Rust is a very common name and we hear it in our daily lives. It is the Iron Oxide which is formed due to Corrosion. Its chemical formula is Fe2O3. The process of rust formation is called rusting, which is an electrochemical process.
When iron comes in contact with the atmospheric moisture, water combines with the Carbon dioxide and forms carbonic acid. This acid dissolves the iron. Some water breaks down into hydrogen and oxygen. The free oxygen combines with the dissolved iron and iron oxide is formed. The chemical equation for the rusting process:
- 2Fe(s) + 2H2O(l) + O2(g) 2Fe2+(aq) + 4OH–(aq)
- Fe2+(aq) + 2OH–(aq) Fe(OH)2(s)
- Fe(OH)2(s) =O2=> Fe(OH)3(s)
- Fe(OH)3(s) =dehydrates=> Fe2O3.nH2O(s) {This is the rust.}
Now that we are aware of what rust is and how it is formed, it becomes an unwanted coating on the metal surfaces or machine tools. Rust formation of tools affects the tool, as it damages the surface and makes it rough.
Also Read: 18 Mechanical Properties Of Material Which Every Mechanical Engineer Should Know
Rust Removal Methods:
The common method used for removing rusts is by using the Vinegar. The rust coated tool is dipped in vinegar and kept aside for few hours. It is then scrubbed for its removal.
Lime and salt is another method used. In this process, salt is spread all over the rusted tool and lime juice is poured all over it and left to work. Then it is removed by scrubbing.
Sandpaper, Steel wool, Wire Brush are sometimes used for rust removal. Depending on the surface of the machine tool different scrubbing materials are used. Abrasive surfaces are excellent tools for rust removal. Simply scrape the rusted area till it disappears. But using this scrubbing method for smooth surfaces is not advisable as it will scratch the shiny surface and make its appearance bad.
Usage of chemicals also comes into account after natural products. The chemical is spread over the affected area which converts it to water-soluble compound that can be easily wiped away. Most of the rust removal chemicals are composed of phosphoric acid or oxalic acid.
Also Read: 18 Mechanical Properties Of Material Which Every Mechanical Engineer Should Know
Another method for rust removal is electrolysis. But this is not suitable for non-ferrous metals. In this process low voltage, DC current is used. The electrolyte used is water and some sodium carbonate. The rusted tool is hanged dipped in the solution. The tool is attached to the negative end of the current supply. The positive end is connected to the anode. When the power is turned on the rust is removed as flakes. The reaction occurs at the surface and the rust gets off.
Leave comments if anything is missed or wrong. 🙂
