Mechanical Engineering - Workshop Technology - Discussion

What about the parkerising process?

Sherardizing is a process of galvanization of ferrous metal surfaces, also called vapour galvanising and dry galvanising. 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 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 sherardized. [citation needed] 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.

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.

What is the correct answer?

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 a diffusion process in which articles are heated in the presence of zinc dust.

The process is normally carried out in a slowly rotating closed container at temperatures ranging from 320-500 degree C.

Why not Galvanizing?

If it's sherardizing and galvanising then what should be the answer?

Galvanising is the process of applying a coating of zinc to steel, in order to protect it against corrosion. The most common method used for the majority of sizes of steel members or fabrications is hot dip galvanising which involves the entire immersion of the steel product into a bath of molten zinc.