Aluminum fluoride is an inorganic substance with the chemical formula AlF ?, prepared by the reaction of aluminum hydroxide or metal aluminum with hydrogen fluoride, or by the reaction of aluminum trichloride with hydrofluoric acid or ammonia water.Colorless or white crystals. Insoluble in water, insoluble in acids and alkalis. The properties are very stable and can be hydrolyzed under heating.Used as an electrolytic regulator and catalyst for aluminum electrolysis.