With the continuous expansion of aluminum alloy materials in various fields of the national economy, higher and higher requirements are put forward for the internal quality of aluminum alloy materials. During the production process, it is necessary to strictly control the chemical composition of aluminum alloy and the defects such as shrinkage, porosity, porosity, slag inclusion of the ingot, because the intrinsic quality of the processed products is affected by the quality of the ingot, and the inner quality of the ingot largely depends on the quality of the melt. Therefore, the purification technology of the aluminum alloy melt is very important. According to the existing equipment and process conditions, discuss the control method of the hydrogen content of the aluminum melt, reduce the hydrogen content of the aluminum melt, in order to obtain high-quality ingots.
Purification Technology for Aluminum
The gas in the aluminum melt is mainly hydrogen (volume fraction is about 60% to 90%), followed by nitrogen, oxygen, carbon monoxide and so on. The purification technology of aluminum melt mainly for hydrogen removal mainly includes bubble floatation method, vacuum treatment method, ultrasonic treatment method, rare earth hydrogen removal method, etc. The bubble floatation method is widely used because of its simplicity and high efficiency. The process of hydrogen removal by bubble floatation of aluminum melt: The hydrogen atoms dissolved in the aluminum liquid undergo migration to the periphery of the purifying agent (argon or nitrogen, etc.) bubbles, are adsorbed around the bubbles, and form hydrogen molecules into the bubbles. Finally, the aluminum melt escapes as the bubbles float upward.
Main equipment: smelting furnace, electromagnetic stirring device, online degassing device, online filtering device, runner system. The electrolytic primary aluminum and materials are smelted and refined in a smelting furnace to obtain a qualified aluminum melt for temperature and composition, and then stand still for treatment. The static melt is further purified and cast after online degassing and online filtration through runners.
The solubility of aluminum when heated to 300°C in air is only 0.001ml/(100g·Al), and solid aluminum basically does not absorb hydrogen. When the aluminum melt enters the casting system, the hydrogen content basically does not change. In addition to raw materials, the hydrogen source of the melt is mainly hydrogen absorption during the smelting and casting process. The purpose of using online degassing equipment is to further purify the aluminum melt outside the furnace, and to better remove the gas and slag in the aluminum melt.