What are the methods and measures for chemical corrosion protection in power plants?

Broadly speaking, it can be divided into physical methods and chemical methods. Physical methods do not change the properties of the original metal, while chemical methods change the properties of the original metal. Common ones are:

1 coverage protection-physical method

Cover the metal surface with a protective layer. For example, paint, electroplating or chemical methods form a dense and corrosion-resistant oxide film on the metal surface.

2 change the structure-chemical method

Change the internal structure of metal. For example, chromium and nickel are added to ordinary steel to make stainless steel.

3 electrochemical protection-chemical method

Electrochemical protection law. Because simple metal can't get electrons, as long as the protected metal is used as the cathode of electrochemical device for reduction reaction, the galvanic reaction causing electrochemical corrosion of metal can be eliminated. The specific methods are as follows: a. impressed current cathodic protection. The protected metal is connected to the negative electrode of the power supply through an electrolytic device, and the inert electrode is used as the anode, so long as a strong enough voltage is applied, the protected metal will not be corroded. Cathodic protection of sacrificial anode. Using the galvanic cell device, the protected metal and another metal that loses electrons more easily form a new galvanic cell. When the galvanic cell reaction occurs, the original metal, as the positive electrode (i.e. cathode), is protected and corroded by the external active metal-negative electrode (i.e. anode). In addition, there are methods such as adding corrosion inhibitors to slow down or prevent metals from being corroded.