1. Environmental factors of corrosion
Latitude and longitude, temperature, humidity, total radiation (uv intensity, sunshine duration), rainfall, pH value, wind speed, wind direction, corrosive sediment (C1, SO2).
2. The influence of sunlight
Sunlight is electromagnetic wave, according to the energy and frequency of the level is divided into gamma rays, X-rays, ultraviolet, visible light, infrared, microwave and radio waves. The ULTRAVIOLET spectrum (UV) belongs to the high frequency radiation, which is more destructive than the low energy spectrum. For example, we know that the dark spots on the skin and skin cancer are caused by the sun’s ultraviolet rays. UV can also break the chemical bonds of a substance, causing it to break, depending on the wavelength of UV and the strength of the chemical bonds of the substance. X-rays have a penetrating effect, and gamma rays can break chemical bonds and produce free charged ions, which are fatal to organic matter.
3. The impact of temperature and humidity
For metal coatings, high temperature and humidity contribute to oxidation reaction (corrosion). The molecular structure of paint on the surface of color coating board is easy to be damaged when it is in high temperature environment for a long time. When the humidity is high, the surface is easy to condensation and electrochemical corrosion trend is enhanced.
4. The influence of ph on corrosion performance
To metal deposits (zinc or aluminum) they are all amphoteric metals and can be corroded by strong acids and bases. But different metal acid and alkali resistance ability has its own characteristics, galvanized plate alkaline resistance is slightly stronger, aluminum zinc acid resistance is slightly stronger.
5. The impact of rain
The corrosion resistance of rainwater to painted board depends on the structure of the building and the acidity of rainwater. For buildings with a large slope (such as walls), rain water has a self-cleaning function to prevent further corrosion, but if the parts are molded with a small slope (such as roofing), rain water will deposit on the surface for a long time, promoting coating hydrolysis and water penetration. For the joints or cuts of steel plates, the presence of water increases the possibility of electrochemical corrosion, orientation is also very important, and acid rain is more serious.
Post time: Jun-10-2022