Sherardising is a process of

galvanization Galvanization or galvanizing (American and British English spelling differences, also spelled galvanisation or galvanising) is the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot ...

of ferrous metal surfaces, also called vapour galvanising and dry galvanizing. The process is named after British metallurgist

Sherard Osborn Cowper-Coles Sherard Osborn Cowper-Coles (8 October 1866 – 9 September 1936) was a British metallurgist, and inventor of the sherardising process of galvanization. Early life He was born in Ventnor, the fourth son of naval inventor Captain Cowper Phipps ...

(son of naval inventor

Cowper Phipps Coles Captain Cowper Phipps Coles, C.B., R.N. (1819 – 7 September 1870), was an English naval captain with the Royal Navy. Coles was also an inventor; in 1859, he was the first to patent a design for a revolving gun turret. Upon appealing for publi ...

) who invented and patented the method c. 1900. This process involves heating the steel parts up to c. 500 °C in a closed rotating drum that contains metallic

zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...

dust and possibly an inert filler, such as sand.H. G. Arlt, "Finishes on the Metal Parts of Telephone Apparatus", ''Bell Laboratories Record'', Volume 9(4), 175 (December 1932) 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 coating of inner surfaces, such as batches of small items. Part size is limited by drum size. It is reported that pipes up to 6 m in length for the oil industry are sherardised. If the metal surface is free of scale or oxides, no pretreatment is needed. The process is hydrogen-free, hence hydrogen embrittlement is prevented.

Application

During and shortly after

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

, German 5

Pfennig The 'pfennig' (; . 'pfennigs' or ; symbol pf or ₰) or penny is a former German coin or note, which was the official currency from the 9th century until the introduction of the euro in 2002. While a valuable coin during the Middle Ages, i ...

and 10 Pfennig coins were sherardised.

Standard

BS EN 13811: 2003 (withdrawn replaced by BS EN ISO 17668:2016) Sherardizing. Zinc diffusion coatings on ferrous products. Specification BS EN ISO 14713-3: 2017 Zinc coatings. Guidelines and recommendations for the protection against corrosion of iron and steel in structures. Part 3. Sherardizing

References

{{reflist Chemical processes Corrosion prevention Metal plating Zinc sk:Zinkovanie

Application

Standard

See also

References