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LESSON PLAN

Date______________ Trade:- Welder

Name___________ Unit/Lesson:-Forty Five

Subject:- Metalizing- types of metalizing, principles, equipments, advantages and

applications. Manual oxy-acetylene powder coating process. Principles of operations and
applications.
Motivation:- In previous lesson we discuss about Resistance welding process types,
principles, power sources and welding parameters. Applications and limitations.

PREPARATION
1) (Materials, Tools, Models, Charts and other aids)

INTRODUCTION:- Metallization process is need to remove wear and tear with low cost.
Topic Information Point Spot Hint
Metalizing This process was evented by Dr. Ulrich
schoop in 1910. In this process we
treated metal as per our requirement .
How need Due to wear and tear metal loss their
property and need for metalizing
process
Wear − mechanical;
− corrosive-mechanical.
Criteria: wear resistance (by mass/volume, relative)

Methods of surface − penning;

reinforcement − surface alloying and hardening;
− coatings (sprayed coatings, vapor deposited
coatings, cladded coatings, galvanic coatings,
diffusion coatings);
metal cladding (bimetal materials).

Process  CHEMICAL
 ELECTROCHEMICAL
 THERMOCHEMICAL
 THERMOCOATING
 VAPOR DEPOSITION
 MECHANICAL
Preparation of metals before metalizing
Purpose: removal of contamintants, such as oil, rust, etc.
 chemical cleaning;
 vapor degreasing;
 baking (porous materials; 315 … 345 ºC);

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 ultrasonic cleaning;
 wet / dry abrasive blasting.
Purpose: to obtain clean in-plane (longtitudal) stress free surface with an increased area,
providing bigger possibility for the sprayed material to form bonds and/or be mechanically
interlocked with the surface.
 dry abrasive grit blasting (angular chilled iron, crushed slag, flint, garnet, silica sand,
Al2O3, SiC);
 machining or macroroughening.
 Rule of thumb: roughening must be done no longer than 2 h before spraying Powders:
drying at 100 ºC at least 8 h [1], polymer powders 50 ºC; 130 … 150 ºC 3 … 5 h,
ceramic powders 600 … 700 ºC 3 … 5 h [4]; thickness of powder layer – no bigger
than 20 mm [4]. Purpose: to eliminate moisture, in order to avoid the coalescence of
powder during spraying and to avoid degradation of coating's properties through
hydroxides' formation.
 Wires: cleaning using washing liquids, bronze wires – using acids [4]. Purpose: to
remove lubricants / oxides.

Types of Metalizing:- Metal Spraying, Flame spraying, Thermal spraying

Flame spraying

- flame temperature:
• acetylene/oxygen 3160 ºC;
• propane/oxygen 2850 ºC;
• hydrogen/oxygen 2660 ºC.
- sprayed materials:
• wire: metals and metal alloys;
• powder: pure metals, alloys, oxides, cermets,
composite powders.

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Comparison between all process

Spray technology Velocity, m/s Porosity, % Adhesion, MPa
Flame spraying powder 30 6 – 15 17 – 70
• wire 180 15 – 20
Arc spraying 240 2–8 40
Plasma spraying 240 – 1200 < (0,5 – 2) 20 – 70
(different modifications)
Detonation gun spraying 910 <1 ≥ 100
HVOF, HVAF 610 – 1500 < 0,5 62 – 83
Cold spraying 500 – 1200 1–3 30 – 100

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Plug Filling

Questins:-
1. What is metalizing and how its need?
2. What is the process of flame spraying?
3. What is the process of arc spraying?

Next Lesson:- Welding codes and standards. Reading of assembly drawing. Welding procedure
specification and procedure qualification records.

Assignments :- Metalizing- types of metalizing, principles, equipments, advantages and

applications. Manual oxy-acetylene powder coating process. Principles of operations and
applications.

Checked by………………….. instructor…………………

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