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PROCESSES

Metval carries out thermal spraying coatings with the following processes: flame spraying, air plasma spraying, HVOF and electric arc. Machining and surface finishing operations (coating grinding, polishing, lapping) eventually requested by customers are carried out internally.

Thermal spraying is a surface treatment that, utilizing different techniques and materials, allow surface improvement of components with many purposes such as:

  • withstanding mechanical wear or corrosion;
  • insulating or making conductor;
  • creating thermal barriers;
  • restoring to original dimensions.

All thermal spraying techniques are based on the same principle: projecting a material, previously brought close to the melting-point, onto a surface that has to be improved. Coating bond to the substrate takes place thanks to the high impact velocity of the fused particles and to the fact that substrate surface has been previously sand blasted to increase surface roughness.

Metval carries out thermal spraying coatings with the following processes: flame spraying, air plasma spraying, HVOF and electric arc.

  • Wire metallization or flame spraying was the first thermal spraying technique to be used, especially to restore original dimensions of worn parts and for anti corrosion coatings.
    Wire metallization means for Metval first of all molybdenum coatings, which are used mainly in the automotive industry to withstand mechanical wear. In this process thermal energy is obtained from the combustion of combustible gas and coating material is in form of wire.
  • In the case of air or atmospheric plasma spraying (APS) thermal energy comes from a plasma obtained by superheating an inert gas. Coating material is in form of powder.
    Metval carries out plasma spraying of ceramics (oxides) to withstand mechanical wear or obtain thermal barriers.
    Main industries served are: pumps, textiles and drawing.   
  • HVOF (High Velocity Oxygen Fuel) process – thanks to the higher impact velocity of coating material onto the substrate – allow to obtain coatings with improved features in comparison to other spraying techniques especially with regard to bond strength and density. Thermal energy is obtained by combustion of gas or liquids and coating material is in form of powder.
    Metval carries out HVOF coatings of carbides (tungsten and chromium) and other metallic materials mainly for the valves (metal to metal seal) and pumps industries.
  • Electric arc metallization uses electric energy to melt coating material which is in form of wire.
    Metval utilizes this technique to spray bronze, steel and nickel.