method for electroplating a steel strip not coated with a coating layer

摘要

This invention relates to a method for electroplating an uncoated steel strip with a coating layer from a trivalent electrolyte, wherein the uncoated strip is subjected to a cleaning and deoxidizing step prior to the process of coating, and then subsequently subjected to a coating process in a coating section comprising a series of consecutive coating cells, wherein in a first stage of the coating process, a current is applied to the strip entering the first coating cell. whose current is insufficient to deposit a trivalent electrolyte coating layer, but which is sufficient to provide cathodic protection of the strip to the electrolyte, and wherein in a second stage of the coating process a higher current is applied to the depositing strip. a coating layer comprising chromium metal, chromium carbide and chromium oxide of the trivalent crolyte.