查看更多>>摘要：The separation of rare earths is difficult due to their similar properties and the complex characteristics of associated vein ores.Complexation-ultrafiltration(CUF)and shear induced orderly dissociation coupling with ultrafiltration(SIODUF)were used to separate metal ions(M,M=La(Ⅲ),Ce(Ⅳ)and Ca(Ⅱ))from simulated bastnaesite leaching solution using acidic phosphonic chitosan(aPCS)and rotating disk membrane.Effect of simultaneous removal of metallic ions was investigated by CUF,and suitable con-ditions were obtained for C/M 10.0(mass ratio of complexant to metal ions)and pH 5.0.The shear stabilities of aPCS-M complexes were explored at different pH values and the results show that the complexes can dissociate at a certain rotational speed,the critical one.The critical shear rates of aPCS-La,aPCS-Ce and aPCS-Ca complexes at pH 5.0 were calculated as 1.42 x 105,1.69 x 105 and 9.75 x 104 s-1,respectively.The order of complexes shear stability is aPCS-Ca＜aPCS-La＜aPCS-Ce.The high selective separation of M and regeneration of aPCS were achieved by SIODUF in the light of the difference of aPCS-M complexes shear stabilities.The separation coefficients βLa/ce and βca/La reach 31.2 and 53.9,respectively.
查看更多>>摘要：Hot-extrusion and cold-rolling were conducted on Mg-Ce binary alloys to explore the effect of cerium(Ce)on microstructure,texture and mechanical properties of Mg alloys.The addition of Ce results in significant grain refinement both in as-cast and hot-extruded samples.The basal texture is also weak-ened after extrusion and an inclined basal texture is formed with Ce addition.The strength and elon-gation of the Mg-Ce alloys are improved simultaneously due to such grain refinement and texture weakening effect.After cold-rolling,plenty of twins are found in the pure Mg and AZ31 plates while grains in the Mg-0.3Ce plate deform more uniformly without lamellar twin structure.Furthermore,Mg-0.3Ce alloys own strong and continuous strain hardening because Ce atoms and Mg-Ce precipitated phases serve as obstacles for dislocation slip.
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