Brief introduction of passivation treatment operation of packaging steel strip

Brief introduction of passivation treatment operation of packaging steel strip
　　 The surface of the packaging steel strip is usually chemically or electrochemically passivated: the main purpose of passivation is to stabilize the surface of the packaging steel strip and prevent the growth of tin oxide on the surface. Excessive tin oxide will cause The packaging steel strip changes color during storage, especially during the baking process of painting or printing.
　　In the packaging steel strip production line, the strip is passivated after reflowing and before oiling. The method is to pass the strip steel through a chemical solution and process it with or without electricity. The most commonly used passivation treatment is to use sodium dichromate solution to conduct electrolysis with strip steel as the cathode. Another method of chemical treatment is simple immersion treatment, without current flow, so that the strip is immersed in a similar solution or chromic acid solution. When tinplate is used for packaging dairy products, some factories also use a cathode treatment in a sodium carbonate solution, and some other treatment methods are sometimes used.
　　 Unless otherwise agreed with the buyer, the manufacturer usually uses the first of the above-mentioned treatment methods, that is, the sodium dichromate cathode passivation treatment. Some production plants use a digital code system to indicate the type of chemical treatment.
　　The packaging steel strip is not passivated during the production process.