Nanjing Shangding Chemical Industrial Co.Ltd

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Tolyltriazole News

What is corrosion?

Metal materials and structures made of them, or in the natural environment under the working conditions, due to its environment medium caused by chemical or electrochemical role of deterioration and damage, this phenomenon is called corrosion. Including the above factors and mechanical factors or work together some physical effects of biological factors such as metal materials in some physical dissolve in the liquid metal can also be classified as metal corrosion category in general, rust specifically to steel and iron base alloy, they are formed under the action of oxygen and water is mainly composed of hydrous ferric oxide corrosion products of rust.
Non-ferrous metals and their alloys can happen but it does not rust, but a form similar to rust corrosion products, such as copper and copper alloy on the surface of the green, is occasionally referred to as the rust.
According to the size of the corrosion when the corrosion area, can be divided into the following kinds:
1. General corrosion.
2. Localized corrosion:
1). Corrosive pitting.
2). Galvanic corrosion.
3). The oxygen concentration cell corrosion.
4). Stainless steel stress rupture.
The factors affecting the corrosion:
1. PH value ( Alkalinity).
2. Temperature.
3. The flow rate of water.
4. Salt content.
5. Corrosive gas.
6. The microorganism.
The damage of corrosion:
1. The corrosion products become part of soft dirt, increase the soft dirt.
2. Damage the equipment.
3. Shorten the service life of the equipment.
4. Increase the cost of repair.
Corrosion control:
1. The use of corrosion resistant material, not easy to be oxidized.
2. Corrosion resistant layer is formed on the metal surface, cut off contact with water.
3. The cathode, anode protection.
4. The use of corrosion inhibitors, passivation of metal.
5. Avoid direct contact of different metals.
Here are the common corrosion inhibitors as following:
1. Membrane type: Poly phosphate, Orthophosphate and Silicate and so on.
2. Oxide film type: Chromate, Molybdate and Tungstate and so on.
3. Metal ion precipitation membrane type: Benzotriazole , Tolyltriazole and Mercaptobenzothiazole and so on.