Phosphating treatment is a chemical and electrochemical reaction, through the formation of a layer of phosphate conversion film (phosphate film) on the surface of the metal, in order to achieve the purpose of protecting the base metal, preventing corrosion, and improving the adhesion of paint.
Author: Anna
Phosphating treatment is a chemical and electrochemical reaction, through the formation of a layer of phosphate conversion film (phosphate film) on the surface of the metal, in order to achieve the purpose of protecting the base metal, preventing corrosion, and improving the adhesion of paint. Phosphate treatment is widely used in the surface treatment of steel, non-ferrous metals and other materials.
Classification of phosphating treatment
Classification by temperature:
High-temperature type: 80 ~ 98 ℃, treatment time of 10-20 minutes, phosphate film thickness of 10-30g / ㎡, the advantages of the film corrosion resistance, good bonding force, but energy consumption, solution volatilization.
Medium temperature type: 50 ~ 75 ℃, treatment time of 5-15 minutes, phosphate film thickness of 1-7 g / ㎡, the advantages of free acidity is stable, short phosphate time, high production efficiency.
Low temperature type: 30~50℃, energy saving, easy to use.
Normal temperature type: 10~40 ℃, time 10-40 minutes, no heating, less drug consumption, stable solution, but long treatment time.
Classified according to the composition of phosphating solution:
Zinc phosphating
Zinc-calcium phosphating
Iron phosphating
Manganese phosphating
Composite phosphating
Classified according to the treatment method:
Chemical phosphating: the workpiece is immersed in the phosphating solution, relying on chemical reactions to achieve phosphating
Electrochemical phosphating: in the phosphating solution, the workpiece is connected to the positive pole, the steel is connected to the negative pole for phosphating.
Classified according to the quality of phosphating film:
Heavyweight (thick film phosphating): film weight of 7.5 g / ㎡ or more.
Sub-weight class (medium film phosphating): film weight 4.6-7.5 g / ㎡.
Lightweight (thin-film phosphating): film weight 1.1-4.5 g/㎡.
Sub-lightweight (special film phosphating): film weight 0.2-1.0 g/㎡1
Classified by construction method:
Dipping phosphating: applicable to high, medium and low temperature phosphating, simple equipment, suitable for a variety of temperature phosphating treatment.
Spray phosphating: applicable to medium and low-temperature phosphating process, treatment of large-area workpieces, such as automobiles, refrigerators, washing machine shells, short treatment time, high productivity.
Application areas and purpose of phosphating treatment
Phosphating treatment is mainly used for corrosion protection of metal surfaces and priming step before painting, to improve the adhesion and corrosion resistance of the paint film layer. In addition, it plays the role of friction reduction and lubrication in metal cold working process.