Sherardising

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Sherardising or sherardizing is a method of galvanising also called vapour galvanising. It is named for its discoverer Sherard Cowper-Coles (1900), who also patented the process and some other similar processes.[1][2][3] Zinc evaporates and diffuses into the metal target object forming Zn-Fe-phases by heating the object in an airtight container with zinc powder. The temperature that the container reaches normally does not exceed the melting point of zinc. Another method of sherardisation is to expose the intended objects to vapour from molten zinc using a reducing gas to prevent oxidation.

Sherardising is ideal for small parts and parts that require coating of inner surfaces, such as batches of small items. The original system was quite complicated and expensive; however, today there are new systems in use which are simple, cost effective, and use less or no preparatory chemicals, making them environmentally friendly.

Application[edit]

During and shortly after World War I German 5 Pfennig and 10 Pfennig coins were sherardised.

Standard[edit]

More information on sherardising: BS EN 13811::2003 (this is the British/European Union standard).

See also[edit]

References[edit]

  1. ^ US patent 701298, "Process of depositing metals on metallic surfaces and the product thereof", published 1902/6/3 
  2. ^ "Original Patent (Google patents)". 
  3. ^ Porter, Frank C. (1991). Zinc Handbook. CRC Press. ISBN 978-0-8247-8340-2.