Nontoxic inactivating liquid for continuous galvanizing and alloy plating coat thereof

Abstract

The invention relates to passivating solution, in particular to non-toxic passivating solution for continuous galvanizing and an alloy coating. The composition comprises chromic salt, cobalt salt and cerium salt, whose molar ratio is 1: 0.01: 0.003 -1: 0.03: 0.009. The concentration of chromium ion is 0.4-1.5 mol / l in working state, wherein the chromic salt is obtained through being reduced by hexavalent chromium, then being fitted with equivalent anion, which also is capable of one or more chromic nitrate, chromium sulfate and chromium chloride. The invention uses different hexavalent alternative substance and uses organic assistant without peculiar smell, the passivating solution has no peculiar smell and toxicity, the application environment is excellent, compared with other similar products, a passive film which is prepared by the passivating solution has excellent corrosion resistance in equal attachment amounts, and the passive film which is obtained from a prepared product still has excellent corrosion resistance after deforming.

Description

technical field [0001] The invention relates to a passivation solution for galvanizing and its alloy surface, in particular to a non-toxic passivation solution for continuous galvanization and its alloy coating. Background technique [0002] Zinc and its alloys are often used as protective layers for steel or other corrosive materials due to their low reduction potential and low price. However, due to their active chemical properties, they are easily corroded, so chemical conversion treatment is usually required for the galvanized layer. The treatment solution containing hexavalent chromium is simple to operate, low in cost, easy to control, and the obtained passivation film has the advantages of good corrosion resistance, beautiful appearance and self-repairing ability, and has been widely used. However, hexavalent chromium is a highly toxic substance with carcinogenic and teratogenic effects. With the enhancement of people's awareness of environmental protection, there is ...

AI Technical Summary

Problems solved by technology

In recent years, people have done a lot of work on how to replace hexavalent chromium. There are two main directions. One is a pure chromium-free passivation agent. This passivation solution combines other inorganic compounds such as titanium, molybdenum, etc. Or chelates, supplemented with organic polymers such as acrylic acid, polyurethane, silicone, etc., have been used in the field of continuous galvanizing and its alloys, but their disadvantages are high costs, which are generally difficult for manufacturers to accept; One is a passivating agent based on trivalent chromium, supplemented by compounds that can replace hexavalent chromium to a certain extent, such as cobalt, molybdenum, tungsten, etc., with certain organic additives, it can make the passivation film The appearance is obviously improved or the uniformity is enhanced. Because of its low cost, this type of passivation solution has been widely used in the field of batch galvanizing, and has certain applications in the field of continuous galvanizing and its alloys. The passivation solution still contains traces of hexavalent chromium (the amount needs to be controlled within the scope of use specified by EU ROSH, but due to different understandings of various industries, the specific control amount is often determined by the user manufacturer, such as the regulations of Haier in China The hexavalent chromium in the trivalent chromium passivation solution that it uses is less than 1000ppm and gets final product), the trivalent chromium passivation solution that adopts hexavalent substitute substance to obtain in the prior art mainly has following three kinds of defects and deficiencies: (1) has Pungent smell, poor operating environment for workers; (2) The solution is prone to produce massive hardened substances during production and operation, which needs to be cleaned regularly, resulting in difficult disposal of the cleaned waste liquid; (3) On the surface of galvanized and its alloy coatings The resulting passivation film has low corrosion resistance

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