Study On Pulse Regulated Metal Dendrite Fractal Growth Behavior In Electrolytic Manganese Cathode

The edge of cathode plate has the characteristics of high current density,curved flow field line and far away from the equilibrium state in industrial electrolytic manganese,which is easy to induce nonlinear dynamic behaviors such as dendrite growth,and easy to lead to short-circuit between electrodes,low current efficiency and high electrolytic energy consumption.At present,there is no suitable way to regulate the growth of manganese dendrite in industry.Therefore,investigating the regulation of dendrite growth in detail is an effective way to achieve low energy consumption and high efficiency in electrolytic manganese process.In this thesis,self-organizing fractal growth behavior is taken as the starting point in the metal electrodeposition process.Pulse electric field is regarded as enhancement method.Dendrite fractal growth is regarded as regulation goal in the electrodeposition process of metal manganese.The fractal dimension is used to characterize the fractal degree of manganese dendrite,and the current efficiency is used to characterize the energy saving and consumption reduction degree in the electrodeposition process of manganese.In order to further explore the mechanism of pulsed electrodeposition regulating the fractal growth of metal dendrite,a new nonlinear dynamic model of interaction between interfacial reaction flow and mass transfer flow is established to reveal the important effect of ion mass transfer on the fractal growth behavior of cathode metal dendrites.Meanwhile,the computational fluid dynamics method is used to simulate the fluid movement in the electrolytic cel.Finally,based on the modified DLA model,metal dendrites fractal growth mechanism is proposed in the pulsed electrodeposition process.Furthermore,the pulse-controlled fractal electrodeposition process enhancement technology is developed to realize the regulation of cross-scale self-assembly behavior,which provides theoretical guidance for increasing current efficiency and reducing electrolytic energy consumption in the electrolytic manganese process.The specific research contents of this thesis are as follows:(1)The phenomenon of dendrite fractal growth generated by cathode in electrolytic manganese process,the effects of constant current electrolysis and pulse electrolysis were investigated on the metal dendrite fractal growth.It was found that pulse electrolysis could regulate the fractal growth of manganese dendrite.It was found that when the pulse frequency was 200 Hz and the pulse duty ratio was 1/3,the dendrite structure products on the cathode surface were less and the fractal characteristics were weak.Meanwhile,it was found that the flow rate had an important effect on the dendrite growth.(2)In order to further explore the mechanism of pulsed electrodeposition regulating metal dendrite fractal growth,a new nonlinear dynamic model of interaction between interfacial reaction flow and mass transfer flow was designed to reveal the important effect of ion migration on the fractal growth behavior of cathode metal dendrites.The effects of electrolyte concentration,flow velocity and flow field direction on the fractal growth of manganese dendrite were investigated.It was found that when the electrolyte flowed from cathode to anode,pulse frequency had little effect on the dendrite morphology and the fractal phenomenon was not obvious.When the electrolyte flowed from anode to cathode,pulse frequency had a great influence on the dendrite growth morphology and the fractal phenomenon was obvious which revealed that the intrinsic mechanism of dendrite fractal growth was ion migration.Finally,CFD simulation was used to calculate the change of flow field in the electrolytic cel.The flow state of the electrolyte was laminar flow by Reynolds number calculation in the electrolytic cel,and it was found that the different fluid velocities would lead to different local microcosmic flow fields of the cathode and then affected the fractal growth of metal dendrite.(3)Based on traditional DLA model,introducing alternated electric field revised traditional DLA model for changing the way of particles migration mode,setting up and writing the Matlab program to simulate the metal dendrite fractal growth mechanism in pulse electrodeposition.The dendrite morphology of particle numbers,the strength of random motion,and alternating electric field intensity was investigated by simulation.It was found that the simulation results were highly similarity to the experimental results,which verified the rationality of the model and further improved the DLA model.In conclusion,pulse electrodeposition method can be used to regulate the fractal growth of electrolysis manganese cathode metal dendrites to obtain dense manganese deposition layer,which provides theoretical guidance for energy saving and consumption reduction in electrolysis manganese process.