Improvement Of Current Distribution Uniformity And Analysis Of Multi-Physics Field During Vertical Electroplating Process

Electroplating technology is currently extensively used in the steelindustry for its role in corrosion prevention, abrasion resistance,conductivity, reflectivity improvements and aesthetics. Electroplating hasthe most extensive applications and takes up60%of the electroplatingindustry. There are17electroplating production line in China at present,contributing3.5million tons of production capacity, the3rdhighest amongthe world. However, due to the low quality of the state madeelectrogalvanized sheets,50%of domestic consumption relies on import.The low quality problems mainly include black patina and dendrite growth.This article focuses on the dendrite growth issues resulted from thethickening of edges by ununiformity of the current density of the cathodeplate.This work is based on Andritz Ruthner Gravitel electrical-galvanizingTank, and discusses the uniformity of plated zinc layer during continuouselectroplating on striped steel surfaces. There are various methods toincrease the uniformity of the plating process. These methods include theuse of insulating shield, optimization of anode plate structure, introductionof auxiliary cathode, improvement of cathode structure or geometries,rational selection and control of electrolyte, sterilization of electrolyte andutilization of proper electric current waveforms. The improvement ofuniformity in this work is done by numerical simulation of optimizedinsulating shield structure and wedge-shaped anode structure. The model ismade in UG with1:1ratio to real entity, and then imported to Ansys CFX module to perform coupled multi-physics field analysis. The parameters ofthe insulating shield structure and the wedge-shaped anode structure are setto different values and the corresponding structures are simulated in groups.The distribution of the electric current densities along the width of thestriped steel, the streamline distribution of the electrolyte flow field, andthe distribution contours of temperature on the cathode plate are obtained.The improved results based on the two measures above are compared withoriginal model, and analyzed quantitatively. The advantages anddisadvantages of the two measures are differentiated, and practicalguidance is pointed out.