1, phosphating film does not produce fastener parts surface work hardening layer, increased sulfate content in the solution, impurities in the phosphating solution, phosphorus pentoxide content is too low, with strong acid corrosion surface, so that it exposed metal grains, barium carbonate treatment of sulfate, should be replaced by phosphating solution, supplement phosphate. 2, phosphating film has blank nitrate is insufficient, the content of phosphorus pentoxide is too low, the temperature is too low, the pickling tank ferric sulfate increase, add zinc nitrate, add phosphate, increase the solution temperature, should be replaced sulfuric acid solution. 3, phosphating parts have yellow and white sediment, rust at the riveting of the assembly, sediment in the solution, insufficient nitrate, phosphating solution is not washed, sediment in the tank, zinc nitrate supplement, phosphating film in the acid solution.
4, the corrosion resistance of phosphating film decreased and yellow rust phosphating film crystallization coarse or too fine, phosphating parts surface residual salt, metal corrosion, free acidity is too high, phosphate lack, adjust the ratio of free acidity and total acidity, strengthen the neutralization and washing before phosphating, control phosphating repetition times, supplement zinc nitrate, supplement nitrate.
5, phosphating film is too thin, crystallization is too fine The phosphating time is not enough, the ferrous content is too low, the total acidity is too high, the surface of the parts has a hardened layer, the temperature is too low, the phosphating time is extended, the iron dihydrogen phosphate is supplemented, the water dilution solution is added or the phosphate is added to adjust the acid ratio, the surface is corroded with strong acid, the temperature is raised, the corrosion resistance of the phosphating film is reduced, the iron slag in the pickling solution is attached to the surface, copper ions penetrate into the phosphating solution, and the pickling solution is replaced Pay attention to the use of copper hanging, phosphating film coarse crystallization, excessive content of ferrous ions, residual salt on the surface of parts, insufficient content of nitric acid in solution, increased content of nitric acid in solution, excessive corrosion on the surface of parts, iron reduction with hydrogen peroxide, increasing temperature, strengthening neutralization or washing, adding zinc nitrate, treatment of nitric acid with barium carbonate, control the concentration and time of acid, uneven phosphating film, hair Oil removal is not clean, phosphating temperature is too low, surface passivation state, parts due to different heat treatment processing methods, strengthen oil removal, adjust the temperature, strengthen pickling, adjust the concentration of acid so that the surface is exposed to metal grains.
