Explanation

The surface treatment process of obtaining a layer of insoluble phosphate film on the surface of steel parts. Phosphate film is mainly zinc phosphate film, manganese phosphate film or iron phosphate film, with a thickness of 5-15 μ m. The size of the processed component remains basically unchanged. The phosphorizing film is electrically insulated, firmly bonded to the matrix, and porous. The phosphorizing film coated with oil, paraffin or paint has high corrosion resistance, but low hardness, brittleness, and low wear resistance. Therefore, the phosphorizing layer is suitable as the bottom layer of coatings. According to the treatment temperature, it can be divided into cold phosphorizing (room temperature), medium temperature phosphorizing (50-70 ° C) and high temperature phosphorizing (90-98 ° C). The phosphating agent is mainly composed of manganese ferric phosphate or aqueous solution of zinc dihydrogen phosphate, and contains zinc nitrate as catalyst. The zinc nitrate content in the cold phosphating agent is high, and the processing time is 30-45 minutes; The zinc nitrate content in the medium temperature phosphating agent is relatively low, and the treatment time is 7-15 minutes; The content of zinc nitrate in high-temperature phosphorizing agent is lower, the treatment time is 10-20min, the acidity of middle temperature phosphorizing is stable, the treatment time is short, and the quality of phosphorizing film is good, so it is widely used.

Classification