Optimizing Phosphating Process for Steel Wire and Properties of Phosphating Film

Phosphating solution was prepared using phosphoric acid,nitric acid and zinc oxide.The process parameters of free acidity,total acidity,phosphating temperature and phosphating time were optimized by copper sulfate drop test.The microstructure,wettability and acid and alkali corrosion resistance of phosphating film were studied by scanning electron microscopy (SEM),contact angle measuring and acid and alkali corrosion testing.The results show that the optimum process parameters for phosphating were free acidity of 17.8 mg/g,total acidity of 93 mg/g,phosphating temperature of 60℃,and phosphating time of 5 min.The phosphating film prepared under the optimum process parameters was dense and uniform,composed of flaky phosphate crystals,with a certain hydrophobicity and good corrosion resistance to acid and alkali.