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用金相显微镜和原子力显微镜分析了存在外加磁场情况下的Zn分枝状电解沉积物的微观形貌,并且根据实验结果提出了磁场使沉积物分枝呈现螺旋状偏转的机理.1)在沉积物晶粒的早期生长阶段,当晶粒已经形成了择优生长方向但又非常小,仍然悬浮于电解液中时,磁流体动力学对流作用于它上面的不平衡力使得晶粒连同它的择优生长方向向着对流下方偏转,直到晶粒足够大,和它的前一个单晶枝晶连接在一起为止.2)当晶粒和它的前一个单晶枝晶连接在一起以后,磁流体动力学对流的作用力已不足使它偏转.此时,如果电解液的浓度比较高,单晶枝晶的一级分枝和二级分枝之间不存在对电解质的竞争关系,则此单晶枝晶将完全按照初期形成的晶体择优生长方向直线生长,直到新的晶粒形核为止;如果电解液浓度较低,造成第一级分枝与第二级分枝的竞争关系,二级分枝总在第一级分枝的上游侧生长,使得一级分枝向下游方向偏转.通过上述两个步骤,无论是枝晶沉积物还是分形沉积物都产生螺旋状偏转.
The microstructure of Zn branching electrodeposited in the presence of an applied magnetic field was analyzed by a metallographic microscope and atomic force microscope, and the mechanism that the magnetic field caused the spiral branching of the deposited branching was proposed according to the experimental results.1) During the early growth phase of the grain, when the grain has formed a preferred direction of growth but is very small and still suspended in the electrolyte, the imbalanced forces acting upon it by the magneto-hydrodynamic convection allow the grain together with its merit The direction of growth is deflected downwards to the convection until the grains are large enough to connect with their previous single crystal dendrites.2) After the grains are connected to their single crystal dendrites, the magnetohydrodynamics Convection force has been insufficient to make it deflection.At this point, if the electrolyte concentration is relatively high, single-stage dendrites and secondary branches of the competition between the electrolyte does not exist, then the single-crystal branches The crystal will grow in a straight line according to the initial preferred crystal growth direction until the new crystal nucleation. If the electrolyte concentration is low, the competition between the first level branches and the second level branches is caused. The second level branches total Branched upstream of the first growth stage, so that a deflection in the downstream direction M. Through the above two steps, either dendrite deposits or deposits are generated fractal spiral deflection.