What is Electroplating?
The term 'Electroplating' refers to the process of coating a metal with another metal by the process of hydrolysis.
The part that is to be coated, behaves as the negative charge which is the cathode of an electrolytic cell. The solution of the salt’s metal which has to be coated is electrolyte.
Hydrolysis is a chemical reaction in which a molecule of water breaks one or more chemical bonds. Metals are electroplated mostly for decorative purposes or for preventing the corrosion of metals. In electroplating, an electric current is used for reducing the dissolved metal cations (positively charged ions) at the cathode (negatively charged electrode) to have a lean coherent metal coating on the electrode. The process is quite often applied in the electrical oxidation of anions (negatively charged ions) on a solid substrate, for instance - in the formation of silver chloride (AgCl3) on the silver wire to form silver chloride electrodes.
Electroplating is primarily used to modify or enhance the surface features of an object for the prevention of corrosion or abrasion. However, the process can also be extensively used to make objects by electroforming or building their thickness.
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Working Concept of Electroplating
For having a better understanding of the process of electroplating, let us consider the example of a gold coating. In this particular scenario, we will enhance the appearance of metallic jewellery by electrodepositing a layer of gold on it. We will begin by connecting the gold plating to the anode, which is the positively charged electrode, and the jewellery to the cathode, which is the negatively charged electrode. Next, we have to immerse both of them in a highly developed electrolytic solution. During this phase, we will supply a DC voltage (direct current) to the anode, so that the gold atoms are oxidized and further get dissolved into the solution. The dissolved ions are then reduced at the cathode and consequently plated on the jewellery. Several factors influence the process of electroplating, namely, the voltage level of the DC, the chemical composition and temperature of the solution, the distance between the anode and the cathode, and the current length of time.
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Strike
A strike also known as a flash, which is a special plating deposit that is used as a very thin plating which is high in quality and good adherence. This works as a foundation for the process of plating. A strike uses a current density which is high and a bath with an ion concentration which is low.
It is a slow process, so all the plating processes which are more efficient are used only when the desired thickness of the strike is obtained.
For the combination with the plating of different plating, a striking method is used.
Deposition of Electrochemical
From the late 1990s, in order to manufacture conductive wires of copper in semiconductor devices that are advanced, electrochemical deposition has been used widely.
The methods which are used previously for making aluminium conductive wires into chips through engraving the metal lines and then fill in an insulating film that has chemical Vapor deposition along with physical Vapor deposition processes, were not working with copper because of the hardness of the metal, to solve this problem, this technology was created.
Applications and Uses of Electroplating
One of the prime uses of electroplating is to coat the surface of an object with a thin layer of metal by using the electrochemical process. Besides, electroplating has a plethora of other applications in many industries. A few practical applications and uses of this process are as follows:
Aesthetics
It is a matter of fact that yes - some metals are way more expensive, rare, and valuable than the others, like silver and gold being the most obvious examples. Through the process of electroplating, an extremely thin layer of gold or silver can be used to coat a less valuable metal so that the final product has all the beauty and lustre at a minimal cost. Electroplating, being one of the widely implemented applications today, is extensively used for designing jewellery and other ornaments. Moreover, thin layers of chromium are also used on automobiles and appliances to give them an attractive and shiny appearance.
Commercial Applications
Electroplating is also used on car parts to give a smooth appearance and texture with the help of a thin layer of chromium. As the car owner's request, electroplating can also be done on various other appliances as well.
Prevention of Corrosion
As some metals are more prone to natural processes such as corrosion (conversion of a metal into a chemically stabilized form like oxide, hydroxide, or sulfide), electroplating protects their surface by covering them with a thin layer of metal, which shall be corrosion resistant. Copper, chromium, and nickel, which are the non-corrosive metals, are spread over corrosive metals like iron and steel to prevent corrosion.
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Conduction of Electricity
Metals like silver and gold are indeed excellent conductors of electricity; however, they are prohibitively expensive. Through the techniques of electroplating, little amounts of these highly conductive and precious metals can be incorporated into the integrated circuits and electrical components like computers, cell phones, amongst many others, to help in the conduction of electricity.
Reduces Friction
Electroplating can reduce the built-up friction of some materials such as the electrical connectors to a great extent by introducing a certain kind of metal plating on them. For instance - nickel plating improves performance and reduces friction and wear and tear.
Protection from Radiation
Electroplating also helps to protect the materials from various other natural phenomena, including radiation and abrasion, simply by imparting the desired features or characteristics to the surface of the metals, which in general, lack them.
FAQs on Uses of Electroplating
1. How is cleanliness important to electroplating?
In order to make electroplating successful, cleanliness plays an important role. It is because oil has molecular layers that can prevent fastening of the coating. Cleaning means to clean the solvent, electro cleaning, hot alkaline detergent cleaning and treatment of acid. There are many Industrial tests for checking cleanliness but the common one is the water break test. In this, the surface is held vertically and is rinsed thoroughly. Hydrophobic contaminants like oil, that makes the water break up and bead, allows the water to channel quickly.
2. Write about the effects of electroplating?
The change in chemical, physical and mechanical properties of the workpiece is done by Electroplating. Plating of nickel Improves corrosion resistance, it is an example of chemical change. When a change happens in the outward appearance, it is an example of physical change. When there is a change in the hardness of the surface or it’s tensile strength, it becomes an example of mechanical change. Electroplating is used to render a metal part radioactive. It is done with the help of aqueous solution of concentration of nickel-phosphorus that contains hypophosphite ions.
3. What are the alternatives of electroplating?
The Alternatives of Electroplating are:
Immersion Coating Process- This process uses displacement reaction that means the substrate metal gets oxidised to soluble ions while it reduces the coating metal of the ions and deposits them in its place. This whole process is restricted to the coatings which are very thin, as when the substrate gets fully recovered, the reaction halts.
Sputtering- In this, a strong electron beam is used to release the microscopic particles of the metal in a vaccum, on the substrate.
Physical Vapor Deposition- It is used in transferring the metal to the substrate by using evaporation.
4. Write about the history of electroplating ?
There is a theory that states the first electroplating happened in the era of Parthian Empire. The assistant at National museum of Iraq, Wilhelm Konig, in the 1930s, had an observation of many silver objects from ancient Iraq that are plated with gold in very thin layers. He suspected that they were all electroplated. Archaeologists of modern times, believed that these objects discovered by Konig were not at all electroplated, they were rather fire-gilded by using mercury. The invention of electroplating was done by the Italian chemist Luigi Valentino Brugnatelli, around 1805.
5. What do you understand by hull cell?
it is a kind of test cell that is used to semi-quantitatively check an electroplating bath’s condition. It calculates the current density range which is usable. It optimises the addictive concentration, impurity effects are recognised and indicates the capabilities of macro-throwing power. The plating bath on a scale of lab is duplicated by Hull cell. It consists of a sample of plating solution, which is an appropriate anode that is connected to a rectifier. A trapezoidal container which consists of 267 ml solution for plating bath is The Hell cell. To know more, visit the Free Online Study Materials for CBSE, ICSE, IIT JEE Mains provided by Vedantu.