This document summarizes a seminar report on thermal barrier coatings. It discusses that thermal barrier coatings consist of a metallic bond coat, thermally grown oxide layer, and ceramic top coat, most commonly yttria-stabilized zirconia. It reviews common deposition methods for thermal barrier coatings like air plasma spray, electron beam physical vapor deposition, and electrostatic spray assisted vapor deposition. The document concludes that thermal barrier coatings improve engine performance by allowing higher operating temperatures and reduce maintenance costs, making them an important technology with applications in industries like aerospace and automotive.

1. SEMINAR REPORT
ON
“ Thermal Barrier Coatings”
Submitted By
Debendra Meher
Guided By Asst
Prof. Debasish Tripathy

2. CONTENT
 Introduction.
 Construction AndWorking.
 Material Selection.
 TBC Coating for Ic Engines.
 Material used for TBC in ic engine.
 TBC Deposition Methods.
 Conclusion.
 Future Scope.
 References.

3. INTRODUCTION
TBCs are refractory-oxide ceramic coatings applied to the surfaces of
hot mettalic parts.
 TBCs perform the important function of insulating components
operating at elevated temperature.
 Coatings can allow higher operating temperatures beyond the
limiting temperature of metal parts.
 TBC not only consist of oxide ceramic coating (topcoat) itself but
also the underlying superalloy engine part, and two other layers in
between.

4. Construction and
Working

5.  Metallic Bond Coat with a thickness of about 0.004” (0.1 mm). The
alloy of the bond coating is MCrAlY, where M is Ni, Fe or Co.e bond
coat is an intermediate layer providing strong adhesion of the outer
ceramic layer to the substrate surface.
 The bond coat also inhibits the diffusion of the substrate and the ceramic
coating components. Aluminum in the amount of about 10% in the bond
coat is required for a formation of an oxide barrier (thermally grown
oxide) on the interface between the bond coatand the ceramic layer. The
thermally grown oxide form as a result of oxidation of the bond coat with
Oxygendiffusing from the combustion gases throghout the ceramic layer.
The oxide laye riscomposed of α-Al2O3.
Outer ceramic layer (Top Coat) Commonly 6-9%yttria (Y2O3) stabilized
zirconia (ZrO2)with tetragonal crystal structure is used for building the outer
ceramic layer. Yttria is added to zirconia in order to stabilize the tetragonal
structure.
Without a stabilizing agent tetragona lzirconia transforms to monoclinic
allotrope stable at low temperatures. The volume change (about 8%) resulting
from the tetragonal-monoclinic transformation causes internal stresses and
cracking. Monoclinic zirconia isalso undesirable because of its low
Coefficient of Thermal Expansion and poor mechanicalproperties.

6. APPLICATION
1. Direct vapour deposition is mainly used for producing coatings on
complex surfaces.
2 . It is capable of producing coatings on internal surfaces ofmachine
parts which cannot be attained by other methods

7. Material Selection for
TBC.
Material selected for TBC should have following properties:-
 Low Thermal Conductivity.
 High Thermal Expansion Coefficient.
 Good Erosion Resistance.
Therefore we use Porous Zirconia (ZrO2) partially stabilized with
yttria (Y2O3) popularly known asYSZ.

8. TBC Failure
 Thermal cycle is the main cause of TBC failure due to Thermalmismatch.
 Spallation: It is a process by which the TBC peels off of the substrate; and
naturally, after the coating has spalled, the continuous thermal protection
layer no longer exists.

9. TBC coating for ic engines and
coating methods
 Thermal barrier coatings are used in order to increase reliability and
strength of hot parts of metal components, increase yield and
performance of engines.
 Engine parts which are coated with thermal barrier are piston,
cylinder head cylinder sleeve and exhaust valves.
 1. Electron Beam Physical Vapour Deposition (EBPVD).
 2. Air Plasma Spray (APS).
 3. Electrostatic Spray Assisted Vapours Deposition(ESAVD).
 4. Direct Vapour Deposition.
 5. ELECTRON BEAM PHYSICAL VAPOR DEPOSITION.

10. Materials used for thermal barier coating
in ( IC ENGINE ).
Zirconates.
Yittria Stabilized Zirconia.
Mullite.
Alumina.
Spinel.
Forsterite.

11. TBC Deposition Methods
11
EB-PVD APS
HVOF ES-AVD
TBC
Production

12. Air Plasma Spray.
 In plasma spraying process, the material to be deposited (feedstock) is
introduced into the plasma jet, emanating from a plasma torch.
 In the jet, where the temperature is of the order of 10,000 K, the
material is melted and propelled towards a substrate.
 There, the molten droplets flatten, rapidly solidify and form a deposit.

13. AdvantageS.
 There is a wide range of coating materials that meet a wide variety of different
needs, with nearly all aterials available in a suitable powder form.
 Higher quality coatings such as flame or electrical arc spraying.
 Many types of substrate material, including metals, ceramics, plastics, glass, and
composite materials can be coated using plasma spraying.
Disadvantages.
 Air plasma spraying equipment is generally very expensive to buy and use.
 It is a line-of-sight process, similar to all other thermal spraying processes,
making it difficult to coat internal bores of small diameters or restricted access
surfaces.

14.  Electron Beam Physical Vapour Deposition or EBPVD is a form of
physical vapour deposition in which a target anode is bombarded
with an electron beam which causes atoms from the target to
transform into the gaseous phase.
 These atoms then precipitate into solid form, coating everything in
the vacuum chamber (within line of sight) with a thin layer of the
anode material.
Electron-beam physical vapor deposition
(EB-PVD).

15. Advantages.
 The material utilization efficiency is high relative to other methods.
 This process has potential industrial application for wear -resistant and TBC in
aerospace industries.
 Due to the very high deposition rate.
Disadvantages.
 This process cannot be used to coat the inner surface.
 Performed at a low enough pressure.

16. High Velocity Oxygen Fuel (HVOF)
The High Velocity Oxygen Fuel (HVOF) process is a subset of flame spray process.
There are two distinct differences between conventional flame spray and HVOF.
Utilizes confined combustion and an extended nozzle to heat and accelerate the
powdered coating material.
Typical HVOF devices operateat hypersonic gas velocities.

17. Applications.
 H VOF coatings can be incorporated into the design of complex
components such as high-tech medical devices used forperforming
complex surgeries.
 To simple components such as bolts used in agricultural combines.
Advantages.
 Produces layers with low porosity, high density and homogeneous
structure.
 Low residual tensions in the decanted layers.
 Low roughness of the obtained surfaces.
 Excellent for wear and corrosion resistance.
Disadvantages.
 lower temperature than plasma spray.
 more complex installation than the ones used for the classic spray.

18. Electrostatic Spray Assisted Vapour Deposition
(ESAVD).
ESAVD is the process of producing coating on a heated substrate by
spraying chemical precursors through an electric field.
It is a non- line-of-sight-process.
The electric field helps to direct the chemicals on to the substrate and
initiate the chemical reaction.

19. Applications.
 Thermal barrier coatings for jet engine turbineblades.
 Various thin layers in the manufacture of flat panel displays and
photovoltaic panels, CIGS and CZTS-based thin film solar cells.
 Electronic components.
 Biomedical coatings.
 Glass coatings (such as self-cleaning).
Advantages.
 It does not require the use of any vacuum electron beam or
plasma so reduces the manufacturing costs.
 It also uses less power and raw materials making it more
environmentally friendly.
Disadvantages.
 Operating cost is very high.

20. Conclusin
 TBC is a very useful technique and has a wide application in industries as
well as in automobile manufacturing.
 Detailed analysis of coating stresses and controlled process, plasma spray
technology has significantly improved the reliability of TBC turbines, diesel
engines and other heat engines.
 Thermal barrier coating allows engineers to improve product and
performance, reduce maintenance time, cost, save energy and reduce
production cost.
 Application of TBC on Turbine blades made dramatic change in increasing
efficiency of Engine.

21. Future
scope.
 Thermal conductivity and thermal expansion coefficent to be conduct at
a various tempreture for different compositions and zirconatematerial.
 Scratch indentation test required on bond and top coat.
 High tempreture corrosion and wear test required both top and bottom
coat.
 Performance test can conduct on zirconate thermal barrier coating
(TBC) by using various other coating techniques.

22.  [1]. H.W. GRUNLING and W. MANNSMANN, “JOURNAL DE
PHYSIQUE IV Colloque C7, supplkment au Journal de Physique
111, Volume 3, novembre 1993” Plasma sprayed thermal barrier
coatings for industrial gas turbines.
 [2]. Sanket Shikhariya1, Bhushan Shimpi2, Abhishek Shinde3,
Swapnil U. Deokar4, “Review on Thermal Barrier Coating in IC
Engine”.
 [3]. Vishnu Sankar1, ‘Thermal Barrier Coatings Material Selection,
Method of Preparation and Applications – Review’,International
journal of mechanical engineering and robotics research,vol.3.
 [4]. Christoffer Blomqvist, “Thermal barrier coatings for diesel
engine exhaust application”
 [5]. T. Sadowski and P. Golewski, “Loadings in Thermal Barrier
Coatingsof Jet Engine Turbine Blades’ Springer Briefs in
Computational Mechanics.
 [6]. V. Guru prakash , N. Hari vignesh, G. Karthik, N. Bose’
“Thermal barrier coating on I.C engine cylinder liner”.
REFERENCES