Corrosion refers to the oxides produced when the metal surface comes into contact with oxygen, moisture, and acidic substances in the air, such as Fe0.Fe3O4.FeO3, etc., is generally called rust. The rust removal methods of diesel generator set mainly include mechanical method, chemical pickling method, and electrochemical corrosion method.
(1) The chemical method is a chemical method to dissolve the corrosion products on the metal surface to dissolve them. The principle of this phenomenon is the dissolution of metals by acid and the mechanical action of hydrogen generated in chemical reactions on the rust layer, which causes the rust layer to fall off. Common acids are hydrochloric acid, phosphorus sulfate, and so on. Due to the different metal materials, the chemical composition of the rust-dissolving products used is also different. The selective rust remover and its use conditions are mainly determined by factors such as the type of metal, chemical composition, surface condition, dimensional accuracy of parts, and surface quality.
(2) Electrochemical corrosion refers to putting parts in the electrolyte of direct current and removing rust through a chemical reaction. This method is faster than the chemical method, can better protect the base metal and reduce acid consumption. Generally speaking, there are two situations: one is to treat the de-rusted part as the anode, and the other is to use the rusted part as the cathode. Anode rust removal is due to the dissolution of metal after electrification, and the oxygen on the anode tears the rust layer, causing the rust layer to separate. Cathodic rust removal is because the hydrogen generated after the cathode is energized can reduce iron oxide and the hydrogen tears the rust layer, causing the rust to fall off the surface of the part. The first two methods, the main disadvantage of the former is that the current density is too large, it is easy to be excessively corroded, and cause damage to the surface of the part, so it is suitable for parts with simpler shapes. Although hydrogen is easy to enter the metal, there is no problem of over-corrosion, which causes hydrogen embrittlement and reduces the plasticity of the parts. Therefore, it is necessary to choose an appropriate rust removal method according to the rusted parts. In addition, in actual production, a rust remover prepared from a variety of materials can be used to remove rust and passivate oil. Most metal rooms, except zinc, magnesium, and other metals, can be sprayed, brushed, dipped and other methods can be used.
(3) The mechanical method is to use friction and cutting between the mechanical parts to remove the rust layer on the surface of the parts. Methods such as brushing, polishing, and sandblasting are usually used. Single small-batch maintenance depends on the manual use of wire brushes, scrapers, emery cloth, and other brushes. Scrape or polish the rust layer. Batches of parts or conditional units can be driven by motors or fans to drive various rust removal tools, such as electric grinding, polishing, and rolling. Sandblasting and rust removal is the use of compressed air to spray the sand with a certain size on the surface of the workpiece. It can not only remove rust quickly but also can be used for painting, painting, electroplating, and other processes. After sandblasting, the surface remains clean and has a certain degree of roughness, which can enhance the bonding force between the coating and the component. For the surface of irrelevant parts, only mechanical derusting can be done.
In addition, the surface of the parts is coated with protective paint, which should be completely or partially removed according to the degree of damage and the requirements of the protective layer. To be cleaned, ready to spray paint.
Manual tools are usually used, such as scrapers, sandpaper, wire brushes, or hand-held electric brushes. Various organic solvents, alkaline solutions, etc. can be used as paint removers. Apply to the paint layer of the workpiece to dissolve and soften it, and then use it by hand Tool to remove the paint layer.
Each cleaning process can use a set of cleaning equipment for different purposes, including spray water gun, bathwater gun, spray gun water gun, integral cleaning machine, circulation cleaning machine, etc. What kind of equipment to choose depends on its use and production location.
