Define cementation. Describe sherardizing with help of neat labeled diagram

Define cementation. Describe sherardizing with help of neat labeled diagram
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Cementation: “Cementation is the process in which metal coatings are obtained by heating the base metal in a revolving drum containing a powder of the coating metal.”

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Process: i) The iron articles (bolts, screws, nails etc) to be coated are first cleaned and then packed with Zn dust and ZnO powder in a steel drum, which is provided with electrical heating arrangement. ii) The drum is slowly rotated for 2-3 hours and its temp. is kept between 350 – 400oC. iii) During this process Zn gets diffused slowly into iron forming Fe - Zn alloy at the surface which protects iron surface from corrosion. 

 

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