What is the Difference Between Anodic and Cathodic Protection?

Anodic and cathodic protection are both electrochemical processes used to protect metal structures from corrosion, but they work in different ways:

• Anodic Protection: In this process, the surface to be protected acts as the anode. The metal to be protected is made the anode by making the potential more positive (above the corrosion potential). This method is less common and is usually applied to stainless steels and other corrosion-resistant metals.
• Cathodic Protection: This is the most commonly used method and is widely used on carbon-steel structures and other structural metals. In cathodic protection, the surface to be protected acts as the cathode. There are two types of cathodic protection:

1. Sacrificial-Anode Cathodic Protection: This operates as a galvanic cell, where the structure to be protected is connected to a metal anode of higher electrochemical activity, which corrodes instead of the protected structure.
2. Impressed-Current Cathodic Protection: This operates like an electrolytic cell, where an external current is applied from a power source to protect the structure.

In summary, the key difference between anodic and cathodic protection is that, in anodic protection, the surface to be protected acts as the anode, whereas, in cathodic protection, it acts as the cathode.

Comparative Table: Anodic vs Cathodic Protection

The main difference between anodic and cathodic protection lies in the role of the protected metal surface in the electrochemical process. Here is a comparison table highlighting the differences between anodic and cathodic protection:

In anodic protection, the protected metal surface is made the anode in the electrochemical process, suppressing its reactivity by adjusting its potential. On the other hand, in cathodic protection, the protected surface acts as the cathode, reversing the flow of current between two dissimilar electrodes.