COMPOSITION FOR CHROMATE-FREE PASSIVATION OF GALVANIZED STEEL SURFACE Russian patent published in 2019 - IPC C23C22/07 

FIELD: technological processes.

SUBSTANCE: invention relates to the processing of protective metal coatings and can be used to increase the corrosion resistance of a galvanized surface in the automotive, shipbuilding, agricultural, petrochemical and other industries. Composition for chromate-free passivation of a galvanized steel surface contains the following components: sodium silicate pentahydrate 20–30 g/l, hydrogen peroxide 20–30 ml/l, oxyethylene diphosphonic acid 0.2–0.3 g/l, saccharin 0.2–0.5 g/l; potassium pyrophosphate 0.004–0.01 g/l, water up to 1 l. Composition is applied to a galvanized steel surface at a temperature of 20–35 °C, pH 1.8–2.2. With these process parameters, the thickness of the formed chromate-free coating reaches 200–230 nm in 1–1.5 minutes.

EFFECT: introduction of potassium pyrophosphate and saccharin into the composition significantly increased the stability of hydrogen peroxide in the working solution and the protective ability of the formed coatings.

1 cl, 6 ex