Abstract:In view of the technical problems of rolling mill load caused by the large reduction of the first pass required for the preparation of copper/stainless steel composite ultra-thin strip by cold rolling, and the problem that the material properties of the copper electrodeposition method on the surface of the stainless steel substrate are not up to standard, the author 's research team proposed the idea of electrodeposition assisted cold rolling to prepare copper/stainless steel ultra-thin composite strip, that is, heat treatment and cold rolling are used to improve the bonding effect between the stainless steel substrate and the copper deposition layer. In this paper, the influence of different process parameters on the macro and micro characteristics of copper deposition layer and the growth mechanism of copper deposition layer are systematically studied. The following main conclusions are drawn. The growth process of the copper deposition layer is affected by the current density value and the surface state of the substrate. When the surface of the substrate is smooth, the initial bonding strength between the copper layer and the substrate is insufficient, and the copper layer falls off during the deposition process, so that the subsequent further processing cannot be carried out. Therefore, it is necessary to select the appropriate grinding method to keep the surface of the substrate rough. With the increase of current density (20~80mA·cm-2), the surface roughness of the copper deposition layer increases, and when the current density reaches 80mA·cm-2, the surface is loose and granular, and the compactness decreases significantly. During the deposition process in the stable plating zone (less than 60mA·cm-2), the reduced copper ions form an initial copper layer on the surface of the stainless steel strip, and then continue to grow at the trough position on the outer surface of the copper deposition layer, and finally evolve into a flat and dense morphology. In the deposition process of unstable electroplating area (more than 60mA·cm-2), copper atoms are attached to the peak position of the surface in the form of spherical particles, forming copper ridges. There are deep gullies between adjacent copper ridges, resulting in loose structure and poor compactness of copper deposition layer. The surface of the substrate was polished by 400 mesh sandpaper, and the electrodeposition effect was better under the current density of 20mA·cm-2. The thickness of the copper deposition layer was approximately linear with the deposition time. The copper deposition layer with the required thickness can be obtained by controlling the deposition time. The results of this study provide a theoretical basis and control strategy for prefabricating the initial copper composite layer during cold rolling of copper/stainless steel ultra-thin composite strips.
