Here is an essay on ‘Electroplating’ for class 10, 11 and 12. Find paragraphs, long and short essays on ‘Electroplating’ especially written for school and college students.
Essay on Electroplating
Essay Contents:
- Essay on the Meaning of Electroplating
- Essay on the Operations Involved in Electroplating
- Essay on the Processes Involved in Electroplating
- Essay on the Equipment and Accessories for Electroplating
- Essay on the Cleaning Process for an Article before Electroplating
- Essay on the Design of Electroplating Tank
- Essay on the Precautions to be Taken in Electroplating Process
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Essay # 1. Meaning of Electroplating:
This is the process of covering the articles made up of cheap metals by a thin layer of superior metal by means of electrolysis. The base metal and coated metal may be same or different. Some common metals and alloys, of which coating can be provided on metallic and non-metallic surfaces, include zinc, chromium, tin, nickel, copper, silver, gold and platinum etc.
The electroplating is done for the following reasons:
(i) Protection of metals against corrosion.
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(ii) Giving shiny appearance to articles.
(iii) Replacing worn-out material.
Essay # 2. Operations Involved in Electroplating:
The following operations are involved while electroplating is done:
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1. Cleaning process
2. Deposition of metal
1. Cleaning Process:
The object to be electroplated is thoroughly cleaned degreased. If the electroplating is done on an unclean and greased surface, the metal deposited will not be well adherent to the base metal and is likely to peel off.
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2. Deposition of Metal:
The article to be electroplated is made cathode, solution is made up of salt of the metal to be deposited and anode is of the same metal which is to be deposited.
The electrolyte used in the electrolytic bath depends upon the nature of the metal to be deposited. For copper plating solution is made of 150 – 200 gm of copper sulphate and 20 to 30 gms of sulphuric acid per 1000 cc of solution. For silver plating 24 gms of silver cyanide, 24 gm of potassium carbonate and 36 gm of potassium cyanide per 1000 cc is used. For chromium 180 – 300 gm of chromic acid 2 – 3 gm H2SO4 per 1000 cc. For nickel plating 180 – 300 gm of chromic acid 2 – 3 gm H2SO4 per 1000 cc.
Essay # 3.
Processes Involved in Electroplating:
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(i) Copper Plating:
It is mostly used for plating iron articles to prevent them from rusting. It is also used as a base coating for silver and nickel plating. The surface of the article to be electroplated should be perfectly clean.
The electrolyte is an acid bath solution made of copper sulphate and sulphuric acid, Anode of pure copper. Time required for plating is 2 to 3 seconds. Voltage required is 4 to 10 volts. Current density 200 – 400 amp/ m2 and temperature of electrolyte 30 – 50°C. The deposit obtained is rough and thick and requires polishing.
For getting thin and smooth deposit, a cyanide bath solution made of copper cyanide, sodium cyanide, sodium carbonate and sodium bisulphate is used.
(ii) Nickel Plating:
Nickel does not stick well on iron and steel articles. Therefore, the article is first coated with a film of copper and then nickel is deposited on the copper plating. The electrolyte used is a nickel bath solution made of nickel sulphate, nickel chloride and boric acid. Time for plating is 30 minutes, voltage 5 – 7 volts, current density 250 – 500 Amps/m2 and temperature of electrolyte is 40 – 60°C. Anode is of pure nickel. Nickel life depends upon the copper coating under neat the nickel coating. The filtration and agitation plant is only used in nickel plating.
(iii) Chromium Plating:
Steel tanks with lead busing are used. Lead electrodes are used as anodes. The electrolyte must be heated and the fumes should be exhaust by exhaust fans.
The article is first nickel plated and then chromium plated and the life of chromium depends upon the nice coating under the chromium plating.
The chromium bath solution is made of chromic acid and sulphuric acid. Current density required is 600 to 5000 amps/m2, time 4 – 8 second, voltage 6 – 10 volts and temperature 50 – 70°C.
(iv) Dry Out:
After copper, nickel or chromium plating the article is buffed with fine polishing mops made of cotton rotating at high speeds.
(v) Rinses:
The articles are rinsed or water dipped between every process of cleaning such as physical cleaning, chemical cleaning, acid dips in order to prevent the carrying over of one processing solution to the other. To meet this requirement in every plating shop, special rinsing tanks with running water are extensively used. So ample supply of water, as well as drainage facilities are to be provided in a plating shop.
(vi) Reverse Current Process of Electroplating:
It is the latest development in electroplating.
In this process the plating current is reversed for a second or so at regular intervals to get following advantages:
1. Inferior metal is depleted during reverse current period.
2. Flat level surface is produced.
3. Metal surface brightened due to reversal of current periodically and it eliminates the buffing or polishing operations.
4. Polarization effect is reduced without affecting the quality of deposit.
(vii) Earthing:
It is essential that positive side of dc supply to the vats (plating tank) should be effectively connected to earth so that any leakage current deposits the plating material on to the work which is the cathode.
If negative of the dc supply is earthed, the leakage current will be from anode to vat. This will deposit the metal on the inner lining of the vat. Moreover by earthing vat i.e. positive side of d.c. supply, the operator is also protected from electric shock.
Essay # 4. Equipment and Accessories for Electroplating:
1. Glass Electroplating tank with plastic lid (Vat)
2. Voltmeter
3. Ammeter
4. Mops for Polishing
5. Rheostat
6. Grinder
7. Motor driven rotary air compressor
8. Flexible wheel of cotton
9. Suspension bar sets
10. Key
11. DC source (Battery)
12. Various solutions i.e. H2SO4 and HCl
13. Alkaline cleaner in powder form or jelly
14. Pieces of sand paper
15. Stirrer
16. Connecting wires.
Essay # 5. Cleaning Process for an Article before Electroplating:
The cleaning processes involved for an article before electroplating in sequence are: 1. Sand Blasting 2. Grinding 3. Polishing 4. Buffing 5. Physical Cleaning 6. Chemical Cleaning 7. Acid Dips 8. Electrolytic Cleaning.
1. Sand Blasting:
To remove oxide layer by projecting fine sand or steel ball on the surface of the article by means of a jet of compressed air.
2. Grinding:
By leather wheel of size 6”, 8” and 10” dressed with glue and energy on the periphery of the wheel.
3. Polishing:
By mops made of leather, canvas or felt dressed with glue and emery. The mops are driven at peripheral speed of 2000 to 3000 meters/minute.
4. Buffing:
A polisining process usually done by flexible wheels of cotton and a suitable abrasive of polishing composition. Buffing is done to make the surface of the metal to be electroplated more fine.
5. Physical Cleaning:
To degrease the metal with solvents like white spirit, solvent naphtha etc. at room temperature.
6. Chemical Cleaning:
By passing the articles through alkaline cleaners (in powder form or jelly) dissolved is water and stored in mild steel tanks.
7. Acid Dips:
To remove films of oxides etc. from the surface of the article, standard acid dips are 10% HCL and 10% H2SO4.
8. Electrolytic Cleaning:
To remove grease, a solution of sodium phosphate is used in an iron tank. The tank is made the anode and the article suspended as a cathode and heavy current is passed. Caustic soda is formed on cathode and hydrogen gas is evolved which removes grease etc. The process is called cathode cleaning and is used for Zinc and aluminium.
Essay # 6. Design of Electroplating Tank:
It is a rectangular welded mild steel tank (also known as plating vat) open at the top. Three brass rods run parallel to each other along the top of the vat, two on the sides and one in the centre. The rods on the side are connected to positive end of supply (called anode bars) and the central rod with negative end of supply (called cathode bar). The articles which are to be electroplated are suspended into the plating solution copper wires connected to the cathode bars.
The anode bars serve for the support of the anodes which are long pieces of metal suspended so that they can reach into the plating solution and serve as the positive pole. When DC supply is applied to the two electrodes, current starts flowing through the electrolyte. The metal ions, (which are positively charged) begin to move towards the article (which is negatively charged) and get deposited on it and the non- metallic ions, being negatively charged, move towards the anode.
Low voltage direct current is used for electroplating and the P.D. used varies from 1 to 16 volts depending upon the nature of electrolyte used and the rate at which the plating is accomplished. The current density used varies with different metals.
With high current density the deposit may be crystalline or powdery and will not adhere well to the cathode. But higher current densities can be employed if the electrolyte solution is rapidly circulated by means of a pump or agitated by blowing in air.
Essay # 7. Precautions to be Taken in Electroplating Process:
1. The object to be electroplated must be cleaned thoroughly.
2. It should not be handled with bare hands. Use a piece of paper or clean rubber gloves.
3. All connections must be clean, tight and free from corrosion.
4. The experiment plate (or the object to be electroplated) must be connected to the negative terminal of the battery.
5. The plates (electrodes) should not touch each other.
6. Keep the current constant during the electroplating process.
7. The plate must be rinse in dilute H2SO4 after removing from electrolyte, otherwise the deposit will turn black.