1, the temperature
 The higher the temperature, phosphate layer thicker, more coarse crystals.
 Lower the temperature, phosphate layer thinner, more crystalline thin.
 But temperature is not too high, or Fe2 + is easily oxidized to Fe3 +, increase the amount of sediment, the solution is unstable.

 2, free acidity
 Free acidity refers to the free acid. Its role is to promote the dissolution of iron, has been the formation of more nuclei, the crystallization of dense membrane.
 Free acidity is too high, then speed up with the role of iron, hydrogen will be a lot of precipitation, so that the interface layer of phosphate is not easy to saturation, leading to nucleation difficulties, film structure loose, porous, corrosion is reduced, so that phosphate longer.
 Free acidity is too low, phosphate film thinning, or no film.

 3, the total acidity
 Acidity refers to the total phosphate, nitrate and acid combined. The total acidity range of general provisions to control the upper limit as well, will help accelerate the phosphating reaction, the thin film grain, phosphating process, decreasing the total acidity, reflecting slow.
 Total acidity is too high, thin film, can be diluted with water.
 Total acidity is too low, the rough film loose.

 4, PH value
 Manganese phosphating solution is generally controlled at 2-3, and when the PH> 3, the surface is easy to generate a total of powder. When the PH <1.5 difficult to film. Iron between the general control of 3-5.5.

 5, the concentration of ions in solution
 ① solution, easily oxidized to Fe2 + Fe3 +, leading to difficult film. However, the concentration of Fe2 + in solution can not be too high, otherwise, the formation of coarse grains membrane, the membrane surface with white floating dust, corrosion resistance and heat resistance decreased.
 ② Zn2 + effect, when the Zn2 + concentration is too high, phosphate coating coarse grains, increased brittleness, surface floating white ash; when the Zn2 + concentration is too low, loose dark film.




Factors affecting the quality of phosphate control