Sherardized iron

Zinc is frequently applied to the surface of iron or steel by other methods. In the Schoop process, molten zinc is sprayed onto the surface by a blast of air in a manner similar to that used in spraying paint. In addition to metals, objects made of wood, leather, paper, and the like may be coated with zinc by this process. In the process of sherardizing, iron is covered with a thin layer of zinc dust at temperatures of 700 to 800°C. Under these conditions, zinc penetrates the surface of the iron to a considerable extent. 

MTiat is the difference in nature and process of manufacture of galvanized iron and Sherardized iron ... 

Sherardizing-the process of coating iron or steel with zinc by heating the product to be coated in zinc powder at a temperature below the melting point of zinc. 

Sherardizing [After the inventor, Sherard Cowper-Cowles, 1900] A process for coating iron articles with zinc. The articles are placed in a sealed drum with zinc dust and sand. The drum is rotated and maintained at a temperature below the melting point of zinc. The mechanism is not understood. In 1990 the world consumption of zinc for this process was several thousand tons. See metal surface treatment. 

Sherardizing n. Method of coating steel or cast iron articles in intimate contact with zinc. The articles are heated with zinc dust for several hours. The zinc forms an alloy, at the interface of the ferrous surface, thus producing a thin, tightly adherent coating. 

Iron can be beneficial in coatings. The iron-zinc alloys formed in hot dipping or sherardizing can be up to 30% more resistant in mildly acidic conditions, but some workers report lower corrosion resistance with some galvannealed coatings. The iron-zinc alloy layers, while continuing to protect... 

In an industrial atmosphere, the best results were obtained with electroplated iron-zinc alloy layers with more than 20% iron (Salt et al., 1965) with a corrosion resistance 30% higher than zinc. Elsewhere, zinc-iron alloy galvanized coatings were as good as coatings with an outer zinc layer. Sherardized coatings were superior to electroplated and equal to galvanized for the same thickness. However, the structure of the alloy layer affects the corrosion resistance, as does its composition. 

The adhesion is good compared with electroplated coatings. Thickness can be varied as desired from 5 pm to more than 70 pm. However, the coating is not alloyed with the steel, nor does it have the hard, abrasion resistance iron-zinc alloy layers of galvanized or sherardized coatings. Conversion coatings can be applied. 

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