Hey.How come iron rust and aluminium does not?DETAILED ANSWER PLEASE.I want to understand this...THANKS.
Aluminum corrodes but it does not rust. Rust refers only to iron and steel corrosion. Aluminum is actually very prone to corrosion. However, aluminum corrosion is aluminum oxide, a very hard material that actually protects the aluminum from further corrosion. Aluminum oxide corrosion also looks a lot more like aluminum, so it isn't as easy to notice as rusted iron. When iron corrodes the color changes and it actually expands. This expanding and color change can produce large red flakes that we all know as rust. Unlike aluminum oxide, the expanding and flaking off of rust exposes new metal to further rusting. This why it is so important to provide a barrier so rust doesn't start.
Aluminum DOES rust..... It oxidizes just like iron does..... Leave a piece of aluminum outside for a few months.... It will get a nice white powder on it which of course is aluminum oxide
Iron is the only metal that rusts (apart from steel which is made from iron), aluminum just like titanium forms an oxide of 3 or 4 atoms on the surface, while rust is the oxide of iron ) rusting is an example of corrosion -- an electrochemical process involving an anode (a piece of metal that readily gives up electrons), an electrolyte (a liquid that helps electrons move) and a cathode (a piece of metal that readily accepts electrons). When a piece of metal corrodes, the electrolyte helps provide oxygen to the anode. As oxygen combines with the metal, electrons are liberated. When they flow through the electrolyte to the cathode, the metal of the anode disappears, swept away by the electrical flow or converted into metal cations in a form such as rust. For iron to become iron oxide, three things are required: iron, water and oxygen.
Aluminum and Iron both form an oxide coating on the surface of the pure metal. Iron oxide and aluminum oxide are very different however. Rust is very soft and wears away quickly, exposing a fresh Iron surface. Aluminum oxide is what a ruby is made from (along with a little Chromium for color). Rubies are only a bit softer than diamonds, the hardest substance known. The oxide coat on Aluminum is very thin but also very hard. It adheres to the surface and prevents any further corrosion. Regarding Chromium, it is the key ingredient in stainless steel. Steel is an Iron alloy with a small amount of Nickel, Molybdnium, Vanadium and even Copper and Phosphorus. Stainless steel resists rust so well because the Chromium will form an oxide coating the same way Aluminum does. Since the Chromium is actually part of the alloy, if the stainless steel is scratched, the fresh surface soon coats with a protective layer of Chromium oxide.
