NOVELTY - A slurry contains suspended aluminum particles in a colloid having dispersed colloidal particles of a metal oxide such as hydroxide and is reducible by metallic aluminum. The slurry has basic pH in which dissolution of aluminum particles in the slurry is inhibited so that when the slurry is subjected to heat treatment, the undissolved aluminum particles are reactable with the colloidal particles to form an aluminum-based mixture resistant to chemical attack made of aluminum oxide, metal aluminum, and the metal of colloidal particles.    USE - Used for forming aluminum-based protective coating on component, preferably of aluminum electrowinning cell or an apparatus for treating molten aluminum (claimed).    ADVANTAGE - The invention is capable of improving aluminum-wettability of components used in molten aluminum environment.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) a method of forming an aluminum-based protective coating on a component, comprising providing the inventive slurry; applying layers of the slurry to a surface of the component; and drying the applied layer(s) to form the aluminum-based coating on the component;    (2) a method of manufacturing an apparatus which during use contains molten aluminum, comprising manufacturing a component having aluminum-based protective coating by above method and placing the component into the apparatus;    (3) a method of producing aluminum, comprising manufacturing by the above method an aluminum electrowinning cell with an aluminum-wetted component, cathodically reducing aluminum which comes into contact with the component;    (4) a method of treating aluminum, comprising manufacturing by the above method the apparatus for treating molten aluminum, and stirring molten aluminum with stirrer or holding molten aluminum within the vessel;    (5) a part manufactured aluminum-based protective coating on a component, comprising dried layers of the slurry; and    (6) an aluminum-based protective coating on a component, comprising a mixture of aluminum oxide, metal aluminum, and another metal and protecting the component against chemical attack.