Abstract
Based on the excellent thermodynamic and service performances of nano-structured coatings, 8YSZ nano agglomerated spraying powder and its nano-structured thermal barrier coating (TBC) were successfully prepared by the integrated application of nanotechnology and atmospheric plasma spraying. The influences of spraying granulation process (solid content of slurry and inlet air temperature) on the spraying powder characteristics and the water quenching-thermal shock cycling behavior at 1050 ?degrees C of 8YSZ nano-structured TBC were investigated, respectively. The results showed that the nano-agglomerated powders exhibit apple-like, hollow spheroids with relatively uniform particle size when the spraying granulation process involved a 40% solid content of slurry, a 240 ?degrees C inlet air temperature, and a 35 Hz atomizer rotation frequency. The fluidity and apparent density were 57.53 s/50 g and 1.39 g/cm(3), respectively. The nano-agglomerated 8YSZ spraying powders met the requirements of plasma-spraying technology. The plasma-sprayed 8YSZ nano-structured coating was composed of a single t-ZrO2 phase, had a layered structure and a certain amount of nanostructures, and presented a special "bimodal microstructure ". The average porosity of the coating was 7.49%. 8YSZ nano structured TBC failed layer-by-layer after water quenching-thermal shock 264 cycles at 1050 ?degrees C. The main reasons for the failure of 8YSZ nano-structured TBC were the large thermal stress and cracks in the substrate caused by the water quench-thermal shock cycle, and the mismatch of thermal expansion between the metal bond coat and the ceramic coat.
NSTL
Elsevier