The document details various coating processes used to improve the utility of materials, including types such as organic, inorganic, metallic, and conversion coatings. It explains the purposes of coating, such as corrosion protection and aesthetic enhancement, along with specific methods like electroplating and electroless plating. Additionally, it covers techniques like hot dipping, pre-coated metal processes, and electroforming, outlining their applications and benefits.

1. Coating and Deposition
Jitendra Hemwani, GPC, Betul (M.P.) 460001

2. Definition
 Coating is defined as the process in which a
“COAT” (Layer of material) is applied over the
material to improve product utility.
 A coating is a covering that is applied to the surface
of an object, usually referred to as the substrate.
J Hemwani, GPC, Betul (M.P.) 460001

3. Reasons or Pupose of Coating/Plating
● Corrosive Protection
● Improve appearance
● Wear Resistance
● Increase electrical conductivity
● Give shiny appearance
● To provide an reflective surface (Glass)
● Fabrication of semiconductors
J Hemwani, GPC, Betul (M.P.) 460001

4. Types of Coating
 Organic Coating
 Inorganic Coating
 Metallic Coating
 Conversion Coating
 Pre-coated Metals Coating
 Hot Dipping Process
 Electroplating
 Electroless Plating
 Electroforming
J Hemwani, GPC, Betul (M.P.) 460001

5. Organic Coating
 An organic coating is a type of coating whose primary
ingredients are derived from either vegetable or animal
matter or from compounds rich in carbon.
 Organic coatings are primarily used to provide additive
type finishes on the materials.
 No. of layers of Organic coatings depends on required
protective barrier against corrosion and oxidation.
 These are durable coatings applied to a substrate for their
decorative or specific technical properties.
 Organic coatings depend primarily on their chemical
inertness and impermeability.
J Hemwani, GPC, Betul (M.P.) 460001

6. Organic Coating
 Various types of organic coatings are available for industrial
purposes including primers, adhesive cements and topcoats
(enamel, varnish and paints).
 Organic coatings are easy to apply with the help of brushes,
sprays, rollers, dips, or by electrostatic means. Brush
application is a slow and lengthy procedure.
 The coating cures or dries by evaporation or loss of solvent,
polymerization and oxidation.
J Hemwani, GPC, Betul (M.P.) 460001

7. Inorganic Coating
 Inorganic coatings provided by chemical action of the
inorganic materials.
 This treatments change the immediate surface layer of
metal into a film of metallic oxide or compound which has
better corrosion resistance than the natural oxide film and
provides an effective base or key for supplementary
protection, such as paints.
 In some instances, these treatments can also be a
preparatory step prior to painting.
 Example of organic coating is Anodizing. Anodizing is an
electrochemical process during which aluminum is the
anode. The electric current passing through an electrolyte
converts the metal surface to a durable aluminum oxide.
J Hemwani, GPC, Betul (M.P.) 460001

8. Inorganic Coating
 The oxidized surface is hard and abrasion resistant, and it
provides some degree of corrosion resistance.
 Chromate filming is another example of inorganic coating.
The number of proprietary chromate filming treatments are
available for aluminum, magnesium, cadmium and zinc
alloys.
 This chromate filming treatments usually involve short
time immersion in strongly acid chromate solutions, but
spraying or application by brushing or swabbing can also be
used for touch-up of parts.
J Hemwani, GPC, Betul (M.P.) 460001

9. Metallic Coating
 Metallic coatings contain a metallic element or alloy.
Metallic coatings can be applied by using a sprayer,
electrochemically, chemically or mechanically.
 These coatings are applied on equipment requiring a
shiny or glossy appearance and protection from sunlight,
corrosion and oxidation.
 Hot dip galvanizing, thermal spraying, electroplating and
sherardizing are the examples of Metallic coating process.
 Hot dip galvanizing is a example of metallic coating. In this
process of coating of iron, steel or ferrous materials is done with
a layer of zinc. This done by passing the metal through molten
zinc at a temperature of 460°C to form zinc carbonate (ZnCO3 ).
Zinc carbonate is a strong material that protects steel and can
prevent corrosion in many circumstances.
J Hemwani, GPC, Betul (M.P.) 460001

10. Metallic Coating
 Thermal spraying – A group of coating processes in which
finely divided metallic coating materials are deposited in a
molten or semi-molten condition to form a coating. The
coating material may be in the form of powder, ceramic rod,
wire or molten materials.
 Electroplating – A process of coating a metal with a thin
layer of another metal by electrolysis to improve the metal's
corrosion resistance.
 Sherardizing – The formation of a corrosion-resistant,
zinc-iron alloy coating on the surface of steel or iron. The
method involves heating the object in an airtight container
that has zinc powder. A thermal diffusion process occurs
and the zinc diffuses into the object’s metal surface, forming
the zinc-iron alloy.
J Hemwani, GPC, Betul (M.P.) 460001

11. https://www.youtube.com/watch?v=2B0eTAIU7Rc
Metallic coating 1:32
J Hemwani, GPC, Betul (M.P.) 460001

12. Conversion Coating
 Conversion coating is a type of coating used on metals in
which the surface that is covered is turned into a coating with
electrochemical or chemical processes.
 In addition to corrosion protection, conversion coating also
offers enhanced surface hardness.
 Conversion coating can be used as a decorative primer.
 Examples of Conversion coatings are phosphate and
chromate coatings as well as black oxide coatings.
 It is normally applied on alloys like aluminum through
chromate conversion or anodizing.
https://www.youtube.com/watch?v=faCl9YMSwPc
 https://www.youtube.com/watch?v=DDHddQlC62M
J Hemwani, GPC, Betul (M.P.) 460001

13. Pre-coated Metals Coating
 Pre-coated metals means, metals taken for production
are coated at initial stages as compared to conventional
production method, in which the metal are coated after the
production process.
 The main advantages of the pre-coated metals are
Beauty, Durability, Innovation, Low cost.
 Benefits of coil-coated metal, including consistent quality,
design flexibility.
 With the appropriate surface treatments, pre-painted steel
and aluminum can be made virtually waterproof and weather
proof.
 The coil coating process is widely known to be the most
efficient, effective and environmentally friendly way to pre-
clean, pre-treat, pre-prime and pre-paint metal.
J Hemwani, GPC, Betul (M.P.) 460001

14. https://www.youtube.com/watch?v=arUbCGHOSAc
Pre coated Metal (Coil coating Process)
https://www.youtube.com/watch?v=Kct87yg-2Qo
J Hemwani, GPC, Betul (M.P.) 460001

15. Hot Dipping Process
 Hot dipping process is a form of galvanization. It is the
process of coating iron and steel with zinc, which alloys with
the surface of the base metal when immersing the metal in a
bath of molten zinc at a temperature of around 449 °C.
 Hot dipping gives non toxic corosion resistance surface.
 Hot dipping is low cost surface hardening process.
 For this Steel is cleaned using a caustic solution. This
removes oil/grease, dirt, and paint. Then this caustic cleaning
solution is rinsed off. Then mill scale is removed with the help
of acidic solution.
J Hemwani, GPC, Betul (M.P.) 460001

16. Hot Dipping Proces
 A flux, like zinc ammonium chloride is applied to the steel to
inhibit oxidation of the cleaned surface upon exposure to air.
The flux is allowed to dry on the steel and aids in the process
of the liquid zinc wetting and adhering to the steel.
 In the Hot dipping steel is dipped into the molten zinc bath
and held there until the temperature of the steel equilibrates
with that of the bath then the steel is cooled in a quench tank to
reduce its temperature and inhibit undesirable reactions of the
newly formed coating with the atmosphere.
 https://www.youtube.com/watch?v=gKy7qN8eHkA
 https://www.youtube.com/watch?v=kwCyq06aatA
 https://www.youtube.com/watch?v=Az87Q0JedG4
 https://www.youtube.com/watch?v=iBwt9J0m2rM
 https://www.youtube.com/watch?v=6pfa89te4iM
J Hemwani, GPC, Betul (M.P.) 460001

17. Electroplating
 Electroplating is process in which an layer of coat is
adherent to metal with the help of electro-chemical
process that is Faraday's Laws of Electrolysis.
 The work piece is chemically cleaned before the process and
the process is controlled by electrical current because the work
piece is cathode and the metal is anode.
 Electro plating method can be applied to any metal to protect
against corrosion. This can be effectively used for precious
metals such as gold, silver and platinum for jwellery making.
 Electro plating is used for chromium plating in
decorative items, Improving wear resistance of
mechanical components and plating of electrical circuits.
 https://www.youtube.com/watch?v=LbpwocW8Rgw
J Hemwani, GPC, Betul (M.P.) 460001

18. Electroless Plating
 Electroless plating, also known as autocatalytic plating,
or conversion coating, is a way of plating the part without
using an external power source.
 The process involves placing the part in an aqueous solution
and depositing nickel, creating a catalytic reduction of nickel
ions to plate the part without any electrical energy dispersal.
 Electroless plating is low cost uniform deposition
process and gives high Corrosion resistance surface.
 Electroless plating can work on insulators such as
plastics and ceramics.
 Electroless plating is used in food processing industries.
 Typical applications of Electroless plating are in making
turbine blade, mould and die making.
J Hemwani, GPC, Betul (M.P.) 460001

19. Electroless Plating
https://www.youtube.com/watch?v=qGvhq3aDJnM&has_verifi
ed=1
 https://www.youtube.com/watch?v=pFF9PBW8jv8
https://www.youtube.com/watch?v=SsUU28Egk54&has_verifi
ed=1
 https://www.youtube.com/watch?v=1dTX21ROglU
 https://www.youtube.com/watch?v=G-PtnwtOR24
 https://www.youtube.com/watch?v=mp5Dp-221FI
J Hemwani, GPC, Betul (M.P.) 460001

20. Electroforming
 Electroforming is a metal forming process that forms parts
through electro-deposition on a model, known in the industry
as a mandrel.
 Conductive (metallic) mandrels are passivated (chemically)
to preclude 'plating' and thereby to allow subsequent
separation of the finished electroform. Non-conductive (glass,
silicon, plastic) mandrels require the deposition of a conductive
layer prior to electrode position.
 Electroforming gives high Dimensional accuracy and high
Surface finish. With electroforming part of any thickness &
shape can be produced and special physical/metallurgical
properties can be achieved.
 Applications are 1. Fine moulds and Dies 2. CDs 3. Jewellery
J Hemwani, GPC, Betul (M.P.) 460001

21. Electroforming
 https://www.youtube.com/watch?v=t7LSLKvwa5Y
 https://www.youtube.com/watch?v=Nx-GwKOH5qc
 https://www.youtube.com/watch?v=9R1n0LX5u9I
 https://www.youtube.com/watch?v=YuQ9ZcEiamg
 https://www.youtube.com/watch?v=P19dcInhfLk
 https://www.youtube.com/watch?v=gwF5r173-Ck
J Hemwani, GPC, Betul (M.P.) 460001

22. J Hemwani, GPC, Betul (M.P.) 460001