Molybdate passivating liquid for continuous hot-dipping galvanizing steel plate

Abstract

The invention relates to a molybdate passivation liquid for a continuous hot dip galvanized steel sheet, and belongs to the technical field of metal surface treatment and corrosion prevention. The molybdate passivation liquid comprises the following components according to the proportion for 1L of water: 30 to 50g / L of molybdate, 3 to 10g / L of fluozirconate, 3 to 15g / L of HEOP, 5 to 25g / L of citric acid, 10 to 30g / L of oxydol, 10 to 30g / L of acidic silicasol, and 15 to 25g / L of phosphoric acid. The molybdate passivation liquid has the advantages that as the recipe does not contain chrome, themolybdate passivation liquid has no impact on human bodies and environment; the salt fog resistance of the galvanized steel sheet which has the galvanizing coating passivated by the molybdate passivation liquid is better than that of the steel sheet passivated by chromates.

Description

technical field [0001] The invention belongs to the technical field of metal surface treatment and anticorrosion, and in particular relates to a molybdate passivation solution for continuous hot-dip galvanized steel sheets. Background technique [0002] Hot-dip galvanized steel sheets are widely used in fields such as automobiles, construction and home appliances. Theoretically speaking, since zinc has a low electrode potential compared to steel materials, it can act as an anode to electrochemically protect the steel substrate when corrosion occurs in a humid environment. However, from the actual situation, the zinc layer can only show the ideal protection effect on the steel substrate under the condition of dry and non-corrosive atmosphere. Therefore, under actual storage and use conditions, condensation will occur on the surface of the zinc layer, causing rust or discoloration. In order to prevent this phenomenon, the galvanized layer must be passivated to improve its co...

AI Technical Summary

Problems solved by technology

After the cost of the passivation solution of this patent application scheme is increased by more than 10 times, the corrosion resistance of the passivation film is still unsatisfactory

[0007] To sum up, although there are many studies at home and abroad on the chromium-free passivation of the zinc coating, various schemes and solutions have also been proposed, but compared with chromate passivation, its disadvantages are: resistance to Corrosion is far

Therefore, so far, there is still no chromium-free passivation solution with corrosion resistance comparable to that of chromate passivation solution or even more ideal.