Manganese Zinc Coatings

Phosphate or Manganese Zinc coatings are a form of crystalline conversion coverings that is used to cover ferrous metal substrates. It is used for pretreatment purposes before coating or painting. It helps to increase protection against corrosion and improves friction properties of smooth components. In some cases manganese zinc or phosphate coatings are coated on threaded machine parts and then top coated with oil to prevent galling and rusting. The process of phosphating starts when the process solution 

comes in contact with the metal substrate and a reaction ensues to providing strong adhesion and corrosion proof coating protection. Typically, manganese/zinc or phosphate coatings can be used on steel and aluminum.

 

Manganese Phosphating

 

Manganese phosphate coatings can be used for protection against corrosion and abrasion, anti-galling and lubrication. Out of the many phosphate coatings, manganese phosphate is the variant that are the hardest of all. They provide unmatched corrosion and abrasion protection. When comparing to other coatings, manganese phosphate coatings offer constant wear and tear protection to the components that may be subject to frequent use. These coating processes is only possible by immersion and their uses 

include production of industrial parts such as bushings or bearings or fasteners bearings. Using manganese phosphate coating ensures smooth functioning of components in projects that make use of sliding parts and automotive engines or motors and transmission systems.

 

The process sequence of manganese phosphate coatings can be summarized and understood as follows:

 

• Degreasing the metal substrate and cleaning

 

• Water rinsing of the substrate

 

• Pickling of the work piece in mineral acid if and when necessary

 

• Water rinsing of the substrate only after pickling

 

• Activation

 

• Manganese phosphating through emmersion technique

 

• Water rinsing again

 

• Final oven drying of the piece, which is optional in some cases

 

• Lubrication of the final product with special oils.

 

 

Zinc Phosphating

 

Zinc phosphate coatings are used for variety for purposes such as rust proofing on metals containing iron. They can either be applied by immersion or a spray technique. Zinc phosphate coatings, as compared to manganese phosphate is a much lighter option and it 

provides protection against harsh elements and abrasion that can wear the products. In most instances, where it is important that the finished work pieces have high corrosion resistance, conversion coatings are usually applied using zinc phosphates. This type of zinc phosphating is typically favored by the automotive industry and by some appliance and electronics producers also. 

 

In the most popular immersion method of zinc phosphate coating, these are the individual steps: 

 

•  The first stage is the cleaning at temperatures ranging from(°C) 55-95 for about 5-10 minutes.

 

•  Water rinsing is the second stage which is carried out at temperatures ranging from(°C) 15-30 for 30 seconds to 1.5 minutes.

 

•  The activation process comes next and it lasts for 30 seconds to 1.5 minutes at temperature(°C) 20-40.

 

•  Now comes the immersion for phosphating at temperatures(°C)40-60 for 3-10 minutes.

 

•  Next is water rinsing at (°C) 15-30 for 0.5-1.5 minutes

 

•  Post-rinse process at (°C) 20-40, again for about 0.5-1.5 minutes.