Trivalent chromium passivation concentrated solution

Abstract

The invention relates to a chemical surface treatment solution, in particular to a trivalent chromium passivation concentrated solution used for forming a protective film on the surface of zinc coated or zinc alloy coated workpiece. The trivalent chromium passivation concentrated solution comprises the following components in weight percentage: 4-6% of chromic chloride, 8-12% of nitrate, 8-12% ofcobalt salt or nickel salt, 3-5% of tartaric acid, 1-2% of gamma- aminopropyltriethoxy silane and the balance of water. The pH value of the concentrated solution is 2-3. The concentrated solution hasthe advantages of good passivation effect, no harm to human bodies and no pollution to environment. The concentrated solution is prepared into a working solution with 10% weight percentage concentration so as to passivate the zinc coated or zinc alloy coated workpiece. After the zinc coated or zinc alloy coated workpiece is passivated by using the concentrated solution, the surface of the zinc coated layer or zinc alloy coated layer can become uniform sky blue protective film, the film has good protection property, the corrosion resistance of the workpiece can be effectively improved, and thecondition of maintaining no white rust for 120 h can be reached in a salt spray test.

Description

technical field [0001] The invention relates to a surface chemical treatment solution, in particular to a trivalent chromium passivation concentrated solution used to form a protective film on the surface of galvanized or galvanized alloy workpieces. Background technique [0002] Hexavalent chromium compounds are easily absorbed by the human body, and they can invade the human body through the digestive system, respiratory tract, skin and mucous membranes. The consequences of occupational exposure to hexavalent chromium compounds can be severe. Human body inhalation concentration as low as 2μg / m 3 If the hexavalent chromium compound is contained, it will cause sneezing and nasal discomfort, causing hoarseness and nasal mucosa atrophy in different degrees. In severe cases, it can also cause nasal septum perforation and bronchiectasis; Cause vomiting, abdominal pain; when hexavalent chromium compounds invade the human body through the skin, dermatitis and eczema will occur. ...

AI Technical Summary

Problems solved by technology

[0003] Zinc-plated or galvanized alloy workpieces need to be passivated after electroplating. The existing passivation concentrate used contains hexavalent chromium compounds. Although the stability of the passivation treatment process and the protection formed on the workpiece after passivation treatment The appearance quality of the membrane is relatively ideal, but because the hexavalent chromium compound in the existing passivation concentrate is a poisonous substance harmful to the human body, and its pollution to the environment is also very serious and has a long-lasting hazard