Phosphating Process with High Corrosion Resistance

A phosphating process with high corrosion resistance was developed.The optimal phosphating conditions were determined based on orthogonal test.The morphology and structure of the phosphating film were analyzed by means of metallographic,scanning electron microscopy.The optimal phosphating bath was determined to be composed of 70 g/L zinc dihydrogen phosphate,30 g/L manganese dihydrogen phosphate,40 g/L zinc nitrate,2 g/L ammonium citrate and 1 g/L nickel nitrate.The optimal phosphating temperature and duration were determined to be 65 ℃ and 20 min.