Question

Electrodes used in anodizing process are:

• A. Iron as cathode and work piece as anode
• B. Lead as cathode and work piece as anode
• C. Work piece as cathode and copper as anode
• D. Work piece as cathode and zinc as anode

Hint:

In anodizing, always remember: \textbf{work piece = anode} (undergoes oxidation), and the cathode must be inert — often lead is used.

Answer 1

The Correct Option is B

Step 1: Understanding Anodizing
Anodizing is an electrolytic process used to increase the thickness of the natural oxide layer on the surface of metal parts, most commonly aluminum. The purpose is to enhance corrosion resistance, surface hardness, and aesthetic appearance. Step 2: Electrode Configuration in Anodizing
In anodizing, the metal work piece (usually aluminum) is connected to the anode of the power supply, meaning it loses electrons and undergoes oxidation. A suitable inert or corrosion-resistant material is chosen as the cathode, which does not dissolve into the electrolyte. Lead is often used for this purpose due to its resistance to corrosion and chemical inertness. Step 3: Evaluating the Options
- (A) Iron as cathode may corrode or react, which is not ideal.
- (B) Correct: Lead is inert and ideal as the cathode. The work piece is correctly used as anode.
- (C) Wrong polarity — work piece should be anode.
- (D) Again, wrong polarity — work piece should not be cathode. Conclusion: For the anodizing process, the work piece acts as the anode, and a material like lead acts as the cathode.