Chromium-free passivation solution

Abstract

The invention discloses a chromium-free passivation solution, which has the pH value 1-5 and consists of rare-earth salt, inorganic salt, boric acid, nitric acid and water serving as raw materials. In the chromium-free passivation solution, the content of the rare earth salt is 1-15 g / L, the content of the inorganic salt is 3-30 g / L, the content of the boric acid is 0.1-3 g / L, and the content of the nitric acid is 3-30 ml / L; the rare earth salt is a mixture of vanadate and cerium slat in the weight ratio 1:(1.33-6.5); and the inorganic salt is sodium chloride or potassium chloride. The chromium-free passivation solution has the advantages of good passivation effect, low application cost, high production efficiency, stable performance, difficulty in deteriorating and long storage time.

Description

technical field [0001] The invention relates to a passivation solution for surface treatment of metal materials, in particular to a chromium-free passivation solution. Background technique [0002] The protective galvanized layer is widely used in modern industry, but the galvanized layer is easily oxidized and darkened in the air, and finally produces "white rust" corrosion. In order to improve the corrosion resistance of the galvanized layer, passivation treatment is usually carried out to cover a protective film on the galvanized layer and make the zinc in a passive state. Generally, the method of chromic acid passivation treatment is adopted. In the process of chromic acid passivation, hexavalent chromium is highly toxic and seriously pollutes the environment. With the enhancement of people's awareness of environmental protection, low-chromium passivation is mostly used now to reduce costs and harm to the environment. Therefore, it is of great economic and environment...