The problem of impressed current cathodic protection

Satisfied answer

This method can protect steel equipment from erosion, because the natural electron flow of metal oxidation is opposite to the direction of the applied current. I don't know, what is the natural electron flow direction of metal oxidation? How to reverse the direction of the impressed current?

Topic of impressed current cathodic protection Law

.

The difference between the so-called Yin and Yang level and the positive and negative electrode lies in that the latter only depends on the level of potential, and the high potential is the positive electrode; The former is defined as the anode where oxidation occurs, and vice versa.

Please refer to the Cathodic Protection Manual for details.

An impressed current is used to protect the protected body (like steel) from erosion by giving it a cathodic current to make up for the electrons lost by Fe.

On the other hand, the external power supply has positive and negative poles, and the positive pole can only be connected with copper, and the positive pole is the electron flow of copper to the positive pole of the external power supply, so the copper loses electrons to be oxidized, and the copper is "sacrificed". The electrons gained by copper, the anode, are sacrificed to protect the zinc, so we call this cathodic protection by sacrificing the anode. In a galvanic cell, obviously, the direction of the current is from zinc to copper, so that zinc loses electrons and is oxidized.

And cathodic protection, is to protect easily oxidized zinc, so as to give zinc an external electron flow, so that the external power supply is connected to the negative electrode of zinc, so that the external power supply will transfer electrons to zinc, so as to offset the loss of zinc to copper electrons, to prevent zinc oxidation.

For example, Cu and Zn, if the two contact to become a galvanic cell, according to the fluidity of the metal, resulting in the loss of zinc electron erosion, zinc is oxidized. In the above mentioned electrolytic cell with an external power supply, the zinc is the ultimate electron, the electrode reduction reaction, is the cathode, so called cathodic protection.

Metals lose electrons in oxidation and become cations, while iron changes to Fe2+ and then to rust.

We often talk about cathodic protection at the expense of the anode.