Can you imagine that the engine will no longer "drink" gasoline but "eat" iron powder in the future? Recently, scientists have proposed a new concept-using fine metal particles as large as refined white powder or sugar powder to drive external combustion engines. Compared to hydrogen, biofuels, or batteries, metal powders are more likely to be a long-term alternative to fossil fuels. With the development of technology, water atomized pure iron powder is changing with each passing day, and the application fields of metal powder are becoming more and more extensive.

In the process of metal powder spraying, the powder coating is fluidized and then delivered to the spray gun through the airflow. The spray gun passes through a high-voltage electrostatic generator to generate a corona discharge at the electrode needle of the nozzle, which generates a dense negative charge near the electrode. At this time, the trapped charge becomes a charged powder, and under the action of air flow, electric field, and its own gravity, it flies to the grounded workpiece and is adsorbed on the surface of the substrate. Therefore, we need to take adequate precautions during our spraying process.

1. Coating method for metal powder spraying

In most cases, electrostatic spray guns are used for spraying. Because this type of product contains metal pigments, the system should be well grounded when spraying with electrostatic guns. At the same time, a lower electrostatic voltage and powder output should be set to prevent spraying Fire phenomenon. The effect of coating film formation has a lot to do with the settings, quality, or brand of the spray gun. After a long time spraying, a large amount of metal powder may accumulate at the discharge needle of the spray gun, and the sprayer needs to be cleaned regularly.

2.Gloss of metal powder coating

In most cases, due to the large error, it is not recommended to use a gloss meter to measure the gloss of the metallic appearance coating film, and only the visual comparison method is used to determine whether it is consistent with the standard sample.

3.Recyclability of metal powder coatings

For powders produced by dry blending, separation occurs during spraying and recycling, so there will be a certain difference in the content of metal pigment between recycled powder and new powder, which may cause inconsistent appearance of the coating film and color discoloration. . This is due to the difference in properties between the metallic pigment and the powder particles. Experts recommend a ratio of recycled powder to new powder of at least 1: 4. If the powder coating produced by the bonding and fixing method is relatively fixed, the ratio between the metallic pigment and the powder particles can be completely recycled.

4.Material of metal powder coating

Spraying the overcoating layer on the metal powder coating film has the following advantages: enhancing the stone impact resistance of the metal powder coating film; increasing the aesthetic effect of the metal powder coating film; completely solving the erasability of the metal pigment; improving the metal powder coating film Weatherability. In order to ensure the appearance of the finish, it is required that the sprayed workpieces not be contaminated in any way. Therefore, it is generally necessary to have a fully automated spraying line and two independent spray booths to spray separately. It is recommended not to spray overcoat in general.

5.Erasability of metallic pigments

Regardless of whether the powder is manufactured by the dry blending method or the adhesive fixing method, the problem of the erasability of metallic pigments cannot be completely solved. The solution to the erasability is to spray a transparent coating on the metal powder coating film.

6. Try to keep the spray conditions as stable as possible

Use the same set of spray equipment, use the same voltage, air pressure and other parameters; try to keep the distance between the spray gun and the workpiece as much as possible, and keep the thickness of the film as stable as possible; ensure that the powder coating has been fully fluidized before spraying; The ratio of powder to new powder is at least 1: 4; try to avoid using metal powder coating to spray workpieces with complex shapes or deep depressions; it is recommended that multiple workpieces used for assembly should be sprayed at the same time.