It is more important to use suitable aluminum liquid purification methods, so as to eliminate pores and inclusions in aluminum castings.
It is necessary to select the furnace charge used for melting, and prevent vapor and various dirt from entering the furnace. Refining agent is used to purify molten aluminum to eliminate hydrogen and oxide inclusions in molten aluminum. That is, the hydrogen in the molten aluminum can be partially or completely dissolved in the alloy structure during solidification, so that it will not exist in the casting in the form of pores.
When using metal mold casting, die-casting, low-pressure casting, squeeze casting and other processes, even poor-quality molten aluminum can obtain qualified castings without pores. Properly arrange and implement liquid aluminum purification process measures, and implement them in specific smelting operations.
Practice has proved that if there are many inclusions in the furnace charge and the operating tools are damp and not clean, even if the best refining method is used, the effect will be minimal. Choosing a reasonable refining method is the key to eliminate the gas and oxide inclusions in the molten aluminum and achieve the purpose of purifying the molten aluminum.
Nowadays, there are many aluminum liquid purification methods. According to the mechanism of action, they are basically divided into two categories: The first category is adsorption refining: using chloride salts and other fluxes, or venting chlorine and nitrogen (called floatation method). Use active or inactive media for filtration ( CFF filtration method). The second category is non-adsorption refining: the use of vacuum melting, vacuum treatment, ultrasonic treatment, etc. If two or more refining methods are used at the same time, it is called joint refining. The above-mentioned non-adsorption refining requires equipment, such as a vacuum device, to ensure that it is not easy to be widely used. Therefore, the current focus is still on the selection of refining agents for adsorption refining and the method of adding molten aluminum to research and discuss in order to obtain better results.