Seven diaryl ethers were synthesized with potassium fluoride coated alumina as a strong base and the addition of catalytic amount of PTC. The yield of diaryl ethers with addition of PTC was much higher than that witho...Seven diaryl ethers were synthesized with potassium fluoride coated alumina as a strong base and the addition of catalytic amount of PTC. The yield of diaryl ethers with addition of PTC was much higher than that without PTC.A discussion of the catalysis mechanism was given in this paper.展开更多
A hot wind tunnel of annular cascade test rig is established for measuring temperature distribution on a real gas turbine blade surface with infrared camera.Besides,conjugate heat transfer numerical simulation is perf...A hot wind tunnel of annular cascade test rig is established for measuring temperature distribution on a real gas turbine blade surface with infrared camera.Besides,conjugate heat transfer numerical simulation is performed to obtain cooling efficiency distribution on both blade substrate surface and coating surface for comparison.The effect of thermal barrier coating on the overall cooling performance for blades is compared under varied mass flow rate of coolant,and spatial difference is also discussed.Results indicate that the cooling efficiency in the leading edge and trailing edge areas of the blade is the lowest.The cooling performance is not only influenced by the internal cooling structures layout inside the blade but also by the flow condition of the mainstream in the external cascade path.Thermal barrier effects of the coating vary at different regions of the blade surface,where higher internal cooling performance exists,more effective the thermal barrier will be,which means the thermal protection effect of coatings is remarkable in these regions.At the designed mass flow ratio condition,the cooling efficiency on the pressure side varies by 0.13 for the coating surface and substrate surface,while this value is 0.09 on the suction side.展开更多
This study systematically presents the corrosion performance of plasma transferred arc(PTA)cladding,twin wire arc spraying(TWAS)and high-velocity oxygen-fuel(HVOF)spraying coatings through field trials in a 400 t/d wa...This study systematically presents the corrosion performance of plasma transferred arc(PTA)cladding,twin wire arc spraying(TWAS)and high-velocity oxygen-fuel(HVOF)spraying coatings through field trials in a 400 t/d waste-to-energy plant.The results revealed that the high-temperature superheater(HTS)tube exhibited significantly more severe corrosion than the low-temperature superheater(LTS)tube did,primarily due to the higher Cl content in its deposits and elevated tube wall temperature,which promoted the formation of volatile metal chlorides rather than protective oxides.The 2700 h field trial showed that the PTA-NiCr1 coating can be used in both the LTS and HTS areas.The HVOF-NiCr1 coating was competent in the LTS area and performed well on the HTS tube only in the first 900 h,whereas the TWAS-NiCr1 coating was not suitable even in the less corrosive LTS area.Based on microstructure characterization and thermodynamic calculations,the mechanism by which the preparation technique affects the corrosion resistance of the three coatings was further elucidated.The PTA-NiCr1 coating formed a dense dual-layer oxide with a Ni-rich outer layer and Cr-rich inner layer,contributing to the superior corrosion resistance.The Cr oxides formed in the HVOF-NiCr1 coating reacted with NaCl and KCl vapors to generate non-protective chromates,leading to reduced corrosion resistance.The low density of the TWAS-NiCr1 coating enabled the penetration of Cl2 and O_(2) gases into its interior,inducing Fe oxidation in the substrate and thereby increasing the risk of coating delamination.展开更多
文摘Seven diaryl ethers were synthesized with potassium fluoride coated alumina as a strong base and the addition of catalytic amount of PTC. The yield of diaryl ethers with addition of PTC was much higher than that without PTC.A discussion of the catalysis mechanism was given in this paper.
基金funded by the National Natural Science Foundation of China(Funding No.51206109)
文摘A hot wind tunnel of annular cascade test rig is established for measuring temperature distribution on a real gas turbine blade surface with infrared camera.Besides,conjugate heat transfer numerical simulation is performed to obtain cooling efficiency distribution on both blade substrate surface and coating surface for comparison.The effect of thermal barrier coating on the overall cooling performance for blades is compared under varied mass flow rate of coolant,and spatial difference is also discussed.Results indicate that the cooling efficiency in the leading edge and trailing edge areas of the blade is the lowest.The cooling performance is not only influenced by the internal cooling structures layout inside the blade but also by the flow condition of the mainstream in the external cascade path.Thermal barrier effects of the coating vary at different regions of the blade surface,where higher internal cooling performance exists,more effective the thermal barrier will be,which means the thermal protection effect of coatings is remarkable in these regions.At the designed mass flow ratio condition,the cooling efficiency on the pressure side varies by 0.13 for the coating surface and substrate surface,while this value is 0.09 on the suction side.
基金support provided by the National Natural Science Foundation of China(No.52206143).
文摘This study systematically presents the corrosion performance of plasma transferred arc(PTA)cladding,twin wire arc spraying(TWAS)and high-velocity oxygen-fuel(HVOF)spraying coatings through field trials in a 400 t/d waste-to-energy plant.The results revealed that the high-temperature superheater(HTS)tube exhibited significantly more severe corrosion than the low-temperature superheater(LTS)tube did,primarily due to the higher Cl content in its deposits and elevated tube wall temperature,which promoted the formation of volatile metal chlorides rather than protective oxides.The 2700 h field trial showed that the PTA-NiCr1 coating can be used in both the LTS and HTS areas.The HVOF-NiCr1 coating was competent in the LTS area and performed well on the HTS tube only in the first 900 h,whereas the TWAS-NiCr1 coating was not suitable even in the less corrosive LTS area.Based on microstructure characterization and thermodynamic calculations,the mechanism by which the preparation technique affects the corrosion resistance of the three coatings was further elucidated.The PTA-NiCr1 coating formed a dense dual-layer oxide with a Ni-rich outer layer and Cr-rich inner layer,contributing to the superior corrosion resistance.The Cr oxides formed in the HVOF-NiCr1 coating reacted with NaCl and KCl vapors to generate non-protective chromates,leading to reduced corrosion resistance.The low density of the TWAS-NiCr1 coating enabled the penetration of Cl2 and O_(2) gases into its interior,inducing Fe oxidation in the substrate and thereby increasing the risk of coating delamination.
