Experimental study of insulating properties and behaviour of thermal barrier coating systems in thermo cyclic conditions

Highlights: • Three TBC systems deposited using atmospheric plasma spray process were tested. • Microhardness and temperature difference between the surfaces were measured. • Network of microcracks was analyzed using scanning electron microscopy. • Correlation between the substrate temperature and coating quality is established. • Stabilizers have great influence on the insulating properties of the coatings. - Abstract: The aim of this study was to improve the resistance of turbo jet engine parts exposed to high temperatures and overheating and sudden changes in temperature. For this purpose, three thermal barrier coating (TBC) systems NiCrAlCoY₂O₃/ZrO₂MgO, NiCrAlCoY₂O₃/ZrO₂Y₂O₃ and NiCrAlCoY₂O₃/ZrO₂CeO₂Y₂O₃ were tested. They were deposited using the atmospheric plasma spray process (APS). In order to develop a TBC with the best thermal insulating properties and the highest reliability in relation to aging of materials under the influence of sudden changes in temperature, TBC systems that were deposited on cold and preheated substrates were tested. The network of microcracks on the surfaces of the ceramic layers in deposited condition was analyzed using scanning electron microscopy (SEM). Insulating characteristics of TBC systems were examined by measuring the temperature difference ΔT between the top and bottom surfaces of the samples at a temperature of 1200 °C. Testing of TBC for resistance to thermal cyclic behaviour was performed by exposing samples to alternate heating at 1200 °C and rapid cooling of the samples to 180 °C. Microhardnesses of the TBC system, after completion of thermal cycles, were compared with the values in deposited state. Analyses of thermal insulation properties and thermal cyclic behaviour have shown a correlation between the substrate temperature and quality of the TBC system in thermal cyclic conditions