrate through the reduction of cations of that metal by means of a direct electric current . The part to be coated acts as the cathode (negative electrode ) of an electrolytic cell ; the electrolyte is a solution of a salt whose cation is the metal to be coated, and the anode (positive electrode) is usually either a block of that metal, or of some inert conductive material. The current

1022-499: Is an important parameter that provides a measure of the uniformity of electroplating current, and consequently the uniformity of the electroplated metal thickness, on regions of the part that are near the anode compared to regions that are far from it. It depends mostly on the composition and temperature of the electroplating solution. Micro throwing power refers to the extent to which a process can fill or coat small recesses such as through-holes . Throwing power can be characterized by

1095-482: Is an important term in Ampere's circuital law , one of Maxwell's equations, since absence of this term would not predict electromagnetic waves to propagate, or the time evolution of electric fields in general. Since charge is conserved, current density must satisfy a continuity equation . Here is a derivation from first principles. The net flow out of some volume V (which can have an arbitrary shape but fixed for

1168-478: Is calculated by multiplying the duty cycle and peak value of the current or potential. Pulse electroplating could help to improve the quality of electroplated film and release the internal stress built up during fast deposition. A combination of the short duty cycle and high frequency could decrease surface cracks. However, in order to maintain the constant effective current or potential, a high-performance power supply may be required to provide high current/potential and

1241-423: Is chromium-plated to prevent dulling of the surface due to oxidation of tin. There are a number of alternative processes to produce metallic coatings on solid substrates that do not involve electrolytic reduction: Electroplating was invented by Italian chemist Luigi Valentino Brugnatelli in 1805. Brugnatelli used his colleague Alessandro Volta 's invention of five years earlier, the voltaic pile , to facilitate

1314-400: Is fabricated out of perspex or glass. 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. The Hull cell replicates the plating bath on a lab scale. It is filled with

1387-424: Is highly dependent on agriculture it is not farfetched to imagine an Ethiopian economy that is based on manufacturing and modern heavy industries like mining. While the mining Industry is still for most part in the preliminary stage of development the manufacturing sector is off to a good start. One among the few home grown manufacturing sectors is the huge Bishoftu Automotive Industry outside Addis Ababa. The complex

1460-431: Is now a complex function . In many materials, for example, in crystalline materials, the conductivity is a tensor , and the current is not necessarily in the same direction as the applied field. Aside from the material properties themselves, the application of magnetic fields can alter conductive behaviour. Currents arise in materials when there is a non-uniform distribution of charge. In dielectric materials, there

1533-429: Is provided by an external power supply . Electroplating is widely used in industry and decorative arts to improve the surface qualities of objects—such as resistance to abrasion and corrosion , lubricity , reflectivity , electrical conductivity , or appearance. It is used to build up thickness on undersized or worn-out parts and to manufacture metal plates with complex shape, a process called electroforming . It

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1606-549: Is simply the sum of the free and bound currents: j = j f + j b {\displaystyle \mathbf {j} =\mathbf {j} _{\mathrm {f} }+\mathbf {j} _{\mathrm {b} }} There is also a displacement current corresponding to the time-varying electric displacement field D : j D = ∂ D ∂ t {\displaystyle \mathbf {j} _{\mathrm {D} }={\frac {\partial \mathbf {D} }{\partial t}}} which

1679-624: Is structured in five departments as follows: Maintaining light and heavy trucks used by the Ethiopian ground forces. The department manufacturing engines and produces spare parts for tanks, armored vehicles and military trucks. Repair and support of supply logistics by repairing and overhauling medium and heavy weapons. The electroplating shop is the largest both in its diversity and capacity in Ethiopia. Repair and maintain various communications apparatuses and electronic equipment in use with

1752-403: Is the dot product of the unit vectors. That is, the component of current density passing through the surface (i.e. normal to it) is j cos θ , while the component of current density passing tangential to the area is j sin θ , but there is no current density actually passing through the area in the tangential direction. The only component of current density passing normal to the area

1825-540: Is the cosine component. Current density is important to the design of electrical and electronic systems. Circuit performance depends strongly upon the designed current level, and the current density then is determined by the dimensions of the conducting elements. For example, as integrated circuits are reduced in size, despite the lower current demanded by smaller devices , there is a trend toward higher current densities to achieve higher device numbers in ever smaller chip areas. See Moore's law . At high frequencies,

1898-404: Is the integral of the flux of j across S between t 1 and t 2 . The area required to calculate the flux is real or imaginary, flat or curved, either as a cross-sectional area or a surface. For example, for charge carriers passing through an electrical conductor , the area is the cross-section of the conductor, at the section considered. The vector area is a combination of

1971-426: Is the reverse of the process of electroplating. Throwing power is an important parameter that provides a measure of the uniformity of electroplating current, and consequently the uniformity of the electroplated metal thickness, on regions of the part that are near to the anode compared to regions that are far from it. It depends mostly on the composition and temperature of the electroplating solution, as well as on

2044-474: Is used to deposit copper and other conductors in forming printed circuit boards and copper interconnects in integrated circuits. It is also used to purify metals such as copper . The aforementioned electroplating of metals uses an electroreduction process (that is, a negative or cathodic current is on the working electrode). The term "electroplating" is also used occasionally for processes that occur under electro-oxidation (i.e positive or anodic current on

2117-503: Is used to probe the physics underlying the nature of solids, including not only metals, but also semiconductors and insulators. An elaborate theoretical formalism has developed to explain many fundamental observations. The current density is an important parameter in Ampère's circuital law (one of Maxwell's equations ), which relates current density to magnetic field . In special relativity theory, charge and current are combined into

2190-608: The Parthian Empire using a device resembling a Baghdad Battery , but this has since been refuted; the items were fire-gilded using mercury. Boris Jacobi in Russia not only rediscovered galvanoplastics, but developed electrotyping and galvanoplastic sculpture . Galvanoplastics quickly came into fashion in Russia, with such people as inventor Peter Bagration , scientist Heinrich Lenz , and science-fiction author Vladimir Odoyevsky all contributing to further development of

2263-413: The insulating material failing, or the desired electrical properties changing. At high current densities the material forming the interconnections actually moves, a phenomenon called electromigration . In superconductors excessive current density may generate a strong enough magnetic field to cause spontaneous loss of the superconductive property. The analysis and observation of current density also

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2336-633: The magnetization M , lead to magnetization currents : j M = ∇ × M {\displaystyle \mathbf {j} _{\mathrm {M} }=\nabla \times \mathbf {M} } Together, these terms add up to form the bound current density in the material (resultant current due to movements of electric and magnetic dipole moments per unit volume): j b = j P + j M {\displaystyle \mathbf {j} _{\mathrm {b} }=\mathbf {j} _{\mathrm {P} }+\mathbf {j} _{\mathrm {M} }} The total current

2409-648: The 1850s. Electroplating baths and equipment based on the patents of the Elkingtons were scaled up to accommodate the plating of numerous large-scale objects and for specific manufacturing and engineering applications. The plating industry received a big boost with the advent of the development of electric generators in the late 19th century. With the higher currents available, metal machine components, hardware, and automotive parts requiring corrosion protection and enhanced wear properties, along with better appearance, could be processed in bulk. The two World Wars and

2482-399: The Ethiopian forces. In order to fully utilize its capacity and generate income, the center provides services to civilian customers through spare parts supply, electroplating services, and manufacturing machineries for various civilian industries. FDRE Defense Industry, May 2008 Electroplating Electroplating , also known as electrochemical deposition or electrodeposition ,

2555-488: The Heatley throwing power 100% × ( L − M ) / ( L − 1) , and Field throwing power 100% × ( L − M ) / ( L + M − 2) . A more uniform thickness is obtained by making the throwing power larger (less negative) according to any of these definitions. Parameters that describe cell performance such as throwing power are measured in small test cells of various designs that aim to reproduce conditions similar to those found in

2628-863: The SI units of newtons per coulomb (N⋅C ) or, equivalently, volts per metre (V⋅m ). A more fundamental approach to calculation of current density is based upon: j ( r , t ) = ∫ − ∞ t [ ∫ V σ ( r − r ′ , t − t ′ ) E ( r ′ , t ′ ) d 3 r ′ ] d t ′ {\displaystyle \mathbf {j} (\mathbf {r} ,t)=\int _{-\infty }^{t}\left[\int _{V}\sigma (\mathbf {r} -\mathbf {r} ',t-t')\;\mathbf {E} (\mathbf {r} ',t')\;{\text{d}}^{3}\mathbf {r} '\,\right]{\text{d}}t'} indicating

2701-421: The ability to plate items that for some reason cannot be tank plated (one application was the plating of portions of very large decorative support columns in a building restoration), low or no masking requirements, and comparatively low plating solution volume requirements. Disadvantages compared to tank plating can include greater operator involvement (tank plating can frequently be done with minimal attention), and

2774-435: The bulk solution to the electrode surface. The ideal stirring setting varies for different metal electroplating processes. A closely-related process is brush electroplating, in which localized areas or entire items are plated using a brush saturated with plating solution. The brush, typically a stainless steel body wrapped with an absorbent cloth material that both holds the plating solution and prevents direct contact with

2847-445: The case of plated solder, it is sometimes deemed necessary to have a true alloy, and the plated solder is melted to allow the tin and lead to combine into a true alloy. The true alloy is more corrosion-resistant than the as-plated mixture. Many plating baths include cyanides of other metals (such as potassium cyanide ) in addition to cyanides of the metal to be deposited. These free cyanides facilitate anode corrosion, help to maintain

2920-422: The cathode is plated, and thus the ions in the electrolyte bath are continuously replenished by the anode. The net result is the effective transfer of metal from the anode to the cathode. The anode may instead be made of a material that resists electrochemical oxidation, such as lead or carbon . Oxygen , hydrogen peroxide , and some other byproducts are then produced at the anode instead. In this case, ions of

2993-460: The cathode, the Cu is reduced to metallic copper by gaining two electrons. When the anode is made of the metal that is intended for coating onto the cathode, the opposite reaction may occur at the anode, turning it into dissolved cations. For example, copper would be oxidized at the anode to Cu by losing two electrons. In this case, the rate at which the anode is dissolved will equal the rate at which

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3066-504: The charge contained in the volume formed by dA and v d t {\displaystyle v\,dt} will flow through dA . This charge is equal to d q = ρ v d t d A , {\displaystyle dq=\rho \,v\,dt\,dA,} where ρ is the charge density at M . The electric current is d I = d q / d t = ρ v d A {\displaystyle dI=dq/dt=\rho vdA} , it follows that

3139-437: The coating. ASTM B322 is a standard guide for cleaning metals prior to electroplating. Cleaning includes solvent cleaning, hot alkaline detergent cleaning, electrocleaning, ultrasonic cleaning and acid treatment. The most common industrial test for cleanliness is the waterbreak test, in which the surface is thoroughly rinsed and held vertical. Hydrophobic contaminants such as oils cause the water to bead and break up, allowing

3212-429: The conducting region in a wire becomes confined near its surface which increases the current density in this region. This is known as the skin effect . High current densities have undesirable consequences. Most electrical conductors have a finite, positive resistance , making them dissipate power in the form of heat. The current density must be kept sufficiently low to prevent the conductor from melting or burning up,

3285-437: The current density assumes the current simply is proportional to the electric field, as expressed by: j = σ E {\displaystyle \mathbf {j} =\sigma \mathbf {E} } where E is the electric field and σ is the electrical conductivity . Conductivity σ is the reciprocal ( inverse ) of electrical resistivity and has the SI units of siemens per metre (S⋅m ), and E has

3358-444: The current density vector is the vector normal d A {\displaystyle dA} (i.e. parallel to v ) and of magnitude d I / d A = ρ v {\displaystyle dI/dA=\rho v} j = ρ v . {\displaystyle \mathbf {j} =\rho \mathbf {v} .} The surface integral of j over a surface S , followed by an integral over

3431-557: The definition given above: d A = d A n ^ . {\displaystyle d\mathbf {A} =dA\mathbf {\hat {n}} .} If the current density j passes through the area at an angle θ to the area normal n ^ , {\displaystyle \mathbf {\hat {n}} ,} then j ⋅ n ^ = j cos ⁡ θ {\displaystyle \mathbf {j} \cdot \mathbf {\hat {n}} =j\cos \theta } where ⋅

3504-437: The deposited film's composition and thickness. The experimental parameters of pulse electroplating usually consist of peak current/potential, duty cycle, frequency, and effective current/potential. Peak current/potential is the maximum setting of electroplating current or potential. Duty cycle is the effective portion of time in a certain electroplating period with the current or potential applied. The effective current/potential

3577-472: 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. A small gap-to-sample-area ratio may cause uneven distribution of current and affect the surface topology of the plated sample. Stirring may increase the transfer/diffusion rate of metal ions from

3650-459: The desired strike thickness is obtained. The striking method is also used in combination with the plating of different metals. If it is desirable to plate one type of deposit onto a metal to improve corrosion resistance but this metal has inherently poor adhesion to the substrate, then a strike can be first deposited that is compatible with both. One example of this situation is the poor adhesion of electrolytic nickel on zinc alloys, in which case

3723-455: The dimensionless Wagner number : Wa = R T κ F L α | i | , {\displaystyle {\text{Wa}}={\frac {RT\kappa }{FL\alpha |i|}},} where R is the universal gas constant , T is the operating temperature , κ is the ionic conductivity of the plating solution, F is the Faraday constant , L is

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3796-545: The electric current less sensitive to voltage), and raising the solution conductivity (e.g. by adding acid ). Concurrent hydrogen evolution usually improves the uniformity of electroplating by increasing | i |; however, this effect can be offset by blockage due to hydrogen bubbles and hydroxide deposits. The Wagner number is rather difficult to measure accurately; therefore, other related parameters, that are easier to obtain experimentally with standard cells, are usually used instead. These parameters are derived from two ratios:

3869-587: The entire past history up to the present time. The above conductivity and its associated current density reflect the fundamental mechanisms underlying charge transport in the medium, both in time and over distance. A Fourier transform in space and time then results in: j ( k , ω ) = σ ( k , ω ) E ( k , ω ) {\displaystyle \mathbf {j} (\mathbf {k} ,\omega )=\sigma (\mathbf {k} ,\omega )\;\mathbf {E} (\mathbf {k} ,\omega )} where σ ( k , ω )

3942-453: The equivalent size of the plated object, α is the transfer coefficient , and i the surface-averaged total (including hydrogen evolution ) current density. The Wagner number quantifies the ratio of kinetic to ohmic resistances. A higher Wagner number produces a more uniform deposition. This can be achieved in practice by decreasing the size ( L ) of the plated object, reducing the current density | i |, adding chemicals that lower α (make

4015-569: The first electrodeposition. Brugnatelli's inventions were suppressed by the French Academy of Sciences and did not become used in general industry for the following thirty years. By 1839, scientists in Britain and Russia had independently devised metal-deposition processes similar to Brugnatelli's for the copper electroplating of printing press plates. Research from the 1930s had theorized that electroplating might have been performed in

4088-510: The growing aviation industry gave impetus to further developments and refinements, including such processes as hard chromium plating , bronze alloy plating, sulfamate nickel plating, and numerous other plating processes. Plating equipment evolved from manually-operated tar -lined wooden tanks to automated equipment capable of processing thousands of kilograms per hour of parts. One of the American physicist Richard Feynman 's first projects

4161-409: The inability to achieve as great a plate thickness. This technique of electroplating is one of the most common used in the industry for large numbers of small objects. The objects are placed in a barrel-shaped non-conductive cage and then immersed in a chemical bath containing dissolved ions of the metal that is to be plated onto them. The barrel is then rotated, and electrical currents are run through

4234-406: The item being plated, is connected to the anode of a low-voltage direct-current power source, and the item to be plated is connected to the cathode . The operator dips the brush in plating solution and then applies it to the item, moving the brush continually to get an even distribution of the plating material. Brush electroplating has several advantages over tank plating, including portability,

4307-424: The lag in response by the time dependence of σ , and the non-local nature of response to the field by the spatial dependence of σ , both calculated in principle from an underlying microscopic analysis, for example, in the case of small enough fields, the linear response function for the conductive behaviour in the material. See, for example, Giuliani & Vignale (2005) or Rammer (2007). The integral extends over

4380-403: The magnitude of the area through which the charge carriers pass, A , and a unit vector normal to the area, n ^ . {\displaystyle \mathbf {\hat {n}} .} The relation is A = A n ^ . {\displaystyle \mathbf {A} =A\mathbf {\hat {n}} .} The differential vector area similarly follows from

4453-409: The metal to be plated must be replenished (continuously or periodically) in the bath as they are drawn out of the solution. The plating is most commonly a single metallic element , not an alloy . However, some alloys can be electrodeposited, notably brass and solder . Plated "alloys" are not "true alloys" (solid solutions), but rather they are tiny crystals of the elemental metals being plated. In

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4526-418: The motion of the charges during the limit process. The current density vector j is the vector whose magnitude is the electric current density, and whose direction is the same as the motion of the positive charges at M . At a given time t , if v is the velocity of the charges at M , and dA is an infinitesimal surface centred at M and orthogonal to v , then during an amount of time dt , only

4599-481: The operating current density . A higher throwing power of the plating bath results in a more uniform coating. The electrolyte in the electrolytic plating cell should contain positive ions (cations) of the metal to be deposited. These cations are reduced at the cathode to the metal in the zero valence state. For example, the electrolyte for copper electroplating can be a solution of copper(II) sulfate , which dissociates into Cu cations and SO 4 anions. At

4672-423: The production plating bath. The Haring–Blum cell is used to determine the macro throwing power of a plating bath. The cell consists of two parallel cathodes with a fixed anode in the middle. The cathodes are at distances from the anode in the ratio of 1:5. The macro throwing power is calculated from the thickness of plating at the two cathodes when a direct current is passed for a specific period of time. The cell

4745-516: The ratio M = m 1 / m 2 of the plating thickness of a specified region of the cathode "close" to the anode to the thickness of a region "far" from the cathode and the ratio L = x 2 / x 1 of the distances of these regions through the electrolyte to the anode. In a Haring-Blum cell, for example, L = 5 for its two independent cathodes, and a cell yielding plating thickness ratio of M = 6 has Harring-Blum throwing power 100% × ( L − M ) / L = −20% . Other conventions include

4818-644: The technology. Among the most notorious cases of electroplating usage in mid-19th century Russia were the gigantic galvanoplastic sculptures of St. Isaac's Cathedral in Saint Petersburg and gold-electroplated dome of the Cathedral of Christ the Saviour in Moscow , the third tallest Orthodox church in the world . Soon after, John Wright of Birmingham , England discovered that potassium cyanide

4891-464: The time duration t 1 to t 2 , gives the total amount of charge flowing through the surface in that time ( t 2 − t 1 ): q = ∫ t 1 t 2 ∬ S j ⋅ n ^ d A d t . {\displaystyle q=\int _{t_{1}}^{t_{2}}\iint _{S}\mathbf {j} \cdot \mathbf {\hat {n}} \,dA\,dt.} More concisely, this

4964-429: The various pieces in the barrel, which complete circuits as they touch one another. The result is a very uniform and efficient plating process, though the finish on the end products will likely suffer from abrasion during the plating process. It is unsuitable for highly ornamental or precisely engineered items. Cleanliness is essential to successful electroplating, since molecular layers of oil can prevent adhesion of

5037-479: The water to drain rapidly. Perfectly clean metal surfaces are hydrophilic and will retain an unbroken sheet of water that does not bead up or drain off. ASTM F22 describes a version of this test. This test does not detect hydrophilic contaminants, but electroplating can displace these easily, since the solutions are water-based. Surfactants such as soap reduce the sensitivity of the test and must be thoroughly rinsed off. Throwing power (or macro throwing power )

5110-406: The working electrode), although such processes are more commonly referred to as anodizing rather than electroplating. One such example is the formation of silver chloride on silver wire in chloride solutions to make silver/silver-chloride (AgCl) electrodes . Electropolishing , a process that uses an electric current to selectively remove the outermost layer from the surface of a metal object,

5183-556: Was a suitable electrolyte for gold and silver electroplating. Wright's associates, George Elkington and Henry Elkington were awarded the first patents for electroplating in 1840. These two then founded the electroplating industry in Birmingham from where it spread around the world. The Woolrich Electrical Generator of 1844, now in Thinktank, Birmingham Science Museum , is the earliest electrical generator used in industry. It

5256-403: Was to develop technology for electroplating metal onto plastic . Feynman developed the original idea of his friend into a successful invention, allowing his employer (and friend) to keep commercial promises he had made but could not have fulfilled otherwise. Current density In electromagnetism , current density is the amount of charge per unit time that flows through a unit area of

5329-455: Was used by Elkingtons . The Norddeutsche Affinerie in Hamburg was the first modern electroplating plant starting its production in 1876. As the science of electrochemistry grew, its relationship to electroplating became understood and other types of non-decorative metal electroplating were developed. Commercial electroplating of nickel , brass , tin , and zinc were developed by

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