Aluminum is a silver-gray metal with a relative density of 2.55 and a purity of 99.5%. The melting point of aluminum is 685 degrees, the boiling point is 2065 degrees, and the melting heat absorption is 323kJ/g. Aluminum is reductive, easy to oxidize, and exothermic in the oxidation process. During rapid oxidation, the heat release per gram is 15.5kJg. Aluminum is a ductile metal and easy to process. The oxide film on the surface of aluminum is transparent and has good chemical stability.