There are four methods for removing rust on metal surfaces: manual treatment, mechanical treatment, chemical treatment and flame treatment.
(1) Manual processing:
Manual treatment mainly uses tools such as shovel, wire brush, emery cloth, broken hacksaw blade, etc., to remove rust by manual knocking, shoveling, scraping, brushing, and sanding. This is the traditional rust removal method of painters and the easiest method. , There are no restrictions on the environment and construction conditions, but due to poor efficiency and effects, only a small range of rust removal treatment can be applied.
(2) Mechanical derusting method
Mechanical rust removal method mainly uses some electric and pneumatic tools to achieve the purpose of removing rust. Commonly used electric tools such as electric brushes and electric grinding wheels; pneumatic tools such as pneumatic brushes. Electric brushes and pneumatic brushes use the rotation of a special round wire brush to remove rust or oxide scale by impact and friction. Especially for surface rust, the effect is better, but it is difficult to remove deep rust spots. The electric grinding wheel is actually a portable grinding wheel machine, which can be moved at will in the hand. The high-speed rotation of the grinding wheel is used to remove rust. The effect is good, especially for the deeper rust spots. It has high work efficiency, good construction quality, and easy use. The ideal rust removal tool. But be careful not to punch through the metal skin during operation.
(3) Sandblasting, shot blasting
Sand blasting and shot blasting are the same as the previous section to remove the old film.
(4) Flame treatment method The flame treatment method uses a gas torch to burn a small amount of deep rust spots that are difficult to remove by hand, so that the high temperature causes the rust oxide to change the chemical composition to achieve the purpose of rust removal. When using this method, be careful not to burn through the metal surface and prevent thermal deformation of a large surface.
(5) Chemical treatment method
The chemical treatment method is actually pickling and rust removal, which uses an acidic solution to chemically react with metal oxides (rust) to form salts and leave the metal surface. Commonly used acid solutions are: sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid. During the operation, apply acidic solution to the metal rust part and let it chemically react with the rust to be removed. After the rust is removed, it should be rinsed with clean water, and neutralized with a weak alkali solution, then rinsed with clean water, dried and dried to prevent rapid rust.
The pickled metal surface needs to be roughened or phosphated, mainly to increase the adhesion between the metal surface and the primer.
When diluting concentrated sulfuric acid, slowly pour the sulfuric acid into the water in the container and keep stirring. Do not do the reverse operation to prevent the sulfuric acid from splashing and hurting people.
