Know-how

The manufacturing process: a crucial aspect for a perfect metal coating

With a wealth of experience and know-how of more than 150 years, Zinacor will supply you with first-rate wire providing longer lasting, better anti-corrosion protection for each of your projects.

Our product speaks for itself: it’s actually the best proof of our know-how!

 

Thermal spraying: ideal corrosion protection

Metallising is a process subject to the ISO 2063 STANDARD, which consists of melting metal in wire or powder form inside a flame or electric arc spraying gun, and of spraying it molten using compressed air, over steel stripped beforehand with abrasive jets.

Zinc sprayed in this way, instantaneously solidifies in contact with the steel surface, and forms a zinc coating. Anti-corrosion protection is thus immediate. Adding a sealer is recommended though, since the metal coating is slightly porous.

 

Moreover, the porous character of the metal coating layer provides an ideal substrate for applying an additional paint layer, either for aesthetic reasons or for reinforced anti-corrosion performances of the metal coating. In this case, we talk about a duplex system (metal coat + paints).

The thickness of the metal coating obtained can vary between 50 and 200 µm. This provides long-term protection against corrosion! This flexibility also allows the metal coating operator to adapt to all corrosion classes, and to technical specifications.

The metallising process can be carried out in a workshop or on site, and is perfectly suitable for structures too large to be hot-galvanised.

 

Pictures Tilkin Powder Coatings

Perfection has to do with the end product, but excellence has to do with the process.

01

Surface preparation for metallising by blasting

Process

Good surface preparation is crucial for providing perfect adhesion of the metal coating to the substrate. Blasting is in this sense ideal: it consists of manually spraying steel or angular cast iron shots using compressed air or turbines, over the part to be treated until achieving the requirements of the ISO 2063 standard. In other words:

  • adequate roughness: Rz 50 µm – 100 µm when using angular shots;
  • a minimum degree of cleanliness: Ra 2.5. oil, grease, oxide and other deposits must thus be removed from the surface to be protected.

View images: blasting

Do you want to know more about surface preparation before metallising? Read our Tips and Recommendations

 

 

02

Metallising

Process

Ideal atmospheric conditions for metallising:

  • temperature of the support, 3°C higher than the dew point;
  • relative humidity of less than 85%;
  • room temperature of more than 5°C.

The data must be checked before starting any metallising work. Once these conditions are fulfilled, metallising can start as soon as possible after shot peening. Two types of application will be then possible: by flame spraying gun and by electric arc spraying gun.

View images: Metallising by flame spraying gun and by electric arc spraying gun

Do you want to know more about metallising?

Read our Tips and Recommendations

03

Additional paint system

Process

Zinc and zinc-aluminium coatings are generally reinforced by applying liquid or powder paints. Apart from the aesthetic appearance, the paints protect the surface and increase the lifetime of a metal coating.

Liquid paint is applied in several layers: the first layer, mandatory for an optimum anti-corrosion result, called the sealer layer, is very diluted in order to properly penetrate the porosity of the metal coating. The additional paint layers, called intermediate or finish layers, are then applied. As for powder paint, it can be applied as a single layer or as a double layer.

View images: powder paint and liquid paint

Do you want to know more about the paint system?

Read our Tips and Recommendations

The advantages

  • 01

    Long-term anti-corrosion protection

    the lifetime of a metal coating is proportional to Its thickness which varies depending on how aggressive an environment is
  • 02

    Very good resistance to abrasion

    A metallised structure can withstand intensive use
  • 03

    Immediate anti-corrosion protection

    No drying wait nor cooling period
  • 04

    Great implementation flexibility

    In a workshop or on site, irrespective of the size of the parts to be protected
  • 05

    No risk of deformation by thermal shocks

    Metallising is possible on all steel qualities and all types of assemblies
  • 06

    Perfect adhesion of the metal coating

    Guaranteed by a good prior surface preparation
  • 07

    Ideal basis for additional paints

    Due to the slight porosity of the metal coat
  • 08

    One application is enough

    Finishing operations can start immediately

Why metallise using zinc or zinc-aluminium?

Zinc-aluminium metallising coating combines the advantages of the two metals. It provides the cathodic protection which is specific to zinc, and also provides high chemical resistance against aggressive environments by the addition of aluminium.

Metallising Al Zn Zn/Al15
Barrier protection Large Large Large
Patina protection Yes Yes Yes
Cathodic protection In sea water In all environments In all environments
Can be used in a duplex system Dans certains milieux In all environments In all environments
Can be used in all corrosion classes No Yes Yes
Thickness for thermal spraying alone 150 - 350 µm 80-150 µm 80-250 µm
Thickness for thermal spraying + paint 150 - 200 µm 50-250 µm 50-150 µm
Efficiency 65% 55% 70%
Coverage rate 12 m2/h (thickness 200 µm) 27 m2/h (thickness 100 µm) 38 m2/h (thickness 100 µm)
Theoretical consumption of wire 0,84 kg/m2 1,3 kg/m2 0,82 kg/m2
Risk of explosion (dust) Yes Yes No
Surface preparation Sa 3 Sa 2,5 Sa 2,5
Resistance to traction 4,5 Mpa 4 Mpa 4 Mpa

Tips & Recommendations

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