利用等离子喷涂法在发动机铝合金活塞上制得 Ni Cr Al Co Y与用质量分数为 8%的 Y2 O3 稳定的 Zr O2 梯度热障层。经热震实验、金相分析、SEM分析和 TEM分析 ,结果表明该热障层具有良好的抗热冲击性和高温热稳定性 ,并且 Ni Cr Al Co Y...利用等离子喷涂法在发动机铝合金活塞上制得 Ni Cr Al Co Y与用质量分数为 8%的 Y2 O3 稳定的 Zr O2 梯度热障层。经热震实验、金相分析、SEM分析和 TEM分析 ,结果表明该热障层具有良好的抗热冲击性和高温热稳定性 ,并且 Ni Cr Al Co Y与 Zr O2 间形成了化学键结合。展开更多
A columnar Al film was firstly deposited on the top of 7%Y2O3？stabilized zirconia （7YSZ） ceramic coating in thermal barrier coating （TBC） system by magnetron sputtering. A vacuum treatment was then carried out at...A columnar Al film was firstly deposited on the top of 7%Y2O3？stabilized zirconia （7YSZ） ceramic coating in thermal barrier coating （TBC） system by magnetron sputtering. A vacuum treatment was then carried out at 700 °C for 1 h and 900 °C for 5 h to improve the erosion resistance of Al-deposited TBC. Aα-Al2O3 layer was in situ synthesized on the top of 7YSZ coating via vacuum heat treatment. The microstructure evolution of Al-deposited TBC illustrated that a loose surface-layer and a dense sub-layer formed on the top of 7YSZ coating after vacuum treatment. The phase structures of the as-sprayed TBC and the Al-deposited TBC after vacuum heat treatment were characterized by X-ray diffraction （XRD） and transmission electron microscope （TEM） assisted with focused ion beam （FIB）. Particulate erosion resistances of the as-sprayed TBC and treated TBC were compared at room temperature. In addition, erosion mechanism and schematic diagram were proposed. The results show that the Al-deposited TBC after vacuum heat treatment has better particulate erosion resistance than the as-sprayed one.展开更多
3Gd2O3-3Yb2O3-4Y2O3 （mole fraction, %） co-doped ZrO2 （GY-YSZ） thermal barrier coatings （TBCs） were produced by electron beam physical vapor deposition （EB-PVD）. The oxidation behavior of GY-YSZ at 1 050 ℃ was...3Gd2O3-3Yb2O3-4Y2O3 （mole fraction, %） co-doped ZrO2 （GY-YSZ） thermal barrier coatings （TBCs） were produced by electron beam physical vapor deposition （EB-PVD）. The oxidation behavior of GY-YSZ at 1 050 ℃ was investigated using impedance spectroscopy （IS） combined with scanning electron microscopy （SEM）, Raman spectroscopy and X-ray diffractometry （XRD）. Various electrical responses observed in the impedance spectra corresponding to GY-YSZ grains and grain boundaries were explained using circuit modeling. The change in the conduction mechanism of GY-YSZ was found to be related to the O^2- vacancy and lattice distortion due to the stabilizer diffusion during the oxidation. The results also suggested that the specific oxidation information about the GY-YSZ grains and grain boundaries should be acquired at a moderate measurement temperature, which was related to the resistance value in the impedance spectra. The resistance values of the GY-YSZ grains and grain boundaries should be measured at 200 ℃ and 300 ℃, respectively.展开更多
This work was attempted to modify the current technology for thermal barrier coatings（TBCs） by adding an additional step of surface modification,namely,supersonic fine particles bombarding（SFPB） process,on bond co...This work was attempted to modify the current technology for thermal barrier coatings（TBCs） by adding an additional step of surface modification,namely,supersonic fine particles bombarding（SFPB） process,on bond coat before applying the topcoat.After isothermal oxidation at 1000 °C for different time,the surface state of the bond coat and its phase transformation were investigated using X-ray diffraction（XRD）,scanning electron microscopy（SEM） equipped with energy-dispersive X-ray spectrometry（EDS）,transmission electron microscopy（TEM） and Cr3＋ luminescence spectroscopy.The dislocation density significantly increases after SFPB process,which can generate a large number of diffusion channels in the area of the surface of the bond coat.At the initial stage of isothermal oxidation,the diffusion velocity of Al in the bond coat significantly increases,leading to the formation of a layer of stable α-Al2O3 phase.A great number of Cr3＋ positive ions can diffuse via diffusion channels during the transient state of isothermal oxidation,which can lead to the presence of（Al0.9Cr0.1）2O3 phase and accelerate the γ→θ→α phase transformation.Cr3＋ luminescence spectroscopy measurement shows that the residual stress increases at the initial stage of isothermal oxidation and then decreases.The residual stress after isothermal oxidation for 310 h reduces to 0.63 GPa compared with 0.93 GPa after isothermal oxidation for 26 h.In order to prolong the lifespan of TBCs,a layer of continuous,dense and pure α-Al2O3 with high oxidation resistance at the interface between topcoat and bond coat can be obtained due to additional SFPB process.展开更多
Perovskite is a versatile group of oxide materials allowing their properties to be tailored by composition towards specific requirements. La Al O3 was prepared to study and report its properties in the context of its ...Perovskite is a versatile group of oxide materials allowing their properties to be tailored by composition towards specific requirements. La Al O3 was prepared to study and report its properties in the context of its potential in thermal barrier coatings（TBCs） technology. A citric acid method was used for synthesis and the perovskite structure was confirmed using XRD and FT-IR. Viscosity of the solution precursor was checked as well as the particle size by laser particle size analysis. Densification behavior of the material was followed by conventional sintering and by spark plasma sintering. Apparent porosity by the Archimedes method, thermal conductivity and thermal expansion coefficient were studied. Mechanical and fracture properties were measured at elevated temperatures up to 1300 ℃ For samples sintered at 1200-1400 ℃, coefficient of thermal expansion ranged from 5.5×10^-6 to 6.5×10^-6 K^-1 and thermal conductivity ranged between 2.2 and 3.4 W/（m？K）. Elastic modulus and ultimate stress were measured at 1000-1300 ℃, while by micro-indentation, fracture toughness was found to be 3 MPa·m1/2. As the sintering temperature increased from 1200 to 1500 ℃, significant densification from 3.21 to 5.81 g/cm^3 was found, indicating that material annealing should be made at least at 1400 ℃. Under this condition, negligible dimensional change in phase transition temperature of La Al O3 from the rhombohedral（R3 c） to the ideal cubic（Pm3 m） is found. Data reported in this work can be useful for comparing the mechanical and fracture behaviours of different TBCs developed involving La Al O3 as well as input for numerical simulations.展开更多
The thermal stability and failure mechanism of thick thermal barrier coatings(TBCs) with and without vertical type cracks were investigated through the cyclic thermal exposure and thermal-shock tests. The TBC systems ...The thermal stability and failure mechanism of thick thermal barrier coatings(TBCs) with and without vertical type cracks were investigated through the cyclic thermal exposure and thermal-shock tests. The TBC systems with thickness of about 2000 μm in the top coat were prepared by an air plasma spray(APS) on the bond coat of about 150 μm in thickness prepared by APS. The adhesive strength values of the as-prepared TBCs with and without vertical type cracks were determined to be 24.7 and 11.0 MPa, respectively, indicating the better interface stability in the TBC with vertical type cracks. The TBC with vertical type cracks shows a better thermal durability than that without vertical type cracks in the thermal cyclic exposure and thermal-shock tests. The hardness values of the as-prepared TBCs with and without vertical type cracks were found to be 6.6 and 5.3 GPa, respectively, which were increased to 9.5 and 5.5 GPa, respectively, after the cyclic thermal exposure tests. These results indicate that the vertical type cracks developed in the top coat are important in improving the lifetime performance of thick TBC in high temperature environment.展开更多
The commonly-employed material for thermal barrier coatings(TBCs)is 7 wt.%Y2O3 ZrO2(7YSZ),generally deposited by electron beam-physical vapor deposition(EB-PVD).Due to the increasing demand for higher operating temper...The commonly-employed material for thermal barrier coatings(TBCs)is 7 wt.%Y2O3 ZrO2(7YSZ),generally deposited by electron beam-physical vapor deposition(EB-PVD).Due to the increasing demand for higher operating temperature in aero-derivative gas turbines,a lot of effort has been made to prevent the premature failure of columnar 7YSZ TBCs,which is induced by the microstructure degradation,sintering and spallation after the deposition of infiltrated siliceous mineral(consisting of calcium magnesium aluminum silicate(CaO MgO Al2O3 SiO2,i.e.,CMAS)).A new method called Al-modification for columnar 7YSZ TBCs against CMAS corrosion was present.The Al film was magnetron-sputtered on the surface of the columnar 7YSZ TBCs,followed by performing vacuum heat treatment of the Al-deposited TBCs.During the heat treatment,the molten Al reacted with ZrO2 to formα-Al2O3 overlay that effectively hindered CMAS infiltration.Moreover,the Al film could evaporate and re-nucleate,leading to the generation of Al2O3 nanowires,which further restrained the moving of molten CMAS.展开更多
文摘利用等离子喷涂法在发动机铝合金活塞上制得 Ni Cr Al Co Y与用质量分数为 8%的 Y2 O3 稳定的 Zr O2 梯度热障层。经热震实验、金相分析、SEM分析和 TEM分析 ,结果表明该热障层具有良好的抗热冲击性和高温热稳定性 ,并且 Ni Cr Al Co Y与 Zr O2 间形成了化学键结合。
基金Project(2012CB625100)supported by the National Basic Research Program of ChinaProject(2012AA03A512)supported by the National High-tech Research and Development Program of China
文摘A columnar Al film was firstly deposited on the top of 7%Y2O3？stabilized zirconia （7YSZ） ceramic coating in thermal barrier coating （TBC） system by magnetron sputtering. A vacuum treatment was then carried out at 700 °C for 1 h and 900 °C for 5 h to improve the erosion resistance of Al-deposited TBC. Aα-Al2O3 layer was in situ synthesized on the top of 7YSZ coating via vacuum heat treatment. The microstructure evolution of Al-deposited TBC illustrated that a loose surface-layer and a dense sub-layer formed on the top of 7YSZ coating after vacuum treatment. The phase structures of the as-sprayed TBC and the Al-deposited TBC after vacuum heat treatment were characterized by X-ray diffraction （XRD） and transmission electron microscope （TEM） assisted with focused ion beam （FIB）. Particulate erosion resistances of the as-sprayed TBC and treated TBC were compared at room temperature. In addition, erosion mechanism and schematic diagram were proposed. The results show that the Al-deposited TBC after vacuum heat treatment has better particulate erosion resistance than the as-sprayed one.
基金Projects (50771009, 50731001 and 51071013) supported by the National Natural Science Foundations of China Project (2010CB631200) supported by the National Basic Research Program of China
文摘3Gd2O3-3Yb2O3-4Y2O3 （mole fraction, %） co-doped ZrO2 （GY-YSZ） thermal barrier coatings （TBCs） were produced by electron beam physical vapor deposition （EB-PVD）. The oxidation behavior of GY-YSZ at 1 050 ℃ was investigated using impedance spectroscopy （IS） combined with scanning electron microscopy （SEM）, Raman spectroscopy and X-ray diffractometry （XRD）. Various electrical responses observed in the impedance spectra corresponding to GY-YSZ grains and grain boundaries were explained using circuit modeling. The change in the conduction mechanism of GY-YSZ was found to be related to the O^2- vacancy and lattice distortion due to the stabilizer diffusion during the oxidation. The results also suggested that the specific oxidation information about the GY-YSZ grains and grain boundaries should be acquired at a moderate measurement temperature, which was related to the resistance value in the impedance spectra. The resistance values of the GY-YSZ grains and grain boundaries should be measured at 200 ℃ and 300 ℃, respectively.
基金Foundation item: Project (50575220) supported by the National Natural Science Foundation of ChinaProject supported by State Key Laboratory of Engines,China
文摘This work was attempted to modify the current technology for thermal barrier coatings（TBCs） by adding an additional step of surface modification,namely,supersonic fine particles bombarding（SFPB） process,on bond coat before applying the topcoat.After isothermal oxidation at 1000 °C for different time,the surface state of the bond coat and its phase transformation were investigated using X-ray diffraction（XRD）,scanning electron microscopy（SEM） equipped with energy-dispersive X-ray spectrometry（EDS）,transmission electron microscopy（TEM） and Cr3＋ luminescence spectroscopy.The dislocation density significantly increases after SFPB process,which can generate a large number of diffusion channels in the area of the surface of the bond coat.At the initial stage of isothermal oxidation,the diffusion velocity of Al in the bond coat significantly increases,leading to the formation of a layer of stable α-Al2O3 phase.A great number of Cr3＋ positive ions can diffuse via diffusion channels during the transient state of isothermal oxidation,which can lead to the presence of（Al0.9Cr0.1）2O3 phase and accelerate the γ→θ→α phase transformation.Cr3＋ luminescence spectroscopy measurement shows that the residual stress increases at the initial stage of isothermal oxidation and then decreases.The residual stress after isothermal oxidation for 310 h reduces to 0.63 GPa compared with 0.93 GPa after isothermal oxidation for 26 h.In order to prolong the lifespan of TBCs,a layer of continuous,dense and pure α-Al2O3 with high oxidation resistance at the interface between topcoat and bond coat can be obtained due to additional SFPB process.
基金Financial support by THEBARCODE-Development of Multifunctional Thermal Barrier Coatings and Modeling Tools for High Temperature Power Generation with Improved Efficiency FP7-NMP2012-SMALL-6,Collaborative projectby MATENERGY project of Technological Educational Institute of Sterea Ellada
文摘Perovskite is a versatile group of oxide materials allowing their properties to be tailored by composition towards specific requirements. La Al O3 was prepared to study and report its properties in the context of its potential in thermal barrier coatings（TBCs） technology. A citric acid method was used for synthesis and the perovskite structure was confirmed using XRD and FT-IR. Viscosity of the solution precursor was checked as well as the particle size by laser particle size analysis. Densification behavior of the material was followed by conventional sintering and by spark plasma sintering. Apparent porosity by the Archimedes method, thermal conductivity and thermal expansion coefficient were studied. Mechanical and fracture properties were measured at elevated temperatures up to 1300 ℃ For samples sintered at 1200-1400 ℃, coefficient of thermal expansion ranged from 5.5×10^-6 to 6.5×10^-6 K^-1 and thermal conductivity ranged between 2.2 and 3.4 W/（m？K）. Elastic modulus and ultimate stress were measured at 1000-1300 ℃, while by micro-indentation, fracture toughness was found to be 3 MPa·m1/2. As the sintering temperature increased from 1200 to 1500 ℃, significant densification from 3.21 to 5.81 g/cm^3 was found, indicating that material annealing should be made at least at 1400 ℃. Under this condition, negligible dimensional change in phase transition temperature of La Al O3 from the rhombohedral（R3 c） to the ideal cubic（Pm3 m） is found. Data reported in this work can be useful for comparing the mechanical and fracture behaviours of different TBCs developed involving La Al O3 as well as input for numerical simulations.
基金Project(2011-0030058) supported by the National Research Foundation of Korea(NRF) Funded by the Korean Government(MSIP)Project(20134030200220) supported by the Human Resources Development Program of the Korea Institute of Energy Technology Evaluation and Planning(KETEP)Funded by the Korea Government Ministry of Trade,Industry and Energy and by the Korea Institute of Materials Science(KIMS) in 2013
文摘The thermal stability and failure mechanism of thick thermal barrier coatings(TBCs) with and without vertical type cracks were investigated through the cyclic thermal exposure and thermal-shock tests. The TBC systems with thickness of about 2000 μm in the top coat were prepared by an air plasma spray(APS) on the bond coat of about 150 μm in thickness prepared by APS. The adhesive strength values of the as-prepared TBCs with and without vertical type cracks were determined to be 24.7 and 11.0 MPa, respectively, indicating the better interface stability in the TBC with vertical type cracks. The TBC with vertical type cracks shows a better thermal durability than that without vertical type cracks in the thermal cyclic exposure and thermal-shock tests. The hardness values of the as-prepared TBCs with and without vertical type cracks were found to be 6.6 and 5.3 GPa, respectively, which were increased to 9.5 and 5.5 GPa, respectively, after the cyclic thermal exposure tests. These results indicate that the vertical type cracks developed in the top coat are important in improving the lifetime performance of thick TBC in high temperature environment.
基金Project(2017YFB0306100) supported by the National Key Research&Development Plan of ChinaProjects(51801034,51771059) supported by the National Natural Science Foundation of China+3 种基金Projects(2018GDASCX-0949,2018GDASCX-0950,2017GDASCX-0111) supported by the Guangdong Academy of Sciences,ChinaProjects(2017B090916002,2017A070701027) supported by the Guangdong Technical Research Program,ChinaProjects(2016A030312015,2017A030310315) supported by the Natural Science Foundation of Guangdong Province,ChinaProjects(201605131008557,201707010385) supported by the Technical Research Program of Guangzhou City,China
文摘The commonly-employed material for thermal barrier coatings(TBCs)is 7 wt.%Y2O3 ZrO2(7YSZ),generally deposited by electron beam-physical vapor deposition(EB-PVD).Due to the increasing demand for higher operating temperature in aero-derivative gas turbines,a lot of effort has been made to prevent the premature failure of columnar 7YSZ TBCs,which is induced by the microstructure degradation,sintering and spallation after the deposition of infiltrated siliceous mineral(consisting of calcium magnesium aluminum silicate(CaO MgO Al2O3 SiO2,i.e.,CMAS)).A new method called Al-modification for columnar 7YSZ TBCs against CMAS corrosion was present.The Al film was magnetron-sputtered on the surface of the columnar 7YSZ TBCs,followed by performing vacuum heat treatment of the Al-deposited TBCs.During the heat treatment,the molten Al reacted with ZrO2 to formα-Al2O3 overlay that effectively hindered CMAS infiltration.Moreover,the Al film could evaporate and re-nucleate,leading to the generation of Al2O3 nanowires,which further restrained the moving of molten CMAS.
