Phosphate coating UK

manganese phosphate coating on drills

Phosphate coating, the most common pretreatment for metal

Phosphate coating, results from a chemical reaction between metal surface (usually steel) and a chemical substance which contains phosphoric acid; the substance converts the metal  surface into a thin coating layer. Phosphate coatings are almost exclusively used as pretreatment for preparing metals substrates for further coating.

The pretreatment has three main purposes:

  1. Inhibiting corrosion;
  2. Lubricating machine parts and components;
  3. Improving adhesion of further coatings.

There are however, three main types of phosphate coatings. Therefore, we will provide more insight into those and their uses. We’ll also take a look at phosphate coating services in the UK.

Types of phosphate coatings

Phosphate coatings come in many types, of which three are the most common; manganese, zinc and iron phosphate coatings. All these coatings are used for one purpose; surface preparation. However, they have slightly different properties and uses.

1. Manganese phosphate treatment – the toughest

Manganese phosphate coatings are the hardest, most rust retardant and abrasion resistant phosphate coatings. Compared to zinc phosphate coatings, these coatings are tougher and more wear resistant. Therefore, they are the mot suitable coatings for bearings, fasteners and bushings. They are also applied on automotive engine and transmission parts due to the fact that the parts are often sliding and require abrasion resistance. Manganese phosphating can only be done in immersion and the product is usually finished with a wax or oil.

2. Iron phosphate coating – the most economical

Iron phosphate coatings are commonly used as pretreatment for powder coating. They provide additional protection from corrosion and make sure the powder adheres well. Iron phosphating is the most economical pretreatment method for metals.

However, bear in mind that the cheapest is not always the best; iron phospahting is not recommended for products that must meet extremely high quality requirements. The application methods suitable for iron phosphate coatings include immersion and spraying.

a part being coated on zinc phosphate coating line

Zinc phosphating immersion process can be automatised and integrated into a powder painting line.

3. Zinc phosphating – the most common

When it comes to preventing oxidation on ferrous metals, zinc phosphate coatings are suitable. Zinc phosphating results in a lighter coating than manganese solutions, yet they still provide sufficient protection from corrosion and weathering.

They are also suitable for priming powder paint; zinc phosphate coating is slightly more expensive than iron phosphating, but they also result in the best possible basis for powders. Zinc phosphating takes place either in immersion or as spray.

Phosphate coating services in the UK

Zinc and manganeseAshton & Moore LimitedSmith Street, Hockley, Birmingham B119 3EX
Zinc and manganeseSurface TechnologyLyons Park, Coventry, CV 9PF
IronRodman BrothersTariff Road, Tottenham, London N17 0DY

If you are in need of any further assistance regarding phosphate coatings, do not hesitate to contact us! We are experts in finding the best coating solution for any project!

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