According to the different ways of steel wire surface purification and activation, the hot aluminum plating process of steel wire is divided into three kinds, which are described as follows:
1. Flux method
According to the situation of oil and oxide film on the surface of the steel wire, the rolling oil, lubricant and other dirt can be removed by acid erosion, molten lead treatment, direct fire heating and burning, alkali washing and other methods. When treated with molten lead, the temperature of molten lead is maintained at 400-430 degrees Celsius. When the steel wire passes through the molten lead groove, the high-temperature lead liquid can evaporate or burn the oil on the surface of the steel wire, and the dirt or drawing lubricant adhering to the surface of the steel wire is also easy to be “scraped” by the lead liquid. Molten lead treatment has a great effect on the removal of grease on the surface of the steel wire, but because of the poison of lead vapor, this method is no longer used.
Second, molten salt preheating method
Molten salt is used to preheat the steel wire and then immersed in aluminum plating method, the essence of the method is to use the low melting point of the eutectic composition of the two salts and its high specific gravity, so that the aluminum liquid floats on the surface of the molten salt, the steel wire is preheated by the molten salt, and the aluminum plating is entered into the upper aluminum liquid under the condition of no contact with air. After the oil removed, pickling steel wire is dipped with aqueous solution flux, it is dried and immediately immersed in the molten mixture of molten salt. In molten salt, the steel wire is heated by the salt to the aluminized temperature, bypassing the submerged roll (press roll) directly through the molten aluminum layer above the molten salt, where the steel wire is plated with aluminum, and then lifted vertically into the air for cooling and winding.
Third, ultrasonic vibration method
The essence of ultrasonic vibration method is to increase the contact density of molten metal and steel wire surface by using ultrasonic vibration transmitted to liquid aluminum and steel wire. When the steel wire enters the aluminum liquid, because the steel wire is cold, ultrasonic vibration can prevent the molten metal adhering to the surface of the steel wire from rapidly forming a solidified layer, which will facilitate the heat transfer effect of dry aluminum on the steel wire and improve the speed of aluminum plating.
In addition, ultrasonic vibration can also make the solid particles off the surface of the steel wire, mainly the iron oxide film particles automatically gather, and away from the moving steel wire, so as not to adhere to the dry steel wire surface. With the continuous addition of metal aluminum alloy ingots to the plating pot, it can ensure that there is sufficient molten metal around the steel wire is not polluted by the above-mentioned solid particles, so the resulting coating does not contain impurities and the surface is smooth. 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.
Post time: 20-07-23