Will 99.85% aluminum ingot rust? Many friends have doubts. I have seen copper rust and iron rust, but I have never seen aluminum rust. Is n’t aluminum rust? In fact, aluminum products such as aluminum powder and aluminum grains will of course rust, but aluminum does not rust like iron until it finishes rusting.
Oxidation of metal by oxygen in the air is rust. Aluminum ingot chemically reacts with oxygen to form alumina, which is aluminum rust. Aluminum rust is very thin, its thickness is only one ten thousandth of a millimeter, but it is very hard and very wear-resistant. It clings to the surface of aluminum, so that the aluminum inside can not contact the outside air, preventing the aluminum from continuing to rust.
Alumina films also have "busters": one is alkali and the other is acid. When alumina meets them, a chemical reaction occurs to generate compounds, which will cause the aluminum oxide film on the surface of the aluminum ingot to fall off easily.
In daily life, dishes often contain acid and alkali components. Therefore, do not put dishes and wine in aluminum utensils to avoid corrosion and damage to the aluminum pan. In addition, do not rub the surface of the aluminum pan with sand because it is embarrassed. Although the aluminum pan is brighter, the aluminum pan also loses the protective film on the surface, and the aluminum pan continues to oxidize, affecting its service life.
crack. The reason is that the temperature of the molten aluminum is too high and the speed is too fast, which increases the residual stress. The aluminum in the aluminum solution contains more than 0.8% silicon, which generates an aluminum-silicon co-melt, and then generates a certain amount of free silicon, which increases the thermal crackability of the metal. Or insufficient cooling water. When the surface of the mold is rough or no lubricant is used, cracks may also occur on the surface and corners of the aluminum ingot.