Shot Peening Process's Influence on Oxidation Behaviour of Thermal Barrier Coatings

Thermal Barrier Coating (TBC) is a type of coating widely used to provide thermal insulation for the parts of gas turbines which are exposed to high temperatures. With use of this coating type having more than one layer, it is aimed to provide protection against high temperatures generated during service conditions. In this study, metallic bond material CoNiCrAlY was coated on Inconel 718 super-alloy substrate material by Atmospheric Plasma Spray (APS) method. Shot-peening process was employed on the produced bond coats with 6-8 and 8-10 Almen (A) intensities. Both shot-peened and unpeened samples were coated with ZrO2+Y2O3 (YSZ), thus the TBCs were produced. Surface roughness, porosity content and micro-hardness values of shot-peened TBCs were compared with those of un-peened TBCs. Produced all coating samples were subjected to oxidation tests under 1000 °C and 1100°C for 8, 24, 50 and 100 hour periods. SEM, EDX-elemental analysis, TGO thickness values as well as growth behavior of oxidized samples were examined making comparisons. Obtained results are evaluated making comparisons with current literature studies.