Phosphating Meaning:
Phosphating is the process of creating conversion coating on the surface of the metal. Phosphate Coating creates tiny crystalline and water insoluble on the metal surfaces using phosphoric acid solutions. Metal such as carbon steel, low-alloy steel and cast iron uses Phosphate coating.
For this purpose it is cleaned with acid and then immersed in the solutions. As a result of chemical reaction of base metal with acid, fine crystalline structure form on the metal.
Thus,Phosphating is a surface treatment technique that involves the chemical reaction of an aqueous phosphate solution with a metallic surface. As a result, a hardly soluble metal phosphate conversion layer is produced. The material is first cleansed with acid for this purpose, and after that, a phosphate layer is created.
Features Of Phosphate Coating are:
- Layer of Manganese ,Zinc or Zinc/Calcium of Pale to grey in colour
- Fine to Coarse Crystalline Phosphates depending upon the procedure
- Additional Layer
- Presence of many Capillaries in the layer helps in absorbing corrosion protection oils, lacquers, paints, etc.
- Allow excellent corrosion Protection
- Electrically Non-Conductive nature of phosphate layer
What is Phosphating Process?
Phosphating is a chemical/electro-chemical process that involves dipping or spraying phosphoric acid solutions over metal surfaces to produce thin, fine-crystalline, and water-insoluble phosphates. The pale or dark grey colored metal phosphate layers, which include numerous holes and capillaries, are firmly embedded in the metal surface as a result of a chemical reaction with the base metal.
The phosphate layers have demonstrated their usefulness as corrosion protection and as an adhesive substrate for paint and varnishes because of this property, which provides them with the best absorption capacity for oils, waxes, color pigments, and lacquers. The phosphate layer’s capacity to disperse friction forces—which are produced during deformation, drawing, or sliding processes—is another feature.
Therefore, a longer tool’s service life can result in a significant rise in processing speed in addition to an improvement in the surface quality of the items handled.
Layer-forming and non-layer-forming phosphating are two different type of phosphating. In the latter case, the layer’s metal cations originate only from the base material and do not arise from the solution. These cations originate from the phosphate solution in the layer-forming phosphating variety.
Phosphating process can be 7 Tank Process or 8 Tank Process. Also, It can be 9 Tank Process of phosphate coating. Following are the general steps of Phosphating
- Cleaning
- Rinsing
- Surface activation
- Phosphating
- Rinsing
- rinse
- Drying
Types
phosphate coatings are of 3 types which are manganese, iron, and zinc.
- Manganese phosphate coatings helps in corrosion resistance and lubricity and method used is immersion.
- Iron phosphate coatings generally forms a base for further coatings or painting and method used is immersion or spray.
- Zinc phosphate coatings helps in corrosion resistance, also act as lubricant-holding layer, and as a paint/coating base and method used is immersion or spray. They can also be applied to galvanized steel.
If you are looking for the best phosphating chemical , M. Chem. L. P. Series of chemical for Phosphate Coating gives the best result in 7 Tank Phosphating Process.
