Thermal barrier coating (TBC) technology is used in the process of manufacturing of hot sections of turbine and diesel engines to improve the component life. Performance of micro- and nano-structured compositionally graded layer (CGL) TBCs produced by atmospheric plasma spray (APS) was investigated in thermal shock (TS) and thermal cyclic fatigue (TCF) conditions. Two groups of CGL-TBCs systems consisting of five layers: one bond coat layer with 100% NiCrAlY and four layers of NiCrAlY/YSZ in the weight ratios of 70:30, 50:50, 30:70 and 0:100 as top coat were investigated. In the micro- and nano-structured CGL-TBCs, conventional and nano-structured YSZ were used as TBC powders, respectively. TCF and TS tests were run at 900 °C and continued until 1200 cycles. The results of the experimental studies on thermal cyclic behavior and microstructural evolution of micro- and nano-structured CGL-TBCs were compared and discussed. It was shown that after 1200 cycles of TS and TCF tests, no change in the phase composition of coatings is observed. Moreover, in both TS and TCF tests the signs of macroscopic damages appeared in micro CGL-TBC while no significant visible damage was seen in nano-structured one. Microscopic investigation revealed that although in both micro- and nano-structured CGL-TBCs, the integrity of underneath layers (bond coat and the other three gradient layers) up to top coat are preserved, different kinds of damage are seen in top coats. The presence of nanozones in the nano-structured CGL-TBC led to the toughening of the coatings through crack arresting techniques therefore, the nano-structured CGL-TBC showed better resistance than the micro one in the two tests.

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