The influence of exfoliation corrosion on the tensile properties of a high strength Al-Zn-Mg-Cu alloy was investigated by ambient temperature tensile testing, optical microscopy, transmission electron microscopy （TEM...The influence of exfoliation corrosion on the tensile properties of a high strength Al-Zn-Mg-Cu alloy was investigated by ambient temperature tensile testing, optical microscopy, transmission electron microscopy （TEM）, scanning electron microscopy （SEM） and electron backscatter diffraction （EBSD）. After exfoliation corrosion immersion, blisters and corrosion pits can be seen on the sheet surface, which lead to loss of materials and notches. A number of intergranular cracks are observed to initiate at the bottom of the corrosion-induced notches and propagate rapidly into the bulk materials during tensile. Consequently, exfoliation corrosion results in significant loss of strength and brittle fracture. EBSD results show that the crack propagation path is primarily along the grain boundaries with misorientation of-45°, and coincidence site lattice （CSL） boundaries are slightly more resistant to crack.展开更多
The Mo modified Ni/Al_2O_3 catalysts were prepared and sulfided at different temperatures, and their catalytic activity for thioetherification of mercaptans and olefins(or dienes), hydrogenation of dienes and olefins ...The Mo modified Ni/Al_2O_3 catalysts were prepared and sulfided at different temperatures, and their catalytic activity for thioetherification of mercaptans and olefins(or dienes), hydrogenation of dienes and olefins in the thioetherification process using fluidized catalytic cracking(FCC) naphtha as the feedstock was investigated. In order to disclose the correlation between the physicochemical characteristics of catalysts and their catalytic activity, the surface structures and properties of the catalysts sulfided at different temperatures were characterized by the high resolution transmission electronic microscopy(HRTEM), X-ray photoelectron spectroscopy(XPS) and H2-temperature programmed reduction(H_2-TPR) technique. The results showed that an increase of sulfurization temperature not only could promote the sulfurization degree of active metals on the catalysts, but also could adjust the micro-morphology of active species. These changes could improve the catalytic performance of thioetherification, and hydrogenation of dienes and olefins. However, an excess sulfurization temperature was more easily to upgrade the ability of the catalyst for hydrogenation of olefins, which could lead to a decrease of the octane number of the product. It was also showed that a moderate sulfurization temperature not only could improve the catalytic performance of thioetherification and hydrogenation of dienes but also could control hydrogenation of olefins.展开更多
基金Project(2012CB619500) supported by the National Basic Research Program of ChinaProject(201012200238) supported from the Freedom Explore Program of Central South University, China
文摘The influence of exfoliation corrosion on the tensile properties of a high strength Al-Zn-Mg-Cu alloy was investigated by ambient temperature tensile testing, optical microscopy, transmission electron microscopy （TEM）, scanning electron microscopy （SEM） and electron backscatter diffraction （EBSD）. After exfoliation corrosion immersion, blisters and corrosion pits can be seen on the sheet surface, which lead to loss of materials and notches. A number of intergranular cracks are observed to initiate at the bottom of the corrosion-induced notches and propagate rapidly into the bulk materials during tensile. Consequently, exfoliation corrosion results in significant loss of strength and brittle fracture. EBSD results show that the crack propagation path is primarily along the grain boundaries with misorientation of-45°, and coincidence site lattice （CSL） boundaries are slightly more resistant to crack.
基金support provided by the National Natural Science Foundation of China(Granted No.21276276)
文摘The Mo modified Ni/Al_2O_3 catalysts were prepared and sulfided at different temperatures, and their catalytic activity for thioetherification of mercaptans and olefins(or dienes), hydrogenation of dienes and olefins in the thioetherification process using fluidized catalytic cracking(FCC) naphtha as the feedstock was investigated. In order to disclose the correlation between the physicochemical characteristics of catalysts and their catalytic activity, the surface structures and properties of the catalysts sulfided at different temperatures were characterized by the high resolution transmission electronic microscopy(HRTEM), X-ray photoelectron spectroscopy(XPS) and H2-temperature programmed reduction(H_2-TPR) technique. The results showed that an increase of sulfurization temperature not only could promote the sulfurization degree of active metals on the catalysts, but also could adjust the micro-morphology of active species. These changes could improve the catalytic performance of thioetherification, and hydrogenation of dienes and olefins. However, an excess sulfurization temperature was more easily to upgrade the ability of the catalyst for hydrogenation of olefins, which could lead to a decrease of the octane number of the product. It was also showed that a moderate sulfurization temperature not only could improve the catalytic performance of thioetherification and hydrogenation of dienes but also could control hydrogenation of olefins.
