Filtering molten aluminum is the most effective method to remove non-metallic slag in molten aluminum. In the casting of aluminum alloy, multi-layer glass cloth filter or ceramic foam filter is generally used. No matter what kind of filtration method is adopted, in order to ensure the normal filtration of the molten aluminum, the surface scum should be removed before the filtration of the molten aluminum, because the surface scum is easy to block the filter mesh of the filter material and make the filtration impossible. The easiest way to remove the scum on the surface of the molten aluminum is to set a slag baffle in the launder, so that the molten aluminum can remove the scum before filtering.
To produce high-quality aluminum alloy casting rods, in addition to selecting reasonable ingredients, strictly controlling the melting temperature, casting temperature, grain refining treatment, alloy liquid refining, filtering molten aluminum and other process measures, it is also necessary to carefully operate to avoid the cracking and rolling of the oxide film.
During casting, avoid the turbulence and rolling of the molten aluminum as much as possible. Do not use tools to stir the molten aluminum in the trough and the shunt plate easily, so that the molten aluminum flows into the mold smoothly under the protection of the surface oxide film. This is because the tool agitating the molten aluminum and the flow of the molten aluminum will rupture the oxide film on the surface of the molten aluminum, causing new oxidation, and at the same time, the oxide film is drawn into the molten aluminum.
Studies have shown that the oxide film has a very strong adsorption capacity, it contains 2% of water. When the oxide film is involved in the molten aluminum, the water in the oxide film reacts with the molten aluminum, causing hydrogen absorption and slag inclusion. Before pouring, fully preheat and dry the casting launder, distributing launder and other casting systems to prevent the reaction of moisture and molten aluminum from causing hydrogen absorption.
Finally, the aluminum rods are homogenized, so that high-quality aluminum rods can be produced, which provides a reliable material basis for the production of high-quality profiles.
