کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1261048 | 971776 | 2014 | 21 صفحه PDF | دانلود رایگان |
Bi-layered thermally grown oxide (TGO) layer plays a major role in the spallation of Y2O3 stabilized ZrO2 (YSZ) layer form the bond coat in the thermal barrier coating (TBC) systems during oxidation. On the other hand, bi-layered TGO formation and growth in the TBC systems with nanostructured YSZ have not been deeply investigated during cyclic oxidation. Hence, Inconel 738/NiCrAlY/normal YSZ and Inconel 738/NiCrAlY/nano YSZ systems were pre-oxidized at 1000 °C and then subjected to cyclic oxidation at 1150 °C. According to microstructural observations, nanostructured YSZ layer over the bond coat should have less micro-cracks and pinholes, due to the compactness of the nanostructure and the presence of nano zones that resulted in lower O infiltration into the nanothermal barrier coating system, formation of thinner and nearly continuous mono-layered thermally grown oxide on the bond coat during pre-oxidation, lower spinels formation at the Al2O3/YSZ interface and finally, reduction of bi-layered thermally grown oxide thickness during cyclic oxidation. It was found that pre-heat treatment and particularly coating microstructure could influence microstructural evolution (bi-layered TGO thickness) and durability of thermal barrier coating systems during cyclic oxidation.
Schematic illustration of oxygen penetration into the nano TBC system and TGO formation during oxidation (a) Lower oxygen penetration in nano YSZ layer; (b) Formation of somewhat continuous but thinner Al2O3 layer in NiCrAlY/nano YSZ coating during isothermal pre-oxidationFigure optionsDownload as PowerPoint slide
Journal: Journal of Rare Earths - Volume 32, Issue 1, January 2014, Pages 57–77