兩種金屬之間也存在電位差，所以會導致電位低的金屬加速腐蝕，反之，電位高的金屬則會受到保護，例如：銅的標準還原電位差0.34 volts，鐵則是－ 0.44 volts，當兩者相接時，鐵會加速腐蝕。
Potential difference corrosion solution
• When two different metals are in contact
• Lower potential will begin to corrode first
• The greater the potential difference, the faster the response
Accelerated corrosion factor
• A sufficient amount of water, oxygen, ions
• Small anode area and large cathode area
• High pressure, high temperature environment
Metal, because of its abundant production and easy processing, makes it one of the most widely used materials in construction, bridges, shipbuilding, etc. However, due to its characteristics, as long as it is exposed to the air, there will be an oxidation reaction, and partial oxidation will cause metal damage. The most easily overlooked is the "isometallic corrosion" condition. If it is not established, it is easy. Cause an unexpected disaster.
What is "potential corrosion"?
The oxidation of metal is actually a natural phenomenon. Any kind of material will have this phenomenon. If it occurs in iron, it will rust. If it is expressed in copper, it will produce green rust in the outer layer.... All are different. Some metals are not affected in nature, and some metals are corroded, causing irreparable damage.
There are three main causes of metal corrosion: chemical corrosion, electrochemical corrosion, and biological corrosion. Among them, "electrochemical corrosion" is the most common, that is, the oxidation reaction that is generally known, that is, the reaction of the metal itself with water and oxygen in the air, and finally the loss of electrons and the retention of oxides.
Why does metal lose electrons? It is because the "standard reduction potential difference" is lower than oxygen, so the electrons are taken away by the oxygen with high potential, resulting in structural damage and affecting the original characteristics. And this phenomenon of corrosion caused by the potential difference, we call it "potential corrosion"
Corrosion caused by two different metals
But what few people know is that when two different metals are put together, they actually accelerate corrosion. For example, if the window frame and the lock are made of different metals, the contact surface is easily corroded.
The reason why the dissimilar metal joint accelerates the corrosion is because different metals, such as iron, aluminum, steel, copper, etc., have different "potentials", just as the potential of iron is lower than oxygen, so it will cause rust. .
There is also a potential difference between the two metals, which will cause the metal with low potential to accelerate corrosion. On the contrary, the metal with high potential will be protected. For example, the standard reduction potential difference of copper is 0.34 volts, and the iron is - 0.44 volts. When connected, iron accelerates corrosion.
Although the problem of local corrosion does not cause a large loss of metal materials, it may cause sudden damage due to imperceptibility, and even unpredictable disasters. For example, if the pipeline is made of different metal materials, local perforation may occur. The situation that causes gas leakage and liquid outflow may cause fire or explosion.
Therefore, the problem of metal potential difference corrosion can not only look at the surface, but must establish the correct concept, and thoroughly prevent it. It must be isolated in places where there are joints of different metals, especially for hanging or fixing parts outside the building, otherwise it will be corroded. The resulting loss will not only be limited to materials and money, but will cause irreparable damage.
Ju Su Xin material co.,ltd can provide an effective solution for metal potential differential corrosion, efficient and qualified by government agencies.