Which method is commonly used for cathodic protection?

The method of using sacrificial anodes is widely recognized as a standard approach for cathodic protection. This technique involves attaching materials that are more reactive to corrosion, typically zinc, magnesium, or aluminum, to a metal structure that needs protection, such as pipelines or ship hulls. These sacrificial anodes act by corroding preferentially, thereby sacrificing themselves and protecting the underlying metal from corrosion. This process effectively redirects the electrochemical reactions that would normally attack the protected metal.

In contrast, the other options do not serve as effective forms of cathodic protection. Enhancing paint thickness may offer some degree of physical protection against environmental factors but does not address the electrochemical reactions that lead to corrosion. Applying heat to the substrate has no relevance in preventing corrosion or providing cathodic protection. Likewise, using alkaline solutions does not serve as a method for cathodic protection; it may alter pH levels but does not create the necessary electrical conditions to protect metal from corrosion. Thus, the use of sacrificial anodes stands out as the appropriate and effective method for cathodic protection in various applications.