Environmentally friendly galvanized sheet

What is environmentally friendly galvanized sheet?
  We often hear customers request environmentally friendly galvanized sheets. It is impossible to tell with the naked eye whether galvanized sheets are environmentally friendly or not. The so-called environmental protection refers to the different passivation methods on the surface of galvanized sheets. After being galvanized in a zinc pot, a normal substrate must undergo surface finishing and other processing processes. Finally, a layer of passivation liquid must be applied to the surface of the galvanized sheet to achieve an anti-corrosion effect. This layer of passivation liquid is the key point that determines whether the galvanized sheet is environmentally friendly. There are five main processing methods in domestic galvanizing production, namely non-passivation (untreated), trivalent chromium passivation, hexavalent chromium passivation, chromium-free passivation, and fingerprint-resistant passivation. The European Union and other countries require that imported galvanized sheet products do not contain heavy metal elements such as hexavalent chromium ions. Therefore, the mainstream hexavalent chromium passivation methods in the market are not environmentally friendly products. Some domestic steel mills use trivalent chromium passivation. The chemical method avoids the EU's requirement to strictly prohibit the inclusion of hexavalent chromium ions. It can also be called environmentally friendly, but it is not environmentally friendly in the strict sense (trivalent chromium can be converted into hexavalent chromium under certain conditions). Environmental protection in the true sense should be chromium-free passivation. The passivation liquid uses silicon dioxide, which fully complies with the testing requirements of European and American countries. Relevant test reports include SGS report and ROCH test report.