Chromium sulfuric acid and chromium(VI) are usually used in the conditioning of plastics for chrome plating. There are many arguments against the use of these substances; in addition to the high energy consumption, the environmentally harmful effects are serious. The search for alternative processes and chemicals is becoming increasingly important in order to reduce potential hazards during the manufacturing process. According to the Galvanized Plastics Association (FGK), an alternative to electroplating plastics can only be to use other starting chemicals to create an electroplated chrome finish. Paint coatings, PVD coatings or foil techniques do not offer a real alternative, because their optical effect cannot compete with chromium-plated surfaces; moreover, the materials cannot be disposed of sustainably. Chromium trioxide can be reduced in several steps during electrolytic chromium plating and deposited on the product as metallic chromium ("zero-valent"). The metallic chromium has completely different properties from the starting chemical and is not dangerous, but the process is around ten percent more expensive. For the plant technology, the use of chromium trioxide means that additional hardware must be installed and more time must be allowed in the treatment process, and wastewater treatment is also more complex. In the field of chromium-free pickling (CFE), there are various development directions. Today, the use of manganese-based pickling is favored, although interesting alternative pickling concepts are also being tested and pursued. It is still unclear which system will prevail in the long term.
More details can be found in the article in mo 11 2022 or online here!