The document provides an overview of surface coating technologies, detailing various types of coatings such as zinc, aluminum, nickel, titanium, chrome, and ceramic coatings, along with their applications and methods of deposition. It also explains coating technologies including chemical vapor deposition (CVD) and physical vapor deposition (PVD), highlighting their processes and material properties. The document emphasizes the significance of coatings in enhancing surface properties, preventing corrosion, and improving overall performance across different industries.

1. Surface Coating Technologies

2. Introduction
• A coating is a covering that is applied to the surface
of an object, usually referred to as the substrate.
• The purpose of applying the coating may be
decorative, functional, or both. Coatings may be
applied as liquids, gases or solids e.g. Powder
coatings.
• the paint on large industrial pipes is for
preventing corrosion and identification e.g. blue for
process water, red for fire-fighting control.

3. • Functional coatings may be applied to change the
surface properties of the substrate, such
as adhesion, wet ability, corrosion resistance, or
wear resistance.
• In other cases, e.g. semiconductor device
fabrication (where the substrate is a wafer), the
coating adds a completely new property, such as
a magnetic response or electrical conductivity,
and forms an essential part of the finished
product.

4. Coating Materials
• Metal coatings are a crucial component in many
industries, as they provide a protective layer to
metals and improve their overall performance.
• They can prevent corrosion, reduce wear and
tear, enhance appearance, and even add unique
features like electrical conductivity. With
numerous types of metal coatings available in
the market, it can be challenging to determine
the best one for your application.

5. Zinc Coating
• Are one of the most popular and affordable types of
metal coatings. They are commonly used to prevent
corrosion and rusting of ferrous metals, especially
steel.
• Zinc coatings can be applied through various
methods, including hot-dip galvanizing,
electroplating, and zinc-rich paint. The coating forms
a protective layer that prevents oxygen and water
from corroding the metal surface. maintenance.

6. Aluminum Coating
• Aluminum coating are another popular type of
metal coating, especially in the automotive and
aerospace industries.
• They are lightweight and offer excellent
corrosion resistance, making them ideal for
use in harsh environments. Aluminum coatings
can be applied through various methods,
including electroplating, spraying, and powder
coating.

7. Nickel Coating
• Nickel coatings are a sought-after choice for
industries that require high wear and corrosion
resistance, such as the aerospace, marine, and oil
and gas industries.
• Nickel coatings can be applied through
electroplating or thermal spraying, and they
provide a hard and durable surface that resists
abrasion, corrosion, and oxidation. They also
provide excellent adhesion, making them
suitable for use with various substrates.

8. Titanium Coating
• Titanium coatings are a relatively new type of
metal coating that offers unique advantages
over other coatings.
• They are commonly used in the medical,
aerospace, and automotive industries, where
high wear and corrosion resistance are
essential.
• Titanium coatings can be applied through
physical vapor deposition or ion plating.

9. Chrome Coating
• Chrome coatings are a type of metal coating
used in the automotive and aerospace
industries.
• They offer excellent wear and corrosion
resistance, making them ideal for use in harsh
environments. Chrome coatings can be applied
through electroplating, vacuum deposition, or
spraying, and they provide a shiny and
reflective finish.

10. Ceramic Coating
• Ceramic coatings are a well-liked choice for
industries that require high-temperature
resistance, such as the aerospace, automotive, and
energy industries.
• They provide a hard and durable surface that
resists wear, abrasion, and corrosion.
• Ceramic coatings can be applied through thermal
spraying or chemical vapor deposition, and they
provide excellent thermal insulation and chemical
resistance.

11. Coating Technologies
• The material is dispersed into particles in a fine
mist and accelerated to push the particles to the
prepared surface to be coated
Types of Coating
• Chemical Vapor Deposition
• Physical Vapor Deposition
• Electroplating
• High Velocity Oxy-Fuel Coating
• Thermal Coating

12. Chemical Vapor Deposition
• Chemical vapor deposition (CVD) is a vacuum deposition
method used to produce high-quality, and high-performance,
solid materials.
• The process is often used in the semiconductor industry to
produce thin films
• Chemical vapor deposition (CVD) is one of the most
common processes used to coat almost any metallic or
ceramic compound, including elements, metals and their
alloys and intermetallic compounds.
• The CVD process involves depositing a solid material from a
gaseous phase; this is achieved by means of a chemical
reaction between volatile precursors and the surface of the
materials to be coated.

13. • As the precursor gases pass over the surface of the heated
substrate, the resulting chemical reaction forms a solid phase
which is deposited onto the substrate. The substrate
temperature is critical and can influence the occurrence of
different reactions.
• There are several types of CVD process, including
atmospheric pressure chemical vapor deposition, metal-
organic chemical vapor deposition, low pressure chemical
vapor deposition, laser chemical vapor deposition,
photochemical vapor deposition, chemical vapor infiltration,
chemical beam epitaxy, plasma-assisted chemical vapor
deposition and plasma-enhanced chemical vapor deposition.

15. Physical Vapor Deposition
• Physical vapor deposition (PVD), sometimes
called physical vapor transport (PVT), describes
a variety of vacuum deposition methods which
can be used to produce thin films and coatings on
substrates including metals, ceramics, glass, and
polymers.
• PVD is characterized by a process in which the
material transitions from a condensed phase to a
vapor phase and then back to a thin film
condensed phase.

16. • Physical vapor deposition (PVD) is a
vaporization coating technique that involves
the transfer of material at the atomic level. The
process can be described according to the
following sequence of steps.
• The material to be deposited is converted into
a vapor by physical means (high-temperature
vacuum or gaseous plasma)
• the vapor is transported to a region of low
pressure from its source to the substrate, and
• the vapor undergoes condensation on the
substrate to form a thin film.

17. • Typically, PVD processes are used to deposit
films with thicknesses in the range of a few
nanometers to thousands of nanometers.
• The most common PVD processes
are sputtering and evaporation
• Sputtering is a physical process in which the
vaporization occurs of a solid material by
bombarding it by ion energy.
• This is a process widely used in the formation of
thin films on materials

18. •

21. Electroplating
• Electroplating is a process of coating or plating a
metal onto another by hydrolysis It is usually done
to avoid metal corrosion or for ornamental purposes.
• Anode: The metal to be used for coating
• Cathode: The metal on which coating is to be done.
• Electrolyte: It should be the aqueous salt solution
of anode metal.
• Power Source: Usually DC supply

22. • When two metals acting as electrodes are
immersed in the salt bath of anode metal and a
potential difference is created between them by
supplying current, then the metal on the anode
oxidizes and dissolves into the electrolyte salt
and later gets reduced and deposit itself as a thin
layer on the metal on cathode.

26. High-Velocity Oxygen Fuel (HVOF)
coating
• High-Velocity Oxygen Fuel (HVOF) coating is a
thermal spray coating process used to improve or
restore a component’s surface properties or
dimensions, thus extending equipment life by
significantly increasing erosion and wear resistance,
and corrosion protection.
• Molten or semi-molten materials are sprayed onto
the surface by means of the high temperature, high-
velocity gas stream, producing a dense spray coating
which can be ground to a very high surface finish.

27. • The utilization of the HVOF coating technique allows the
application of coating materials such as metals, alloys,
and ceramics to produce a coating of exceptional hardness
• High Velocity Oxygen Fuel (HVOF) coating is a thermal
spray process in which a fuel and oxygen are mixed, fed
into a combustion chamber, and ignited. The gas produced
in the combustion chamber has an extremely high
temperature and pressure and is ejected through a nozzle
at supersonic speeds.
• Powder is injected into the high velocity gas stream and
propelled at the substrate to be coated. The result is a
coating that has a low porosity and a high bond strength
to the substrate material, which provides it with wear
and / or corrosion resistance.

29. Powder Metallurgy
• Powder metallurgy (PM) is a term covering a
wide range of ways in which materials or
components are made from metal powders. PM
processes can reduce or eliminate the need for
subtractive processes in manufacturing, lowering
material losses and reducing the cost of the final
product.
• Powder metallurgy is also used to make unique
materials impossible to get from melting or
forming in other ways.

30. • A very important product of this type is tungsten
carbide. Tungsten carbide is used to cut and form other
metals and is made from tungsten carbide particles
bonded with cobalt. It is very widely used in industry
for too
• The powder metallurgy "press and sinter" process
generally consists of three basic steps: powder blending
(or pulverization), die compaction, and sintering.
• Compaction of the powder in the die is generally
performed at room temperature. Sintering is the process
of binding a material together with heat without
liquefying it. It is usually conducted at atmospheric
pressure, and under carefully controlled atmosphere
composition

31. • Powder metallurgy – science of producing metal
powders and making finished / semi finished
objects from mixed or alloyed powders with or
without the addition of nonmetallic constituents
• Steps in powder metallurgy: Powder production,
Compaction, Sintering, &
• Secondary operations
• Powder production:
• Raw materials => Powder; Powders can be pure
elements, pre-alloyed powders
• Methods for making powders – Atomization:
Produces powders of both ferrous and

32. • non-ferrous powders like stainless steel, super
alloys, Ti alloy powders;
• Reduction of compounds: Production of iron,
Cu, tungsten, molybdenum; Electrolysis: for
making Cu, iron, silver powders
• Powders along with additives are mixed using
mixers
• Lubricants are added prior to mixing to facilitate
easy ejection of compact and to minimize wear
of tools; Waxes, metallic stearates, graphite etc.
• Powder characterization – size, flow, density,
compressibility tests

33. • Compaction: compaction is performed using dies
machined to close tolerances
• Dies are made of cemented carbide, die/tool steel;
pressed using hydraulic or mechanical presses
• The basic purpose of compaction is to obtain a
green compact with sufficient strength to withstand
further handling operations The green compact is
then taken for sintering
• Hot extrusion, hot pressing, hot isostatic pressing
=> consolidation at high temperatures

34. Sintering: Performed at controlled atmosphere to
bond atoms metallurgically; Bonding occurs by
diffusion of atoms; done at 70% of abs. melting point
of materials
It serves to consolidate the mechanically bonded
powders into a coherent body having desired on
service behavior

36. Production of powders
• Metal powders => Main constituent of a P/M
product; final properties of the finished
• P/M part depends on size, shape, and surface area
of powder particles
• Single powder production method is not sufficient
for all applications
• Powder production methods:
• 1. Mechanical methods,
• 2. Physical methods,
• 3. Chemical methods

37. 1. Mechanical methods => cheapest of the powder
production methods; These methods involve using
mechanical forces such as compressive forces, shear or
impact to facilitate particle size reduction of bulk
materials; Eg.:Milling
Milling: During milling, impact, attrition, shear and
compression forces are acted upon particles. During
impact, striking of one powder particle against another
occurs. Abrasion refers to the production of wear debris
due to the rubbing action between two particles. Shear
refers to cutting of particles resulting in fracture.

38. The particles are broken into fine particles by squeezing
action in compression force type.
Main objective of milling: Particle size reduction (main
purpose), Particle size growth, shape change, collection
(joining of particles together), solid state alloying,
mechanical or solid state mixing, modification of
material properties
Mechanism of milling: Changes in the morphology of
powder particles during milling
results in the following events.
1. Micro-forging, 2. Fracture, 3. Agglomeration, 4.
Deagglomeration

39. Milling equipment: The equipment's are generally
classified as crushers & mills
Crushing => for making ceramic materials such as
oxides of metals;
Grinding => for reactive metals such as titanium,
zirconium, niobium, tantalum