Metal surface pre-treatment degreasing and phosphating

Newstime: October 31, 2016

Skim:

  Phosphating solution phosphate coating quality can be formed only in the removal of the oil on the surface thoroughly, cleaning agent remaining on the surface because the oil will not only seriously impede the growth of phosphate film, but also affect the adhesion of the coating, drying performance decorative properties and corrosion resistance.

 Commonly used degreasing agent are: strong alkaline degreasing agent, weak alkaline degreasing agent, an organic solvent degreasing agent; divided by temperature: high temperature, medium temperature, low temperature various degreasing agent.

 Strong alkaline degreasing agent contains a large number of caustic soda (NaOH), is not easy to clean; In addition, the temperature of the degreasing agent is not too high (usually about 40 deg.] C), washed with water and dried to prevent the workpiece prior to, after causing return phosphate rust phenomenon.

 The choice of cleaning agent degreasing solution should take full account of the surface condition of the oil, the amount of foam the size of the degreasing agent in order to avoid bubble caused by excessive production difficult or unnecessary waste.

 Degreasing station a number of spray pressure should be high, in order to ensure the degreasing effect, typically a pressure of 0.1 ~ 0.5mpa. Spray time control in two minutes, in order to ensure sufficient reaction of oil and degreaser.


Phosphate: phosphate liquid

 The so-called phosphating phosphating solution, refers to the metal parts after the acid solution containing dihydrogen phosphate, detergent chemical reaction on the surface of a layer of stabilized insoluble or sparingly soluble phosphate film method, the generated film called phosphating film. The main role of phosphate coatings are: to improve the adhesion of the coating and increased corrosion resistance.

 Phosphating station spray pressure is too low, easy to cause phosphating incomplete;Pressure is too high, easily causing huge splash of phosphating solution, is not conducive to the film.Usually the spray pressure should be controlled at about 0.05 Mpa, phosphating station spray time should be controlled in 3 minutes, to ensure the full response of phosphating liquid and base material, give phosphating film growth sufficient time, lest produce hole and yellowing phenomenon.


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