EVALUATION OF OPTIMAL TOP COAT THICKNESS IN COMPOSITE LTA/YSZ THERMAL BARRIER COATING BY COMPARATIVE STRESS DISTRIBUTION USING FINITE ELEMENT METHOD

R. Aziz, R. Pasha, M. Abbas

Abstract


Demand of high operating temperature in gas turbines for better efficiencies has forced researchers to explore novel materials with improved thermal properties. In this regard, LaTi2Al9O19 (LTA) is recently declared as a brilliant candidate for thermal barrier coatings (TBCs). Owing to potential advantages like high temperature stability & low thermal conductivity, researchers are striving to use it for modern gas turbines. An innovative concept of composite ceramic coating (LTA+YSZ) has been introduced to achieve improved set of thermal & mechanical properties. In this paper, a finite element analysis (FEA) has been employed to observe stress scattering with relatively varying thicknesses of compositional ceramic coats using commercially available software ANSYS. Optimum set of variables has been proposed based on the associative stress state data calculated from FEA results. Radial & axial stresses (σxx, σyy) are ascertained for composite system and ultimate values of stress are offered for comparison on quantitative grounds. Elastic strain energy stored in TGO is determined based on FE results to estimate the structural reliability of TBC. Conclusively, trend reveals that both radial & axial stresses are respectively proportional to increasing & decreasing thickness of YSZ. Comparing elastic strain energies, maximum life is evaluated in 1:4 for YSZ: LTA which shows that composite layer TBC system have improved stability than single layer system as reported in literature.

Full Text:

PDF

References


References

J. Wu, HongboGuo, M. Abbas and S. Gong, “Evaluation of plasma

sprayed YSZ thermal barrier coatings with the CMAS deposits

infiltration using impedance spectroscopy”, Prog. Nat. Sci.: Mater.

Int., vol. 22, No 1, pp. 40-47, 2012.

N.P. Padture, M. Gell and E.H. Jordan, “Thermal barrier coatings

for gas-turbine engine applications”, Science, vol. 296,

no. 5566, pp. 280-284, 2002.

M. Abbas, H.B. Guo and M.R. Shahid, “Comparative study on

effect of oxide thickness on stress distribution of traditional and

nanostructured zirconia coating systems”, Ceram. Int., vol. 39,

no. 1, 2012, pp. 475-481.

R. Vaßen, M.O. Jarligo, T. Steinke, D.E. Mack and D. Stöver,

“Overview on advanced thermal barrier coatings”, Surf. Coat.

Technol.,vol. 205, pp. 938-942, 2010.

R.A. Miller, “Current status of thermal barrier coatingsan overview”, Surf. Coat Technol., vol. 30 , pp. 1-11, 1987.

F. Cernuschi, P. Bianchi, M. Leoni and P. Scardi, “Thermal

diffusivity/microstructure relationship in Y-PSZ thermal barrier

coatings”, Therm. Spray Technol., vol. 8, No. 1, pp.102-109, 1999.

H. H. Yu, M. Y. He and J. W. Hutchinson, “Edge effects in thin

film delamination”, Acta Mater., vol. 49, pp. 93-107, 2001.

R.A. Milller, “Thermal barrier coatings for aircraft engines; history

and directions”, Therm., Spray Technol. vol. 6, No. 1, pp. 35-42,

X.Q. Cao and R. Vassen, “Ceramic materials for thermal barrier

coatings”, J. Eur. Ceram. Soc. vol. 24, No. 1, pp. 1-10, 2004.

M.N. Rahman, J.R. Gross, R.E. Dutton and H. Wang, “Phase

stability, sintering and thermal conductivity of plasma-sprayed

ZrO2–Gd2O3 compositions for potential thermal barrier coating

applications”, Acta Mater., vol. 54, pp. 1615-1621, 2006.

M. Matsumoto, N. Yamaguchi and H. Matsubara, “Low thermal

conductivity and high temperature stability of ZrO2-Y2O3--La2O3

coatings produced by electron beam PVD”, Scripta Mater., vol. 50,

pp. 867–871, 2004.

H. Lehmann, D. Pitzer, G. Pracht, R. Vaβen and D.Stöver,

“Thermal conductivity and thermal expansion coefficients of the

lanthanum rare-earth-element zirconate system”, Am. Ceram. Soc.,

vol. 86, p. 1338-44, 2003.

J.H. Yu, H.Y. Zhao, S.Y. Tao, X.M. Zhou and C.X. Ding,

“Thermal conductivity of plasma sprayed Sm2Zr2O7 coatings”,

Eur. Ceram. Soc., vol. 30, p. 799–804, 2010.

R. Vaβen, X. Cao, F. Tietz, D. Basu and D. Stöver, “Zirconates as

new materials for thermal barrier coatings”, Am. Ceram. Soc.,

vol. 83, pp. 2023-2028, 2000.

X.L. Chen, Y.F. Zhang, X.H. Zhong, J.F. Zhang, Y.L. Cheng,

Y. Zhao, “Thermal cycling behaviors of the plasma sprayed

thermal barrier coatings of hexaluminates with magnetoplumbite

structure”, Eur. Ceram. Soc., vol. 30, pp.1649-1657, 2010.

N.P. Bansal, D.M. Zhu, “Thermal properties of oxides with

magnetoplumbite structure for advanced thermal barrier coatings”,

Surf. Coat. Technol., vol. 202, no.12, p. 2698-703, 2008.

X.Q. Cao, Y.F. Zhang, J.F. Zhang, X.H. Zhong, Y. Wang,

H.M. Ma, Z.H. Xu, L.M. He and F. Lu, “Failure of the plasmasprayed coating of lanthanum hexaluminate”. Eur. Ceram. Soc.,

vol. 28, p. 1979-6, 2008.

H.B. Guo, H.J. Zhang, G.H. Ma and S.K. Gong, “Thermo-physical

and thermal cycling properties of plasma-sprayed BaLa2Ti3O10

coating as potential thermal barrier materials”, Surf. Coat.

Technol., vol. 204, pp. 691-696, 2009.

W. Ma, D. Mack, J. Malzbender, R. Vaβen and D.Stöver, “Yb2O3

and Gd2O3 doped strontium zirconate for thermal barrier coatings”,

Eur. Ceram. Soc., vol. 28, pp. 3071-3081, 2008.

X.Y. Xie, H.B. Guo, S. Gong and H. Xu, “Hot corrosion behavior

of double-ceramic-layer LaTi2Al9O19/YSZ thermal barrier coatings,

Chin. J. Aeronaut., vol. 25, pp.137-142, 2012.

H.B. Guo, X. Xie and H B Xu, “The manufacturing of thermal

barrier coating with columnar grain structure”, China Patent

5, 2007-07-03.

X. Xie, H.B. Guo, S. Gong and H. Xu, “Lanthanum-titaniumaluminum oxide: A novel thermal barrier coating material for

applications at 1300 oC”, J. Eur. Ceram. Soc. vol. 31, pp. 1677-

, 2011.

X.Y. Xie, H. BGuo and S.K. Gong, “Mechanical properties of

LaTi2Al9O19 and thermal cycling behaviors of plasma sprayed

LaTi2Al9O19/YSZ thermal barrier coatings”, J. Therm. Spray

Technol., vol. 19, no. 6, pp.1179-1185, 2010.

A. Liu and Y. Wei, “Finite element analysis of anti-spallation

thermal barrier coatings”, Surf. Coat. Technol., vol. 165, pp. 154-

, 2003.

M. Singh and T Jessen, “25th Annual Conference on Composites”,

Advanced Ceramics, Materials, and Structures - B: Ceramic

Engineering and Science Proceedings, vol. 22, no. 4. 2009.

X. Xie, H.B. Guo, S. Gong and H. Xu, “Thermal cycling behavior

and failure mechanism of LaTi2Al9O19/YSZ thermal barrier

coatings exposed to gas flame”, Surf. Coat. Technol., vol 205,

pp. 4291–4298. 2011

E.A.G. Shillington, D.R. Clarke, “Spalling failure of a thermal

barrier coating associated with aluminum depletion in the

bond-coat”, Acta Mater. vol. 47, pp. 1297–1305, 1999.

J.A. Haynes, M.K. Ferber, W.D. Porter, E.D. Rigney, “Mechanical

properties and fracture behavior of interfacial alumina scales

on plasma-sprayed thermal barrier coatings”, Mater. High Temp.,

vol. 16, pp. 49–69, 1999.

S. Bose, “High temperature coatings”, 1st ed., ButterworthHeinemann, Elsevier, USA, 2007.

J.W. Hutchinson, M.D. Thouless, E.G. Liniger, “Growth and

configuration stability of circular, buckling-driven film

delaminations”, Actametall. Mater., vol. 40, no. 2, pp. 295-308,

P.K. Wright, A.G. Evans, “Mechanisms governing the

performance of thermal barrier coatings”, Princeton Materials

Institute Report PMI-99-11, Princeton University, New Jersey,

February, 1999.


Refbacks

  • There are currently no refbacks.