Rust is a natural corrosive process observed on steel and iron. It is caused due to the action of oxygen and moisture on a metallic surface. Rust is actually the reddish brown oxide formed on the surface of the metal when it comes in direct contact with the atmosphere. However, rust takes place not only on iron and steel but also on metals like zinc and aluminum.
Stainless steel does not corrode as easily as iron but it is not stain proof. Stainless steel is an alloy of iron. Although, there is a layer of chromium oxide on it which prevents further corrosion, it cannot be regarded as damage proof. It is essential to learn a little about rust prevention methods if you want to stop rust on metals.
Prevention and removal of rust
The most common way to prevent rust is to not allow the steel or iron to come in contact with the atmospheric oxygen. This is achieved by applying a rust preventive coating on the surface of the metal.
A very natural process is to dip the corroded metal in an undiluted solution of vinegar, which softens the rust which then can be scrubbed off. Even baking soda when mixed with water creates a paste, which if applied on the corroded metal and allowed to sit and dry, reduces surface corrosion.
Citric acid present in cola drinks cleans corrosion on metal. The commonest way to stop rust on metals is by scrapping or brushing the metallic surface using sandpaper.
Another popular rust removal method is to apply phosphoric acid, which converts iron oxide into black ferric phosphate on direct application to rusted iron. Sometimes, rust leaves large spots on the surface of steel, which can be filled up by a product made from fiberglass called bondo.
Galvanization and its benefits
Galvanization is a widely used industrial procedure for rust removal. The first step is to dip the steel in molten zinc, which protects it from corrosion (The corrosion resistance properties of zinc are greater than that of iron or steel). Zinc reacts with oxygen to form zinc oxide, which again reacts with water molecules in air to form zinc hydroxide.
Zinc hydroxide, in turn, reacts with carbon dioxide to form an impermeable, insoluble layer of zinc carbonate, which adheres well to the underlying zinc thus protecting it from further corrosion. In this process, zinc acts as the sacrificial anode and it cathodically protects the exposed steel.
This means that even if the coating is scratched or abraded the exposed steel will be protected from corrosion by the remaining zinc. This is the advantage that galvanizing has over other methods like enamel, powder coating or paint.
Moreover, galvanizing is cost effective and has a long low maintenance service life. So, it is regarded as one of the most efficient methods to stop rust on metal. Remember, rust and corrosion can severely damage the object so prevention is definitely better than cure in this case.
