Overview: How to Quantify the Capability of Yttrium Silicates to be Used as an Environmental Barrier Coating


Article Preview

To be used as environmental barrier coatings, yttrium silicates must be thermally and chemically stable at high temperatures, under high pressures in a moist environment. This work proposes a full method to quantify their thermo chemical and mechanical stabilities: (i) in a corrosive environment at high temperature and (ii) against the covered material to protect. These stabilities were first estimated by thermodynamic calculations and further confirmed with corrosion tests. This first step needed: (i) to measure the partial pressures of yttrium hydroxides through corrosion tests on the simple oxide, Y2O3 and (ii) to extract the free energies of formation of gaseous yttrium-hydroxides formed. In a second step, the measured values of coefficients of thermal expansion (CTE) on these materials allowed identifying what compositions should be preferentially used, to get CTE close to that of the substrate material to prevent delaminating or cracking due to CTE mismatch stress. Finally, these materials are deposited on SiC/SiC composites by plasma spraying. The impact of the morphology, crystallinity, porosity and composition of elaborated coatings on their corrosion behaviour is highlighted.



Edited by:





E. Courcot and F. Rebillat, "Overview: How to Quantify the Capability of Yttrium Silicates to be Used as an Environmental Barrier Coating", Advances in Science and Technology, Vol. 66, pp. 80-85, 2010

Online since:

October 2010




[1] E.J. Opila, J. Am. Ceram. Soc., Vol. 82 (1999), p.625.

[2] K.N. Lee, Surf. and Coat. Tech., Vol. 1 (2000), p.133.

[3] K. N. Lee, D. S. Fox and N.P. Bansal, J. Europ. Ceram. Soc., Vol. 25 (2005), p.1705.

[4] M. Aparicio and A. Duran , J. Am. Ceram. Soc., Vol. 83 (2000), p.1351.

[5] B. Cheynet, P. -Y. Chevalier and E. Fischer, Thermosuite Calphad, Vol. 26 (2002), p.167.

DOI: https://doi.org/10.1016/s0364-5916(02)00033-0

[6] O. Fabrichnaya, H. J. Seifert, R. Weiland, T. Ludwig, F. Aldinger and A. Navrotsky, Zeit. Metallk., Vol. 92 (2001), p.1083.

[7] H. Mao, M. Selleby and O. Fabrichnaya, Comp. Coupl. Phase Diag. Thermochem., Vol. 32 (2008), p.399.

[8] OH. Krikorian, High Temp – High Press, Vol. 14 (1982), p.387.

[9] D. Cubicciotti, J Nucl Mater, Vol. 154 (1988), p.53.

[10] Association Thermodata GEMINI 2 Code. B.P. 66, 38402 St. Martin d'Heres Cedex, France.

[11] D. Djurovic, M. Zinkevich and F. Aldinger, Comp. Coupling Phase Diag. Thermochem., Vol. 31 (2007), p.560.

[12] M.D. Allendorf and T. M Besmann, Thermodynamics Resource (database Sandia National Laboratory), http: /public. ca. sandia. gov/HiTempThermo.

[13] L. Quémard, F. Rebillat, A. Guette, H. Tawil and C. Louchet-Pouillerie, J. Europ. Ceram. Soc., Vol. 27 (2007), p.377.

[14] E.J. Opila AND D.L. Myers, J. Am. Ceram. Soc., Vol. 87 (2004), p.1701.

[15] E. Courcot , F. Rebillat , F. Teyssandier, C. Louchet-Pouillerie, J Eur Ceram Soc; in press.

[16] T. Iwata, K. Fukuda, E. Béchade, O. Masson, I. Julien, E. Champion, P. Thomas, Solid State Ionics, Vol. 178 (2007), p.1523.

[17] E. Courcot, F. Rebillat, A. Quet, C. Louchet-Pouillerie, D. Gravelle and F. Gitzhofer, Eurocorr 2009, CDrom, The Europeen Corrosion Congress, EFC event No. 310 (2009).