Mechanical Engineering - Workshop Technology - Discussion

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.

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.

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

Galvanizing - coating zinc to steel.

Anodising - oxidizing process for aluminum and magnesium.

Parkerising - phosphate coating to steel.

Sherardizing - zinc diffusion.

How does zinc diffuse?

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. 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.

Sherardising is ideal for small parts and parts that require a coating of inner surfaces, such as batches of small items. Part size is only limited by the drum size. It is reported that pipes up to 6 m in length for the oil industry are sherried. If the metal surface is free of scale or oxides, no pretreatment is needed. The process is hydrogen free, therefore a hydrogen embrittlement is excluded.

What is sherardizing?