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-lay...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 mi-cro-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.展开更多
A thermally grown oxide(TGO)layer is formed at the interface of bond coat/top coat.The TGO growth during thermal exposure in air plays an important role in the spallation of the ceramic layer from the bond coat.High t...A thermally grown oxide(TGO)layer is formed at the interface of bond coat/top coat.The TGO growth during thermal exposure in air plays an important role in the spallation of the ceramic layer from the bond coat.High temperature oxidation resistance of four types of atmospheric plasma sprayed TBCs was investigated.These coatings were oxidized at 1000°C for 24,48 and 120 h in a normal electric furnace under air atmosphere.Microstructural characterization showed that the growth of the TGO layer in nano NiCrAlY/YSZ/nano Al2O3 coating is much lower than in other coatings.Moreover,EDS and XRD analyses revealed the formation of Ni(Cr,Al)2O4 mixed oxides(as spinel)and NiO onto the Al2O3(TGO)layer.The formation of detrimental mixed oxides(spinels)on the Al2O3(TGO)layer of nano NiCrAlY/YSZ/nano Al2O3 coating is much lower compared to that of other coatings after 120 h of high temperature oxidation at 1000°C.展开更多
基金Project supported by the Ministry of Higher Education of Malaysia and Research Management Center of UTM(Post-Doctoral part)
文摘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 mi-cro-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.
基金financed by Institutional Scholarship provided by Universiti Teknologi Malaysia and the Ministry of Higher Education of Malaysiathe Ministry of Higher Education of Malaysia and Universiti Teknologi Malaysia(UTM)for providing research facilities and financial support under the grant Q.J130000.2524.02H55
文摘A thermally grown oxide(TGO)layer is formed at the interface of bond coat/top coat.The TGO growth during thermal exposure in air plays an important role in the spallation of the ceramic layer from the bond coat.High temperature oxidation resistance of four types of atmospheric plasma sprayed TBCs was investigated.These coatings were oxidized at 1000°C for 24,48 and 120 h in a normal electric furnace under air atmosphere.Microstructural characterization showed that the growth of the TGO layer in nano NiCrAlY/YSZ/nano Al2O3 coating is much lower than in other coatings.Moreover,EDS and XRD analyses revealed the formation of Ni(Cr,Al)2O4 mixed oxides(as spinel)and NiO onto the Al2O3(TGO)layer.The formation of detrimental mixed oxides(spinels)on the Al2O3(TGO)layer of nano NiCrAlY/YSZ/nano Al2O3 coating is much lower compared to that of other coatings after 120 h of high temperature oxidation at 1000°C.
