November 8, 2022
I. The whole process of etching galvanized sheet
In the whole application cycle time of galvanized sheet, the first corrosion is the air oxidation of the surface layer of hot dip galvanized layer, which is transformed into "white rust". After a while, the "white rust" on the surface is further reflected in the wet and cold gas and the residual vapor such as carbon dioxide, transforming into "macula". When the galvanized sheet has been used for a long time, the corrosion of hot dip galvanized layer is more serious, and the steel base loses the "duty corrosion prevention" effect of zinc, and it just starts air oxidation and transforms into "red rust". Once the steel base begins air oxidation, the erosion rate becomes more and more rapid, and the galvanized sheet comes to an end of its service life.
Two, harm the key elements of galvanized sheet erosion
1. Air humidity
The amount of water vapor contained in a gas is expressed as ambient humidity. When the temperature is certain and the air humidity is low, the rust is slow; When the air humidity increases slowly, over a certain degree, the rust rate suddenly increases significantly.
2. Temperature
Under a certain humidity condition, when the metal material is corroded, the rust rate increases to about 2 times when the temperature rises 10℃. When the temperature is greatly reduced, it will cause the metal surface essence dew, resulting in accelerated erosion. If the temperature difference between day and night is large, or the outdoor temperature difference is large, it is the essence of dew. The corrosion is more serious when the essence is produced during the cycle time. In wet, cold and musty rain, very hot and rainy or foggy areas or season air humidity is very large, metal materials rust easily produced.
3. co2
Water and oxygen are the key factors of metal rusting in air. The shrinking water layer adsorbed in the air and on the surface of the metal is too thin, so co2 is very easy to melt and penetrate into it, which promotes the depolarization process of oxygen to carry out very successfully, and plays a key role in the erosion of the air.
4. Environmental pollution elements
When there is environmental pollution in the gas or the metal surface is not clean, under the low air humidity, the metal material will also quickly erode. When the ambient humidity is below the critical value, the air humidity rises again, and the corrosion rate further and slowly expands.
