Environmentally friendly chromium-free passivation solution for galvanization and preparation method thereof

The invention provides an environmentally friendly chromium-free passivation solution without containing chromium for galvanization, with excellent passivation property, low cost, good appearance quality and high qualified rate and a preparation method thereof. The passivation solution comprises the following components of 5-15g/L of sodium silicate, 10-20ml/L of phosphoric acid, 1-3 g/L of boric acid, 1-2 g/L of sodium fluoride, 5-15ml/L of hydrogen peroxide and the balance of water, wherein the pH value of the passivation solution is 1.5-2.5. With silicate as a main raw material instead of chromium salts, the passivation solution overcomes the defects of large toxicity and pollution of the traditional chromium salt passivation process; meanwhile, the passivation solution does not contain heavy metals (ions) of Ag, Cu, Pb, Ni and the like and completely accords with the environmental protection standards of electroplating wastewater effluent standard in China, RoHS (Restriction of the use of certain Hazardous Substances) commands in European Union, and the like, thus the invention is a real environmentally friendly passivation solution and a preparation process thereof, can realize clean production of the galvanization industry, and has great application prospect.