Thermal barrier coatings （TBCs） were developed to protect metallic blades and vanes working in turbo-engines. The two-layered structure TBCs, consisting of NiCoCrAlY bond coat and yttria stabilized zirconia （YSZ）,...Thermal barrier coatings （TBCs） were developed to protect metallic blades and vanes working in turbo-engines. The two-layered structure TBCs, consisting of NiCoCrAlY bond coat and yttria stabilized zirconia （YSZ）, were deposited on a cylinder of superalloy substrate by the electron beam-physical vapor deposition （EB-PVD）. The failure mechanism of the TBCs was investigated with a thermo-mechanical fatigue testing system under the service condition similar to that for turbine blades. Non-destructive evaluation of the coated specimens was conducted through the impedance spectroscopy. It is found that the crack initiation mainly takes place on the top coat at the edge of the heated zones.展开更多
Yttria-stabilized zirconia(YSZ)thin nanocrystalline coatings at different substrate preheating temperatures were deposited via electron beam-physical vapour deposition(EB-PVD).Nanocrystalline ZrO_(2)-Y_(2)O_(3) was de...Yttria-stabilized zirconia(YSZ)thin nanocrystalline coatings at different substrate preheating temperatures were deposited via electron beam-physical vapour deposition(EB-PVD).Nanocrystalline ZrO_(2)-Y_(2)O_(3) was deposited on the bond coat in order to compensate for the coefficient of thermal expansion(CTE),which can be functionalized as a thermal barrier coating(TBC).The aim of this study was to evaluate mechanical properties with respect to adhesion of zirconia nanocrystalline’s top ceramic layer to the interfacial bond coat by utilizing micro and nano indentation tests.In the present paper,the structural studies were carried out using X-ray diffraction(XRD)analysis of coating content(8 mol%of Y_(2)O_(3)).The tetragonal phase of stabilized zirconia was observed.Field emission scanning electron microscopy(FESEM)and atomic force microscopy(AFM)were employed to characterize the coatings’morphology and microstructure.The mechanical behavior of ZrO_(2)-Y_(2)O_(3) thin films under point loading conditions was studied by nanoindentation using a Berkovich indenter with 130 nm tip radius.Therefore,adhesion of top coat to the interfacial underlying metallic bond coat known as MCrAlY(M=Ni,Co)was estimated according to the highest peak load tests;for a 120 mN peak load,the film manifested tolerable adhesion properties.Moreover,nanoindentation of ZrO_(2)-Y_(2)O_(3) nanostructure deposited at 1050℃substrate preheating temperature produced the highest hardness value of about 21.7 GPa.Vickers micro hardness was utilized with the aid of the Tabor equation in order to achieve deeper insight into the correlation between adhesion and deposition process parameters.展开更多
Thermal barrier coating is a crucial thermal insulation technology that enables the underlying substrate to operate near or above its melting temperature. Such coatings bolster engineers＇ perpetual desire to increase...Thermal barrier coating is a crucial thermal insulation technology that enables the underlying substrate to operate near or above its melting temperature. Such coatings bolster engineers＇ perpetual desire to increase the power and efficiency of gas turbine engines through increasing the turbine inlet tempera- ture. Advances in recent years have made them suitable for wider engineering and defense applications, and hence they are currently attracting considerable attention. A thermal barrier coating system is itself dynamic; its components undergo recurrent changes in their composition, microstructure and crystalline phases during its service life. Nevertheless, the performance of multi-layered and multi-material sys- tems tailored for high temperature applications is closely linked to the deposition process. The process improvements achieved so far are the outcome of increased understanding of the relationship between the coating morphology and the operating service conditions, as well as developments in characterization techniques. This article presents a comprehensive review of various processing techniques and design methodologies for thermal barrier coatings. The emphasis of this review is on the particle technology; the interrelationship between particle preparation, modification and the resulting properties, to assist developments in advanced and novel thermal barrier coatings for engineering applications.展开更多
The high-temperature oxidation behaviors of the NiCrAIYSi/P-YSZ thermal barrier coatings （TBCs） produced by electron beam-physical vapor deposition （EB-PVD） on directionally solidified （DS） and single crystalli...The high-temperature oxidation behaviors of the NiCrAIYSi/P-YSZ thermal barrier coatings （TBCs） produced by electron beam-physical vapor deposition （EB-PVD） on directionally solidified （DS） and single crystalline （SC） Ni-based superalloy substrates were investigated. The cross-sectional microstructure investigation, isothermal and cyclic oxidation tests were conducted for the comparison of oxidation behaviors of TBCs on different substrates. Although TBC on DS substrate has a relatively higher oxidation rate, it has a longer thermal cycling lifetime than that on SC substrate. The primary factor for TBC spallation is the mismatch of thermal expansion coefficient （TEC） of the bond coat and substrate. The morphological feature of thermally grown oxide （TGO） has a strong influence on the TBC performance. By optimizing the elemental interdiffusion between bond coat and substrate, a high quality TGO layer is formed on the DS substrate, and therefore the TBC oxidation behavior is improved.展开更多
基金National Natural Science Foundation of China (50571005)
文摘Thermal barrier coatings （TBCs） were developed to protect metallic blades and vanes working in turbo-engines. The two-layered structure TBCs, consisting of NiCoCrAlY bond coat and yttria stabilized zirconia （YSZ）, were deposited on a cylinder of superalloy substrate by the electron beam-physical vapor deposition （EB-PVD）. The failure mechanism of the TBCs was investigated with a thermo-mechanical fatigue testing system under the service condition similar to that for turbine blades. Non-destructive evaluation of the coated specimens was conducted through the impedance spectroscopy. It is found that the crack initiation mainly takes place on the top coat at the edge of the heated zones.
文摘Yttria-stabilized zirconia(YSZ)thin nanocrystalline coatings at different substrate preheating temperatures were deposited via electron beam-physical vapour deposition(EB-PVD).Nanocrystalline ZrO_(2)-Y_(2)O_(3) was deposited on the bond coat in order to compensate for the coefficient of thermal expansion(CTE),which can be functionalized as a thermal barrier coating(TBC).The aim of this study was to evaluate mechanical properties with respect to adhesion of zirconia nanocrystalline’s top ceramic layer to the interfacial bond coat by utilizing micro and nano indentation tests.In the present paper,the structural studies were carried out using X-ray diffraction(XRD)analysis of coating content(8 mol%of Y_(2)O_(3)).The tetragonal phase of stabilized zirconia was observed.Field emission scanning electron microscopy(FESEM)and atomic force microscopy(AFM)were employed to characterize the coatings’morphology and microstructure.The mechanical behavior of ZrO_(2)-Y_(2)O_(3) thin films under point loading conditions was studied by nanoindentation using a Berkovich indenter with 130 nm tip radius.Therefore,adhesion of top coat to the interfacial underlying metallic bond coat known as MCrAlY(M=Ni,Co)was estimated according to the highest peak load tests;for a 120 mN peak load,the film manifested tolerable adhesion properties.Moreover,nanoindentation of ZrO_(2)-Y_(2)O_(3) nanostructure deposited at 1050℃substrate preheating temperature produced the highest hardness value of about 21.7 GPa.Vickers micro hardness was utilized with the aid of the Tabor equation in order to achieve deeper insight into the correlation between adhesion and deposition process parameters.
文摘Thermal barrier coating is a crucial thermal insulation technology that enables the underlying substrate to operate near or above its melting temperature. Such coatings bolster engineers＇ perpetual desire to increase the power and efficiency of gas turbine engines through increasing the turbine inlet tempera- ture. Advances in recent years have made them suitable for wider engineering and defense applications, and hence they are currently attracting considerable attention. A thermal barrier coating system is itself dynamic; its components undergo recurrent changes in their composition, microstructure and crystalline phases during its service life. Nevertheless, the performance of multi-layered and multi-material sys- tems tailored for high temperature applications is closely linked to the deposition process. The process improvements achieved so far are the outcome of increased understanding of the relationship between the coating morphology and the operating service conditions, as well as developments in characterization techniques. This article presents a comprehensive review of various processing techniques and design methodologies for thermal barrier coatings. The emphasis of this review is on the particle technology; the interrelationship between particle preparation, modification and the resulting properties, to assist developments in advanced and novel thermal barrier coatings for engineering applications.
文摘The high-temperature oxidation behaviors of the NiCrAIYSi/P-YSZ thermal barrier coatings （TBCs） produced by electron beam-physical vapor deposition （EB-PVD） on directionally solidified （DS） and single crystalline （SC） Ni-based superalloy substrates were investigated. The cross-sectional microstructure investigation, isothermal and cyclic oxidation tests were conducted for the comparison of oxidation behaviors of TBCs on different substrates. Although TBC on DS substrate has a relatively higher oxidation rate, it has a longer thermal cycling lifetime than that on SC substrate. The primary factor for TBC spallation is the mismatch of thermal expansion coefficient （TEC） of the bond coat and substrate. The morphological feature of thermally grown oxide （TGO） has a strong influence on the TBC performance. By optimizing the elemental interdiffusion between bond coat and substrate, a high quality TGO layer is formed on the DS substrate, and therefore the TBC oxidation behavior is improved.
