Mechanical Engineering - Workshop Technology - Discussion

What is the Difference between Sherardizing and galvanising? Explain.

Why sherardising is ideal for small articles?

How does zinc diffuse?

Galvanizing - coating zinc to steel.

Anodising - oxidizing process for aluminum and magnesium.

Parkerising - phosphate coating to steel.

Sherardizing - zinc diffusion.

Sherardizing is a zinc diffusion coating process, which uses zinc vapor to form zinc alloys with the base material.

Sherardising uses a rotating drum to vaporize the zinc which then clings to the steel, whilst galvanizing involves the steel being dipped in a bath containing the zinc.

The correct answer is: sherardizing.

Sherardizing is a zinc diffusion process that involves heating steel in a zinc powder pack to create a zinc-iron alloy layer on the surface. This process is used to provide corrosion protection and wear resistance.

Here's a brief overview of the other options:

- Galvanizing: A process of dipping steel in a bath of molten zinc to create a zinc coating.
- Anodising: An electrochemical process that converts the surface of aluminium into a decorative, durable, and corrosion-resistant finish.
- Parkerising: A phosphating process that involves immersing steel in a phosphoric acid solution to create a corrosion-resistant coating.

Sherardizing is distinct from galvanizing in that it:

- Uses a zinc powder pack instead of a molten zinc bath.
- Creates a zinc-iron alloy layer through diffusion.
- Provides a more uniform and controlled coating thickness.

Sherardizing is commonly used for small parts, such as fasteners, gears, and bearings, where a uniform and corrosion-resistant coating is essential.