Chromate Conversion Coating

Chromate conversion coatings are mainly used to slow the effects of corrosion on aluminium, zinc, magnesium and their alloys. These coatings are so named because surface film is formed by a chemical reaction which converts the metal surface.

These conversion coatings form an ideal substrate for paints and powder coating, providing a clean, essentially inert surface which exhibits excellent adhesion properties. Most organic coatings applied directly to aluminium surfaces will not adhere well, and if subjected to any deformation, they will tend to flake off exposing the bare aluminium. Scratching off the paint surface also provides a nucleation site for aluminium corrosion leading to further undercutting of the coating.

A pre-treatment is therefore required which can be applied to aluminium to provide a suitable basis for subsequent coatings. Chromate conversion coatings have been developed which can be used on aluminium alloys and which are compatible with most paint systems.

Key Properties

Alocrom 1200

Offers good electrical conductivity with excellent corrosion resistance, providing an ideal base for powder coating and paint.

• A rapid, non-electrolytic, chromate conversion treatment.
• Excellent corrosion protection with or without paint.
• Excellent paint or powder coating adhesion allowing metal deformation after painting.
• The coating has a low electrical resistance (less than 5k micro-ohms/square inch).
• Can be used to repair anodised coatings and refresh them before painting.

Alocrom 1000

Particularly suited for high electrical conductivity. Benefits are:

• Can be applied by dip or brush.
• Improved adhesion and corrosion resistance for lacquered and painted surfaces.

Alocrom 407 / 47

Often specified for construction parts and is an excellent base for paint, but can also be left uncoated. Benefits are

• A rapid, non-electrolytic conversion process.
• Excellent for paint, powder and plastic adhesion. Excellent corrosion resistance.

SurTec 650

Hexavalent Chromium free system, using trivalent chromate passivation chemistry, offers an environmentally friendly coating that offers excellent corrosion resistance and provides an ideal base for paint.

• Hexavalent chromium free, chromate conversion treatment.
• Excellent corrosion protection with or without paint.
• Excellent paint or powder coating adhesion, allowing metal deformation after painting.

E / Clps

Chromium free system, offers an environmentally friendly coating that offers excellent electrical conductivity and provides an ideal base for paint.

• Chromium free, chromate conversion treatment.
• No effect on substrate electrical conductivity performance.
• Excellent paint or powder coating adhesion, allowing metal deformation after painting.