The high temperature corrosion resistance of Ni-25.9Cr-13.5Al-1.2Y-0.6Si and Ni-10.2Co-12.4Cr16.0Al-0.5Y-0.2Hf alloys was assessed in sulfidation/oxidation envi-ronments. In the environment with a sulfur partial press...The high temperature corrosion resistance of Ni-25.9Cr-13.5Al-1.2Y-0.6Si and Ni-10.2Co-12.4Cr16.0Al-0.5Y-0.2Hf alloys was assessed in sulfidation/oxidation envi-ronments. In the environment with a sulfur partial pressure of 1Pa. and an oxygenpartial pressure of 10^(-19)Pa, both these alloys exhibited three distinct stages in theweight gain-time curve when tested at 700℃. In the initial stage, selective sulfidationof Cr suppressed the formation of the other metal sulfides, resulting in lower weightgains. In the transient stage, breakdown and cracking of Cr sulfides and insufficientconcentration of Cr at the outer zone led to the rapid formation of Ni sulfides anda rapid increase in weight. In the steady-state stage, corrosion was controlled by thediffusion of anions and/or cations, which led to a parabolic rate law.展开更多
ZnO thin films were deposited on a glass substrate by dc (direct current) and rf (radio frequency) magnetron sputtering. Post-deposition annealing was performed in different atmospheres and at different temperatures. ...ZnO thin films were deposited on a glass substrate by dc (direct current) and rf (radio frequency) magnetron sputtering. Post-deposition annealing was performed in different atmospheres and at different temperatures. The correlation of the annealing conditions with the microstructure and properties of the ZnO films wer e investigated by ultraviolet-visible spectroscopy, X-ray diffraction, conductiv ity measurement and scanning electron microscopy. Only the strong 002 peak could be observed by X-ray diffraction. The post-deposition annealing of ZnO films wa s found to alter the film's microstructure and properties, including crystallini ty, porosity, grain size, internal stress level and resistivity. It was also fou nd that after annealing, the conductivity of poorly conductive samples often imp roved. However, annealing does not improve the conductivity of samples with high conductivity prior to annealing. The resistivity of as-grown films can be decre ased from 102 to 10-4Ω·cm after annealing in nitrogen. To explain the effects of annealing on the conductivity of ZnO, it is believed that annealing may alter the presence and distribution of oxygen defects, reduce the lattice stress, cau se diffusion, grain coarsening and recrystallization. Annealing will reduce the density of grain boundaries in less dense films, which may decrease the resistiv ity of the films. On the other hand, annealing may also increase the porosity of thin films, leading to an increase in resistivity.展开更多
Zeolite membranes offer great application potentials in membrane separation and/or reaction due to their excellent separation performance and catalytic ability. Up to present, various synthesis methods of zeolite mem-...Zeolite membranes offer great application potentials in membrane separation and/or reaction due to their excellent separation performance and catalytic ability. Up to present, various synthesis methods of zeolite mem- branes have been developed, including embedded method, in-situ hydrothermal synthesis method, and secondary growth method etc. Compared with the in-situ hydrothermal synthesis method, the secondary growth method possesses a variety of advantages such as easier operation, higher con- trollability in crystal orientation, microstructure and film thickness, leading to much better reproducibility. This review provides a concise summary and analysis of various synthesis methods reported in the literature. In particular, the secon- dary growth method was discussed in detail in terms of crys- tal orientation, defects and crystal grain layers. Some critical issues were also highlighted, which were conducive to the improvement in the synthesis technology of zeolite mem- branes.展开更多
文摘The high temperature corrosion resistance of Ni-25.9Cr-13.5Al-1.2Y-0.6Si and Ni-10.2Co-12.4Cr16.0Al-0.5Y-0.2Hf alloys was assessed in sulfidation/oxidation envi-ronments. In the environment with a sulfur partial pressure of 1Pa. and an oxygenpartial pressure of 10^(-19)Pa, both these alloys exhibited three distinct stages in theweight gain-time curve when tested at 700℃. In the initial stage, selective sulfidationof Cr suppressed the formation of the other metal sulfides, resulting in lower weightgains. In the transient stage, breakdown and cracking of Cr sulfides and insufficientconcentration of Cr at the outer zone led to the rapid formation of Ni sulfides anda rapid increase in weight. In the steady-state stage, corrosion was controlled by thediffusion of anions and/or cations, which led to a parabolic rate law.
基金This work was supported by New Zealand Foundation for Research,Science and Technology(Top Achiever Doctoral Scholarship)Australian Institute of Nuclear Science and Engineering(Postgraduate Award).The authors would also like to thank Mrs.Catherine Hobbis for technical support.
文摘ZnO thin films were deposited on a glass substrate by dc (direct current) and rf (radio frequency) magnetron sputtering. Post-deposition annealing was performed in different atmospheres and at different temperatures. The correlation of the annealing conditions with the microstructure and properties of the ZnO films wer e investigated by ultraviolet-visible spectroscopy, X-ray diffraction, conductiv ity measurement and scanning electron microscopy. Only the strong 002 peak could be observed by X-ray diffraction. The post-deposition annealing of ZnO films wa s found to alter the film's microstructure and properties, including crystallini ty, porosity, grain size, internal stress level and resistivity. It was also fou nd that after annealing, the conductivity of poorly conductive samples often imp roved. However, annealing does not improve the conductivity of samples with high conductivity prior to annealing. The resistivity of as-grown films can be decre ased from 102 to 10-4Ω·cm after annealing in nitrogen. To explain the effects of annealing on the conductivity of ZnO, it is believed that annealing may alter the presence and distribution of oxygen defects, reduce the lattice stress, cau se diffusion, grain coarsening and recrystallization. Annealing will reduce the density of grain boundaries in less dense films, which may decrease the resistiv ity of the films. On the other hand, annealing may also increase the porosity of thin films, leading to an increase in resistivity.
文摘Zeolite membranes offer great application potentials in membrane separation and/or reaction due to their excellent separation performance and catalytic ability. Up to present, various synthesis methods of zeolite mem- branes have been developed, including embedded method, in-situ hydrothermal synthesis method, and secondary growth method etc. Compared with the in-situ hydrothermal synthesis method, the secondary growth method possesses a variety of advantages such as easier operation, higher con- trollability in crystal orientation, microstructure and film thickness, leading to much better reproducibility. This review provides a concise summary and analysis of various synthesis methods reported in the literature. In particular, the secon- dary growth method was discussed in detail in terms of crys- tal orientation, defects and crystal grain layers. Some critical issues were also highlighted, which were conducive to the improvement in the synthesis technology of zeolite mem- branes.
