Mechanical Engineering - Workshop Technology - Discussion

Galvanizing - coating zinc to steel.

Anodising - oxidizing process for aluminum and magnesium.

Parkerising - phosphate coating to steel.

Sherardizing - zinc diffusion.

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.

How does zinc diffuse?

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

Why sherardising is ideal for small articles?

What is the Difference between Sherardizing and galvanising? Explain.

Sherardizing is a process of galvanization of ferrous metal surfaces, also called vapour galvanising and dry galvanizing. The process is named after the British metallurgist Sherard Osborn Cowper-Coles (son of naval inventor Cowper Phipps Coles) who invented and patented the method ca. 1900. This process involves heating the steel parts up to ca. 500°C in a closed rotating drum that also contains metallic zinc dust and possibly an inert filler, such as sand. At temperatures above 300°C, zinc evaporates and diffuses into the steel substrate forming diffusion bonded Zn-Fe-phases.

Sherardizing is a process of galvanization of ferrous metal surfaces, also called vapour galvanising and dry galvanizing.

Normal galvanizing is a different process, diffusion doesn't take place there.

Sherardizing is the diffusion process and galvanising is the coating process both zinc oriented but different.

Sherardizing provides a zinc diffusion coating on iron or copper based materials.