ceramic coated piston

1. EXPERIMENTAL STUDY OF
CERAMIC COATED PISTON CROWN
FOR COMPRESSED NATURAL GAS
DIRECT INJECTION ENGINES
PRESENTED BY:
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2. CONTENTS
INTRODUCTION
METHODOLOGY
RESULTS AND DISCUSSION
ADVANTAGES
DISVANTAGES
CONCLUSIONS
REFERENCES
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3. Alternative gaseous fuels like natural gas have higher
octane levels than gasoline which allows the engine to
operate at higher compression’s levels, and thus at higher
efficiency
A thermal barrier coating was applied onto the top part
of a compressed natural gas direct injection (CNGDI)
engine piston to reflect heat into the combustion
chamber. This approach increases exhaust gas velocity
and extends piston life by decreasing the rate of heat
transfer.
INTRODUCTION
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4. Zirconia-based ceramic coating such as yttria partially
stabilised zirconia (YPSZ) possesses low thermal
conductivity and a relatively high coefficient thermal
expansion that would reduce detrimental interfacial stresses.
Plasma spray technique was utilized because of its low
thermal stress on substrate parts with high deposition rates.
Bond coat was required to improve the top coat adhesion
by mechanical interlocking and to prevent or delay the
oxidation of the substrate material by forming a dense oxide
layer that acts as an oxygen diffusion barrier. Here bond coat
is NiCrAl
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5. NOMENCLATURE
CNGDI compressed natural gas direct injection
TBC thermal barrier coating
YPSZ yttria partially stabilized zirconia
NiCrAl bentonite
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6. METHODOLOGY
Sample preparation and deposition works
Characterization and mechanical tests
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7. A prototype of CNGDI piston with a thickness of
approximately 11.7 mm and the diameter was about 75 mm was
used where the crown of CNGDI piston were cut.
The surfaces of piston crown samples were grit blasted and
followed by ultrasonic cleaning using ethanol. The bond coat
and topcoat with powder size as sprayed in piston crown.
SAMPLE PREPARATION AND DEPOSITION
WORKS
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8. CNGDI piston crown surface coated with thicknesses
between 100 to 150 μm of bond coat NiCrAl and 300 to
350 μm of YPSZ topcoat.
CNGDI piston crown surface coated with thicknesses
between 100 to 150 μm of bond coat NiCrAl.
uncoated piston crown.
Three samples are there
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9. Parameters YPSZ
(91wt%Zr, 7.5wt%Y)
Current (A) 700
Voltage (V) 45
Spray Settings for thermal barrier
coating
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10. The samples of plasma sprayed YPSZ (7.5Y2O3-
ZrO2)/NiCrAl-coated piston crowns were observed for the
surface structure by using a scanning electron microscope
(SEM).
 The YPSZ/NiCrAl-coated samples were cut into small pieces
for necessary quantities. After that, the samples were washed
with acetone and were dried before the cross-section of samples
were polished.
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11. Then, the pieces of polished sample were hardened
and mounted in the mixture of epoxy resin and
epoxide hardener for metallographic examination.
The microstructure images were taken for surfaces of
bond coat NiCrAl and topcoat YPSZ, and its cross-
sectional view.
Perthometer M1 was used to measure the average
surface roughness of the NiCrAl bond coating and
the YPSZ topcoat.
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12. Actual plasma sprayed YPSZ coated piston
crown
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13. The piston crown sample was clamped in a
distance where it just has minimal contact with
the flame.
 To record the surface temperature of the piston
crown, the K-type (chromel-alumel) probe of
digital thermocouples with a temperature range
of from -200°C to +1370°C were installed on the
surface of piston crown and the backside of
piston crown.
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14.  The combination of acetylene and oxygen was used as
flame source for local heating the piston sample which the
nozzle of the flame was clamped in front of a steel cylinder
to cover the long flame from wind influence, so that the
flame could be in stable position and could directly heat the
surface of piston crown.
The amount of acetylene and oxygen were standardized
after a long blueflame was achieved, so that it could
contribute to a high temperature up to 1000°C.
Finally, the temperature of top surface and back surface of
piston crowns were recorded and the heat fluxes of each
sample were calculated
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15. Experimental apparatus of burner rig
test in horizontal view
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16. Microstructure of TBC
Burner Rig Test
RESULTS AND DISCUSSION
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17. The structure exhibited the particles of both
material were deformed on impact during plasma
spraying process and melted on piston crown
surface.
The structure of the NiCrAl bond coating had a
bigger dense splat like and a few of big voids which
showed low porosity.
MICROSTRUCTURE OF TBC
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18. Microstructure of top surface of NiCrAl
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19. The structure of the top layer of YPSZ ceramic layer
exhibited a high porosity and a numbers of small voids
and cracks with micro size.
High porosity characteristic of YPSZ contributed to
brittleness of the structure.
This explains the low thermal conductivity that leads
to heat transfer reduction.
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20. Microstructure of top surface of
YPSZ
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21. Cross sectional microphotograph of plasma sprayed
YPSZ -NiCrAl aluminium alloy
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22. Temperature difference of piston crowns
during elevated temperature
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23. Heat flux on piston crowns during
elevated temperature
BURNER RIG TEST
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24. ADVANTAGES
 It increases exhaust gas velocity.
The ceramic coated piston increases the life of the
piston by decreasing the rate of heat transfer.
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25. DISADVANTAGES
The ceramic bond coat interface region which
was determined to be the weakest link in the
(7.5Y2O3-ZrO2)/NiCrAl system.
Adhesive plus cohesive failure of the ceramic
layer in this region occurred when the coating was
subjected to a normal tensile load at room
temperature as well as when applied on bars
subjected to axial tension or compression at
elevated temperature.
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26. CONCLUSIONS
The average heat flux of coated piston crown
exhibited 98% lower than uncoated piston crown .
This is due lower conductivity of ceramic
material.
The ceramic coated piston increases the life of
the piston.
The ceramic coated piston is better than
uncoated piston.
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27. REFERENCES
[1] Helmisyah Ahmad Jalaludina, Shahrir Abdullah,
Experimental Study of Ceramic Coated Piston Crown for
Compressed Natural Gas Direct Injection Engines, The
Malaysian International Tribology Conference 2013.
[2] Helmisyah A.J, Characterisation of Thermal Barrier
Coating on Piston Crown for Compressed Natural Gas Direct
Injection (CNGDI) Engines ,AIJSTPME (2012) 5(4): 73-77.
[3] G. Sivakumar, S. Senthil Kumar, Investigation on effect of
Yttria Stabilized Zirconia coated piston crown on performance
and emission characteristics of a diesel engine, Alexandria
Engineering Journal (2014) 53, 787–794. 27

28. THANK YOU
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