Coating of magnesium casting

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Coating of magnesium casting

Magnesium has become more and more important particularly in the automobile sector due to several of its excellent properties. The advantageous properties of this metal are described adequately in the technical literature: lighter than aluminum, very good hardness-weight-ratio, high resistance to impact, and excellent dimensional stability, just to mention a few. The challenge for the coating company is the high reactivity and the corrosion susceptibility of magnesium associated with it.

Due to its years of experience, the Heiche Group offers its customers considerable knowledge of pre-treatment and coating.

The main focuses are:


  • Pre-treatment for adhesion
  • Pre-treatment for painting
  • Corrosion protection with electro-coating
  • Corrosion protection and activation of the surface through sol-gel coating (nanotechnology)

Pre-treatment for adhesion

Using a process developed by the Heiche Group, it is possible to activate magnesium-cast surfaces in such a way that an excellent conglutination is given between metal and wood veneers, for example, from phenolic resin.

Pre-treatment for painting

The application and combination of various pre-treatment processes and conversion coatings assure excellent, corrosion-resistant adhesionwith powder and wet paint coatings.

Electro-coating

Through our own developed pre-treatment process, especially adjusted fore-coating, we succeeded in obtaining e-coat on magnesium cast with high corrosion protection: 240 h up to 1000 h in the salt spray test (depending on the cast quality).

Sol-gel coating

When the highest corrosion demands are made on magnesium parts, our constructed nano-sized, sol-gel coatings offer excellent protective functions. The possible synthesis variations in these sol-gel systems can have additional property advantages in addition to the corrosion protection, such as, hydrophoby, hydrophilicity, oleophoby, etc.

Property features


  • Excellent adhesion
  • Excellent corrosion protection (> 1000 h Salt spray test)
  • Hydrophobic
  • Resistant to mechanical stress
  • Resistant to organic solvents
  • Resistant to thermal stress (up to 250°C)
  • Layer thicknesses of 2-20µ

 
It is important that the pre-treatment of the magnesium parts be adjusted to the sol-gel coating. In doing so, the excellent property profile of the sol-gel coating is further increased particularly with regard to adhesion and corrosion protection.

Most of the applications refer to the most common magnesium-cast-alloys AM50 and AZ91. Our development department will gladly check other cast alloys using sample coatings.