The surface of the steel drum is most easily oxidized and corroded before coating. The scale and rust on the surface are mainly ferrous oxide, ferric oxide, hydrous iron oxide and triiron tetroxide. If the scale and rust on the surface are not removed before the steel drum is painted, it will affect the adhesion, decoration and service life of the paint film on the surface of the steel drum. Because the rust structure is loose, the surface of the steel drum is not firmly attached, and it is easy to fall off along with the coating. The scale will form triiron hydride under the action of water raft, and the volume will increase, causing the film to foam, crack and fall off. In the corrosive battery composed of the oxide film under the paint film and the metal iron of the steel drum, it is a cathode, which promotes the corrosion of the metal on the surface of the steel drum, so that the coating is quickly destroyed.
The method of removing rust on the surface of steel drum is divided into two major categories: chemical method and mechanical method.
Chemical derusting is the use of chemical melons or electrochemical melons to dissolve the general rust, oxide scale and various corrosion products from the surface of the steel drum without affecting the steel base metal. The most common chemical descaling method is pickling, which uses organic or inorganic acids to fold oxides and yellow rust from the surface of the steel drum from the surface of the steel drum.
Mechanical derusting is the use of mechanical forces such as friction, hammering, scouring, etc., so that the abrasive grains remove rust, high temperature oxide scale and other dirt on the surface of the steel drum. The most common mechanical descaling method for steel drum enterprises is manual grinding, mechanical grinding, rust removal, manual rust removal using simple tools, and the method is simple and easy, but the labor intensity is high, the production efficiency is low, and the rust removal quality is poor. Generally only loose or lighter rust can be removed.