At present, most domestic aluminum alloy smelting uses chlorine salts such as ZnCl_2, C_2Cl_8 and other fluxes to degas the aluminum liquid. When these substances are added to the aluminum liquid, harmful gases such as HCl and AlCl_3 are generated, which seriously pollutes the environment and damages the health of workers. Degassing effect. Nitrogen has good degassing effect and no pollution, but it is easy to form AlN and other non-metallic inclusions in aluminum liquid. In recent years, some units have developed and produced some non-toxic refining agents. This type of flux is mainly composed of N_2NO_3 and graphite Composition, when molten aluminum is added, it boils violently, oxidation is serious, and Al_2O_3 impurities in aluminum alloy castings increase, and it only has a degassing effect. Most of the smelting of foreign aluminum alloys uses a composite (combined) process to remove the inclusions and gases of aluminum alloy. The "FILD" method adopted by the United Kingdom and the United States, that is, through the process of combining N_2 and active
flux filtration to remove inclusions and gases. N_2 is also used as a carrier and flux.
