Thermal barrier coatings were originally developed for aircraft engines in 1940 but are now being tested for use in diesel engines. These coatings can reduce the metal temperature of engine components by up to 170°C. There are two main coating techniques - surface preparation and thermal spraying. Thermal barrier coatings improve the brake thermal efficiency of a single cylinder diesel engine from 16% without a coating to 20.4% with a coating.

1. BY
G.ARUN KUMAR
V.ASHOKKUMAR

2.  Thermal barrier coatings were originally
developed for air craft engine applications
in 1940
 only recently have they been modified and
tested for use in diesel engines
 This result in reduction of metal
temperature of the component up to 170
deg C

3.  Two coating techniques are used
Surfacepreparation and
Thermal spraying

4.  Coating of a material on a substance is made to
serve in the specific environment
 It is possible only if the coating is adherent to
the surface of the component
 The coating flakes off or leaves the
surface, the entire effort will go waste
 The adhesion and other properties of the
coating mainly depend on the surface condition
of the substrate

5.  Cleaning
 To remove foreign materials like
grease, scale, rust, dirt etc from the surface of a
component
 roughness
 and rough enough to make the mechanical
bonding, adequate

6.  Wire flame spraying
 Plasma arc spraying

7.  This technique involves feeding of a metallic
wire into a flame produced by combustion of
fuel gas
 This flame melts the wire and surrounding
stream of compressed air spray the molten
metal onto the substrate
 The temperature produced in this process is
about 2600-31000C
 The wire has melting point about 2500 deg c

8.  The plasma spraying uses coating materials in
the form of powders, which are melted with
plasma heat source
 The primary arc bas, usually argon or
nitrogen are ionized by the electrical
discharge from a high frequency arc starter
 the plasma can conduct currents as high as
2000A direct current, with voltage potentials
ranging from approximately 30 to 80V

9.  Prolonged exposure to a higher temperature
oxidizing environment may lead to coating
failure
 thermal expansion mismatch between the
ceramic and metallic layers and failure
appears to be strongly influenced by bond
coat oxidation

10. :
ENGINE:
 A single cylinder water cooled Kirloskar
engine is used for our analysis. The water at
room temperature is allowed to pass through
the water jacket in the engine.
 A The engine is coupled with the
mechanical rope dynamometer for leading.
The specification of the engine is given as
follows.

11. Engine name Kirloskar engine
Type Single cylinder vertical diesel engine.
Rated rpm 1500
Bore 79.9
Stroke 110
Capacity 553 cc
Compression 16.5:1
Ignition CI
Power 5 Hp

12.  without ceramic coating, the maximum brake
thermal efficiency is 16%
 with ceramic coating, the maximum brake
thermal efficiency is 20.4%.

13. 60
50
40
30
Series
2
20
10
0
Category Category Category Category 5
1 2 3 4

14.  Ceramic thermal barrier coating is a problem
solving technology which contributes to
almost every branch of engineering.
 thermal barrier coating allows engineering to
improve product and performance, reduce
maintenance time, cost, save energy and
reduce production cost.