Experimental Mechanics

, Volume 50, Issue 1, pp 85–97 | Cite as

Mechanical Characterization of Coatings Using Microbeam Bending and Digital Image Correlation Techniques

Article

Abstract

A new technique for characterizing end-supported microbeams of coating materials is presented. Microbeams are fabricated using micro-EDM machining to isolate the material under investigation from the underlying substrate. Three- and four-point bending is realized by a custom-built microspecimen testing system, and digital image correlation is employed to capture full-field strains and displacements in theses microbeams. These experiments provide the foundation for the use of finite element modeling and inverse methods to determine the mechanical properties (elastic moduli, strength, interfacial toughness) of the coatings. Here, the experimental details of the microbeam bending experiments are explained, discussed and illustrated through application to a multilayered metal/oxide/ceramic thermal barrier coating system commonly used in aero-turbines.

Keywords

Digital image correlation Microbeam bending Thermal barrier coatings Aerospace materials Young’s modulus Fracture toughness 

References

  1. 1.
    Evans AG, Mumm DR, Hutchinson JW, Meier GH, Pettit FS (2001) Mechanisms controlling the durability of thermal barrier coatings. Prog Mater Sci 465:505–553CrossRefGoogle Scholar
  2. 2.
    Evans AG, Hutchinson JW (2007) The mechanics of coating delamination in thermal gradients. Surf Coat Technol 201:7905–7916, doi:10.1016/j.surfcoat.2007.03.029 CrossRefGoogle Scholar
  3. 3.
    Levi CG (2004) Emerging materials and processes for thermal barrier systems. Curr Opin Solid State Mater Sci 81:77–91CrossRefGoogle Scholar
  4. 4.
    Padture NP, Gell M, Jordan EH (2002) Thermal barrier coatings for gas-turbine engine applications. Science 296:280–284, doi:10.1126/science.1068609 CrossRefGoogle Scholar
  5. 5.
    Pan D, Chen MW, Wright PK, Hemker KJ (2003) Evolution of a diffusion aluminide bond coat for thermal barrier coatings during thermal cycling. Acta Mater 51:2205–2217, doi:10.1016/S1359-6454(03)00014-4 CrossRefGoogle Scholar
  6. 6.
    Mendis BG, Tryon B, Pollock TM, Hemker KJ (2006) Microstructural observations of as-prepared and thermal cycled NiCoCrAlY bond coats. Surf Coat Technol 201:3918–3925, doi:10.1016/j.surfcoat.2006.07.249 CrossRefGoogle Scholar
  7. 7.
    Mayville RA, Finnie I (1982) Uniaxial stress–strain curves from a bending test. Exp Mech 226:197–201, doi:10.1007/BF02326357 CrossRefGoogle Scholar
  8. 8.
    Herbert H (1910) Über den Zusammenhang der Biegungselastizität des Gusseisens mit seiner Zug- and Druckelastizität (On the connection between bending deformation and tension and compression deformation for cast iron), Mitt. und Forschungsarb. Veb. deut. Ing. 89, 39–81Google Scholar
  9. 9.
    Laws V (1981) Derivation of the tensile stress–strain curve from bending data. J Mater Sci 6:1299–1304CrossRefGoogle Scholar
  10. 10.
    Allen HG (1971) Stiffness and strength of two glass-fiber reinforced cement laminates. J Comp Mater 5:194, doi:10.1177/002199837100500205 CrossRefGoogle Scholar
  11. 11.
    Piggott MR (1964) A method of determining plastic deformation in near-brittle materials. Br J Appl Phys 15:851–855, doi:10.1088/0508-3443/15/7/310 CrossRefGoogle Scholar
  12. 12.
    Brunet M, Morestin F, Godereaux S (2001) Nonlinear kinematic hardening identification for anisotropic sheet metals with bending–unbending tests. J Eng Mater Technol 123:378–383, doi:10.1115/1.1394202 CrossRefGoogle Scholar
  13. 13.
    Meuwissen MHH, Oomens CWJ, Baaijens FPT, Petterson R, Janssen JD (1998) Determination of the elasto-plastic properties of aluminium using a mixed numerical–experimental method. J Mater Process Technol 75:204–211, doi:10.1016/S0924-0136(97)00366-X CrossRefGoogle Scholar
  14. 14.
    Grédiac M, Pierron F (2006) Applying the virtual fields method to the identification of elasto-plastic constitutive parameters. Int J Plast 22:602–627, doi:10.1016/j.ijplas.2005.04.007 MATHCrossRefGoogle Scholar
  15. 15.
    Hemker KJ, Mendis BG, Eberl C (2008) Characterizing the microstructure and mechanical behavior of a two-phase NiCoCrAlY bond coat for thermal barrier systems. Materials Science and Engineering A 483–484:727–730, doi:10.1016/j.msea.2006.12.169 CrossRefGoogle Scholar
  16. 16.
    Peters WH, Ranson WF (1982) Digital imaging techniques in experimental stress analysis. Opt Eng 21:427Google Scholar
  17. 17.
    Chu TC, Ranson WF, Sutton MA (1985) Applications of digital-image-correlation techniques to experimental mechanics. Exp Mech 25:232, doi:10.1007/BF02325092 CrossRefGoogle Scholar
  18. 18.
    Bruck HA, McNeill SR, Sutton MA, Peters WH (1989) Digital image correlation using Newton–Raphson method of partial differential correction. Exp Mech 29:261, doi:10.1007/BF02321405 CrossRefGoogle Scholar
  19. 19.
    Suo Z, Hutchinson JW (1988) Interface crack between two elastic layers. Int J Fract 43:1–18, doi:10.1007/BF00018123 CrossRefGoogle Scholar

Copyright information

© Society for Experimental Mechanics 2008

Authors and Affiliations

  1. 1.Institut für Zuverlässigkeit von Bauteilen und SystemenUniversität KarlsruheKarlsruheGermany
  2. 2.Institut für Material Forschung IIForschungszentrum KarlsruheKarlsruheGermany
  3. 3.Department of Mechanical EngineeringThe Johns Hopkins UniversityBaltimoreUSA

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