Extended introduction
Aluminum is a silvery white light metal. It has plasticity. Commodities are often made into bars, sheets, foils, powders, tapes and wires. An oxide film can be formed in humid air to prevent metal corrosion. Aluminum powder can burn violently when heated in air, and give off a dazzling white flame. Soluble in dilute sulfuric acid, nitric acid, hydrochloric acid, sodium hydroxide and potassium hydroxide solution, insoluble in water.
The most abundant metal element in the crust is 8.3%. It mainly exists in aluminosilicate ores, as well as bauxite and cryolite. Alumina is a white amorphous powder with many variants. Naturally occurring corundum is second only to diamond in hardness, melting point and acid and alkali resistance. It is usually used to make some bearings, abrasives and refractories. Such as corundum crucible, can withstand the high temperature of 1800℃.