有机凝胶-热还原法制备超细金属镍、铁纤维

Preparation of Superfine Ni and Fe Fibers by the Organic Gel-Thermal Reduction Method

分别以柠檬酸和碱式碳酸镍、乳酸和硝酸铁为原料,采用有机凝胶-热还原法分别成功制备了超细(直径<1μm)金属镍纤维和铁纤维,镍纤维长2m,铁纤维长0.5m,组成2种纤维的晶粒约100nm。通过FTIR,XRD,TG/DSC和SEM对纤维前驱体凝胶的结构、热分解过程及热还原产物的形貌进行了表征。凝胶的可纺性与组成凝胶的羧酸盐分子结构有关。柠檬酸和乳酸中的羟基分别单齿配位于Ni2+和Fe3+离子,可能形成线型分子[(C6H6O7)Ni]n和[C3H4O3]3Fe,由这些线型分子组成的凝胶显示出了良好的可纺性。同时,可能由于在柠檬酸与Ni2+离子的反应中存在Ni2+离子的架桥作用,因而柠檬酸镍凝胶显示出了比乳酸铁凝胶更好的可纺性。

Superfine metallic nickel and iron fibers were prepared using the citric acid, lactic acid and their metal salts as the raw materials by organic gel-thermal reduction method. The superfine metallic nickel and iron fibers have diameters of less than Ipm and length of 2 m for nickel fibers and 0.5 m for iron fibers, and the fine crystalline particles of less than 100 nm. The structure, thermo-decomposition process and surface morphologies of the fibers derived from thermal reduction of the gel precursors were characterized by FTIR, XRD, TG/DSC and SEM. It is found that the gels showed a good spinnability, largely depends on the molecular structures of carboxylates formed in the gel. It is reasoned that these gels may consist of linear-type structural molecules [（C6H6O7）Ni]n for the nickel citrate gel, and [C3H4O3]3Fe for the ferric lactate gel, respectively. Moreover, the nickel citrate gel exhibited a better spinnability than the ferric lactate gel possibly due to the bridging behavior of Ni^2＋ ions during reactions between citric acid and nickel ions.