AZ31-4.6% Mg2Si （mass fraction） composite was prepared by conventional casting method. Repetitive upsetting （RU） was applied to severely deforming the as-cast composite at 400 ℃ for 1, 3, and 5 passes. Finite ele...AZ31-4.6% Mg2Si （mass fraction） composite was prepared by conventional casting method. Repetitive upsetting （RU） was applied to severely deforming the as-cast composite at 400 ℃ for 1, 3, and 5 passes. Finite element analysis of the material flow indicates that deformation concentrates in the bottom region of the sample after 1 pass, and much more uniform deformation is obtained after 5 passes. During multi-pass RU process, both dendritic and Chinese script type Mg2Si phases are broken up into smaller particles owing to the shear stress forced by the matrix. With the increasing number of RU passes, finer grain size and more homogeneous distribution of Mg2Si particles are obtained along with significant enhancement in both strength and ductility. AZ31-4.6%Mg2Si composite exhibits tensile strength of 284 MPa and elongation of 9.8%after 5 RU passes at 400 ℃ compared with the initial 128 MPa and 5.4%of original AZ31-4.6%Mg2Si composite.展开更多
2-Methyl-4-methoxyaniline （MMA） was synthesized by one-pot method through the hydrogenation and Bamberger rearrangement of o-nitrotoluene in methanol using acidic ionic liquid and 3% Pt/C as catalyst system. The eff...2-Methyl-4-methoxyaniline （MMA） was synthesized by one-pot method through the hydrogenation and Bamberger rearrangement of o-nitrotoluene in methanol using acidic ionic liquid and 3% Pt/C as catalyst system. The effects of ionic liquid type, dosage of ionic liquid and 3% Pt/C, reaction temperature and reaction pressure on o-nitrotoluene conversion and MMA selectivity were investigated. The results indicated that the imidazolium-based acidic ionic liquid which contains SO3H-functionalized cation showed higher selectivity to MMA than other acidic ionic liquids used in this work. Using 1-（propyl-3-sulfonate）-3-methylimidazolium hydrosulfate （[HSO3-pmim][HSO4]） as the acid catalyst, the selectivity to MMA was as high as 67.6% at 97.8% of o-nitrotoluene conversion. As 3% Pt/C increased from 0.01 g to 0.025 g, the selectivity to MMA decreased from 73.4% to 62.5%, because of the hydrogenation of intermediate o-methyl-phenylhydroxylamine to o-toluidine becoming more dominant. An increase in hydrogen pressure also had obviously dramatic effect in lowering the MMA selectivity. After easy separation from the products, the catalyst system could be reused at least 3 times.展开更多
基金Projects(51074106,51374145)supported by the National Natural Science Foundation of ChinaProject(09JC1408200)supported by the Science and Technology Commission of Shanghai Municipality,China+1 种基金Project(2014M561466)supported by China Postdoctoral Science FoundationProject(14R21411000)supported by Shanghai Postdoctoral Scientific Program,China
文摘AZ31-4.6% Mg2Si （mass fraction） composite was prepared by conventional casting method. Repetitive upsetting （RU） was applied to severely deforming the as-cast composite at 400 ℃ for 1, 3, and 5 passes. Finite element analysis of the material flow indicates that deformation concentrates in the bottom region of the sample after 1 pass, and much more uniform deformation is obtained after 5 passes. During multi-pass RU process, both dendritic and Chinese script type Mg2Si phases are broken up into smaller particles owing to the shear stress forced by the matrix. With the increasing number of RU passes, finer grain size and more homogeneous distribution of Mg2Si particles are obtained along with significant enhancement in both strength and ductility. AZ31-4.6%Mg2Si composite exhibits tensile strength of 284 MPa and elongation of 9.8%after 5 RU passes at 400 ℃ compared with the initial 128 MPa and 5.4%of original AZ31-4.6%Mg2Si composite.
基金Supported by the National Natural Science Foundation of China （21106134） and the Natural Science Foundation of Zlaejlang Province （Y4100671）.
文摘2-Methyl-4-methoxyaniline （MMA） was synthesized by one-pot method through the hydrogenation and Bamberger rearrangement of o-nitrotoluene in methanol using acidic ionic liquid and 3% Pt/C as catalyst system. The effects of ionic liquid type, dosage of ionic liquid and 3% Pt/C, reaction temperature and reaction pressure on o-nitrotoluene conversion and MMA selectivity were investigated. The results indicated that the imidazolium-based acidic ionic liquid which contains SO3H-functionalized cation showed higher selectivity to MMA than other acidic ionic liquids used in this work. Using 1-（propyl-3-sulfonate）-3-methylimidazolium hydrosulfate （[HSO3-pmim][HSO4]） as the acid catalyst, the selectivity to MMA was as high as 67.6% at 97.8% of o-nitrotoluene conversion. As 3% Pt/C increased from 0.01 g to 0.025 g, the selectivity to MMA decreased from 73.4% to 62.5%, because of the hydrogenation of intermediate o-methyl-phenylhydroxylamine to o-toluidine becoming more dominant. An increase in hydrogen pressure also had obviously dramatic effect in lowering the MMA selectivity. After easy separation from the products, the catalyst system could be reused at least 3 times.
