Multifunctional iron steel surface treatment liquid and preparation method and application thereof

The invention discloses a multifunctional iron steel surface treatment liquid and a preparation method and application thereof. The surface treatment liquid comprises the following raw materials by weight percent: 25-35 percent of phosphoric acid, 1-5 percent of zinc dihydrogen phosphate, 0.8-1.2 percent of tartaric acid, 0.5-0.8 percent of thiocarbamide, 0.1-0.2 percent of polyethyleneglycol, 1.0-3.0 percent of sodium doodecyl benzene sulfonate, 0.08-0.15 percent of ammonium molybdate, and 54.65-71.52 percent of water. The preparation method comprises the following steps: smashing zinc dihydrogen phosphate into small pieces and adding phosphate acid to obtain a slimy solution through dissolution; adding tartaric acid, thiocarbamide and polyethyleneglycol in water to be dissolved to obtain a mixture, mixing the mixture and the slimy solution, sequentially adding phosphate acid, ammonium molybdate and sodium doodecyl benzene sulfonate, and uniformly mixing for sound dissolution; and obtaining the product through filtering and packing. The surface treatment liquid is environment-friendly and integrates deoiling, rust removal, phosphorization and passivation; various ways such as impregnating, spraying, brushing and the like can be adopted under the ordinary temperature.