High Speed Dacromet Coating Brake Disc Without Chrome Coating
1. Features of Dacromet Coating
1.2.1 excellent heat-resistant corrosive Dacromet anticorrosive film curing temperature of 300 ℃ or so, so even if the workpiece for a long time at high temperatures, the appearance will not change color, excellent heat and corrosion resistance. The traditional galvanized layer in the above 70 ℃ under the conditions, there will be a small crack in the 200 ~ 300 ℃ conditions will change color, corrosion resistance is also greatly reduced.
1.2.2 excellent weather resistance and chemical stability of the test, the unpurified galvanized layer, salt spray test in general ten hours corrosion of a micron; thickness of three microns rainbow color purification film, by two hundred Hour salt spray test was etched. Dacromet coating was etched off a micron after a hundred hours of salt spray test. Dacromet process than the traditional surface galvanized treatment process, so that the corrosion resistance of the workpiece increased by seven to ten times. Shanghai, a car factory using Dacromet process coated lamp stand, salt spray test reached more than a thousand hours.
2. Dacromet Coating Technical data
| No. | Item | Data |
| 1 | PH | 3.8-5.2 |
| 2 | Cr6+ | ≥25g/L |
| 3 | Specific gravity | 1.30±0.05 |
| 4 | Viscosity | 20~60s(Spray Coating) ; 60~90S(Dip-Spin Coating) . 20℃ Zahn 2# cup |
| 5 | Operating temperature | 22±2℃ |
3. Mix Diagram
Caution: Temperature should be controlled in above operation.
4. Coating Process
5.1 Degreasing
The workpiece should be degreased if there is oil on the surface. There are three processing methods:
1.High temperature
2.Neutral water-base degreasing agent
3.Organic solvent such as methylene chloride.
5.2 Derusting
The workpiece can not be coated if there is rust or burr on the surface.The best processing method is shot blasting. The corrosion resistance of coating will be effected if acid cleaning adopted.
5.3 Coating
The workpiece afer degreasing and shot blasting should be coated through Dip-Spin coating or Spraying Coating.
5.4 Pre-heating
The workpiece after coated should be Pre-heated as soon as possible at 80~150℃ for 8~15 mins to evaporate. ( according to heat absorption of workpiece.)
5.5 Curing
The workpiece after pre-heating should be cured at 300-340℃ for 20-40 mins. ( according to heat absorption of workpiece.)
6. Attentions
Other chemicals such as any kinds of acid, alkali salt can not be mixed into coating, for these can activate Zn & Al plate to aging the coating.
Avoid irradiation of sunshine and ultraviolet ray for long time when operating, otherwise it will accelerate aging or polymerization of the coating .
It is very important to control the temperature of coating. If the temperature of coating changes when operating, it will effect the viscosity, then effec the coating quatity on workpiece. So the relations among temperature,viscosity and spinning process shoud be controlled well when coating.
The viscosity will be different if coating method is different. Choose low data if spray coating,and choose high data if dip spin coating.
