The principle of thermal aluminum spraying, the working principle of aluminum spraying machine

The sand particles are blown to the surface of the workpiece by high-pressure air and pipes to remove the rust and oxide scale on the metal surface, and at the same time, the surface is added to the surface to increase the adsorption force of the hot spray coating, and then the aluminum wire is atomized and sprayed to the metal surface at ultra-high speed by using the arc through compressed air and special tools (spray guns).

Thermal spray coating is generally used for low melting point metal spraying, hot spray zinc, hot spray aluminum; Electroplating energy potential is too negative metal aluminum; Chemical plating can better plating potential, compared with negative metals, zinc, aluminum and other thermal spray coatings are generally thicker, with strong anti-corrosion ability and strong decoration; The single-layer electroplating layer has poor anti-corrosion ability (zinc-nickel alloy has strong anti-corrosion ability, compared with thermal spraying), and the combination improves strong decorative properties, and the shortcomings of the coating thickness are especially complex shapes, and the workpiece even leaks plating; Chemical plating coating is uniform and suitable for brush plating, single plating has poor corrosion resistance, poor decoration, low porosity of plating, it is recommended that such a question is meaningless, you can check the information yourself.

Hot-dip galvanizing and arc spraying zinc (aluminum) coating are both effective methods for preventing corrosion of outdoor steel structures. In view of the fact that hot-dip galvanizing is quite different from arc spray zinc (aluminum) in terms of manufacturing process and coating performance, generally speaking, in severe corrosive environments such as ocean, acid rain and industrial atmosphere, when the shape of steel structural parts is complex and when the root corrosion protection life is more than 25 years, the use of arc spray zinc (aluminum) long-term anti-corrosion technology is the best choice. The literature shows that the hot-dip galvanized coating can only provide more than 10 years of anti-corrosion life of the steel structure in the general corrosive environment, and the thickness of the coating must reach more than 85 m and the organic coating should be added for coating.

In the ISO14713 standard and BS5493 standard, for severely corrosive environments such as marine environments, only a thermal spray zinc or aluminum coating (closure is best) can achieve the first maintenance-free for more than 30 years. Comparison of arc spraying and hot-dip plating technologyArc spraying (zinc) hot-dip plating (zinc) coating formation principleThe arc spraying equipment uses arc spraying equipment to heat, melt, atomize and spray pure metal wires (zinc, aluminum and their alloys, etc.) to the surface of steel workpieces after sandblasting and rust removal through arc heating, melting, atomization and spraying to form an arc spraying coating. After sealing with organic sealing coating and topcoat coating, it can form a long-term anti-corrosion composite coating with good appearance.

After the steel workpiece is pickled and rusted, it is immersed in a high-temperature hot-dip galvanized molten pool of 480 520 for several minutes, so that the work is stained with molten zinc, and then the workpiece is immersed in room temperature water to cool to form a hot-dip galvanized coating. Whether the coating thickness is sprayed mechanically or manually, a uniform thickness can be obtained. Depending on the corrosive environment and protection life requirements, different coating thicknesses can be designed, and any value between 50 and 1000 m can be controlled during the spraying operation.

In the hot-dip galvanizing process, liquid zinc adheres to the surface of the workpiece, and due to the thickness of the zinc layer in the low concave part, the thickness of the coating layer is uneven, which also leads to the difference in the corrosion resistance of the paint. The thickness of the galvanized layer is thin, less than 100 m. There is no requirement for the size of the workpiece, and both large and small workpieces can be sprayed, but there can be no dead angle that cannot be sprayed.

Due to the limitation of the hot-dip plating tank, the workpiece with a large size cannot be hot-dip plating. The thermal influence on the workpiece is really good on the surface of the workpiece, and the temperature rise is generally not more than 100 150, and the heat is dissipated quickly, the temperature holding time is very short, and it will not cause the workpiece to deform and anneal. High temperature, long components and thin-walled workpieces will inevitably be deformed, so the workpiece needs to be straightened after plating, and it is difficult to achieve the original state for the straightening of the workpiece with complex shape, and the local damage of the plating may also be caused during the straightening process.

The pre-treatment process is sandblasting and rust removal.

The working principle of the aluminum spraying machine is as follows:

Powder coating is to spray powder coating onto the surface of the workpiece with powder spraying equipment, and under the action of electrostatic, the powder will be evenly adsorbed on the surface of the workpiece to form a powdery coating; The powder coating is leveled and cured by high-temperature baking, and the comma is transformed into a final coating with different effects (different types of powder coating effects); The spraying effect of powder coating is better than the painting process in terms of mechanical strength, adhesion, corrosion resistance, aging resistance, etc., and the cost is also lower than that of spraying with the same effect. In the powder supply device, the powder is in a fluidized state, which is realized by the action of compressed air, and then the powder is carried by the high-speed flowing air flow through the siphon action, forming a powder gas mixture, passing through the venturi powder pump, the powder cong shouting tube, and finally reaching the spray gun. The powder conveyed to the spray gun can be controlled, and the parameters of the powder and air can be adjusted separately to change the amount of powder and the atomization state of the powder, so that different coating film thicknesses can be achieved to meet the needs of different products.

The high voltage and low current generated by the electrostatic generator make the electrode needle located at the front of the spray gun discharge in the air, and when the powder is sprayed out through the nozzle of the gun head, the powder particles will be charged, and reach the surface of the workpiece that has been grounded through the dual action of electrostatic adsorption and air flow.

Aluminum spraying is a thermal spraying process, and aluminum powder is sprayed onto the surface of steel at high temperature and high speed to form a spray coating layer, which has strong anti-corrosion ability.

Compared with other construction methods, the thermal spray aluminum construction on the inner wall of the storage tank has the following advantages:

1. Comparison from the investment aspect: it can save 55% of the money compared with the investment of all stainless steel wall panel products; It has a long service life compared to the products of all-carbon steel siding.

2. Compared with other spraying: less harmful to human health; High binding strength.

Thermal spray aluminum pre-surface treatment:

1. Sandblasting and rust removal.

1) Before spraying aluminum on the inner surface of the storage tank, copper ore must be used to blast and remove rust on the metal surface, and the rust removal result should meet the requirements of the national standard SA3 level: there is no visible grease, dirt, oxide scale and paint coating and other attachments on the steel surface, and the surface should show uniform metallic luster. The surface roughness reaches 75 m or more.

2) The compressed air must pass through the oil-water separator and buffer tank with good performance before entering the spray gun, and the pressure is not lower than that. (3) In order to ensure the roughness and cleanliness of the metal surface, the copper ore must be clean and dry and the particle size must be 3 5mm.

2. Dust removal treatment: After sandblasting and rust removal, a vacuum cleaner should be used to dust the metal surface.

The metal surface that has passed the sand blasting and rust removal qualification shall not be touched by hand, and sprayed as soon as possible, and the time interval shall not exceed 12h on sunny days, and shall not exceed 2h on rainy or wet weather. Otherwise, the surface treatment should be re-applied. If the sandblasting does not meet the predetermined requirements, it is easy to form the following defects:

The sandblasting layer has poor adhesion to the metal layer and is easy to fall off; The sprayed aluminum layer peels and shells.