The so-called non-rusting means that it has atmospheric corrosion resistance.
Why is galvanized steel plate corrosion resistant? Mainly reflected in the following aspects:
1) First, after galvanizing, the coating is intact
Since zinc isolates the air from the steel base, only zinc corrosion occurs. Since the zinc corrosion products have a good protective effect on zinc, the corrosion rate is very slow, and the lifespan is 15 to 30 times that of ungalvanized steel plates.
For example, in a neutral or slightly acidic (pH>5.2) atmospheric environment, the turbid products formed after corrosion of the galvanized metal steel plate are insoluble compounds (zinc hydroxide, zinc oxide and zinc carbonate), and these products will precipitate as The form precipitates and forms a dense thin layer, generally up to 8µm thick. This film has a certain thickness, is not easily soluble in water, and has strong adhesion. Therefore, it can act as a barrier between the atmosphere and the galvanized sheet to prevent further corrosion.
2) If the zinc layer is damaged
sacrificial corrosion
The zinc in the coating and the iron in the steel strip form a primary battery in a humid environment. Since the standard electrode potential of zinc is only -1.05V, which is lower than iron's -0.036V, zinc serves as the anode and is oxidized, while iron serves as the cathode. be protected. Since the products after zinc corrosion are very dense, the reaction speed is very slow, which means that the overall corrosion resistance is greatly improved. This method of embalming is called sacrificial embalming.
After the coating is damaged, the steel base will also be protected due to sacrificial corrosion. However, if the damage reaches the steel base, the sacrificial protection effect will become weaker after the steel base is damaged, so deeper damage must be treated with anti-rust treatment (coating paint, etc.) to avoid further corrosion.
When the protective galvanized coating is damaged and part of the steel surface is exposed to the atmospheric environment, zinc and iron form a micro-battery. The potential of zinc is significantly lower than that of iron, and zinc acts as an anode to protect the steel substrate as a sacrificial anode. Function to prevent corrosion of steel plates.
GNEE steel, located in Henan Province, China, is a leading galvanized steel supplier, supplying steel coils, galvanized steel sheets, and galvalume sheets. Our products are corrosion-resistant and fully stocked, so we can guarantee short delivery times. We have a technical team to ensure that the product you inquire about is accurate. Our company sells well in countries in America, Europe, the Middle East and East Africa. Our aim is to operate with integrity, provide enthusiastic service, and have a professional team. Trust us, choose us, we will make you very satisfied and look forward to long-term cooperation with you. Get a quote now!
