Question

What is meant by anodizing agent? Why is it done?

Answer 1

Anodizing is a process which is used for producing oxide layers on metal surfaces. Mostly aluminum is used for anodizing. It is done to make the metal corrosion resistant, durable and decorative. Solution of sulfuric acid is used to produce anodizing coatings.

Complete step by step answer:
Anodizing is referred to as an electrolytic process in which an oxide layer is formed on the surface of metal. The thickness of the oxide layer is typically 5-30 micrometers. Mostly anodizing is done on aluminum and its alloys. The surface of aluminum is washed and cleaned properly on which anodizing is to be done. It is then placed in an electrolytic solution; mainly sulfuric acid is used for this process. Aluminum is made anode and the plates suspended in the electrolyte are made cathode. Pores are created on the surface of aluminum during the electrochemical process as positive ions escape from it and get attracted towards cathode. These pores then form a regular pattern and begin to erode down in the substrate. Now aluminum ions combine with oxygen ions to form an oxide layer and anodizing is achieved. This oxide layer formed acts as a barrier layer and protects the metal surface from corrosion. Anodizing makes the metal surfaces more decorative and protects them from wear-tear by making them corrosion resistant and increasing their durability.

Note:
Other non-ferrous metals like magnesium and titanium can also be anodized. It is used to improve the metal surface chemistry. Anodizing process is completely safe, an anodized finish is non-toxic and heat resistant to the melting point of the metal which is used for anodizing. There also exists Hard Anodizing in which the thickness of the layer is more compared to normal anodizing.