Briefly describe the three hot-dip aluminizing processes for steel wire

Briefly describe the three hot-dip aluminizing processes for steel wire

According to the different methods of surface purification and activation of steel wire, the hot-dip aluminizing process of steel wire can be divided into three types.

1. Flux method

According to the condition of oil stain and oxide film on the steel wire surface, methods such as acid erosion, molten lead treatment, direct fire heating and burning, alkaline washing, etc. can be used to remove rolling oil, lubricants and other contaminants. When using molten lead, the temperature of molten lead is maintained at 400-430 degrees Celsius. When the steel wire passes through the molten lead tank, the high-temperature lead liquid can evaporate or burn off the oil on the surface of the steel wire, and the dirt or drawing lubricant adhering to the surface of the steel wire can easily be "scraped" by the lead liquid. The molten lead treatment has a great effect on the removal of grease stains on the surface of the steel wire, but due to the poisoning of lead vapor, this method is not widely used.

2. Molten salt preheating method

American researcher Moeler (Moeler) proposed in 1953, the use of molten salt to preheat the steel wire and then immersed in the aluminum liquid aluminum plating method. The essence of this method is to use the low melting point and higher specific gravity of the eutectic composition of the two salts to make the aluminum liquid float on the surface of the molten salt. The aluminum liquid on the upper part is plated with aluminum. The degreasing and pickling steel wire is dipped in aqueous flux, then dried and immediately immersed in the molten mixed molten salt. In the molten salt, the steel wire is heated by the salt to the aluminizing temperature, bypassing the sinking roller (press roller) and directly passing through the molten aluminum layer above the molten salt. The steel wire is plated with aluminum in the molten aluminum layer, and then lifted vertically to the air Medium cooling and coiling.

3. Ultrasonic vibration method

The essence of the ultrasonic vibration method is to use the ultrasonic vibration energy transmitted to the molten aluminum and the steel wire to increase the contact density between the molten metal and the surface of the steel wire. When the steel wire enters the aluminum liquid, because the steel wire is cold, the ultrasonic vibration energy can prevent the molten metal adhering to the surface of the steel wire from rapidly forming a solidified layer, which will benefit the heat transfer effect of the dry aluminum to the steel wire and increase the aluminizing speed. In addition, ultrasonic vibration can also make the solid particles separated from the surface of the steel wire, mainly iron oxide film particles, automatically gather and stay away from the moving steel wire, so as not to adhere to the surface of the dry steel wire. With the continuous replenishment of the metal aluminum alloy ingot into the plating pot, it is possible to ensure that there is sufficient molten metal around the steel wire not to be contaminated by the above-mentioned solid particles and the like. Therefore, the resulting plating layer is free of impurities and has a smooth surface. To promote the destruction of the oxide film on the surface of the steel wire and the diffusion of molten metal to the surface of the steel wire.