JECH David Vysoké učení technické v Brně

Spoluautoři ČELKO Ladislav, KLAKURKOVÁ Lenka, HUTAŘOVÁ Simona, JULIŠ Martin, ŠVEJCAR Jiří

In present work, the influence of isothermal heat treatment on structural changes of conventional thermal barrier coatings (TBCs) was studied. The CoNiCrAlY as metallic bond coat (BC) in thickness of 200 micrometres and 8wt. % yttria stabilized zirconia (YSZ) as ceramic top coat (TC) in thicknesses of 200, 500 and 1000 micrometres were produced by means of atmospheric plasma spraying (APS). These coatings were sprayed onto the surface of newly developed fine-grained cast polycrystalline nickel-based superalloy Inconel 713LC. As-prepared samples were exposed to the temperature of 1050 °C for 10 - 500 hours in ambient atmosphere. In comparison with the initial state, where discontinual islands of alumina was found on the bond coat–top coat interface, the uniform and continuous oxide layer, also termed thermally grown oxide (TGO), was observed there after the isothermal heat treatment. The growth of TGO layer in dependence on dwell time was also found on the expense of depletion of aluminium from the bond coat. Structural changes of bond coat promoted by above mentioned mechanism and growth of TGO were evaluated by means of electron microscopy and image analysis techniques.