1) Surface cleaning: proper cleaning methods must be selected according to the nature of the surface to be rusted and the current conditions. Generally, solvent cleaning method, chemical treatment cleaning method and mechanical cleaning method are commonly used.
2) After the surface is dry and cleaned, it can be dried with filtered dry compressed air, or dried with a dryer at 120 ~ 170 ℃, or wiped with clean gauze.
1) Immersion method: some small items are immersed in antirust grease and a layer of antirust grease is adhered to their surface. The thickness of oil film can be achieved by controlling the temperature or viscosity of antirust grease.
2) The brushing method is used for outdoor construction equipment or products with special shapes that are not suitable for soaking or spraying. During brushing, attention should be paid not only to avoid accumulation, but also to prevent missing coating.
3) spray method can not be used to soak some large antirust substances by immersion method. Generally, the filter compressed air of about 0.7Mpa pressure is used for spraying in the clean air area. Spray method is suitable for solvent dilution antirust oil or thin layer antirust oil, but must adopt perfect fire protection and labor protection measures.
What are the main factors affecting bearing corrosion?
The main causes of bearing corrosion are external and internal factors:
① Chemical composition and structure of bearing material itself;
② Bearing surface finish (oxygen concentration difference, battery corrosion);
③ Solution composition and pH value in contact with bearing surface;
④ Ambient temperature and humidity;
⑤ Various environmental media in contact with the bearing surface.
Why does hand sweat cause bearing corrosion?
Human sweat is a colorless, transparent or light yellow liquid with salty taste and weak acid. Its pH value is 5 ~ 6. In addition to sodium, potassium, calcium and magnesium salts, it also contains a small amount of urea, lactic acid, citric acid and other organic acids. When sweat comes into contact with the bearing, a layer of sweat film will be formed on the bearing surface, which will cause electrochemical effect on the bearing and corrode the bearing. Sweating is inevitable. To prevent corrosion caused by hand sweat, production personnel should wear gloves, finger covers, or take parts with special tools. Do not touch the product with hands.Rust Prevention Method
What are the methods of bearing rust prevention?
The common way to prevent rust is to dress the iron – paint the iron surface or coat it with other bearings that are not easy to rust For example, cars wear shiny spray paint; The heating pipe is coated with aluminum paint; Tin plated tinplate for cans; The white iron sheet on the roof is coated with zinc; Your fountain pen is plugged in and plated with chromium or nickel A more thorough way is to inject iron with a “strong heart needle” – adding other bearings to make stainless alloy The famous stainless steel is an alloy made by adding a little nickel and aluminum to the steel.Rust Prevention Method
Anti rust measures shall be taken according to the causes of bearing corrosion. Common methods include:Rust Prevention Method
[change the internal structure of the bearing] for example, make various corrosion-resistant alloys, such as adding chromium and nickel into ordinary steel to make stainless steel.Rust Prevention Method
[protective layer method] cover the bearing surface with a protective layer to isolate the bearing products from the surrounding corrosive medium, so as to prevent corrosion. For example: 1. Apply oil, Vaseline, paint or cover enamel, plastic and other corrosion-resistant non bearing materials on the surface of steel parts. 2. Use electroplating, hot plating, spray plating and other methods to coat the steel surface with a layer of bearings that are not easy to be corroded, such as zinc, tin, chromium, nickel, etc. These bearings often form a dense oxide film due to oxidation, so as to prevent the corrosion of steel by water and air. 3. A fine and stable oxide film is formed on the surface of steel by chemical method. For example, a thin black Fe3O4 film is formed on the surface of machine parts, guns and other steel products.Rust Prevention Method
[electrochemical protection method] use the principle of primary cell to protect the bearing and try to eliminate the primary cell reaction causing electrochemical corrosion. Electrochemical protection methods are divided into anode protection and cathode protection. Cathodic protection is widely used.Rust Prevention Method
[treatment of corrosive media] eliminate corrosive media, such as often wiping out bearing equipment, placing desiccant in precision instruments and adding a small amount of corrosion inhibitor that can slow down the corrosion rate.Rust Prevention Method
[electrochemical protection] the protected bearing is used as the cathode of the corrosion battery to prevent it from corrosion, so it is also called cathodic protection method. There are two main methods:Rust Prevention Method
[sacrificial anode protection method] this method is to connect the active bearing (such as zinc or zinc alloy) to the protected bearing. When electrochemical corrosion occurs, the active bearing will react as the negative electrode, so as to reduce or prevent the corrosion of the protected bearing. This method is often used to protect steel piles and ship shells in water, such as the protection of steel gates in water. Usually, several zinc blocks are welded below the waterline of the ship shell or on the rudder close to the propeller to prevent the corrosion of the ship shell.Rust Prevention Method
[impressed current protection method] connect the protected bearing to the negative pole of the power supply, and select another conductive inert material to connect to the positive pole of the power supply.
After power on, the negative charge (electron) will accumulate on the bearing surface, so as to inhibit the loss of electron in the bearing and achieve the purpose of protection. This method is mainly used to prevent the bearing equipment in soil, sea water and river water from corrosion.
Another method of electrochemical protection is called anode protection method, which is the process of passivating the anode within a certain potential range through applied voltage. It can effectively block or prevent the corrosion of bearing equipment in acid, alkali and salt.