The Essential Welding Technique Of A Permanent Cathode Plate

Permanent steel cathode(PSC) electrolysis technology is a kind of process for copper electrolytic refining using stainless steel plate with higher rigidity and toughness as cathode instead of the traditional starting-sheet. The stripping and processing system of the traditional starting-sheet are omitted in the electrolytic process, and the cathode plate can be used repeatedly. As a result, the process is shortened and the cost of production is reduced. Permanent steel cathode(PSC) electrolysis technology contains the advantages of higher current density and higher yield per unit area, so it is very suitable for large scale copper electrolytic production(200kt/a). At present, all the large-scale copper electrolytic projects in China adopt the permanent steel cathode electrolysis technology. However, it is still an unsolved problem that the manufacturing technology of high performance cathode plate. In this way, China needs to import directly from a large number of permanent steel cathode. Thus it is significant in engineering application and latent economy benefit to study the manufacturing process of the high performance cathode plate. Therefore this article used High-frequency Induction Brazing to realize the stable connection of the copper-steel dissimilar metal. Besides, the stainless steel panel and the conductor pole are welded by the pulse TIG and the plasma welding.Firstly, the key manufacturing technologies of the imported permanent steel cathode, such as the conductive properties and the microstructure of the imported permanent cathode plate, are measured and analyzed. The CMM(three coordinate measuring machines) is used to measure and analyze the flatness, and the profiler is used to measure and analyze the straightness, and then analyzing and processing the detected data by using least-square theory; The electrical conductivity of the conductor pole and welding seam were measured and analyzed by the conductivity meter, and then the current distribution and variation tendency of the current from the conductive rod to the stainless steel plate are obtained; The structure and morphology of the conductor pole and welding seam were detected by SEM and EDS.Secondly, high frequency induction welding with low heat input and non-contact heating is used to study the welding of copper and steel. The real-time monitoring and control of the brazing temperature is realized by using FR1 B Raytek infrared temperature measurement system in the experiment. Research shows that the firm and imperishable joint between steel base and copper was realized by using high-frequency induction brazing with the brazing filler metal of SnCu0.7, and by properly controlling the brazing current and time.Then, In order to study the reasons for the different conductivity of the joints under different heat inputs, the conductivity of the high frequency induction brazing joint with different process parameters were measured. At the same time, the structure and morphology of the different conductivity of the joints were detected by SEM and EDS. It is assumed that the high temperature accelerates the movement of atoms, improves the diffusion of the liquid phase Sn from weld seam to base metal. To improve the conductivity of the high frequency induction brazing joint, not high temperature is necessary, but all kinds of factors such as reactive temperature and time, etc must be considered. When the temperature is too high, the base metal melts, which leads to the change of the matrix structure, although the conductivity of some joints is improved, but the total conductivity of the metal is lost. The results show that the optimum brazing temperature range is 800-1200 °C, and the average conductivity of the brazing joint is 36 %IACS.At last, the welding process test of the conductor pole and stainless steel panel is carried out by using pulse TIG welding and pulse Plasma welding. When the pulse TIG welding is used, with the increase of the average current of the welding, the weld depth is obviously increased, and the weld formation has been greatly improved. Among the welding parameters, the peak current is the most influential to the weld shape and weld depth. The base current has played a role in maintaining the stability of the welding in the whole welding experiment, so as long as the basic value of the current is greater than 10 A, the welding process will be stable. The influence of duty cycle is also more important, especially in the depth of penetration, with the increase of the base value current, the decrease of the peak current, the welding process becomes worse, and the penetration depth decreases. When the pulsed Plasma welding is used, a large arc force in the plasma leads to the appearance of burn through. Plasma arc stability is poor. The change of welding process and welding parameters have great influence on the stability of plasma arc welding process, it is difficult to maintain. Due to the large energy of plasma welding, the welding heat affected zone increases, the stress of the specimen is not uniform, resulting in a large internal stress and welding deformation. Through the above analysis, the pulse TIG welding process is more suitable for welding the conductor pole and stainless steel panel than the pulse Plasma welding.