Medium-low temperature high corrosion resistant black phosphating solution on steel surface

Abstract

A middle and low temperature high corrosion black phosphating liquid on steel surface is characterized in that one liter of phosphating liquid contains 40-50g/L of dihydrogen phosphate Mn, 60-70g/L of zinc nitrate, 1-2g/L nickel nitrate, 3-4ml/L acetic acid (36 percent), 2-3g/L of ammonium citrate and 1-2g/L bismuth molybdate, and the rest is water. The phosphating liquid can produce film and then produce 18-22 Mu m of phosphating films after 20m at the temperature of 60-65 DEG C. the invention has the advantages of low phosphating temperature, small energy consumption, less sediment, reduced pollutions, environment protection, uniform and dense phosphating films and good appearance color sensory characters, and especially that the corrosion resistance complies with the national relative standard.

Description

technical field [0001] The invention belongs to the technical field of metal surface treatment, and in particular relates to a medium-low temperature and high corrosion-resistant black phosphating solution for iron and steel surfaces. Background technique [0002] The phosphating process is a process in which the surface of the metal substrate is treated with a phosphate solution to form a firmly attached conversion film on the surface. Oxidative alkaline blackening process is a method of using sodium nitrate high-temperature (120-140 ° C) oxidation system to form a blue-black oxide film mainly composed of ferric oxide on the surface of the workpiece. [0003] For a long time, in the field of surface treatment, a considerable number of steel workpieces have been treated by phosphating and oxidation to improve the protective and decorative properties of the steel surface. Because the color of the phosphating film is not as good as that of the oxide film, but its corrosion re...

AI Technical Summary

Problems solved by technology

[0004] There are many inventions about phosphating solution in Chinese patent applications, but due to the different ingredients used in the formula, the corrosion-resistant phosphating temperature can only be carried out at 75-90°C, which consumes a lot of energy and causes serious environmental pollution. The phosphating process also has a lot of sediment, and the production cost is also high

The most important thing is that the thickness of the phosphating film cannot meet the process requirements, the corrosion resistance is poor, and the color of the phosphating film is not good, so it is difficult to be used in actual production.