1、 Dacromet process steps:

1. Rust treatment and edge removal: it is prohibited to apply any product workpiece with rust or rough edge immediately. It is necessary to remove the rough edge according to the rust prevention treatment process. This process is better used mechanical equipment to prevent pickling passivation and alkali embrittlement. Besides, pickling passivation and rust prevention treatment are harmful to the corrosion resistance of Dacromet coating.

2. Coating: clean the workpieces after oil removal and rust prevention treatment, and make sure to conduct surface coating as soon as possible according to the method of immersion coating / painting / painting. When the product is coated, the proportion, pH, viscosity, cr6+ composition, temperature and fluidity of the coating solution will immediately harm the actual effect of the coating and all kinds of characteristics of the coating. Therefore, the temperature, water solution index value and the centrifuge speed in the process of coating should be adjusted.

3. Pre baking: the product parts of Dacromet wet film must be at 120 as early as possible ± At 20 ℃, pre bake for 10-15 minutes (according to the heat absorption of the product workpiece), make the water evaporate and the coating varnish evenly.

4. Calcination: the pre baked product workpiece must be calcined at high temperature of 300 ℃, the calcination time is 20-40 minutes (determined according to the heat absorption of the product workpiece), and the temperature can be appropriately increased to reduce the calcination time.

5. Refrigeration: after calcining the product workpiece, it is necessary to carry out subsequent solution or quality inspection after sufficient refrigeration of the refrigeration system.

2、 Dacromet technology has the following advantages compared with traditional phosphating and hot dip zinc technology

1. Corrosion resistance of over shift. The controllable photocatalysis maintenance effect of zinc, shielding effect of zinc and aluminum block and self repairing effect of chromium triox make Dacromet coating have high corrosion resistance. When the neutral salt spray test of Dacromet coating is tested, it takes 100 hours to soak the coating 1 um, which is 7-10 times higher than that of traditional hot galvanizing, The neutral salt spray test time can be up to 1000 hours (coating on a thin thickness of 8um), some or even higher, which can not be achieved by phosphating and hot dip zinc coating.

2. Good temperature resistance. Because there is no crystal water in the chromate polymer of Dacromet coating and the dissolution point of aluminum / zinc sheet is high, the coating has good corrosion resistance at high temperature. The high temperature resistance of Dacromet coating can reach 300 ℃, and it can be used for a long time at 250 ℃, and its corrosion resistance is almost unaffected. However, the passivation treatment film on the surface of phosphating treatment layer is gradually destroyed at 70 ℃ and the corrosion resistance capability drops sharply.

3. No hydrogen ductility. In Dacromet treatment, there are no process processes such as pickling, passivation, electric accumulation, electric oil removal, etc., and there is no electrochemical corrosion of hydrogen evolution caused by the whole process of phosphating treatment, so it is not easy to make the material brittle. Therefore, it is especially suitable for solving ductile parts and high toughness products.

4. Excellent repainting property. Dacromet coating has excellent combination of dark gray, plate and various architectural coatings. It can be used as the whole surface layer and also as the bottom application of various architectural coatings. In the production and manufacture of American and Japanese vehicles, it will be used as the bottom layer of building paint instead of acid pickling and phosphating with environmental pollution, and further improve the overall corrosion resistance.

5. Avoid electrochemical reaction to aluminum. Electrochemical corrosion will occur in the metal materials due to the difference of potential difference. For hot-dip galvanized coating, the safety protection of the coating, whether iron base or aluminum base, will produce photocatalysis and greatly reduce the corrosion resistance.

For Dacromet corrosion protection layer, because its corrosion prevention is created above the passivation effect of chromate and controllable abandonment maintenance effect of the porphyritic zinc layer, it does not cause electrochemical reaction, so the relative inhibition of Zn consumption and the corrosion of Al are also prevented.

6. Excellent water permeability. Dacromet treatment solution can penetrate into the close contact of the products and produce rust proof coating. If phosphating treatment is applied, because of shielding effect, the inner part of the tubular member is basically electroplating process. However, Dacromet treatment is applied by coating method and has excellent water permeability, so it can be used to improve the anti rust treatment capability of internal and external sides. For example, after the processing of Dacromet, the experiment of salt water sprayer was carried out under the condition of rashen, which still showed excellent anti rust treatment ability.

7. The environmental pollution is small. There are some industrial wastewater problems with zinc, alkali and chromic acid in phosphating treatment, which will cause great environmental pollution. The temperature is high when hot dip zinc is high. The released zinc vapor and HCl are harmful to health. At present, most of the hot dip zinc production and manufacturing must avoid the development of big cities and rural areas. Dacromet process has opened up a new field of metal corrosion, because Dacromet treatment is a closed treatment method. The chemical substances evaporated during the whole process of baking are mainly water, without other harmful substances required to be manipulated, which is less polluted to the air.