ATRIA INSTITUTE OF TECHNOLOGY

(AN AUTONOMOUS INSTITUTION)

A REPORT ON

“Electroplating: Principle, Procedure, and Applications”

Submitted in partial fulfilment of the required

BACHELOR OF ENGINEERING IN
COMPUTER SCIENCE ENGINEERING / ARTIFICIAL
INTELLIGENCE AND MACHINE LEARNING
Submitted by
Nitin Koley 1AT24AI073
Punith.S 1AT24CS160

UNDER THE GUIDANCE OF

Prof. VINOD NADIG B M
Assistant professor- Chemistry

DEPARTMENT OF
BASIC SCIENCE ENGINEERING & HUMANITIES

1
 DEPARTMENT OF

BASIC SCINCE ENGINEERING & HUMANITIES

SEMINAR REPORT

SEMINAR TITLE:

SI NO STUDENT NAME MARKS

01
Nitin Koley

02
Punith.S

03

SEMESTER & SECTION II- Section F

COURSE Engineering Chemistry

COURSE CODE BHEB202

MODULE NAME Corrosion Science,

Electroplating & Electroless
plating

DATE OF SUBMISSION 28-05-2025

FACULTY NAME Prof. VINOD NADIG B M

FACULTY SIGNATURE

2
 CERTIFICATE

This is to certify that Nitin Koley (1AT24AI073), Punith.S (1AT24CS160)

students of II-nd Semester AI.ML and CSE respectively, Department of Basic
Science Engineering & Humanities, has successfully completed the seminar on
the topic:

“Electroplating: Principle, Procedure, and Applications”

As a part of the academic requirements prescribed by Atria Institute of

Technology, for the partial fulfillment of the Bachelor of Engineering (B.E.)
degree during the academic year 2024-25.

The seminar was carried out under the guidance of Vinod Nadig B M.

We hereby declare that this work is the result of the student’s own effort and
has not been submitted elsewhere for any academic purpose. The seminar report
has been approved as it satisfies the academic requirements in respect of
seminar work prescribed for the said degree.

. .

Prof. Vinod Nadig B M Dr. Punith Kumar D N

Assistant Professor Associate Professor & HOD

Department of BSE&H Department of BSE&H
Atria IT, Bengaluru-24 Atria IT, Bengaluru-24

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Sr.No. Section Title Page No.

1. Principles of Electroplating 5

2. Procedure of Electroplating 6

3. Applications of Electroplating 6-7

4. Decorative Chromium Plating 7-8

5. Hard Chromium Plating 8-9

6. Summary and Conclusion 9-10

7. References 10

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1. Principle of Electroplating

Electroplating is an electrochemical process used to deposit a thin, adherent layer of one

metal onto the surface of another. This process enhances the surface characteristics of the
object being plated, such as improving corrosion resistance, reducing friction, enhancing
appearance, or increasing surface hardness. The fundamental requirement for electroplating is
a direct current (DC) electrical supply and an electrolyte solution containing the metal ions
to be deposited.

Key components of an electroplating setup:

 Electrolyte: This is a conducting solution that contains ions of the metal to be

deposited. The type and concentration of the electrolyte significantly influence the
plating quality.
 Cathode: The workpiece or the object on which the plating is to be done. It is
connected to the negative terminal of the DC source.
 Anode: A rod or plate of the metal to be plated (if soluble), or an inert material like
graphite or platinum. It is connected to the positive terminal.
 Electrolytic Cell Container: Typically made of materials resistant to chemical
attack, such as PVC, rubber-lined steel, or ceramic.

During electrolysis, oxidation occurs at the anode where metal atoms lose electrons to
become metal cations. These cations migrate through the electrolyte and gain electrons at the
cathode, forming a solid metal coating.

Chemical Reactions:

 Anode: M(s) → Mⁿ⁺(aq) + ne⁻

 Cathode: Mⁿ⁺(aq) + ne⁻ → M(s)

If a soluble anode is used, the metal ions released help maintain the electrolyte's
concentration. In contrast, when an inert anode is used, metal salts must be added

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periodically to replenish ions in the bath. Proper current density and bath composition are
crucial for uniform deposition and avoiding issues like burning, pitting, or poor adhesion.

2. Procedure of Electroplating

The procedure of electroplating involves several carefully controlled steps, each of which
plays a crucial role in ensuring that the final plated object has the desired mechanical and
chemical properties. These steps must be executed under strict process parameters such as
temperature, voltage, and electrolyte concentration.

Step-by-step Electroplating Process:

1. Surface Preparation: This is the most critical step. The object is degreased using
organic solvents or alkaline cleaners to remove oils. It is then pickled in dilute acid to
eliminate oxides and surface films. Sometimes abrasive cleaning is used.
2. Setting Up the Cell: The cleaned workpiece is mounted as the cathode, while the
anode is either a slab of the plating metal or an inert electrode. Both are immersed in
the plating bath.
3. Preparation of Electrolyte: The electrolyte is prepared using distilled water and
high-purity salts. Temperature and pH of the bath are monitored closely.
4. Electrolysis: DC power is supplied. Metal ions move from anode to cathode. The
voltage and current are adjusted based on the surface area of the cathode and type of
plating required.
5. Post-Treatment: The plated item is washed in deionized water, dried, and sometimes
polished or heat-treated to improve surface finish or hardness.

In automated systems, this process is performed using robotic arms or rotating barrel systems
for high-volume plating, ensuring consistency across thousands of parts.

3. Applications of Electroplating

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Electroplating is a widely applied technique across several industries due to its ability to
modify the surface properties of objects without altering their internal structure. Some
applications are purely decorative, while others serve highly functional roles.

Main application categories:

 Corrosion Protection: Electroplating metals like zinc (galvanization), nickel, and

chromium on iron or steel protects them from rust and prolongs their life in harsh
environments.
 Aesthetics: Jewelry and decorative items are often plated with gold, silver, or
rhodium to improve their shine and perceived value. This is a cost-effective way to
mimic expensive materials.
 Wear and Abrasion Resistance: Tools and mechanical parts are plated with hard
metals like nickel or chromium to withstand wear and tear from regular usage or
friction.
 Electrical and Thermal Conductivity: Copper or silver plating is used on electrical
contacts and circuit boards to enhance conductivity and reduce resistance. It’s
essential in electronics and semiconductors.
 Chemical Resistance: Electroplating can provide a protective barrier against
chemical attack in aggressive industrial environments, especially in the oil and gas
sectors.

Emerging uses also include medical implants, 3D-printed electronics, and satellite
components, where lightweight, precise coatings are critical.

4. Decorative Chromium Plating

Decorative chromium plating, also known as bright chrome plating, serves aesthetic and
light protective purposes. It is typically applied over a base layer of copper or nickel to
enhance smoothness and reflectivity. The actual chromium layer is very thin — generally
between 0.25 to 0.75 micrometers.
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Key aspects:

 Bath Composition:
o 250 g/L of chromic acid (H₂CrO₄)
o 2.5 g/L of sulfuric acid (H₂SO₄)
o 1 g/L of trivalent chromium (Cr³⁺)
 Electrodes:
o Anode: Insoluble lead-tin alloy with a lead dioxide (PbO₂) surface
o Cathode: The item being plated

Decorative chrome is not intended for heavy wear resistance, but it provides a hard, shiny,
and corrosion-resistant finish. The lead-based anode is inert and does not dissolve during
plating; instead, chromic acid serves as the chromium ion source.

Common uses:

 Automotive parts: grilles, rims, bumpers

 Bicycles, plumbing fixtures
 Furniture hardware, musical instruments
 Surgical and dental tools for their sterile finish

This type of plating provides excellent durability and visual appeal, often associated with
luxury finishes.

5. Hard Chromium Plating

Hard chromium plating, often called industrial chromium plating, involves depositing a
thick chromium layer (2.5 to 300 microns) onto metal components for engineering
applications. It is distinct from decorative plating in both thickness and functionality.

Key features:

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  Bath Composition (same as decorative, but adjusted for industrial use):
o 250 g/L chromic acid
o 2.5 g/L sulfuric acid
o 19 g/L trivalent chromium
 Electrodes:
o Anode: Inert Pb-Sn alloy with PbO₂ coating
o Cathode: The workpiece

During the process, Cr(VI) is reduced to Cr(III) and then to metallic chromium on the
cathode. However, buildup of Cr(III) in the bath can cause undesirable, black porous
deposits. PbO₂ in the anode oxidizes excess Cr(III) back to Cr(VI), maintaining bath quality.

Applications:

 Engineering components: piston rings, valves, engine liners

 Repair and restoration: builds up undersized or worn components
 Textile and printing rolls: requires low friction and high hardness
 Aerospace and marine parts: exposed to severe mechanical stress

Hard chromium plating imparts high hardness (~800-1000 HV), low coefficient of friction,
and excellent resistance to heat and abrasion.

6. Summary and Conclusion

Electroplating is a powerful and adaptable process that allows engineers and technologists to
enhance the performance, appearance, and lifespan of various products. From protecting steel
structures from rust to making jewelry more attractive, it combines principles of chemistry,
physics, and engineering.

Chromium plating stands out due to its dual application: decorative and functional. While
decorative chrome is prized for its sleek finish, hard chrome excels in heavy-duty
environments, offering unmatched durability and precision.

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However, environmental and health hazards — especially involving hexavalent chromium —
pose regulatory challenges. Modern developments focus on eco-friendly plating
alternatives, trivalent chromium baths, and waste treatment systems to make
electroplating more sustainable.

A solid understanding of electrochemical principles, equipment design, and quality control is

essential to mastering this valuable industrial technique.

7. References

1. Engineering Chemistry Og Palanna

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