Difference Between Electroplating and Anodizing

The key difference between electroplating and anodizing is that electroplating is the process of coating one metal on another metal surface whereas anodizing is the process of increasing the thickness of the natural oxide layer on the surface of the metal surfaces.

In the process of electroplating, the object of interest is used as the cathode of an electrochemical cell while in the anodizing process, the object acts as an anode, which leads to its name, anodizing.

CONTENTS

1. Overview and Key Difference
2. What is Electroplating 
3. What is Anodizing
4. Similarities Between Electroplating and Anodizing
5. Side by Side Comparison – Electroplating vs Anodizing in Tabular Form
6. Summary

What is Electroplating?

Electroplating is an industrial and analytical process in which we can coat one metal on another metal using electrical energy. This process involves an electrochemical cell containing two electrodes that are immersed in the same electrolyte. In this process, we need to use the object (that we are going to coat with the metal) as the cathode. Therefore, the anode is either the metal that we are going to apply on the cathode, or it can be an inert electrode.

During the process of electroplating, the system is first given an electrical current from the outside, which makes the electrons in the electrolyte pass from the anode to cathode. The cathode has removable electrons. In the electrolytic solution, there are metal ions that can receive electrons. Thereafter, these metal ions undergo reduction and become metal atoms. Then these metal atoms can deposit on the surface of the cathode. This whole process is called “plating”.

However, we need to carefully choose the electrolyte. If the electrolyte contains other metal ions that can deposit along with the desired metal ion, the plating will be inaccurate. Therefore, the cathode on to which the metal is plated should be clean and free of contaminants. Otherwise, the plating becomes uneven. The major uses of the electroplating process are for decorative purposes or for prevention of corrosion.

What is Anodizing?

Anodizing is an electrochemical process in which electrolytic passivation occurs. This method is important in increasing the thickness of the natural oxide layer on the surface of the metal parts. This process is named as such because the part that we are treating acts as an anode in the electrochemical cell. The process of anodizing can increase the corrosion resistance and wear resistance of the object. Also, it provides the object with a better adhesion for paint primers and glues than bare metal does.

Further, the anodizing technique is useful in preventing galling of threaded components and in making dielectric films for electrolytic capacitors. Most commonly, the anodic films are applied to protect aluminum alloys and for titanium, zinc, magnesium, niobium and zirconium.

What are the Similarities Between Electroplating and Anodizing?

• Both are electrochemical techniques.
• These techniques involve the deposition of a material on a metal surface.

What is the Difference Between Electroplating and Anodizing?

Electroplating and anodizing are important electrochemical processes. The key difference between electroplating and anodizing is that electroplating is the process of coating one metal on another metal surface whereas anodizing is the process of increasing the thickness of the natural oxide layer on the surface of the metal surfaces.

Below infographic tabulates the differences between electroplating and anodizing.

Summary – Electroplating vs Anodizing

Both electroplating and anodizing processes involve the deposition of a material on a metal surface. Both are electrochemical processes.  The key difference between electroplating and anodizing is that electroplating is the process of coating one metal on another metal surface whereas anodizing is the process of increasing the thickness of the natural oxide layer on the surface of the metal surfaces.

Reference:

1. “Anodizing.” Wikipedia, Wikimedia Foundation, 8 Nov. 2020, Available here.

Image Courtesy:

1. “Copper electroplating principle (multilingual)” By Torsten Henning (Multilingual Perhelion) – Own work (Public Domain) via Commons Wikimedia
2. “Cheap carabiners” By User:Polyparadigm – Own work, Public Domain) via Commons Wikimedia