Passivator and passivation for hot galvanized sheet

Abstract

The invention discloses a passivator for hot galvanized sheet. The passivator comprises water and components with the following concentrations: 230g / L-90g / L of nano SiO, 30g / L-60g / L of water-soluble acrylic resin, 40g / L-80g / L of phytic acid and / or phosphoric acid, 3g / L-12g / L of titanium acetylacetonate, 10g / L-30g / L of vanadyl acetylacetonate and 50g / L-100g / L of isopropanol. A hot galvanized sheet passivation method by using the passivator provided by the present invention is as below: passivator is coated on the hot galvanized sheet on a production line by means of spraying, blade coating or roll coating, with a drying plate at a temperature of 80-100 DEG C. The passivator provided by the invention has advantages of simple formula, easily available raw materials and convenient usage; besides, the passivator shows good passivation effect, and is healthy and environment-friendly.

Description

technical field [0001] The invention belongs to the technical field of surface treatment of steel plates, and in particular relates to a passivating agent and a passivating method for steel plates. Background technique [0002] Hot-dip galvanizing is the most commonly used protective cathodic protection method for cold-rolled steel sheets, but the galvanized layer is easily corroded in the air (especially in humid air). In order to prevent the corrosion of the galvanized layer, passivation treatment is required. The traditional passivation method is to coat the surface of the hot-dip galvanized steel sheet with a hexavalent chromium passivation agent, and form a passivation layer containing hexavalent chromium salt after drying. , but hexavalent chromium is toxic and carcinogenic, which not only affects human health, but also easily causes harm to the environment, and it will be gradually eliminated by the market. The ROHS directive issued by the European Union clearly rest...

AI Technical Summary

Problems solved by technology

[0003] Existing chromium-free passivators either use molybdate as the main component or rare earth metal salts as the main component, but the cost of these passivators is relatively high, and the passivation effect is not ideal, and they cannot fully meet the requirements of the cold environment. To meet the needs of hot-dip galvanizing lines in rolling mills, so far, there has not been a chromium-free passivator that is truly satisfactory and has good market prospects in this technical field