1. Introduction to Sacrificial Anodes

Electrodes are fundamental components in both industrial production and daily life. Among them, sacrificial anodes—commonly made of aluminum, zinc, or magnesium—play an essential role in corrosion prevention. However, few people truly understand how they work. This article explains the concept and function of sacrificial anodes with expert insights.

2. Expert Explanation and Basic Principle

According to experts specializing in aluminum alloy anode development, a sacrificial anode is a metal that gradually dissolves as electric current flows through it—hence the term “sacrificial.” Because these anodes corrode over time, they must be installed where replacement is easy and safe.

Low-potential metals such as magnesium, zinc, and aluminum alloys are typically used. During operation, electrochemical oxidation occurs at the anode surface, forming an oxide film that enhances corrosion resistance, hardness, and wear resistance, while protecting the underlying metal structure.

3. Cathodic Protection Methods

Cathodic protection is achieved through two main methods:

• Sacrificial Anode System — A galvanic cell system in which the anode metal corrodes naturally to protect the structure.

• Impressed Current System — An electrolytic cell driven by an external DC power source to control potential and current distribution.

For example, when using Fe electrodes with NaCl or NaOH electrolyte, Fe²⁺ ions are released at the anode while hydrogen evolves at the cathode, promoting electrolysis and demonstrating the oxidation–reduction behavior of metals.

4. Key Components and Questions Explained

1. What is the role of the power supply?
          It provides continuous current to the cathodic protection system, ensuring stable potential control. Typical units include constant current, constant voltage, and constant potential rectifiers.

2. What is the sacrificial anode cathodic protection system?
          It connects a more active metal (more negative potential) to the protected metal. The sacrificial metal corrodes instead, generating current that protects the primary structure.

3. What are the components of the impressed current cathodic protection system?
          Power supply, control cabinet, auxiliary anode, coke (carbon) backfill, cables, reference electrodes, test piles, and insulation devices are all included in the complete system.

4. What are the main types of power supplies?
          Rectification types include thyristor, magnetic saturation, and CNC high-frequency switching. The CNC switching rectifier provides the best accuracy, smallest ripple, and highest efficiency, making it ideal for modern corrosion protection systems.

5. Summary

Sacrificial anodes are a cornerstone of modern corrosion prevention. Whether in pipelines, storage tanks, or marine structures, selecting the right anode type and cathodic protection method can significantly extend service life and ensure safety in industrial operations.