An electrochemical process that thickens the oxide layer on aluminium for protection and appearance.

• A. Powder coating
• B. Anodising
• C. Quality control
• D. Risk assessment

Answer: (B)

Anodising describes an electrochemical process that thickens the oxide layer on aluminium. By placing the aluminium in an electrolytic bath and passing current, the metal acts as the anode and forms a much thicker aluminium oxide layer than occurs naturally. This thicker layer provides improved corrosion resistance and hardness, and its porous structure can be dyed or sealed for enhanced appearance. The oxide growth is built up electrochemically on the surface, giving a durable protective coating that is integral to the metal itself. In contrast, powder coating adds a separate polymer coating rather than growing oxide, and quality control or risk assessment are management activities, not surface treatments of the metal.