dacromet达克罗技术

DACROMET 320 is a non-electrolytic water-based thin-film coating for the corrosion protection of articles made from steel, cast iron or other iron metals. The Coating Contains Zinc and aluminium flakes in a chromium binder. The coating is metallic silver in appearance.

DACROTIZING is the process whereby the aqueous dispersion is applied by cold immersion or spray and is therefore free of any risk of hydrogen embrittlement. The coating thus produced is passivated throughout the film and provides high performance corrosion protection.

CHARACTERISTICS

The corrosion resistance of DACROMENT 320 depends upon the thickness of the coating and is due to the combination of several mechanisms:

A barrier effect due to the tile-like structure of the film, Controlled sacrificial protection of the zinc in relation to the metal substrate,

The film passivation which reduces the speed at which the zinc and aluminum are consumed.

COATING THICKNESS

Two coating weights are commonly used to meet the automobile industry’s requireme nts;

Grade A: coating weight > 24 g/m2, average thickness 5 to 7 um

Grade B: coating weight >36 g/m2, average thickness 8 t0 10 um Greater coating weights may be applied to increase the duration of the corrosion protection.

PROPERTIES

1/No hydrogen embrittlement

When surface preparation is done according to recommended techniques, the non-electrolytic application of the film does not induce hydrogen embrittlement. DACROMET 320 is therefore especially indicated for protecting security parts.

2/Corrosion resistance

DACROMET 320 meet all automobile manufacturer specifications for the corrosion protection of mechanical parts. It is also very well suited for numerous other applications such as building, civil engineering, railway equipment…

Salt spray test(ISO 9227):

>600 hours (Grade A) without red rust.

>1000 hours (Grade B) without red rust.

No white rust (zinc corrosion) before 250 hours.

Salt spray test after 8 hour thermal shock at 260℃

Ditto

Cyclical corrosion tests: 3C test

Test method: RENAULT : >10 cycles without red rust

Bimetallic corrosion resistance:

DACROMET 320 behaves very well in contact with aluminium and performs as well as other zinc-based coatings in contact with copper, stainless steel or magnesium.

3/Resistance to automotive fluids:

Standardized test fuel, diesel fuel, motor oil, organic solvents, cooling fluid, brake fluid; no coating alteration (VDA 621-412)

Immersion in brake fluid for 24 hours at 80℃; no coating alteration.

4/Ductility:

Sufficient for elastic deformations of springs, clip

5/Electrical conductivity:

DACROMET 320 is conductive. It allows for use of electrodeposited paints.

6/Heat resistance:

DACROMET 320 is cured at 300℃, thus providing excellent heat resistance.

7/Paintability:

DACROMET 320 may be covered by most organic coatings and in particular, those applied by electrodeposition.

8/Throwing power

The application on parts by cold immersion allows for the total covering of the internal surfaces.